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

Area of Science:

• Nephrology
• Gerontology
• Public Health

Background:

• Kidney function naturally declines with age.
• Understanding this decline in healthy individuals is crucial for identifying early signs of kidney disease.
• Previous research has not systematically synthesized data on kidney function decline rates in healthy populations.

Purpose of the Study:

• To determine the distribution of kidney function, measured by glomerular filtration rate (GFR), in healthy individuals.
• To assess the rate of kidney function decline with age in both male and female healthy subjects.
• To establish a benchmark for normal kidney function decline in the absence of pre-existing medical conditions.

Main Methods:

• A systematic review and structured synthesis of relevant literature.
• Searched major databases (PubMed, Embase, etc.) and clinical trial registries up to October 2023.
• Included observational cohort studies and non-treatment arms of controlled trials assessing age-related kidney function decline.

Main Results:

• Analyzed 12 studies (1958-2021) involving 129,359 healthy participants.
• Annual kidney function decline rates ranged from -0.24 to -3.60 mL/min/1.73 m²/year (or -0.37 to -1.07 in those without hypertension).
• Conflicting results were observed regarding whether decline rates accelerate with age or differ between sexes; ethnicity-specific rates could not be determined.

Conclusions:

• This is the first systematic review to examine longitudinal kidney function decline in healthy individuals.
• A normal decline rate is estimated between -0.37 and -1.07 mL/min/1.73 m²/year for healthy adults without hypertension.
• These findings can assist clinicians in anticipating patient kidney trajectories and determining the necessity of chronic kidney disease care.