Journal of Clinical Epidemiology
Volume 59, Issue 9 , Pages 947-956, September 2006

Simulated computerized adaptive test for patients with lumbar spine impairments was efficient and produced valid measures of function

  • Dennis L. Hart

      Affiliations

    • Focus On Therapeutic Outcomes, Inc., 551 Yopps Cove Road, White Stone, VA 22578, USA
    • Corresponding Author InformationCorresponding author. Tel.: 804-436-9727.
    • ,
  • Jerome E. Mioduski

      Affiliations

    • Focus On Therapeutic Outcomes, Inc., Knoxville, TN, USA
    • ,
  • Mark W. Werneke

      Affiliations

    • Spine Rehabilitation at CentraState Medical Center, Freehold, NJ, USA
    • ,
  • Paul W. Stratford

      Affiliations

    • School of Rehabilitation Science and Department of Clinical Epidemiology and Biostatistics, McMaster University, Ontario, Canada

Accepted 16 October 2005. published online 03 July 2006.

Abstract 

Objective

To equate physical functioning (PF) items with Back Pain Functional Scale (BPFS) items, develop a computerized adaptive test (CAT) designed to assess lumbar spine functional status (LFS) in people with lumbar spine impairments, and compare discriminant validity of LFS measures (θIRT) generated using all items analyzed with a rating scale Item Response Theory model (RSM) and measures generated using the simulated CAT (θCAT).

Methods

We performed a secondary analysis of retrospective intake rehabilitation data.

Results

Unidimensionality and local independence of 25 BPFS and PF items were supported. Differential item functioning was negligible for levels of symptom acuity, gender, age, and surgical history. The RSM fit the data well. A lumbar spine specific CAT was developed that was 72% more efficient than using all 25 items to estimate LFS measures. θIRT and θCAT measures did not discriminate patients by symptom acuity, age, or gender, but discriminated patients by surgical history in similar clinically logical ways. θCAT measures were as precise as θIRT measures.

Conclusion

A body part specific simulated CAT developed from an LFS item bank was efficient and produced precise measures of LFS without eroding discriminant validity.

Keywords: Item response theory, Back Pain Functional Scale, Rehabilitation, True-score equating, Computerized Adaptive Testing, Lumbar spine

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PII: S0895-4356(06)00118-1

doi:10.1016/j.jclinepi.2005.10.017

Journal of Clinical Epidemiology
Volume 59, Issue 9 , Pages 947-956, September 2006

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