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.