Association of serum creatinine-to-cystatin C ratio with skeletal muscle mass and strength in nonalcoholic fatty liver disease in the Iwaki Health Promotion Project

We evaluated the feasibility of using serum creatinine-to-cystatin C ratio in the assessments of muscle mass and strength in nonalcoholic fatty liver disease. In a community-based cross-sectional study, skeletal muscle mass and handgrip strength were assessed in 641 Japanese adults. Low skeletal muscle mass index and low handgrip strength were defined as indicated in the sarcopenia diagnostic criteria of the Japan Society of Hepatology. Nonalcoholic fatty liver disease was defined as fatty liver on ultrasonography in the absence of other causes of steatosis. The creatinine-to-cystatin C ratio was useful for identifying the participants with low skeletal muscle mass index, with an area under the receiver-operating characteristic curve of 0.84 [95% confidence interval (CI), 0.77-0.91] in men and 0.72 in women (95% CI, 0.65-0.78), and those with low handgrip strength, with an area under the receiver-operating characteristic curve of 0.96 (95% CI, 0.93-0.99) in men and 0.79 (95% CI, 0.66-0.92) in women. Moreover, the creatinine-to-cystatin C ratio correlated with skeletal muscle mass index (r = 0.511, p<0.001) and handgrip strength (r = 0.657, p<0.001), whereas it did not correlate with exacerbation of hepatic steatosis. In this study, creatinine-to-cystatin C ratio correlated with muscle mass and strength in nonalcoholic fatty liver disease regardless of hepatic steatosis.