Longitudinal construct validity - Establishment of clinical meaning in patient evaluative instruments

OBJECTIVES. Although widely used and reported in research for the evaluatio n of groups, measures of health status and health-related quality of life h ave had little application in clinical practice for the assessment of indiv idual patients. One of the principal barriers is the demonstration that the se measures add clinically significant information to measures of function or symptoms alone. Here, we review the methods for evaluation of construct validity in longitudinal studies and make recommendations for nomenclature, reporting of study results, and future research agenda. METHODS. Analytical review. RESULTS. The terms "sensitivity" and "responsiveness" have been used interc hangeably, and there are few studies that evaluate the extent to which heal th status or health-related quality-of life measures capture clinically imp ortant changes ("responsiveness"). Current methods of evaluating responsive ness are not standardized or evaluated. Approaches for the assessment of a clinically significant or meaningful change are described; rather than norm ative information, however, standardized transition questions are proposed. They would be reported routinely and as separate axes of description to ca pture individual perceptions. CONCLUSIONS. Research in methods to assess the subject's evaluation of the importance and magnitude of a measured change are critical if health status and health-related quality-of-life measures are to have an impact on patie nt care.