The responsiveness and interpretability of psychosocial patient-reported outcome measures in chronic musculoskeletal pain rehabilitation.

Abstract

For several widely used patient-reported outcome measures (PROMs) in chronic musculoskeletal pain (CMSP) rehabilitation, it is still not known whether they are responsive to change, and what the smallest detectable change (SDC) and minimal clinically important change (MCIC) are. Knowledge of these values can be used to accurately interpret change scores in research and clinical practice. In this retrospective cohort study, the responsiveness, the SDC and the MCIC of the mental components of the Research and Development 36-Item Health Survey (RAND-36), the Pain Catastrophizing Scale (PCS) and the Tampa Scale of Kinesiophobia (TSK) were investigated in CMSP patients. Responsiveness, the SDC and MCIC were determined by using both anchor and distribution-based methods. For all outcome measures, there was a progression from smallest to largest mean change scores between participants who did not perceive change and those who reported change after treatment. However, correlations of the Global Perceived Effect (GPE) with the change scores on the outcome measures were low. For all outcome measures, the SDC was larger than the MCIC. For this population, the questionnaires were shown not to be responsive. Furthermore, the questionnaires appeared not to be able to distinguish clinically important change from measurement error in individual patients. The finding of large measurement errors of PROMs is in line with previous research in pain rehabilitation. Using generic PROMs only, to examine changes in psychosocial status due to a pain rehabilitation programme, is therefore questionable. This study shows that widely used generic psychosocial PROMs might not be responsive and not able to distinguish clinically important change from measurement error in individual chronic musculoskeletal pain patients. It therefore seems reasonable to reconsider the (compulsory) use of these PROMs for assessing the quality of pain rehabilitation programmes, and necessary to consider other, more objective, outcome measures for this purpose in this population.