Muscle Mass and Serum Creatinine Concentration by Race and Ethnicity among Hemodialysis Patients

Abstract

Background: Differences in serum creatinine concentration among groups defined by race and ethnicity have been ascribed to differences in muscle mass. We examined differences in serum creatinine by race and ethnicity in a cohort of patients receiving hemodialysis in whom creatinine elimination by the kidney should have little or no effect on serum creatinine concentration and considered whether these differences persisted after adjustment for proxies of muscle mass. Methods: We analyzed data from 501 participants in the ACTIVE/ADIPOSE study who had been receiving hemodialysis for >1 year. We examined the independent associations among race/ethnicity (Black, Asian, non-Hispanic White, and Hispanic), serum creatinine, and intracellular water [ICW, L/m2], a proxy for muscle mass, derived by whole-body multi-frequency bioimpedance spectroscopy, using multivariable linear regression with adjustment for several demographic, clinical, and laboratory characteristics. We examined the association of race/ethnicity with serum creatinine concentration with and without adjustment for ICW. Results: Black, Asian, and Hispanic patients had higher serum creatinine concentrations (+1.68 mg/dl [95%CI 1.09, 2.27], +1.61 mg/dl [95%CI 0.90, 2.32], and +0.83 [95% CI 0.08, 1.57], respectively) than non-Hispanic White patients. Overall, ICW was associated with serum creatinine concentration (0.26 mg/dl per L/m2 ICW, 95% CI 0.006, 0.51) but was not statistically significantly different by race/ethnicity. Black, Asian, and Hispanic race/ethnicity remained significantly associated with serum creatinine concentration after adjustment for ICW. Conclusion: Among patients receiving dialysis, serum creatinine was higher in Black, Asian, and Hispanic patients than in non-Hispanic Whites. Differences in ICW did not explain the differences in serum creatinine concentration across race groups.

Does Serum Creatinine Reflect Muscle Mass in Patients with Kidney Failure?

“…4 Delgado et al evaluated differences in serum creatinine in a secondary analysis of the ACTIVE/ADIPOSE (A Cohort Study to Investigate the Value of Exercise in ESRD/Analyses Designed to Investigate the Paradox of Obesity and Survival in ESRD) study of patients undergoing prevalent hemodialysis (n5501, who had been treated by dialysis for at least a year). 5 They examined associations of race and ethnicity (groups classified as Black, Asian, Non-Hispanic White, and Hispanic patients) with serum creatinine and intracellular water (ICW) using whole-body multifrequency bioimpedance spectroscopy (BIS) to serve as a proxy for the size of muscle mass. 5 Compared with values from non-Hispanic White participants, Black, Asian, and Hispanic participants had higher levels of serum creatinine after adjusting for covariates.…”

“…5 They examined associations of race and ethnicity (groups classified as Black, Asian, Non-Hispanic White, and Hispanic patients) with serum creatinine and intracellular water (ICW) using whole-body multifrequency bioimpedance spectroscopy (BIS) to serve as a proxy for the size of muscle mass. 5 Compared with values from non-Hispanic White participants, Black, Asian, and Hispanic participants had higher levels of serum creatinine after adjusting for covariates. Although ICW was associated with serum creatinine levels, it did not differ statistically among different races or ethnic groups.…”