Health Utilities Index Mark 3: evidence of construct validity for stroke and arthritis in a population health survey.

BACKGROUND The Health Utilities Index Mark 3 (HUI3) is a comprehensive, compact health status classification and health state preference system. The HUI3 system has been included in 4 Canadian population health surveys and numerous clinical trials. OBJECTIVES To evaluate the construct validity of the HUI3 for the measurement of health-related quality of life (HRQL) and attribute-specific morbidity in respondents to the 1990 Ontario Health Survey reported to have arthritis or stroke. The authors assessed (1) whether those with stroke, arthritis, and both conditions had lower HRQL scores than those with neither condition and (2) whether HUI3 detects morbidity in specific health attributes affected by arthritis and stroke. Stroke (but not arthritis) were expected to affect speech and cognition; arthritis (but not stroke) to affect pain; both to affect mobility, dexterity, and emotion; and neither to affect vision and hearing. RESEARCH DESIGN Linear regression models of HRQL and attribute-specific utilities were estimated as a function of 3 indicator variables of health problem (stroke only, arthritis only, both) and variables included to reduce confounding. RESULTS Subjects with stroke, arthritis, and both conditions had substantially lower HRQL than those with neither condition. Stroke subjects had greater morbidity in speech and cognition than arthritis subjects; somewhat surprisingly, pain morbidity was only slightly higher among arthritis subjects; neither condition affected vision or hearing. These associations were robust to various model specifications. CONCLUSIONS The HUI3 system appears valid for measuring health status and HRQL for stroke and arthritis in the context of a noninstitutionalized population health survey.