A novel, population-specific approach to define frailty.

The description of frailty, a syndrome of the elderly due to the decline of homeostatic capacities, has opened new opportunities in the study of the biological basis of human aging. However, the noticeable heterogeneity for this trait in different geographic areas makes it difficult to use standardized methods for measuring the quality of aging in different populations. Consequently, the necessity to carry out population-specific surveys to define tools which are able to highlight groups of subjects with homogeneous aging phenotype within each population has emerged. We carried out an extensive monitoring of the status of the elderly population in Calabria, southern Italy, performing a geriatric multidimensional evaluation of 680 subjects (age range 65-108 years). Then, in order to classify the subjects, we applied a cluster analysis which considered physical, cognitive, and psychological parameters such as classification variables. We identified groups of subjects homogeneous for the aging phenotypes. The diagnostic and predictive soundness of our classification was confirmed by a 3-year longitudinal study. In fact, both Kaplan-Meier estimates of the survival functions and Cox proportional hazard models indicate higher survival chance for subjects characterized by lower frailty. The availability of operative frailty phenotypes allows a reappraisal of the biological basis of healthy aging as it regards both biomarkers correlated with the frail phenotype and the genetic variability associated with the phenotypes identified. Indeed, we found that the frailty phenotype is strongly correlated with clinical parameters associated with the nutritional status.