Journal of Clinical Epidemiology - Articles in Press

Noncompliance in lifestyle intervention studies: the instrumental variable method provides insight into the bias - Corrected Proof

Emmy M. Hertogh, A. Jantine Schuit, Petra H.M. Peeters, Evelyn M. Monninkhof — 2010-03-02

Abstract: Objective: In lifestyle intervention trials, participants of the control group often change their behavior despite the request to maintain their usual lifestyle pattern. These changes in the control group and changes in addition to the intended in the intervention group can lead to undesirable confounding effects.Study Design and Setting: We address several considerations for study design to prevent noncompliance or minimize its effects. Furthermore, we demonstrate how the instrumental variable method can give insight into the extent of bias introduced by noncompliance in randomized trials, within the context of the Sex Hormones and Physical Exercise study.Results: Noncompliance can be prevented by measures taken in the design phase of a study, for example, limited duration of the study, clear recommendations, power calculation, intensity of the intervention, involvement of the control group, waiting-list control group, and single-consent design nested within an observational study. When nevertheless noncompliance does occur, the instrumental variable method estimates the intervention effect of treatment among the compliers.Conclusion: Noncompliance can seriously affect validity of lifestyle trial results. Its occurrence should be prevented by taking measures during the design phase of a study. The instrumental variable method can give insight into confounding by noncompliance in randomized trials.

Triage-weighted kappa: toward a more precise reflection of the reliability of emergency department triage systems - Reply - Corrected Proof

Ineke van der Wulp, Henk F. van Stel — 2010-03-02

With this letter we respond to the comments of Twomey on our recent publication “Adjusting weighted kappa for severity of mistriage decreases reported reliability of emergency department triage systems: a comparative study”.

Triage-weighted kappa: a more appropriate triage reliability measure - Corrected Proof

Michele Twomey, Lee A. Wallis, Mary Lou Thompson, Jonathan E. Myers — 2010-03-02

To the Editor: van der Wulp et al. make a compelling argument regarding the assessment of emergency department triage systems. We agree that neither the linear nor quadratically weighted kappa statistics adequately takes into account the severity of mistriage in ordinal triage scales (despite the fact that these appear to be the most commonly quoted statistics) and that an elaborated weighting scheme is long overdue.

A diagnostic model for the detection of sensitization to wheat allergens was developed and validated in bakery workers - Corrected Proof

2010-03-02

Abstract: Objectives: To develop and validate a prediction model to detect sensitization to wheat allergens in bakery workers.Study Design and Setting: The prediction model was developed in 867 Dutch bakery workers (development set, prevalence of sensitization 13%) and included questionnaire items (candidate predictors). First, principal component analysis was used to reduce the number of candidate predictors. Then, multivariable logistic regression analysis was used to develop the model. Internal validation and extent of optimism was assessed with bootstrapping. External validation was studied in 390 independent Dutch bakery workers (validation set, prevalence of sensitization 20%).Results: The prediction model contained the predictors nasoconjunctival symptoms, asthma symptoms, shortness of breath and wheeze, work-related upper and lower respiratory symptoms, and traditional bakery. The model showed good discrimination with an area under the receiver operating characteristic (ROC) curve area of 0.76 (and 0.75 after internal validation). Application of the model in the validation set gave a reasonable discrimination (ROC area=0.69) and good calibration after a small adjustment of the model intercept.Conclusion: A simple model with questionnaire items only can be used to stratify bakers according to their risk of sensitization to wheat allergens. Its use may increase the cost-effectiveness of (subsequent) medical surveillance.

The art and science of knowledge synthesis - Corrected Proof

Andrea C. Tricco, Jennifer Tetzlaff, David Moher — 2010-03-02

Abstract: Objectives: To review methods for completing knowledge synthesis.Study Design and Setting: We discuss how to complete a broad range of knowledge syntheses. Our article is intended as an introductory guide.Results: Many groups worldwide conduct knowledge syntheses, and some methods are applicable to most reviews. However, variations of these methods are apparent for different types of reviews, such as realist reviews and mixed-model reviews. Review validity is dependent on the validity of the included primary studies and the review process itself. Steps should be taken to avoid bias in the conduct of knowledge synthesis. Transparency in reporting will help readers assess review validity and applicability, increasing its utility.Conclusion: Given the magnitude of the literature, the increasing demands on knowledge syntheses teams, and the diversity of approaches, continuing efforts will be important to increase the efficiency, validity, and applicability of systematic reviews. Future research should focus on increasing the uptake of knowledge synthesis, how best to update reviews, the comparability between different types of reviews (eg, rapid vs. comprehensive reviews), and how to prioritize knowledge synthesis topics.

Brier score summarizes model calibration and discrimination - Reply - Corrected Proof

Lisa M. Lix — 2010-03-02

Thank you for the opportunity to respond to the comments of Dr Rufibach. In the article by Lix et al. , the c-statistic (equal to the area under the receiver operator characteristic curve for a binary outcome variable) and Brier score were used to evaluate algorithms for classifying osteoporosis cases and noncases identified from a bone mineral density database. The algorithms were constructed using a number of variables defined from hospital, physician, and prescription administrative databases. The Brier score provided a measure of the agreement between the observed binary outcome (i.e., case vs. noncase) and the predicted probability of that outcome. It is a sum of both a calibration component and a discrimination (or refinement) component , with lower scores indicating improved model accuracy.

Use of Brier score to assess binary predictions - Corrected Proof

Kaspar Rufibach — 2010-03-02

The use of the Brier score in medical research to assess and compare the accuracy of binary predictions or prediction models is increasingly popular; see, for example Refs. . In [, Box 1] an overview of a variety of measures of model performance is offered and propose cutoffs for appraising the value of a computed score. How Brier scores can be formally compared is detailed in Ref. .

The limits of agreement and the intraclass correlation coefficient may be inconsistent in the interpretation of agreement - Corrected Proof

2010-03-02

Abstract: Objective: To compare the interpretation of agreement in the prediction of neonatal outcome variables, using the limits of agreement (LA) and the intraclass correlation coefficient (ICC).Study Design and Setting: Three obstetricians were asked to predict neonatal outcomes independently based on the evaluation of intrapartum cardiotocographic tracings. Interobserver agreement was assessed with the LA and the ICC, and the results obtained were interpreted by six clinicians and six statisticians on a scale that established agreement as very poor, poor, fair, good, or very good.Results: Interpretation of the LA results was less consensual than the ICC results, with proportions of agreement of 0.36 (95% confidence interval [CI]: 0.28–0.44) vs. 0.63 (95% CI: 0.54–0.73), respectively. LA results suggested a fair to good agreement among obstetricians, whereas interpretation of ICC results suggested a poor to fair agreement. LA results were more plausible with reality, suggesting that obstetricians predicted neonatal outcomes better than randomly generated values, whereas it was not always the case with the ICC.Conclusions: LA and ICC can provide inconsistent results in agreement studies. Accordingly, in the absence of better strategies to assess agreement, both should be used for this purpose, but their results need to be interpreted with caution keeping their respective limitations in mind.

The Short Form-12 Health Survey was a valid instrument in Chinese adolescents - Corrected Proof

2010-03-02

Abstract: Objective: To evaluate the construct validity of the standard Chinese Short Form (SF)-12v2 in adolescents.Study Design and Setting: Data collected from the Hong Kong Student Obesity Surveillance project conducted in 2006–2007 were used. The standard Chinese SF-12v2 was first evaluated against clinical criteria previously used for the evaluation of SF-12 or SF-36. The data were then randomly split into training and validation halves for exploratory and confirmatory factor analyses, respectively.Results: A total of 31,357 adolescents with mean age of 14.8 years (standard deviation=1.9; range=11.0–18.9) were included. The standard Chinese SF-12v2 effectively distinguished groups differing in doctor-diagnosed health problems, self-reported illnesses in the past 30 days, gender, perceived health in the past 3 months, and health compared with that 12 months back. The mental health scale had low internal consistency (Cronbach's alpha=0.34). The exploratory factor analysis was influenced by method effects, but confirmatory factor analysis confirmed the hypothesized latent structure and the one-factor structure of the SF-12v2, providing fit indices within acceptable limits.Conclusion: The two components and a single general health component of the standard Chinese SF-12v2 are appropriate health indicators for Chinese adolescents.

A simple tool detected diabetes and prediabetes in rural Chinese - Corrected Proof

Zhong Xin, Jing Yuan, Lin Hua, Ya-Hong Ma, Lei Zhao, Yi Lu, Jin-Kui Yang — 2010-03-02

Abstract: Objective: To develop and evaluate a simple tool, using data collected in a rural Chinese general practice, to identify those at high risk of Type 2 diabetes (T2DM) and prediabetes (PDM).Study Design and Setting: A total of 2,261 rural Chinese participants without known diabetes were used to derive and validate the models of T2DM and T2DM plus PDM. Logistic regression and classification tree analysis were used to build models.Results: The significant risk factors included in the logistic regression method were age, body mass index, waist/hip ratio (WHR), duration of hypertension, family history of diabetes, and history of hypertension for T2DM and T2DM plus PDM. In the classification tree analysis, WHR and duration of hypertension were the most important determining factors in the T2DM and T2DM plus PDM model. The sensitivity, specificity, positive predictive value, negative predictive value, and receiver operating characteristic area for detecting T2DM were 74.6%, 71.6%, 23.6%, 96.0%, and 0.731, respectively. For PDM plus T2DM, the results were 65.3%, 72.5%, 33.2%, 90.7%, and 0.689, respectively.Conclusion: The classification tree model is a simple and accurate tool to identify those at high risk of T2DM and PDM. Central obesity strongly associates with T2DM in rural Chinese.

Medical record validation of maternally reported history of preeclampsia - Corrected Proof

2010-03-02

Abstract: Objective: In this study, we assessed the validity of maternally self-reported history of preeclampsia.Study Design and Setting: This study was embedded in the Generation R Study, a population-based prospective cohort study. Data were obtained from prenatal questionnaires and one questionnaire obtained 2 months postpartum from the mother. All women who delivered in hospital and returned a 2-month postpartum questionnaire (n = 4,330) were selected.Results: Of the 4,330 women, 76 out of 152 (50%) women who self-reported preeclampsia appeared not to have had the disease according to the definition (International Society for the Study of Hypertension in Pregnancy). From the women who self-reported not to have experienced preeclampsia, 11 out of 4,178 (0.3%) had suffered from preeclampsia. Sensitivity and specificity were 0.87 and 0.98, respectively. Higher maternal education level and parity were associated with a better self-reported diagnosis of preeclampsia.Conclusion: The validity of maternal-recall self-reported preeclampsia is moderate. The reduced self-reported preeclampsia might suggest a lack of accuracy in patient–doctor communication with regard to the diagnostic criteria of the disease. Therefore, doctors have to pay attention to make sure that women understand the nature of preeclampsia.

Rating the evidence in comparative effectiveness reviews - Corrected Proof

Yngve Falck-Ytter, Holger Schünemann, Gordon Guyatt — 2010-03-02

Authorities acknowledge that systematic reviews provide the optimal basis for collecting and assessing the evidence that bears on patient management recommendations. In his article introducing JCE's series describing the Agency for Healthcare Research and Quality (AHRQ)'s effective health care program, Mark Helfand distinguishes between systematic reviews and “complex evidence reports” that address a broader range of questions, including “definition, diagnosis, management, and follow-up of a disease or condition.” Aside from definition, all these questions appear to us as an examination of alternative approaches to managing patients. Such issues are best addressed by structured questions and, if brought together in a single document, constitute a series of related systematic reviews or overviews of systematic reviews.

Quality criteria and user-friendliness in self-reported questionnaires on cancer-related fatigue: a review - Corrected Proof

Carla Agasi-Idenburg, Miranda Velthuis, Harriet Wittink — 2010-02-22

Abstract: Objective: Cancer-related fatigue (CRF) is a distressing, persistent, subjective sense of tiredness or exhaustion that occurs in 70–100% of cancer patients. The purpose of this review was to provide an overview of the quality of research performed on existing CRF self-report questionnaires and compare their reported psychometric properties and user-friendliness.Methods: Database searches of CINAHL, Cochrane Library, EMBASE, MEDLINE, Scopus, PEDro, and PsycINFO were undertaken to find published scales. Standardized criteria were used to assess quality and user-friendliness.Results: Thirty-five articles were included that described 18 questionnaires—seven one-dimensional questionnaires and 11 multidimensional questionnaires. The mean item count was 20.8 (range: 3–83). The mean overall score of the one-dimensional questionnaires was 10.4 of a maximum of 18 points (range: 7.6–14.3). The mean overall score of the multidimensional questionnaires was 9.4 of a maximum of 18 points (range: 4.3–14.4).Conclusion: Recommendations were made for the selection of a scale. We argue in favor of repeatedly reassessing psychometric properties of even established questionnaires to ensure they comply with evermore increasing stringent quality criteria.

A review of design and reporting issues in self-reported prevalence studies of leg ulceration - Corrected Proof

2010-02-22

Abstract: Objective: The aim of this review was to examine design and reporting issues that affect prevalence estimates of leg ulceration obtained using self-report and outline strategies to strengthen the validity and reliability of research in this area.Study Design and Setting: We identified leg ulcer prevalence studies and evaluated them against the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement. The authors draw upon the wider literature and their own empirical work in discussing strategies to overcome design and reporting issues.Results: Common deficiencies in the design and reporting of studies include wide variations in diagnostic criteria and age parameters for participant selection, a lack of description of efforts to address bias/study size rationale, and low participation rates in clinical examination stages. These factors and differences in statistical methods of analysis affect the validity and reliability of findings and hinder interpretation, making comparisons across populations difficult. Opportunities for subgroup analyses are frequently missed.Conclusion: Self-report is a valuable means of capturing leg ulcer prevalence, but the future design and reporting of studies need to be strengthened, including addressing weaknesses in validation strategies. Capture–recapture analysis or a multiple-methods approach has the potential to yield the most valid and reliable prevalence estimates.

The Global Activity Limitation Index measured function and disability similarly across European countries - Corrected Proof

2010-02-22

Abstract: Objective: This work aims to validate and increase understanding of the Global Activity Limitation Index (GALI), an activity limitation measure from which the new structural indicator Healthy Life Years is generated.Study Design and Setting: Data from the Survey of Health and Retirement in Europe, covering 11 European countries and 27,340 individuals older than 50 years, was used to investigate how the GALI was associated with other existing measures of function and disability and whether the GALI was consistent or reflected different levels of health in different countries.Results: The GALI was significantly associated with the two subjective measures of activities of daily living score and instrumental activities of daily living (IADL) score, and the two objective measures of maximum grip strength and walking speed (P<0.001 in all cases). The GALI did not differ significantly between countries in terms of how it reflected three of the health measures, with the exception being IADL.Conclusion: The GALI appears to satisfactorily reflect levels of function and disability as assessed by long-standing objective and subjective measures, both across Europe and in a similar way between countries.

Mathematical coupling may account for the association between baseline severity and minimally important difference values - Corrected Proof

2010-02-22

Abstract: Objective: To generate anchor-based values for the “minimally important difference” (MID) for a number of commonly used patient-reported outcome (PRO) measures and to examine whether these values could be applied across the continuum of preoperative patient severity.Study Design and Setting: Six prospective cohort studies of patients undergoing elective surgery at hospitals in England and Wales. Patients completed questionnaires about their health and health-related quality of life before and after surgery. MID values were calculated using the mean change score for a reference group of patients who reported they were “a little better” after surgery minus the mean change score for those who said they were “about the same.” Pearson's correlation was used to examine the association between baseline severity and change scores in the reference group. Baseline severity was expressed in two ways: first in terms of preoperative scores and second in terms of the average of pre- and postoperative scores (Oldham's method).Results: Of the 10 PRO measures examined, eight demonstrated a moderate or high positive association between preoperative scores and MID values. Only two measures demonstrated such an association when Oldham's measure of baseline severity was used.Conclusion: In general, there is little association between baseline severity and MID values. However, a moderate association persists for some measures, and it is recommended that researchers continue to test for this relationship when generating anchor-based MID values from change scores.

There was evidence of convergent and construct validity of Physiotherapy Evidence Database quality scale for physiotherapy trials - Corrected Proof

2010-02-22

Abstract: Objective: To evaluate the convergent and construct validity of the Physiotherapy Evidence Database (PEDro) scale used to rate the methodological quality of randomized trials in physiotherapy.Study Design and Setting: PEDro total scores and individual-item scores were extracted from 9,456 physiotherapy trials indexed on PEDro. Convergent validity was tested by comparing PEDro total scores with three other quality scales. Construct validity was tested by regressing the PEDro score and individual-item scores with the Institute for Scientific Information Web of Knowledge impact factors (IF) and SCImago journal rankings (SJR) for the journals in which the trials were published.Results: Testing of convergent validity revealed correlations with the other quality scales ranging from 0.31 to 0.69. The PEDro total score was weakly but significantly associated with IF and SJR (P < 0.0001). Eight of the 10 individual scale items that contribute to the PEDro total score were significantly associated with IF.Conclusion: This study provides preliminary evidence of the convergent and construct validity of the PEDro total score and the construct validity of eight individual scale items.

It is “the noise of practice” - Corrected Proof

Jürgen Windeler — 2010-02-22

Pragmatic trials are randomized and may use a placebo - Corrected Proof

2010-02-22

Inconsistent trial assessments by the National Institute for Health and Clinical Excellence and IQWiG: standards for the performance and interpretation of subgroup analyses are needed - Corrected Proof

J. Hasford, P. Bramlage, G. Koch, W. Lehmacher, K. Einhäupl, P.M. Rothwell — 2010-02-22

Abstract: Objectives: The methodology for the critical assessment of medical interventions is well established. Regulatory agencies and institutions adhere, in principle, to the same standards. This consistency, however, is not always the case in practice.Study Design and Setting: Using the evaluation of the CAPRIE (Clopidogrel versus Aspirin in Patients at risk of Ischemic Events) trial by the British National Institute for Health and Clinical Excellence (NICE) and the German Institute for Quality and Efficiency in Health Care (IQWiG), we illustrate that there was no consensus for the interpretation of possible heterogeneity in treatment comparisons across subgroups.Results: The NICE concluded that CAPRIE demonstrated clinical benefit for the overall intention-to-treat (ITT) population with sufficient robustness to possible sources of heterogeneity. The IQWiG interpreted the alleged heterogeneity as implying that the clinical benefit only applied to the subgroup of patients with a statistically significant result irrespective of the results of the ITT analysis.Conclusion: International standards for the performance and interpretation of subgroup analyses as well as for the assessment of heterogeneity between strata are needed.

Citation analysis of identical consensus statements revealed journal-related bias - Corrected Proof

Thomas V. Perneger — 2010-01-25

Abstract: Objective: To examine whether the prestige of a journal, measured by its impact factor, influences the numbers of citations obtained by published articles, independently of their scientific merit.Study Design and Setting: In this cohort study, citation counts were retrieved for articles describing consensus statements that were published in multiple journals and were correlated with the impact factors of the source journals.Results: Four consensus statements were published in multiple copies: QUOROM (QUality Of Reporting Of Meta-analyses) was published in three journals, CONSORT (CONsolidated Standards Of Reporting Trials) in eight journals, STARD (STAndards for Reporting of Diagnostic accuracy) in 14 journals, and STROBE (STrengthening the Reporting of OBservational studies in Epidemiology) in eight journals. For each consensus statement, the impact factor of the source journal and the number of citations were highly correlated (Spearman correlation coefficients: QUOROM, 1.00; CONSORT, 0.88; STARD, 0.65; and STROBE, 0.81—all P<0.02). When adjusted for time since publication, each logarithm unit of impact factor predicted an increase of 1.0 logarithm unit of citations (95% confidence interval: 0.7–1.3, P<0.001), and the variance explained was 66% (adjusted r2=0.66).Conclusions: The prominence of the journal where an article is published, measured by its impact factor, influences the number of citations that the article will gather over time. Citation counts are not purely a reflection of scientific merit.

Appropriate statistical methods are required to assess diagnostic tests for replacement, add-on, and triage - Corrected Proof

Andrew Hayen, Petra Macaskill, Les Irwig, Patrick Bossuyt — 2010-01-18

Abstract: Objective: To explain which measures of accuracy and which statistical methods should be used in studies to assess the value of a new binary test as a replacement test, an add-on test, or a triage test.Study Design and Setting: Selection and explanation of statistical methods, illustrated with examples.Results: Statistical methods for comparative diagnostic accuracy studies are described that take into account the purpose of the new diagnostic test. Methods are described within a framework that defines the major purpose of test comparison: assessing the value of a new test as a replacement test, an add-on test, or a triage test. Methods appropriate for both unpaired and paired study designs for binary test data are given, including regression modeling of diagnostic test accuracy. Implications for efficient study designs are also discussed.Conclusions: Appropriate selection of existing statistical methods is necessary to address research questions about the comparative accuracy of new tests.

Mixed treatment comparison analysis provides internally coherent treatment effect estimates based on overviews of reviews and can reveal inconsistency - Corrected Proof

Deborah M. Caldwell, Nicky J. Welton, A.E. Ades — 2010-01-18

Abstract: Objectives: To propose methods for mixed treatment comparisons (MTC) based on pooled summaries of the type produced in overviews of reviews.Study Design and Setting: Overviews of reviews (umbrella reviews) summarize the results of multiple systematic reviews into a single document. They report the summary estimates from the original pairwise meta-analyses and discuss them in narrative form, with the intention of identifying the most effective treatment. We present methods for MTC synthesis, tailored for use with overviews of reviews. These generate a single internally consistent summary of all the relative treatment effects and assessments of whether the summary is consistent with the data. These methods are applied to a published overview of treatments for childhood nocturnal enuresis. We apply the methods to both fixed-effect (FE) and random-effects (RE) meta-analyses of the original trials.Results: The summary relative risks based on FE meta-analyses, as originally published, were highly inconsistent. Those based on RE meta-analyses were consistent and could, given standard assumptions on comparability of treatment effects in meta-analysis, form a basis for coherent decision making.Conclusion: Along with the summaries from systematic reviews, MTC methods should be used in overviews to provide a single coherent analysis of all treatment comparisons and to check for evidence consistency.

Disability, more than multimorbidity, was predictive of mortality among older persons aged 80 years and older - Corrected Proof

2010-01-08

Abstract: Objective: In this study, we evaluate the impact of disability and multimorbidity on the risk of all-cause death in a population of frail older persons living in community.Study Design and Setting: We analyzed data from the Aging and Longevity Study in the Sirente geographic area, a prospective cohort study that collected data on all subjects aged 80 years and older (n=364). The main outcome measure was all-cause mortality over 4-year follow-up.Results: A total of 150 deaths occurred. Sixty-seven subjects (44.6%) died in the nondisabled group compared with 83 subjects (55.3%) in the disabled group (P<0.01). Thirty-nine subjects (31.7%) died among subjects without multimorbidity compared with 111 subjects (46.0%) with two or more diseases (P<0.01). When examining the combined effect of multimorbidity and disability, the effect of disability on the risk of death was higher than that of multimorbidity. After adjusting for potential confounders, relative to those without disability and multimorbidity, disabled subjects showed an increased risk of death when multimorbidity was associated (hazard ratio [HR]=3.91; 95% confidence interval [CI]=1.53–10.00) and in absence of multimorbidity (HR=2.36; 95% CI=0.63–8.83).Conclusion: Our results show that disability exerts an important influence on mortality, independently of age and other clinical and functional variables.

Global Perceived Effect scales provided reliable assessments of health transition in people with musculoskeletal disorders, but ratings are strongly influenced by current status - Corrected Proof

2010-01-08

Abstract: Objective: The study investigated the test–retest reliability and construct validity of the Global Perceived Effect (GPE) scale in patients with musculoskeletal disorders.Study Design and Setting: Data from seven clinical studies including 861 subjects were used for the analyses. Repeat measures taken at the same attendance and from attendances separated by 24 hours were compared to estimate test–retest reliability. Construct validity was evaluated by examining relationships between pre, post, and change scores in pain and disability measures with GPE measures.Results: Intraclass correlation coefficient values of 0.90–0.99 indicate excellent reproducibility of the GPE scale. In all but one data set, change scores on pain and disability measures correlated well (r=0.40–0.74) with GPE; however, post scores nearly always correlated even more strongly (r=0.58–0.84), and pre scores showed much weaker association (r=0.00–0.28). Pre scores accounted for only a small amount of additional R2 when added to regression models including post score.Conclusions: Test–retest reliability of the GPE is excellent. GPE ratings are strongly influenced by current status, with the effect more obvious as transition time lengthens. This result questions whether transition ratings truly reflect change, or rather just current state. This finding also has implications for the use of GPE ratings as an external criterion of change in clinimetric studies.

Systematic reviews on tobacco control from Cochrane and the Community Guide: different methods, similar findings - Corrected Proof

Laura J. Rosen, Michal Ben Noach — 2010-01-08

Abstract: Objectives: To compare the methods and findings of systematic reviews (SRs) on common tobacco control interventions from two organizations: the Cochrane Collaboration (“Cochrane”) and the US Task Force for Community Preventive Services (“the Guide”).Study Design and Setting: Literature review. We retrieved all reviews pertaining to tobacco control produced by the Cochrane and the Guide. We identified seven common topics and compared methods and findings of the retrieved reviews.Results: There was considerable variability in the designs of included studies and methods of data synthesis. On average, Cochrane identified more studies than did the Guide (Mean 43.7 vs. 19.0), with only limited overlap between sets of included studies. Most Cochrane reviews (71.4%) were synthesized narratively, whereas most Guide reviews (85.7%) were synthesized using a median of effect size. Despite these differences, findings of the reviews yielded substantial agreement.Conclusion: Cochrane and the Guide conduct SRs on similar tobacco control-related topics differently. The SRs of the two organizations include overlapping, but nonidentical sets, of studies. Still, they usually reach similar conclusions. Identification of all pertinent original studies seems to be a weak point in the SR process. Policy makers should use reviews from both organizations in formulating tobacco control policy.

A nonparametric two-sample comparison for skewed data with unequal variances - Corrected Proof

Eva Skovlund — 2010-01-08

For practical situations, the pure shift model is probably not very realistic, and it is thus important to assess the robustness of different tests against deviations from this model. It is well established that heteroscedasticity (unequal variances) is at least as deleterious for the properties of the Wilcoxon-Mann-Whitney (WMW) test as for the t-test and that the Welch test should replace the t-test when distributions are approximately normal and variances unequal. It is also worth remembering that the WMW test does not share the asymptotic robustness properties of the t-test. In addition, unequal variance is not the only problem frequently encountered. Distributions can also be skewed, and the skewness of the two distributions may differ. Unfortunately, but not unexpectedly, even the Welch test is unable to maintain the nominal significance level when distributions are skewed .

A nonparametric two-sample comparison for skewed data with unequal variances - Corrected Proof

Markus Neuhäuser — 2010-01-08

Abstract: Objective: The aim of the study was to recommend a statistical test for the situation in which unequal variances are accompanied by skewed distributions. A previous publication in this journal could not recommend any test; instead, transformations were suggested.Study Design and Setting: A recently introduced generalized Wilcoxon test is presented, which can be applied when variances may be unequal and the distribution may be skewed. This test examines the null hypothesis that the relative effect is 0.5. Its type I error rate was investigated in a simulation study.Results: The generalized Wilcoxon test was already recommended for various areas of life sciences and, very recently, it was shown that a permutation test could be performed with the generalized test statistic. Simulation results indicate an acceptable control of the type I error rate even for extreme variance ratios.Conclusion: The generalized Wilcoxon test should be applied when it cannot be assumed that variances are equal and that the distribution is symmetric. This test is preferable to a transformation, because the use of transformations can be problematic, in particular when sample sizes are small.

Opening up the "Black Box": Metabolic phenotyping and metabolome-wide association studies in epidemiology - Corrected Proof

2010-01-08

Abstract: Background: Metabolic phenotyping of humans allows information to be captured on the interactions between dietary, xenobiotic, other lifestyle and environmental exposures, and genetic variation, which together influence the balance between health and disease risks at both individual and population levels.Objectives: We describe here the main procedures in large-scale metabolic phenotyping and their application to metabolome-wide association (MWA) studies.Methods: By use of high-throughput technologies and advanced spectroscopic methods, application of metabolic profiling to large-scale epidemiologic sample collections, including metabolome-wide association (MWA) studies for biomarker discovery and identification.Discussion: Metabolic profiling at epidemiologic scale requires optimization of experimental protocol to maximize reproducibility, sensitivity, and quantitative reliability, and to reduce analytical drift. Customized multivariate statistical modeling approaches are needed for effective data visualization and biomarker discovery with control for false-positive associations since 100s or 1,000s of complex metabolic spectra are being processed.Conclusion: Metabolic profiling is an exciting addition to the armamentarium of the epidemiologist for the discovery of new disease-risk biomarkers and diagnostics, and to provide novel insights into etiology, biological mechanisms, and pathways.

The development of a quality appraisal tool for studies of diagnostic reliability (QAREL) - Corrected Proof

Nicholas P. Lucas, Petra Macaskill, Les Irwig, Nikolai Bogduk — 2010-01-08

Abstract: Background and Objective: In systematic reviews of the reliability of diagnostic tests, no quality assessment tool has been used consistently. The aim of this study was to develop a specific quality appraisal tool for studies of diagnostic reliability.Methods: Key principles for the quality of studies of diagnostic reliability were identified with reference to epidemiologic principles, existing quality appraisal checklists, and the Standards for Reporting of Diagnostic Accuracy (STARD) and Quality Assessment of Diagnostic Accuracy Studies (QUADAS) resources. Specific items that encompassed each of the principles were developed. Experts in diagnostic research provided feedback on the items that were to form the appraisal tool. This process was iterative and continued until consensus among experts was reached.Results: The Quality Appraisal of Reliability Studies (QAREL) checklist includes 11 items that explore seven principles. Items cover the spectrum of subjects, spectrum of examiners, examiner blinding, order effects of examination, suitability of the time interval among repeated measurements, appropriate test application and interpretation, and appropriate statistical analysis.Conclusions: QAREL has been developed as a specific quality appraisal tool for studies of diagnostic reliability. The reliability of this tool in different contexts needs to be evaluated.

Effect of family history on the risk of varicose veins is affected by differential misclassification - Corrected Proof

2010-01-08

Abstract: Objective: We assessed differential misclassification in self-reported family history of varicose veins by comparing consistency of subject's own varicose vein status and the consistency of information on varicose veins in family members.Study Design and Setting: A population-based cohort study of 4,903 middle-aged residents of the city of Tampere, Finland. A questionnaire was used at entry and at the end of the 5-year follow-up.Results: The estimated prevalence of positive family history of varicose veins varied depending on subject's own varicose veins from odds ratio (OR) 0.14 (95% confidence interval [CI]=0.01–0.58), in those with varicose veins reported in the first but not the second survey to OR 6.0 (95% CI=2.0–47.8), in those with varicose veins reported in the second survey but not in the first. The incidence of varicose veins varied from 0.4 (95% CI=0.1–1.4) to 4.1 (95% CI=2.1–7.1) (per 100 person-years) depending how the proband memorized the family history.Conclusion: Results on the effect of family history on varicose veins are subject to bias, which reduces the credibility of the reports proposing a strong hereditary component of varicose veins.

Moving knowledge to action through dissemination and exchange - Corrected Proof

Michelle L. Gagnon — 2009-12-11

Abstract: Objective: The objective of this article is to discuss the knowledge dissemination and exchange components of the knowledge translation process that includes synthesis, dissemination, exchange, and ethically sound application of knowledge. This article presents and discusses approaches to knowledge dissemination and exchange and provides a summary of factors that appear to influence the effectiveness of these processes. It aims to provide practical information for researchers and knowledge users as they consider what to include in dissemination and exchange plans developed as part of grant applications.Study Design and Setting: Not relevant.Results and Conclusions: Dissemination is targeting research findings to specific audiences. Dissemination activities should be carefully and appropriately considered and outlined in a dissemination plan focused on the needs of the audience who will use the knowledge. Researchers should engage knowledge users to craft messages and help disseminate research findings. Knowledge brokers, networks, and communities of practice hold promise as innovative ways to disseminate and facilitate the application of knowledge. Knowledge exchange or integrated knowledge translation involves active collaboration and exchange between researchers and knowledge users throughout the research process.

The Kaiser Permanente inpatient risk adjustment methodology was valid in an external patient population - Corrected Proof

Carl van Walraven, Gabriel J. Escobar, John D. Greene, Alan J. Forster — 2009-12-11

Abstract: Objectives: Accurately predicting hospital mortality is necessary to measure and compare patient care. External validation of predictive models is required to truly prove their utility. This study assessed the Kaiser Permanente inpatient risk adjustment methodology for hospital mortality in a patient population distinct from that used for its derivation.Study Design and Setting: Retrospective cohort study at two hospitals in Ottawa, Canada, involving all inpatients admitted between January 1998 and April 2002 (n=188,724). Statistical models for inpatient mortality were derived on a random half of the cohort and validated on the other half.Results: Inpatient mortality was 3.3%. The model using original parameter estimates had excellent discrimination (c-statistic 89.4, 95% confidence interval [CI] 0.891–0.898) but poor calibration. Using data-based parameter estimates, discrimination was excellent (c-statistic 0.915, 95% CI 0.912–0.918) and remained so when patient comorbidity was expressed in the model using the Elixhauser Index (0.901, 0.898–0.904) or the Charlson Index (0.894, 0.891–0.897). These models accurately predicted the risk of hospital death.Conclusion: The Kaiser Permanente inpatient risk adjustment methodology is a valid model for predicting hospital mortality risk. It performed equally well regardless of methods used to summarize patient comorbidity.

Patient preferences before and after total knee arthroplasty - Corrected Proof

2009-12-11

Abstract: Objective: Patients before total joint arthroplasty vary in the spectrum and importance of their concerns. The objectives of this study were to evaluate the psychometric properties of the Knee Patient-Specific Index (KPSI) and to determine the type and importance of patients' concerns before and after knee arthroplasty.Study Design and Setting: A cohort of 119 patients scheduled for elective primary (or revision) total knee arthroplasty were interviewed at two tertiary care teaching hospitals. Patients also completed the Knee Society Scale (KSS), the Short Form 36, the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), and the McMaster Toronto Arthritis Patient Preference Disability Questionnaire (MACTAR).Results: Patients improved after total knee arthroplasty in all 42 symptoms and physical limitations, except crouching/kneeling and walking up and down stairs. Patients' summated concerns correlated with the WOMAC pain subscale (ranging from 0.72 to 0.79), WOMAC physical function subscale (ranging from 0.72 to 0.76), and KSS (ranging from 0.28 to 0.39). The summated responses changed after knee arthroplasty as demonstrated by the standardized response mean of 1.1.Conclusions: The KPSI captures individual patient unique preferences for patients undergoing total knee arthroplasty. Patients improved in virtually all aspects of their symptoms and function after surgery, with the exception of crouching/kneeling and knee feeling hot.

Expectations, validity, and reality in pharmacogenetics - Corrected Proof

Nita A. Limdi, David L. Veenstra — 2009-12-08

Abstract: In this review, we discuss the potential expectations, validity, predictive ability, and reality of pharmacogenetics in (1) titration of medication dose, (2) prediction of intended (efficacy) drug response, and (3) dose prediction of unintended (adverse) drug response. We expound on what these potential genetic predictors tell us and, more importantly, what they cannot tell us.Although pharmacogenetic markers have been hailed as promising tools, these proclamations are based mainly on associations rather than their evaluation as predictors. To put the expectations of the promise of pharmacogenetics in a realistic perspective, we review three examples. First, warfarin pharmacogenetics, wherein although the validity of the genetic variant dose is established and there is a validity of genetic variant–hemorrhage association, the clinical utility of testing is not clear. Second, the strong and clinically relevant HLA–Stevens–Johnson syndrome/toxic epidermal necrolysis association highlights the role of ethnicity. Third, the influence of CYP2D6 on tamoxifen efficacy, a model candidate with potential clinical utility but unclear validity.These examples highlight both the challenges and opportunities of pharmacogenomics. First, establishing a valid association between a genetic variation and drug response; second, doing so for a clinically meaningful outcome; and third, providing solid evidence or rationale for improvement in patient outcomes compared with current standard of care.

A new graph and scoring system simplified analysis of changing states: disease remissions in a rheumatoid arthritis clinical trial - Corrected Proof

2009-12-07

Abstract: Background: In the setting of multiple remission and relapse periods of a chronic disease, simple endpoint analysis does not fully capture all relevant information, and we need methods to additionally describe both the duration of remission as well as the interruptions in this desired state. Probably the two-state continuous Markov process model comprises the best mathematical approach to data analysis. However, this approach is complex and not intuitive to clinicians. In this paper we propose a simple scoring system and a graph that can enhance the information about the remission experience in a trial or cohort study.Methods: The continuity rewarded (‘ConRew’) score sums up periods in remission, and rewards extended periods by placing more value on uninterrupted periods than on interrupted periods. The ‘patient vector graph’ attempts to plot each patient's remission experience over time as a horizontal line (the ‘vector’) that is visible when the patient is in remission, but interrupted whenever relapse occurs. In this way a pattern is formed that conveys the number of patients experiencing remission, their individual total duration and interruptions, and time when these occur.Results: In a dataset of a randomized trial in early rheumatoid arthritis, the graph clearly showed both early and late benefit of one group over the other. The scoring system demonstrated the main benefit was in the number of remission periods, not in their ‘uninterruptedness’.Conclusion: Both approaches proved feasible and added extra information.

High agreement of self-report and physician-diagnosed somatic conditions yields limited bias in examining mental–physical comorbidity - Corrected Proof

Harald Baumeister, Levente Kriston, Jürgen Bengel, Martin Härter — 2009-12-04

Abstract: Objective: To quantify the misclassification bias of self-reported somatic diseases and its impact on the estimation of comorbidity with mental disorders.Study Design and Setting: Data were drawn from the German National Health Interview and Examination Survey (N=7,124), which assessed both self-reported and physician-diagnosed somatic diseases. Eight chronic diseases were examined: coronary heart disease, heart failure, asthma, chronic bronchitis, diabetes, cancer, arthrosis, and arthritis. Mental disorders were assessed by means of the Munich-Composite International Interview.Results: The agreement of case ascertainment by patient self-report and physician diagnosis was high (kappa: 0.74–0.92), except for arthritis (0.53). False-positive and false-negative disease statuses were partly associated with age, sex, socioeconomic status, somatic comorbidities, marital status, and mood and anxiety disorders. In most conditions, the odds ratios (ORs) of comorbid mental disorders based on self-reported diseases were slightly overestimated with regard to mood disorders (relative OR: 0.91–1.38), whereas there proved to be no such trend regarding anxiety disorders (0.82–1.05). Substance disorders were partly biased without showing an interpretable trend across diseases (0.49–2.58).Conclusions: Evaluation of mental–physical comorbidity based on self-reported and physician-diagnosed physical conditions yielded similar results, with modestly inflated ORs for mood disorders for several self-reported physical conditions.

Good agreement between parental and self-completed questionnaires about allergic diseases and environmental factors in teenagers - Corrected Proof

Linnea Hedman, Anders Bjerg, Matthew Perzanowski, Eva Rönmark — 2009-12-04

Abstract: Objectives: To study whether the methodological change from parent to index subject as questionnaire respondent affected the prevalence estimates and risk factor patterns for allergic diseases in a longitudinal study.Study Design and Setting: A prospective study of asthma and allergic diseases among children was begun in 1996 within the Obstructive Lung Disease in Northern Sweden Study. In 2002, about 3,342 (95% of invited) teenagers (13 to 14 years) completed the annual questionnaire. A random sample of 294 (84% of invited) parents also completed the same extended International Study of Asthma and Allergies in Childhood questionnaire. Skin prick tests were performed in 1996 and 2000.Results: There were no significant differences in the prevalence of rhinitis, eczema, or related environmental factors between parental and self-reports, except for the question of having a dog at home. The absolute agreement was high, whereas the kappa values were fair or moderate. Kappa values of questions regarding parental smoking were 0.8–0.9. Allergic sensitization was the major risk factor for both rhinitis and eczema, and the odds ratios were similar regardless of who reported the condition.Conclusion: The agreement between the parental and teenagers' reports was good, and the methodological change did not affect the study results.

ICD-10 hospital discharge diagnosis codes were sensitive for identifying pulmonary embolism but not deep vein thrombosis - Corrected Proof

2009-12-04

Abstract: Objective: To estimate the sensitivity of International Classification of Diseases, Tenth revision (ICD-10) hospital discharge diagnosis codes for identifying deep vein thrombosis (DVT) and pulmonary embolism (PE).Study Design and Setting: We compared predefined ICD-10 discharge diagnosis codes with the diagnoses that were prospectively recorded for 1,375 patients with suspected DVT or PE who were enrolled at 25 hospitals in France. Sensitivity was calculated as the percentage of patients identified by predefined ICD-10 codes among positive cases of acute symptomatic DVT or PE confirmed by objective testing.Results: The sensitivity of ICD-10 codes was 58.0% (159 of 274; 95% CI: 51.9, 64.1) for isolated DVT and 88.9% (297 of 334; 95% CI: 85.6, 92.2) for PE. Depending on the hospital, the median values for sensitivity were 57.7% for DVT (interquartile range, IQR, 48.6–66.7; intracluster correlation coefficient, 0.02; P=0.31) and 88.9% for PE (IQR, 83.3–96.3; intracluster correlation coefficient, 0.11; P=0.03). The sensitivity of ICD-10 codes was lower for surgical patients and for patients who developed PE or DVT while they were hospitalized.Conclusion: ICD-10 discharge diagnosis codes yield satisfactory sensitivity for identifying objectively confirmed PE. A substantial proportion of DVT cases are missed when using hospital discharge data for complication screening or research purposes.

Most of the Quality of Life in Essential Tremor Questionnaire (QUEST) psychometric properties resulted in satisfactory values - Corrected Proof

2009-12-04

Abstract: Objective: This study sought to assess the psychometric attributes of the Quality of Life in Essential Tremor Questionnaire (QUEST) by undertaking an independent validation.Study Design and Setting: This was an observational, multicenter, cross-sectional study carried out in Neurology Departments of general hospitals. The following assessments were applied: Louis Rating Scale, Clinical Assessment of Tremor, Clinical Global Impression of Severity (CGI-ET), Hospital Anxiety and Depression Scale (HADS), EQ-5D, and QUEST (Spanish version).Results: One hundred and eighteen consecutive patients were included. According to the CGI-ET, most of patients had mild (42.4%) or moderate (43.2%) impact of tremor on performing daily activities. Fully computable QUEST data were 60.2%. The QUEST Summary Index (QUEST-SI) displayed marginal floor or ceiling effect. On the whole, QUEST internal consistency and reproducibility were satisfactory (Cronbach's alpha values: 0.73–0.86; QUEST-SI intraclass correlation coefficient: 0.77). Factor analysis identified eight factors (73.6% of the variance) that could be grouped into six, relatively coincident with the questionnaire's dimensions. The QUEST-SI correlated moderately with the EQ-5D index (rS=−0.40), HADS—Depression (rS=0.39), and CGI-ET (rS=0.39), and strongly with the QUEST scale for self-evaluation of tremor severity (rS=0.63). The standard error of measurement was 8.00.Conclusion: Apart from a substantial problem of acceptability, most of the tested psychometric attributes of the QUEST resulted satisfactory.

Mind the MIC: large variation among populations and methods - Corrected Proof

2009-11-19

Abstract: Objective: There is no consensus on the best method to determine the minimal important change (MIC) of patient-reported outcomes. Recent publications recommend the use of multiple methods. Our aim was to assess whether different methods lead to consistent values for the MIC.Study Design and Setting: We used two commonly used anchor-based methods and three commonly used distribution-based methods to determine the MIC of the subscales: pain and physical functioning of the Western Ontario and McMaster University Osteoarthritis Index questionnaire in five different studies involving patients with hip or knee complaints. We repeated the anchor-based methods using relative change scores, to adjust for baseline scores.Results: We found large variation in MIC values by the same method across studies and across different methods within studies. We consider it unlikely that this variation can be explained by differences between disease groups, disease severity, or lengths of follow-up. The variation persisted when using relative change scores. It was not possible to conclude whether this variation is because of true differences in MIC values between populations or to conceptual and methodological problems of the MIC methods.Conclusion: To better disentangle these two possible explanations, the MIC methodology should be improved and standardized. In the meantime, caution is needed when interpreting and using published MIC values.

Knowledge translation is the use of knowledge in health care decision making - Corrected Proof

Sharon E. Straus, Jacqueline M. Tetroe, Ian D. Graham — 2009-11-18

Abstract: Objective: To provide an overview of the science and practice of knowledge translation.Study Design: Narrative review outlining what knowledge translation is and a framework for its use.Results: Knowledge translation is defined as the use of knowledge in practice and decision making by the public, patients, health care professionals, managers, and policy makers. Failures to use research evidence to inform decision making are apparent across all these key decision maker groups. There are several proposed theories and frameworks for achieving knowledge translation. A conceptual framework developed by Graham et al., termed the knowledge-to-action cycle, provides an approach that builds on the commonalities found in an assessment of planned action theories.Conclusions: Review of the evidence base for the science and practice of knowledge translation has identified several gaps including the need to develop valid strategies for assessing the determinants of knowledge use and for evaluating sustainability of knowledge translation interventions.

A selection strategy was developed for fracture reduction programs in frail older people - Corrected Proof

2009-11-18

Abstract: Objectives: The aims of this study were to develop and evaluate a simple index for assessing the risk of fractures after a fall and to propose a selection strategy for identifying elderly individuals at high risk of both falls and fall-related fractures.Study Design and Setting: Two thousand five institutionalized older men and women were assessed for clinical risk factors and then followed up for falls and fall-related fractures for up to 2 years.Results: Our fracture risk index is derived from seven previously identified significant independent risk factors: weight, lower leg length, balance, cognitive function, type of institution, fracture history, and falls in the past year. The fracture rate was 6.5 times greater in the one-sixth of the falls with the highest index (9.7/100 falls) than in the lowest sixth (1.5/100 falls). Our proposed approach (based on balance, risk of falls, and the fracture risk index) selected a group of older people with high risk of both falls and fall-related fracture. The fracture incidence rate was 144% higher, and the falls incidence rate was 31% higher in the selected residents than in the remainder.Conclusion: The index could help rationalize fracture prevention programs for frail older people.

Cross-sectional reporting of previous Cesarean birth was validated using longitudinal linked data - Corrected Proof

2009-11-18

Abstract: Objective: The aim of this study was to demonstrate the feasibility of using linked health records to assess data quality in population health data.Study Design and Setting: Reproductive histories of 155,897 women were constructed by longitudinal linkage of the New South Wales (Australia) birth records in 1998–2005, and 127,952 birth and hospital discharge records in 2000–2005 were cross-sectionally linked. History of Cesarean section (CS) derived from the longitudinal linkage (“gold standard”) was used to validate the CS history fields (i.e., “Was the last birth by Cesarean section?” and “Total number of previous Cesarean sections?”) in birth records and to validate “vaginal birth after previous Cesarean (VBAC)” and “maternal care for uterine scar” in hospital records.Results: The reporting of CS at last birth was reliable with sensitivity, specificity, positive predictive value (PPV), and negative predictive value all >95% as was the number of previous CS (weighted kappa=0.97). For the hospital data, sensitivity and PPV were 46% and 99% for VBAC, 92% and 99% for maternal care of uterine scar, and 85% and 99%, respectively, for any prior CS.Conclusion: Assessing data quality by record linkage is feasible and can be done more quickly and cheaply than by any traditional validation study.

Validation of an improved area-based method of calculating general practice–level deprivation - Corrected Proof

Thomas Griffin, Tim J. Peters, Debbie Sharp, Chris Salisbury, Sarah Purdy — 2009-11-16

Abstract: Objective: To compare the methods of calculating practice deprivation scores in the absence of patient-level data.Study Design and Setting: Three methods of deriving general practice deprivation scores without patient-level data were compared against “gold standard” patient-level scores in 226 English practices. The three methods were lower super output area (LSOA), middle super output area (MSOA), and a geographical information systems (GIS) method. Working, if necessary, on the log scale, agreement between scores was assessed using Bland and Altman's method, Kappa statistics, and Pitman's test.Results: Based on the antilog 95% limits of agreement from Bland–Altman plots, GIS methods showed least variation compared with gold standard (0.66–1.47), followed by MSOA (0.61–1.70) and LSOA (0.38–2.29) methods. The differences in variances between both GIS and MSOA, and LSOA and MSOA comparisons, were greater than would be expected by chance (Pitman's P<0.001). High levels of agreement (kappa: 0.93, 0.86, and 0.80) were observed between GIS, MSOA, and LSOA methods compared with the “gold standard.”Conclusion: In situations where patient postcodes are unavailable, the GIS method is superior to area-based methods. However, where the GIS method cannot readily be applied, the MSOA method should be used in preference to the LSOA method.

The Italian version of the Lower Extremity Functional Scale was reliable, valid, and responsive - Corrected Proof

2009-11-13

Abstract: Objective: To determine the measurement properties of an Italian Version of the Lower Extremity Functional Scale (LEFS) in patients with lower extremity musculoskeletal dysfunction.Study Design and Setting: This is a prospective methodological study of repeated measures with a sample of 250 consecutive patients. Reliability, validity, and responsiveness were evaluated.Results: The Italian version of the LEFS showed a high degree of internal consistency with a Cronbach alpha of 0.94 (95% confidence interval [CI]: 0.91, 0.96). The test–retest reliability was high for both intra-interviewer and inter-interviewer measures with an ICC(2,1 and 2,k) of 0.91 (95% CI: 0.86, 0.93) and 0.89 (95% CI: 0.83, 0.91), respectively. The LEFS showed a better correlation with the 36-Item Short-Form Health Survey (SF-36) physical component summary score rather than with the SF-36 mental component summary score both at the initial assessment (r=0.61 and 0.26, respectively) and at the discharge (r=0.72 and 0.22, respectively). Receiver operating characteristic curve analysis revealed a large responsiveness for the LEFS (area under the curve [AUC]=0.97) and a moderate responsiveness for the SF-36 (AUC=0.68).Conclusion: The Italian version of the LEFS is a valid, reliable, and responsive tool that can be used to measure function in Italian patients with lower extremity musculoskeletal dysfunction.

Pictogram use was validated for estimating individual's body mass index - Corrected Proof

2009-11-13

Abstract: Objective: We designed this study to assess the validity and reliability of pictogram for estimating body mass index (BMI).Study Design and Setting: Participants of Golestan cohort study during 2000–2004 were recruited in this study. Demographic and anthropometric information (weight, height, and BMI) were collected on all participants. A set of drawings (pictogram) ranging from very lean to obese were used to assess the individual's perception of their body size. Sensitivity and specificity of each pictogram score were calculated and cutoff points were determined using sensitivity/specificity plots. We used receiver operating characteristic curves to assess the validity of pictogram scores.Results: Of the 15,437 subjects enrolled in the study, 6,574 (42.6%) were males and 8,863 (57.4%) were females. Their mean±standard deviation age was 52.58±9.28 years. Pictogram scores 1, 2, and 3 were assigned to normal participants; pictogram score 4 was selected by overweight subjects, and finally, pictogram scores equal or higher than 5 were selected by obese ones (area under curve: 0.83–0.85).Conclusion: According to our results, pictogram is a valid measure for discriminating obese or overweight from normal individuals, and for distinguishing obese from overweight or normal individuals. So it can be concluded that body image pictogram is valid for discriminating normal and obese individuals.

BLISS index using WOMAC index detects between-group differences at low-intensity symptom states in osteoarthritis - Corrected Proof

2009-11-09

Abstract: Objectives: The ability of the Bellamy et al. Low-Intensity Symptom State-attainment (BLISS) Index to differentiate between treatment groups (hylan G-F 20 vs. appropriate care) at low and very low levels of state attainment in patients with knee osteoarthritis was explored using the stiffness, function, and total index (TI) components of the WOMAC.Study Design and Setting: Six different BLISS measures were analyzed using five WOMAC score thresholds: ≤5 normalized units (NUs): ≤10, ≤15, ≤20, and ≤25 (lower=better health).Results: More patients in the hylan G-F 20 group achieved BLISS states in all three WOMAC subscales for all six BLISS analyses. These differences were statistically significant for the BLISS response at any time at all threshold levels except ≤5NU.Conclusions: The six BLISS measures and threshold levels of stiffness, function, and TI score were able to statistically discriminate between treatment groups. BLISS-10 is a therapeutically attainable very low symptom state at which clinically important statistically significant between-group differences are detectable in pain, stiffness, function, and TI score and therefore may provide a benchmark against which therapeutic interventions can be assessed. However, the value to patients of these symptom states requires further elaboration.

Correspondence analysis is a useful tool to uncover the relationships among categorical variables - Corrected Proof

2009-11-09

Abstract: Objective: Correspondence analysis (CA) is a multivariate graphical technique designed to explore the relationships among categorical variables. Epidemiologists frequently collect data on multiple categorical variables with the goal of examining associations among these variables. Nevertheless, CA appears to be an underused technique in epidemiology. The objective of this article is to present the utility of CA in an epidemiological context.Study Design and Setting: The theory and interpretation of CA in the case of two and more than two variables are illustrated through two examples.Results: The outcome from CA is a graphical display of the rows and columns of a contingency table that is designed to permit visualization of the salient relationships among the variable responses in a low-dimensional space. Such a representation reveals a more global picture of the relationships among row–column pairs, which would otherwise not be detected through a pairwise analysis.Conclusion: When the study variables of interest are categorical, CA is an appropriate technique to explore the relationships among variable response categories and can play a complementary role in analyzing epidemiological data.

Successful high-quality knowledge translation research: three case studies - Corrected Proof

Sumit R. Majumdar — 2009-11-05

Articles in this series have examined aspects of knowledge translation in detail, including various theoretical frameworks, types of interventions, implementation methods, issues related to measurement and evaluation of processes and outcomes of care, and the strengths and limitations of various study designs. This article draws upon what has come before and presents some “case studies” of high-quality and successful knowledge-to-action studies. The case studies (Kiefe et al. , examining the use of achievable benchmarks with audit and feedback to improve multiple processes of care for patients with diabetes; Kucher et al. , examining decision support and prompts for improving care of hospitalized patients at risk of thromboembolism; and Gonzales et al. , looking at a multifaceted intervention to decrease antibiotic prescribing for respiratory tract infections in the community) have in common that they addressed common and clinically important problems where the established evidence was already very strong and directed efforts at changing health professional patterns of practice.