Can the health utilities index measure change?

BACKGROUND

The Health Utilities Index (HUI) is a multidimensional, preference-weighted measure of health status. It comprises eight health attributes, aggregated into a single utility score.

OBJECTIVES

The purpose of the study was to investigate the ability of the HUI to detect changes in health status in a general population cohort.

RESEARCH DESIGN

Health status changes were analyzed in the full cohort and in persons who were diagnosed with chronic conditions, hospitalized, or became restricted in daily activities.

SUBJECTS

To assess responsiveness, longitudinal data was used from the National Population Health Survey conducted in Canada in 1994 - 1995 and 1996 - 1997. We used cross-sectional data from the 1996 sample to classify chronic conditions into mild, moderate, and severe.

MEASURES

Two measures of responsiveness were calculated: Standardized Response Mean (SRM) and Sensitivity Coefficient (SC). The HUI was compared with a global health index-the Self-Rated Health (SRH) scale.

RESULTS

HUI scores improved between the two NPHS cycles in all age-sex groups, except men 65 years of age and older. Among the respondents who remained free of chronic conditions, improvements were seen primarily in the cognitive and emotional domains. The HUI deteriorated among persons who were diagnosed between the two cycles with a severe chronic condition, were hospitalized, or became restricted in activity, but not in those diagnosed with a moderate condition. The SRMs were generally smaller for the HUI compared with the SRH.

CONCLUSIONS

The HUI responds to changes in health status associated with serious chronic illnesses. However, changes in the HUI do not always coincide with changes in self-reported health. Properties of the HUI scales require further study.