Evaluation of a population-based measure of quality of life: the Health and Activity Limitation Index (HALex)

This paper briefly discusses the rationale and methods for developing and evaluating the Health and Activity Limitation Index (HALex), a generic measure of health that consists of two attributes: perceived health and activity limitation. Using a multiattribute utility scoring system, information from these attributes was combined to form a single score that represents health-related quality of life (QoL) on a 0.0-1.0 continuum. The construct and incremental validity are evaluated using data from a sample of over 40,000 adults who participated in the 1990 US National Health Interview Survey. The health state distributions for known groups, defined in terms of personal or lifestyle characteristics such as sex, age and smoking status, were comparable to those for similarly defined states that have been studied by other researchers. Of the regression models examined in this analysis, age, years of schooling and being in a high-risk group based on body mass index (BMI) were found to have the largest impact on health as measured by the HALex. Although this measure was developed to be combined with mortality data to form a quality-adjusted life year (QALY) for detecting changes in the health of the US population from 1990 to 2000, it may also be useful for inclusion in clinical studies, in particular as the national data are readily available for use as norms.