Trajectory of Lean Body Mass Assessed Using the Modified Creatinine Index and Mortality in Hemodialysis Patients

Abstract

Rationale & objective: Although a declining body mass index (BMI) is associated with higher mortality in patients on hemodialysis, BMI cannot distinguish lean body mass from fat mass. It remains unclear whether changes over time in lean body mass are associated with mortality. We examined the prognostic significance of changes in the modified creatinine index, a proxy for lean body mass.

Study design: Retrospective cohort study.

Setting & participants: Outpatients (n=349; mean age, 67.4 years; 60% men) undergoing maintenance hemodialysis 3 times a week at a treatment center.

Predictor: Modified creatinine index and BMI trajectories over a 1-year period.

Outcomes: All-cause mortality.

Analytical approach: We calculated the percentage of change in modified creatinine index and BMI over a 1-year period. Patients were categorized according to change in modified creatinine index/BMI: no decline (≥0%) or decline (<0%). Kaplan-Meier and Cox proportional hazard analyses were performed to examine whether modified creatinine index and BMI trajectories were associated with mortality.

Results: During follow-up (median, 1,157 days), 79 patients died. Decreasing modified creatinine index (HR, 1.31; 95% CI, 1.11-1.54) and BMI (HR, 1.25; 95% CI, 1.01-1.54) over time, measured as continuous variables and expressed per 1-standard deviation decrease, were independently associated with higher risk for all-cause mortality. The decline in modified creatinine index/no decline in BMI group (HR, 2.14; 95% CI, 1.04-4.45) and the decline in modified creatinine index/decline in BMI group (HR, 3.05; 95% CI, 1.58-5.90) had higher rates of mortality compared to the no decline in modified creatinine index/decline in BMI group.

Limitations: The absence of a direct measure of lean body and fat mass and limited generalizability to non-Japanese hemodialysis populations.

Conclusions: The modified creatinine index trajectory is independently associated with mortality and provides additional prognostic information to the BMI trajectory in patients on hemodialysis.

Keywords: Hemodialysis; body composition; body mass index (BMI); creatinine index; end-stage renal disease (ESRD); fat mass; lean body mass; mortality; muscle mass; nutritional status; obesity paradox; prognostication; protein-energy wasting (PEW); survival; weight loss; weight trajectory.