TY - JOUR T1 - Urine creatinine concentration and clinical outcomes in older adults: The Cardiovascular Health Study. JF - J Am Geriatr Soc Y1 - 2021 A1 - Barzilay, Joshua I A1 - Bůzková, Petra A1 - Shlipak, Michael G A1 - Lyles, Mary F A1 - Bansal, Nisha A1 - Garimella, Pranav S A1 - Ix, Joachim H A1 - Kizer, Jorge R A1 - Strotmeyer, Elsa S A1 - Djoussé, Luc A1 - Biggs, Mary L A1 - Siscovick, David A1 - Mukamal, Kenneth J AB -

PURPOSE: Loss of muscle mass and strength are associated with long-term adverse health outcomes in older adults. Urine creatinine concentrations (Ucr; mg/dl) are a measure of muscle tissue mass and turnover. This study assessed the associations of a spot Ucr level with muscle mass and with risk of hospitalization, mortality, and diabetes mellitus in older adults.

METHODS: We examined 3424 participants from the Cardiovascular Health Study who provided spot urine samples in 1996-1997 and who were followed through June 2015. All participants underwent baseline measurement of grip strength. In a sub-cohort, 1331 participants underwent dual energy X-ray absorptiometry (DEXA) scans, from which lean muscle mass was derived. Participants were followed for a median of 10 years for hospitalizations and mortality, and 9 years for diabetes mellitus.

RESULTS: In linear regression analysis, a one standard deviation higher Ucr concentration (64.6 mg/dl) was associated with greater grip strength (kg force) β = 0.44 [0.16, 0.72]; p = 0.002) and higher lean muscle mass (kg) (β = 0.43 [0.08, 0.78]; p = 0.02). In Cox regression analyses, each standard deviation greater Ucr concentration was associated with lower rates of hospitalizations (0.94 [95% confidence interval, 0.90, 0.98]; p < 0.001) and lower mortality risk (0.92 [0.88, 0.97]; p < 0.001), while a one standard deviation increase in muscle mass derived from DEXA had no such significant association. Ucr levels were not associated with incident diabetes mellitus risk (0.97 [0.85, 1.11]; p = 0.65).

CONCLUSION: A higher spot Ucr concentration was favorably associated with muscle mass and strength and with health outcomes in older community-living adults. The ease of obtaining a spot Ucr makes it an attractive analyte to use for gauging the health of older adults.

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