Assessing health state utilities in elderly patients at cardiovascular risk

Abstract

Background: Health state preferences can be a crucial component of cost-effectiveness analyses, but off-the-shelf health state utilities specifically for older people are not available.

Objectives: Among participants in PROSPER, a trial of pravastatin in patients>70 years, the authors assessed utilities for the health states that were relevant for the trial's cost-utility analysis.

Subjects and methods: The authors cross-sectionally administered the Health Utilities Index, Mark 3 (HUI) to all PROSPER participants to assess each patient's health state at the time of interview; they then used the scale's multiattribute utility function to estimate the resulting utilities. The population was then stratified into 3 health states, and the mean utility function for each was calculated: recent myocardial infarction (MI, within 3 months), previous MI (>3 months), or no prior MI. Linear and logistic regression were used to control for potential demographic and clinical characteristics.

Results: Of the 5804 patients enrolled in the trial, 4677 were administered the HUI instrument. The likelihood of having a complete HUI response set decreased with higher age (P<0.001) but not with the other variables studied. A complete utility score could be calculated for 3390 participants. Of these, 2755 (81.3%) had no history of MI, 546 (16.1%) had an MI>3 months previously, and 89 (2.6%) had an MI within 3 months. The mean (median) utilities were virtually identical for these states: 0.75 (0.84), 0.74 (0.84), and 0.74 (0.84), respectively. From multivariate analyses, utilities decreased with higher age and the presence of several other comorbidities (diabetes, stroke, peripheral vascular disease); women had lower utilities than men (all P<0.01).

Conclusions: In this large implementation of the HUI in elderly patients, the instrument did not detect any differences in estimated utilities related to having a MI. Potential causes of nondiscrimination for MI include the possibility that competing comorbidities may reduce the impact of MI on quality of life in this age group, as well as the possibility that a standard instrument derived from and validated in younger populations may not perform as well in elderly people.