Modified Creatinine Index and Clinical Outcomes of Hemodialysis Patients: An Indicator of Sarcopenia?

Sarcopenia (especially muscle mass assessed using gold standard techniques) has been suggested as a poorer predictor of mortality than muscle function in patients undergoing hemodialysis. Appropriate methods to estimate muscle mass for use as a good predictor of clinical outcomes remain to be established. We investigated whether the modified creatinine index (mCI), which is a surrogate marker of muscle mass, could predict mortality and cardiovascular (CV) hospitalizations independent of muscle function and other confounders in patients on hemodialysis. In this retrospective study, outpatients (n = 542; mean age, 65.3 years; 60% men; median dialysis vintage, 29 months; mean BMI, 22.0 kg/m2) undergoing hemodialysis were investigated. The mCI, handgrip strength, and gait speed were assessed and related to all-cause mortality and a composite of CV hospitalizations and all-cause mortality. Cox proportional and mixed-effects negative binomial models were fit for mortality and the composite outcomes. Patients were followed up for a median 3 years (interquartile range: 1.5-5.7). Each per SD increase of mCI (HR:0.63, 95% CI:0.62-0.65), handgrip strength (HR:0.51, 95% CI:0.48-0.54), and gait speed (HR:0.60, 95% CI:0.56-0.64) were significantly associated with lower all-cause mortality rates after adjusting for covariates. The mCI was consistently found to be an independent predictor of mortality after additional adjustment for handgrip strength or gait speed. Furthermore, sarcopenic conditions [i.e., lower mCI, and lower handgrip strength (HR:3.79, 95% CI:2.09-6.87) or slower gait speed (HR:4.20, 95% CI:2.38-7.41)] were significantly associated with a higher risk of mortality after adjusting for covariates. Associations of mCI with multiple CV hospitalizations and mortality were similar to those between mCI and mortality. The mCI was a good predictor of clinical outcomes and was comparable to muscle function, including handgrip strength and gait speed. The mCI is likely to provide additional diagnostic and prognostic values for sarcopenia in patients on hemodialysis.