Incidence of frailty: a systematic review of scientific literature from a public health perspective.

Introduction. Because of the dynamic nature of frailty, prospective epidemiological data are essential to calibrate an adequate public health response. Methods. A systematic review of literature on frailty incidence was conducted within the European Joint Action ADVANTAGE. Results. Of the 6 studies included, only 3 were specifically aimed at estimating frailty incidence, and only 2 provided disaggregated results by at least gender. The mean follow-up length (1-22.2 years; median 5.1), sample size (74-6306 individuals), and age of participants (>= 30-65) varied greatly across studies. The adoption of incidence proportions rather than rates further limited comparability of results. After removing one outlier, incidence ranged from 5% (follow-up 22.2 years; age >= 30) to 13% (follow-up 1 year, age >= 55). Conclusions. Well-designed prospective studies of frailty are necessary. To facilitate comparison across studies and over time, incidence should be estimated in person-time rate. Analyses of factors associated with the development of frailty are needed to identify high-risk groups.