Renal function and decline in functional capacity in older adults

Abstract

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.

Keywords: chronic kidney disease; disability; mortality; older adults; older people.