Evaluating changes in health status: reliability and responsiveness of five generic health status measures in workers with musculoskeletal disorders

OBJECTIVES: To compare the measurement properties over time of five generic health status assessment techniques. METHODS: Five health status measures were completed on two occasions by a sample of workers with musculoskeletal disorders. They included the SF-36, Nottingham Health Profile, Health Status Section of the Ontario Health Survey (OHS), Duke Health Profile, the Sickness Impact Profile and a self-report of change in health between tests. SETTING: Subjects were accrued from a work site (within one week of injury) (n = 53), physiotherapy clinics (four weeks after injury), (n = 34), and a tertiary level rehabilitation center (more than four weeks after injury) (n = 40). ANALYSIS: Intraclass correlation coefficients (ICC) derived from nonparametric one-way analysis of variance were used for test-retest reliability in those who had not changed (n = 49). Various responsiveness statistics were used to evaluate responsiveness in those who claimed they had a positive change in health (n = 45) and in those who would have been expected to have a positive change (n = 79). RESULTS: Of the 127 subjects recruited, 114 completed both questionnaires (89.8%). In the subjects who reported no change in health, analysis of targeted dimensions (overall scores, physical function, and pain) demonstrated acceptable to excellent test-retest reliability in all but the Duke Health Profile. In subjects with change in health, the SF-36 was the most responsive measure (moderate to large effect sizes [0.55-0.97] and standardized response means ranging between 0.81 and 1.13). CONCLUSIONS: The results suggest that the SF-36 was the most appropriate questionnaire to measure health changes in the population studied. The selection of a health status measure must be context-specific, taking into account the purpose and population of the planned research