A quantile regression approach to the analysis of the quality of life determinants in the elderly

Objective. The aim of this study is to explain the effect of important covariates on the health-related quality of life (HRQol) in elderly subjects. Methods. Data were collected within a longitudinal study that involves 5256 subject, aged >= 65. The Visual Analogue Scale inclused in the EQ-5D Questionnaire, tha EQ-VAS, was used to obtain a synthetic measure of quality of life. To model EQ-VAS Score a quantile regression analysis was employed. This methodological approach was preferred to an OLS regression becouse of the EQ-VAS Score typical distribution. The main covariates are: amount of weekly physical activity, reported problems in Activity of Daily Living, presence of cardiovascular diseases, diabetes, hypercolesterolemia, hypertension, joints pains, as well as sociodemographic information. Main Results. 1) Even a low level of physical activity significantly influences quality of life in a positive way; 2) ADL problems, at least one cardiovascular disease and joint pain strongly decrease the quality of life.