Crosswalking 4 Pain Impact Measures in a Nationally Representative Sample of Adults With Back Pain.

Objective: To generate crosswalk equations and tables for 4 pain impact measures: the Impact Stratification Score (ISS), Oswestry Disability Index (ODI), Roland-Morris Disability Questionnaire (RMDQ), and the Pain, Enjoyment of Life and General Activity Scale (PEG).

Design: Cross-sectional survey assessing demographics and pain impact. Crosswalks were developed using item-response theory (IRT) cocalibrations and linear regressions between the ISS, ODI, RMDQ, and PEG.

Setting: Online panel.

Participants: Population-based sample of United States adults aged 18 and older. Eligibility criteria were reporting current back pain, not reporting 2 fake health conditions, and having data for 2 or more pain measures (N=1530; 37% of sample). Crosswalks were developed (n=1030) and cross-validated in a subsample of 500 participants (n=125 randomly sampled from each ISS quartile).

Interventions: Not applicable.

Main outcome measures: ISS, ODI, RMDQ, and the PEG.

Results: Associations of the ISS with the PEG and ODI met the criteria for IRT cocalibration. Other measure pairs were crosswalked using regression. Associations were strongest between the PEG and the ISS (r=0.87, normalized mean absolute error [NMAE]=0.38) and between the ODI and the ISS (r=0.85, NMAE=0.39). Associations were weakest between the PEG and the RMDQ (r=0.69, R²=0.48, NMAE: 0.55-0.58). Regression equations and IRT accounted for 48%-64% of the variance (NMAE: 0.38-0.58) in corresponding pain measures in the cross-validation sample.

Conclusions: The crosswalks between the ISS and common legacy pain measures created in this study of a nationally representative sample of United States adults with back pain can be used to estimate 1 pain impact measure from another. Further evaluation in clinical samples is recommended.