Lower serum creatinine clearance is associated with muscle atrophy, decreased walking speed, and more rapid declines in lower-extremity strength over time in older adults, according to a new study.

The study, by Baback Roshanravan, MD, MS, of the Division of Nephrology at the University of Washington in Seattle, and colleagues, included 826 community-living adults with a mean age of 74 years. Of these, 183 had a creatinine clearance of less than 60 mL/min/1.73 m2.

After adjusting for potential confounders, each 10-mL/min/1.73 m2 decrement in creatinine clearance was associated with a 28 mm2 lower calf muscle area, 0.15 mg/cm3 lower calf muscle density, 0.01 m/sec slower 7-m usual walking speed, and 0.008 m/sec slower 400-m walking speed, the researchers reported online ahead of print in the American Journal of Kidney Diseases. Lower creatinine clearance was associated with significantly slower mean 7-m and 400-m walk and knee extension strength during follow-up.

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During a mean follow-up of 7.1 years, each 10-mL/min/1.73 m2 lower baseline creatinine clearance was associated with a significant 0.024 kg/year greater decline in knee strength.

This investigation included individuals aged 65 years and older who enrolled in the Invecchiare in Chianti Study (InCHIANTI). Researchers determined baseline creatinine clearance based on 24-hour urine collection. They chose creatinine clearance “to account for creatinine production within an individual, reducing the potential for confounding in analyses of muscle structure and performance.”

Dr. Roshanravan’s team said they believe their study is the first to evaluate associations of kidney function by creatinine clearance with long-term changes in objectively measured physical performance measures over time.

In background information, they noted that chronic kidney disease is associated with malnutrition and inflammation, processes that may lead to skeletal muscle loss and decreased physical performance.