Understanding seasonal patterns of disease has important implications for clinical care. Yet for many years, little has been known about seasonal variations in acute kidney injury (AKI).
A new study shows that AKI does indeed show a seasonal pattern, with incidence and severity both being higher in the winter months.
Using a Japanese community hospital database, the researchers conducting the Nephrology Dialysis Transplantation study identified 81,279 hospitalized patients with AKI. Patients were identified according to Kidney Disease: Improving Global Outcomes serum creatinine criteria. The patients represented 14.6% of all patients admitted over the 3-year study period, from 2012 to 2014.
The investigators assessed associations between month of admission and AKI, with adjustment for patient characteristics and AKI risk factors. Seasonal variations in AKI severity and 30-day mortality were examined as well.
The proportion of patients with AKI varied by month, from a high of 16.7% in January to a low of 13.4% in June: adjusted odds ratio 1.24. This seasonal pattern appeared to reflect community-acquired AKI in older adults hospitalized for cardiovascular and pulmonary disorders upon subgroup analyses.
Disease severity was also found to be higher in winter than in summer. Thirty-day mortality was 15.6% in autumn, 18.4% in winter, 16.4% in spring, and 14.5% in summer. Disease severity was determined based on AKI stage, proportion of patients receiving acute renal replacement therapy, and number of organ failures.
The new study shows significant seasonal effects in AKI, with incidence, severity, and mortality all being highest in winter. The findings have implications for clinical practice, including hospital resource utilization and preventive care in the community, the authors noted.
Iwagami M, et al. Seasonality of acute kidney injury incidence and mortality among hospitalized patients. Nephrol Dial Transplant 2018; 33:1354–1362.
