Background and Objectives: About 30% of patients with acute kidney injury (AKI) may require ongoing dialysis in the outpatient setting after hospital discharge. A 2017 CMS policy change allows Medicare beneficiaries with AKI requiring dialysis to receive outpatient treatment in dialysis facilities. Outcomes for these patients have not been reported. We compare patient characteristics and mortality among AKI dialysis patients and non-AKI incident dialysis patients.
Design, setting, participants, and measurements: Retrospective cohort design, using 2017 Medicare Claims to follow outpatient AKI dialysis patients and non-AKI incident dialysis patients up to 365 days. Outcomes are unadjusted and adjusted mortality using Kaplan-Meier estimation for unadjusted survival probability, Poisson regression for monthly mortality, and Cox proportional hazards modeling for adjusted mortality.
Results: 10,821 of 401,973 (3%) Medicare dialysis patients had at least one AKI claim, and 52,626 patients were Medicare non-AKI incident dialysis patients. AKI dialysis patients were more likely to be White (76% vs 70%), non-Hispanic (92% vs 87%), and age 60 or greater (82% vs 72%) compared to non-AKI incident dialysis patients. Unadjusted mortality was markedly higher for AKI dialysis patients compared to non-AKI incident dialysis patients. Adjusted mortality differences between both cohorts persisted through month 4 of the follow-up period (all P<0.01) then declined and were no longer statistically significant. Adjusted monthly mortality stratified by Black and other race between AKI dialysis patients vs non-AKI incident dialysis patients was lower throughout month 4 (1.5 v .60, 1.20 v 0.84, 1.00 v 0.80, 0.95 v 0.74, all P<0.001 which persisted through month 7. Overall adjusted mortality risk was 22% higher for AKI dialysis patients (1.22, CI 1.17, 1.27).
Conclusions: In fully adjusted analyses AKI dialysis patients had higher early mortality compared to non-AKI incident dialysis patients, but these differences declined after several months. Differences were also observed by age, race and ethnicity within both patient cohorts.