Abstract
Objective
To determine the influence of methodological quality and homogeneity on the agreement
between pairs of randomized trials (RCTs) and nonrandomized studies (NRSs) of the
same interventions for low-back problems. Homogeneity was assessed regarding settings,
population, interventions, and outcomes.
Study Design and Setting
We searched Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE up
to May 2005 for matching pairs of NRS and RCT. Analyses were done using correlation,
linear and logistic regression.
Results
Forty-eight matched pairs were included with no significant overall correlation between
effect sizes (r=0.09). There was a trend showing more agreement among the 22 pairs with higher methodological
quality (r=0.33). The correlation among the 20 very homogeneous pairs was 0.59, and among the
28 heterogeneous pairs was −0.09. The agreement of authors' recommendations was influenced
by the pair's homogeneity (odds ratio [OR]=2.78, 95% CI=1.44–5.37) rather than by methodological quality of the NRS (OR=0.93, 95% CI=0.67–1.29) or the RCT (OR=1.03, 95% CI=0.73–1.45).
Conclusions
Pairs of low-quality studies disagreed more than pairs where at least one study was
of high quality. However, pairs with similar settings, population, interventions,
and outcomes showed higher agreement than pairs that were not as homogeneous.
Keywords
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Article info
Publication history
Published online: January 15, 2008
Accepted:
April 21,
2007
Identification
Copyright
© 2008 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
