The concept of healthy ageing has become particularly important as life expectancy increases. Identifying trajectories of functional ability will help to guide health-care resources to maximize well-being in old age.

To study kidney function in well-aged home-dwelling old people.

Prospective, population-based 20-year follow-up study.

Community.

A birth cohort of 1032 non-institutionalized people aged 70years at baseline.

Estimated glomerular filtration rate (eGFR) was determined using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and the four-variable Modification of Diet in Renal Disease (MDRD) equations. Assessment of healthy ageing included evaluation of diseases, functional ability, perceived health status, subjective life satisfaction, basic and instrumental activities of daily living, psychological and cognitive functions.

Glomerular filtration rate estimates remained stable at the level of 60mL/min/1.73m² in older people who were able to maintain their functional ability, general welfare and life satisfaction despite increased disease burden. Increased mortality seen in older adults with high GFR estimates was not associated with frailty.

The ability to maintain stable kidney function is important for healthy ageing.