Body Composition Changes Following Dialysis Initiation and Cardiovascular and Mortality Outcomes in CRIC (Chronic Renal Insufficiency Cohort): A Bioimpedance Analysis Substudy

RATIONALE & OBJECTIVE: Bioelectrical impedance analysis (BIA) provides a noninvasive assessment of body composition. BIA measures of nutritional (phase angle) and hydration (vector length) status are associated with survival among individuals with chronic kidney disease (CKD), including those receiving maintenance dialysis. However, little is known regarding changes in these parameters with CKD following the high-risk transition to maintenance dialysis. STUDY DESIGN: Observational study. SETTINGS & PARTICIPANTS: 427 adults enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study, with BIA measurements performed within 1 year before and after initiation of maintenance dialysis. EXPOSURES: We calculated the changes in vector length and phase angle for patients with CKD transitioning to maintenance dialysis. OUTCOMES: We examined the association of changes in vector length and phase angle during the transition to maintenance dialysis with risk for all-cause mortality or nonfatal myocardial infarction, stroke, or heart failure, adjusting for demographics, comorbid conditions, and nutritional parameters. RESULTS: Mean age was 58 ± 12 years and mean estimated glomerular filtration rate using the CKD Epidemiology Collaboration equation before dialysis initiation was 17.0 ± 8.7 mL/min/1.73 m(2). After covariate adjustment, mean changes in vector length and phase angle were 18 (95% CI, 7 to 30) Ω/m and −0.6 (95% CI, −1.3 to 0.1 ), respectively. Changes in both BIA parameters were not associated with risk for heart failure, stroke, myocardial infarction, or all-cause mortality: HR, 1.02 (95% CI, 0.91-1.14) per 1-SD increment in change for vector length and HR, 1.11 (95% CI, 0.88-1.41) per 1-SD increment in change for phase angle. LIMITATIONS: Observational study, relatively small sample size. CONCLUSIONS: In a multicenter cohort of patients with CKD who progressed to kidney failure, the transition to maintenance dialysis was associated with changes in body composition reflecting poorer cellular integrity and improved volume control. However, these longitudinal changes were not associated with adverse clinical events after dialysis initiation.