Rasch analysis of the 23-item version of the Roland Morris Disability Questionnaire

To determine the psychometric properties of the 23-item version of the Roland Morris Disability Questionnaire (RMDQ-23) and to quantify their stability across 2 cultures/languages and 2 types of care-settings. Rasch analysis of data from 1,000 patients with low back pain from primary care (UK and Denmark) and secondary care (Denmark). The RMDQ-23 is unidimensional if local item dependency issues are accommodated, but contains several misfitting or overdiscriminating items, some poor targeting of items, and the scoring of 4-5 items is differentially affected by common clinical characteristics (such as age, gender, pain intensity, pain duration and care setting), depending on the country. As similar results have been found for the RMDQ-24, we believe it is timely to reconsider whether: (i) the RMDQ should be reconstructed using an item-response theory-based approach that includes consideration of new items and response options; or (ii) the use of alternative questionnaires should be recommended, such as the Oswestry Disability Index, that have shown evidence of fitting the Rasch model; or (iii) a completely new condition-specific questionnaire should be developed, perhaps utilizing a computerized adaptive testing platform.