Outcomes of Community-Acquired Acute Kidney Injury: A Cohort Study of US Veterans.

Background: Community-acquired acute kidney injury (CA-AKI) occurs outside of the hospital and is the most common form of AKI. CA-AKI is not well understood, which hinders efforts to prevent, identify, and manage CA-AKI.

Objective: Examine 30-day outcomes following CA-AKI using national administrative and lab data from the Veterans Health Administration (VA).

Research Design: Retrospective cohort study.

Subjects: VA primary care patients with recorded outpatient serum creatinine (SCr) with observed CA-AKI (cases) and a standardized mortality ratio propensity-weighted 5% comparator sample without observed CA-AKI in 2013-2017.

Measures: CA-AKI was defined as a ≥1.5-fold relative increase in outpatient SCr or inpatient SCr (≤24 h from admission) from a reference outpatient SCr ≤12 months prior. Outcomes were 30-day mortality and hospitalization and were assessed in separate weighted Cox regression models.

Results: Among 220,777 CA-AKI events and 492,539 comparators without observed CA-AKI, CA-AKI was associated with a higher risk of 30-day all-cause mortality [hazard ratio (HR)=4.17, 95% CI: 3.74, 4.63] and hospitalization (HR=1.82, 95% CI: 1.74, 1.90) versus comparator. Risks increased with severity (mortality HR=3.02, 7.67, and 12.22 for AKI stages 1-3, respectively). Outpatient CA-AKI was associated with a high risk of mortality (HR=2.04, 95% CI: 1.83, 2.28) and even higher for inpatient CA-AKI, present [≤24 h from admission (HR=11.32, 95% CI: 10.16, 12.61)].

Conclusions: In a national cohort of Veterans, CA-AKI was associated with a 2-fold increased risk of hospitalization and a 3-11-fold risk of mortality. Improving identification and management is critical to mitigate adverse outcomes of CA-AKI.