Association Between Postoperative Acute Kidney Injury and Long-Term Mortality in Patients Undergoing Major Abdominal Surgery: A Cohort-Based Study.

BACKGROUND

Acute kidney injury (AKI) is a frequent complication after major surgery and has significant implications for long-term outcomes. This study aimed to evaluate the incidence and impact of postoperative AKI (PO-AKI) in adults who underwent major abdominal surgeries in 2019 at Hospital Clínico de la Universidad de Chile. The primary focus was on the association between PO-AKI and 2-year mortality, along with other postoperative complications and hospital-related outcomes.

METHODS

A descriptive observational study was conducted with approval from the Local Ethical Committee. Patients aged 18 years and older who underwent major abdominal surgeries were included, excluding those with incomplete records or preoperative renal failure. Data were collected from electronic medical records (TiCares) and included demographics, comorbidities, and surgical details. Postoperative complications, including PO-AKI [defined by kidney disease: improving global outcomes (KDIGO) criteria or clinical diagnosis], in-hospital myocardial infarction, pulmonary thrombosis, pneumonia, sepsis, in-hospital mortality, and 2 years mortality, were recorded. The primary outcome was 2-year mortality, while secondary outcomes included in-hospital mortality and hospital stay length. Multivariable analysis was used to explore the relationship between PO-AKI and these outcomes.

RESULTS

In 214 patients analyzed, PO-AKI occurred in 13.6% of patients and was associated with advanced age (P = .003), high American Society of Anesthesiologists physical status (ASA-PS) scores (P = .02, between ASA-PS 1-2 vs 3-higher), and longer surgical durations (mean [standard deviation {SD}] 282.6 [144.3] vs 227.4 [108.5] min; P = .02). Individual preoperative creatinine and baseline renal function did not significantly differ between those with and without PO-AKI (P = .82 and P = .22, respectively). PO-AKI was associated with a relative risk of 1.4 [95% confidence interval [CI], 1.2-1.8] for 2-year mortality and stayed in the hospital twice as long as those without PO-AKI (median (min - max) 14 (2-67) vs 7 (0-53) P < .0001). Multivariate analysis identified PO-AKI (odds ratio [OR] = 4.1 [95% CI, 2.5-6.5]; P = .003) as an independent predictor of 2-year mortality. Overall, 20.1% of the cohort died within 2 years, and 3.7% experienced in-hospital mortality. Additional complications included sepsis (12.6%), pulmonary thromboembolism (3.7%), and pneumonia (2.8%).

CONCLUSIONS

PO-AKI was found to be an independent predictor of 2-year mortality. These findings highlight postoperative renal function impairment as a key marker of poor long-term prognosis. Acute renal deterioration may reflect systemic damage from surgery and/or increased vulnerability in this population, underscoring the need for targeted preventive strategies and early interventions.