Construct Validity of the Health Utilities Index Mark 3 (HUI3): Alzheimer Disease, Arthritis and Cataract
- Presenter:
Chair: Albert Okunade; Discussant: Albert Okunade Wed June 7, 2006 9:45-11:15 Room 225
BACKGROUND: HUI3 is a prominent measure of health-related quality of life (HRQL) widely used in population health surveys, clinical studies and cost-utility analyses. HUI3 includes 8 attributes (vision, hearing, speech, ambulation, dexterity, emotion, cognition and pain), with 5 or 6 levels for each attribute. HUI3 has been used to assess health status in a number of chronic conditions. However, many of these analyses are based on samples that may not be representative of the entire population and there is little evidence for some important chronic conditions.
AIM: To assess the population-health construct validity of the HUI3 system in people with Alzheimer disease (AD), arthritis (AR) and cataract (CA), all three of which are conditions prevalent among the elderly.
METHODS: 1996/97 Canadian National Population Health Survey community and institutions cross-sectional Microdata files were used for the analyses. Data for those aged 40 and over were analyzed. Overall and single-attribute HUI3 scores for the 5 groups were compared to assess construct validity: AD only, AR only, CA only, AACA (at least two of the three conditions), and REF (none of the three conditions). Community and institutional population were analyzed separately. A total of 18 multiple linear regressions, 9 each for community (sample size is approximately 36,000) and institutional (sample size is approximately 1,100) data, were conducted to estimate effects of AD, AR and/or CA on overall and single-attribute utility scores. In all models, analyses controlled for individual characteristics, socio-economic status, health risk factors and the number of co-morbidities. A total of 76 a priori hypotheses, 38 each for community and institutional samples, were specified; adjusted-mean differences among 5 groups were obtained from each equation for hypothesis testing. For HUI3, differences of 0.03 (0.05) or more in overall (single-attribute) utility scores are interpreted as clearly clinically important. To take account of the complex survey design, bootstrap and Taylor linearization methods were used for variance estimations for community and institutional data, respectively. Statistical analyses were conducted using SUDAAN 9.0.1 and SAS 9.0.
RESULTS: For community and institutional samples, 23 and 28 hypothesis tests were consistent with a priori hypotheses, respectively. In both community and institutional samples, overall scores were lower for those with AD, AR and/or CA than for reference group; cognition scores were lower for AD than those for other groups; pain scores for AR were lower than those for other groups. Speech scores were lower for AD than for others residing in institutions. Adjusted-mean differences were all statistically significant (p<0.05) and clinically important. Consistent with our expectations, there was no statistically significant (at 5%) and clinically important difference in mean hearing scores among the 5 groups.
CONCLUSIONS: HUI3 was able to discriminate various aspects of burden associated with AD, AR and CA in both community and institutional samples. HUI3 was able to describe differences in overall HRQL levels as well as burden associated with vision, speech, cognition and pain. HUI3 is useful in assessing HRQL of AD, AR and CA for those in the community and in institutions.
