Individuals who meet acute kidney injury (AKI) criteria in the community may not always require hospitalization, but they remain at high risk of poor long-term outcomes, according to a new study.
Simon Sawhney, MBBS, of the University of Aberdeen, U.K., and colleagues studied a cohort of 50,835 individuals, applying the NHS England AKI “e-alerts” based on Kidney Disease: Improving Global Outcomes (KDIGO) criteria to identify and follow 3 AKI groups: individuals with hospital-acquired AKI (HA-AKI); individuals with community-acquired AKI hospitalized within 7 days (CAA-AKI); and individuals with community-acquired AKI not hospitalized within 7 days (CANA-AKI). The researchers compared 30-day, 1- and 5-year mortality, 90-day renal recovery, and need for chronic renal replacement therapy (RRT). The researchers defined the start of an AKI episode as the first blood test meeting AKI criteria.
AKI developed in 4,550 patients (9%). Of these, 2,779 (61.1%) were in the HA-AKI group, 1,042 (22.9%) in the CAA-AKI group, and 729 (16%) in the CANA-AKI group. The 30-day mortality rates were similar for the HA-AKI and CAA-AKI groups (24.2% and 20.2%, respectively), but significantly lower for the CANA-AKI group (2.6%), Dr. Sawhney’s team reported online ahead of print in Nephrology Dialysis Transplantation. Five-year mortality rates followed a similar pattern: 67.1%, 64.7%, and 46.2%, respectively.
Compared with the CAA-AKI group, those in the CANA-AKI group had significantly higher rates of renal non-recovery at 90 days (11.8% vs. 3.5%) and chronic RRT at 5 years (3.7% vs. 1.2%).
In addition, CANA-AKI patients were much less likely to undergo repeat testing at 7 days and 90 days. At 7 days, 81.7% of CANA-AKI patients did not have repeat testing compared with 18.6% and 20.4% of the HA-AKI and CAA-AKI groups, respectively. At 90 days, the proportions were 31%, 10.8%, and 14.1%, respectively.
“Despite AKI frequently initiating in the community, and despite the need for early recognition of of AKI, this is the first large population-based study to explore the implications of applying the same systematic AKI criteria to patients both admitted and not admitted within 7 days,” the authors noted.
Dr. Sawhney and his colleagues commented that the high rate of chronic RRT and lack of repeat testing in the CANA-AKI group was unexpected. “One explanation could be misclassification of rapidly progressing CKD patients when the AKI criteria are applied outside the hospital setting,” they stated. The low 30-day mortality might also suggest a less “acute” insult in CANA-AKI, according to the investigators.
Patients in the HA-AKI group were significantly older than those in the CAA-AKI and CANA-AKI groups (median age 77 years vs. 73 and 72 years, respectively). The proportion of patients aged 70 years and older was 71.8% in the HA-AKI group compared with 58.2% and 56% in the CAA-AKI and CANA-AKI groups, respectively.