Frailty, malnutrition risk, and kidney function impairment in older adults: Singapore longitudinal ageing study

Kidney function declines progressively with age, with chronic kidney disease (CKD) affecting more than half of community-dwelling older adults. Identifying risk factors beyond the established ones (such as diabetes and hypertension) is crucial for prevention. Frailty and malnutrition are prevalent in older adults, yet the effect of these factors on their decline of kidney function remains underexplored. This study aimed to elucidate the associations between frailty, malnutrition, and renal function among community-dwelling older adults. In this prospective cohort study, we analysed the data of 2,292 Chinese older adults aged 55 and above from the Singapore Longitudinal Ageing Study. Frailty was assessed using the Cardiovascular Health Study criteria, and malnutrition risk was evaluated using the Nutritional Screening Initiative questionnaire. Kidney function was measured using estimated glomerular filtration rate (eGFR). Baseline and follow-up (3-5 years) associations between frailty, malnutrition, and kidney function, controlling for known confounding risk factors were examined. At baseline, malnutrition was associated with lower eGFR (β = -5.42; 95% CI -8.83--2.01) and higher CKD prevalence (OR = 2.24; 95% CI 1.13-4.46). The combined risk of frailty-malnutrition was also significantly associated with lower eGFR (β = -5.29; 95% CI -9.93--1.65) and CKD prevalence (OR = 3.05; 95% CI 1.22-7.60). At follow-up, malnutrition (aOR = 3.21; 95% CI 1.60-6.44) but not physical frailty (aOR = 0.70; 95% CI 0.19-2.55), was associated with significant kidney function decline. The results suggest that malnutrition plays a vital role in kidney function decline among community-dwelling older adults, more so than frailty. Integrating nutritional screening timely may optimise the long-term kidney health in this population.