Rate of decline in kidney function with age: a systematic review

OBJECTIVE: To determine the distribution of kidney function values as measured by glomerular filtration rate (GFR), and the rate of decline with age in male and female healthy subjects without pre-existing medical conditions. DESIGN: Systematic review and structured synthesis. SEARCH SOURCES: PubMed, Embase, Cochrane Central Register of Controlled Trials and Web of Science, from database inception to 25 October 2023. Unpublished studies were searched from clinical trial registries and the grey literature. SELECTION CRITERIA: Observational cohort studies, including non-treatment arms of randomised, pseudorandomised and non-randomised controlled trials that assessed the age-related decline in kidney function over time. MAIN OUTCOME MEASURES: Primary outcomes were rate of change of kidney function over time (absolute and relative change) and rate of change of kidney function with age. Secondary outcomes included rate of change of kidney function compared with baseline GFR, gender, ethnicity and proportion of participants >60 years defined as having chronic kidney disease. DATA COLLECTION AND ANALYSIS: Two review authors independently screened studies for inclusion, extracted data and assessed risk of bias. Data could not be pooled because of significant heterogeneity. Instead, a descriptive analysis was used to synthesise results. RESULTS: /year (-0.37 to -1.07 in subjects without hypertension). Results were mixed as to whether decline rates sped up or slowed down with age, and whether decline rates differed between women and men, with studies showing conflicting results. This study was unable to determine the decline rates in different ethnicities. CONCLUSIONS: /year in healthy adults without hypertension. Kidney function decline rates in healthy adults may be helpful to clinicians anticipating patients' kidney trajectory and determining whether chronic kidney disease-specific care is required. PROSPERO REGISTRATION NUMBER: CRD42023096888.