Problems in measuring or interpreting change in patient outcomes

Abstract

The measurement and interpretation of change in patient-centered outcomes in OA is likely to be significantly confounded by changes in the ways patients calibrate and conceptualize pain, disability, quality of life and so on. This is particularly the case in long-term intervention studies or studies of the natural history of disease. The prevalence and magnitude of response shift in patient-centered outcomes in OA have not been determined but there is evidence from other musculoskeletal and chronic diseases that it occurs, even over relatively short time periods. There are a number of methods that can be used to identify and quantify response shift and inclusion of the most appropriate of these should be considered in all trials of treatment efficacy.