Renal hyperfiltration (RHF) may have potential as a novel marker of all-cause and cardiovascular mortality in apparently healthy people, a new South Korean study suggests.

A team led by Hyung-Jin Yoon, MD, of Seoul National University College of Medicine, studied 43,503 adults who underwent voluntary health screening at Seoul National University Hospital from March 1995 to May 2006. All subjects had a baseline estimated glomerular filtration rate (eGFR) of 60 mL/min/1.73 m2 or higher. A total of 1,743 deaths occurred during a median follow-up of 12.4 years.

After adjusting for known risk factors, including smoking, subjects with RHF had a 37% increased risk of all-cause mortality and a 66% increased risk of cardiovascular mortality compared with those who did not have RHF, Dr. Yoon’s group reported online ahead of print in the Journal of the American Society of Nephrology. The investigators defined RHF as an eGFR above the 95th percentile after adjusting for sex, age, muscle mass, and history of diabetes and/or hypertension medication use.

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The investigators also examined the association between RHF and all-cause mortality according to smoking status. RHF was associated with a significant 58% and 73% increased risk of all-cause mortality in nonsmokers and former smokers, respectively, but was not significantly associated with all-cause mortality in current smokers.

Additionally, the study showed that RHF was 31% more likely among individuals in the highest versus lowest quartile of lean body mass after adjusting for potential confounders such as sex, age, smoking, regular exercise (exercising more than 30 minutes at least 3 times per week), and regular alcohol use (defined as consumption of alcoholic beverages at least once a week).

The study population had a mean age of 49.2 years at the time of health screening. The researchers calculated subjects’ eGFR using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.