The study is an observational, multicenter, prospective cohort study aimed at evaluating a 5-year screening programme for chronic kidney disease(CKD) in a population of elderly patients, aged 65 years or more, in China.To analyze the etiology and composition spectrum, the incidence of complications and co-morbidities.To assess the correlation between daily living ability, mental and physical function, quality of life, nutritional status and prognosis.To develop biomarkers of renal aging.