Acute kidney injury and 30-day survival in older patients with sepsis: a retrospective cohort study, Joinville (SC), Brazil

Objective: To compare the characteristics and survival rates of older patients with sepsis with and without acute kidney injury (AKI). Methods: This retrospective cohort study included older patients (aged ≥ 60 years) admitted to the intensive care unit of a private hospital in Joinville, SC, Brazil, from December 2017 to August 2021, with a diagnosis of sepsis. Patients with AKI, with or without the need for dialysis, were compared with those without AKI regarding 30-day mortality. Multivariate Cox regression analysis was performed, adjusted for age (modeled using restricted cubic splines) and relevant clinical variables. Results: Of 690 patients, 49.4% had AKI, 14.2% of whom required hemodialysis. Patients with AKI requiring dialysis had higher creatinine and C-reactive protein levels at admission, higher SAPS-3, increased need for mechanical ventilation, and more frequent use of vasoactive drugs and corticosteroids. Among patients without AKI, 30-day survival was 73.8%, compared with 48.6% in patients with AKI not requiring dialysis and 56.8% in those requiring dialysis (log-rank p < 0.001). In multivariate analysis, AKI not requiring dialysis remained associated with increased risk of 30-day mortality (hazard ratio [HR] 2.33; 95% CI, 1.55–3.49; p < 0.001), whereas AKI requiring dialysis was not significantly associated (HR 1.32; 95% CI, 0.80–2.15; p = 0.275). Age did not change the effect of AKI on mortality. Conclusion: In older patients with sepsis, AKI not requiring dialysis was associated with increased risk of mortality, whereas AKI requiring dialysis was not. This finding may reflect differences in clinical characteristics and disease severity between these patient subsets.