BACKGROUND longitudinal relationship between renal function, disability and mortality has not been evaluated.

OBJECTIVE we investigated the temporal association between renal function and disability, and aimed to identify the influence of disability on mortality according to renal function in a cohort of older Koreans.

DESIGN/SETTING Korean Longitudinal Study on Health and Aging is a prospective, population-based cohort.

SUBJECTS community-dwelling Koreans ≥65 years of age.

MAIN OUTCOME MEASURES Korean version of activities of daily living (ADL), Instrumental activities of daily living (IADL) and all-cause mortality.

RESULTS a total of 984 participants were followed for 5 years with a 70.9% participation rate. The participants were categorized into three groups according to their baseline estimated glomerular filtration rates (eGFRs) (Group I, ≥60; Group II, 45-59; and Group III, <45 ml/min/1.73 m(2)). Baseline eGFR was higher in participants who maintained functional status compared with participants who died or had disability at follow-up examination. The incidence of ADL/IADL decline was 13, 12.5 and 29.5% in participants who showed improvement, no change, and decline in renal function, respectively (P = 0.01). The hazard ratio for mortality in the subgroup with IADL disability was 1.87 (95% CI: 1.10-3.20, P = 0.022) in Group I, and 2.53 (95% CI: 1.57-4.09, P<0.001) in Groups II and III after adjustment.

CONCLUSIONS impaired renal function was related to disability and ADL/IADL decline. The effect of ADL/IADL disability on mortality was more prominent in participants with impaired eGFR.