Cross-national determinants of quality of life from six longitudinal studies on aging: The CLESA Project

Background and aims: The Comparison of Longitudinal European Studies on Aging (CLESA) Project, here presented for the first time, is a collaborative study involving five European and one Israeli longitudinal study on aging. The aim of this paper is to describe the methodology developed for the harmonization of data and the creation of a Common Data Base (CDB), and to investigate the distribution of some selected common variables among the six countries. The design of each study is briefly introduced and the methodology leading to the harmonization of the common variables is described. Methods: The study base includes data from five European countries (Finland, Italy, the Netherlands, Spain, Sweden) and Israel, for older people aged 65-89 living both in the community and in institutions (total, 11557 subjects). For two age classes (65-74 and 75-84), the prevalence ratios or the mean values of the following selected variables are provided: a) sociodemographic variables; b) health habits; c) health status; d) physical functioning; e) social networks and support; and f) health and social services utilization. Results: Statistically significant differences were found between most of the investigated characteristics across the CLESA countries, with very few exceptions. While some of the differences found may be due to cultural variations, others require further investigation and should be encompassed in the main framework of the Project, which is to identify predictors of hospitalization, mortality, institutionalization and functional decline. Conclusions: A common data base is available for the study of the aging process in five European and one Israeli population. These data provide a unique opportunity to identify common risk factors for mortality and functional decline and increase our understanding of country-specific exposures and vulnerability.