Associations between abrupt transition, dialysis-requiring AKI, and early mortality in ESKD among U.S. veterans

BACKGROUND: Mortality is high within the first few months of starting chronic dialysis. Pre-ESKD trajectory of kidney function has been shown to be predictive of early death after dialysis initiation. We aim to better understand how two key aspects of pre-dialysis kidney function—an abrupt transition pattern and an episode of dialysis-requiring AKI (AKI-D) leading directly to ESKD—are associated with early mortality after dialysis initiation. METHODS: We extracted national data from U.S. Veterans Health Administration cross-linked with the United States Renal Data System (USRDS) to identify patients who initiated hemodialysis during 2009–2013. We defined abrupt transition as having a mean outpatient eGFR ≥ 30 ml/min/1.73m(2) within 1 year prior to ESKD. AKI-D was identified using inpatient serum creatinine measurements (serum Cr increase by at least 50% from baseline) along with billing codes for inpatient receipt of dialysis for AKI within 30 days prior to the ESKD start date. We used multivariable proportional hazards models to examine the association between patterns of kidney function prior to ESKD and all-cause mortality within 90 days after ESKD. RESULTS: Twenty-two thousand eight hundred fifteen patients were identified in the final analytic cohort of Veterans who initiated hemodialysis and entered the USRDS. We defined five patterns of kidney function decline. Most (68%) patients (N = 15,484) did not have abrupt transition and did not suffer an episode of AKI-D prior to ESKD (reference group). The remaining groups had abrupt transition, AKI-D, or both. Patients who had an abrupt transition with (N = 503) or without (N = 3611) AKI-D had the highest risk of early mortality after ESKD onset after adjustment for demographics and comorbidities (adjusted HR 2.10, 95% CI 1.66–2.65 for abrupt transition with AKI-D; adjusted HR 2.10, 95% CI 1.90–2.33 for abrupt transition without AKI-D). In contrast, patients who experienced AKI-D without an abrupt transition pattern (N = 2141 had only a modestly higher risk of early death (adjusted HR 1.19, 95% CI 1.01–1.40). CONCLUSIONS: An abrupt decline in kidney function within 1 year prior to ESKD occurred in nearly 1 in 5 incident hemodialysis patients (18%) in this national cohort of Veterans and was strongly associated with higher early mortality after ESKD onset.