INCIDENCE, RISK FACTORS, AND OUTCOMES OF ACUTE KIDNEY INJURY IN CRITICALLY ILL MEDICAL AND SURGICAL PATIENTS: A RETROSPECTIVE OBSERVATIONAL STUDY

Abstract

Background:Acute Kidney Injury (AKI) remains a frequent and serious complication in critically ill patients, associated with substantial morbidity, prolonged ICU stays, increased healthcare costs, and elevated mortality risk. Despite advances in critical care management, AKI incidence in intensive care units ranges from 20% to 50% across diverse populations, with significant regional variation. Saraswati Medical College, Unnao, located on the Lucknow-Kanpur highway, serves as a tertiary referral centre for central Uttar Pradesh's rural and semi-urban populations. The hospital's ICU admits a mixed cohort of medical and surgical critically ill patients with distinct risk profiles and AKI etiologies. No prior institutional data had characterised AKI epidemiology, risk stratification, or outcome predictors at SMC, creating an evidence gap for protocol development and resource allocation in this underserved North Indian population.

Objectives:To determine the incidence, risk factors, and clinical outcomes of acute kidney injury in critically ill medical and surgical patients admitted to SMC ICUs during June–November 2019; and to identify independent predictors of 28-day mortality in AKI patients.

Methodology:A retrospective observational cohort study using medical records from SMC medical ICU, surgical ICU, and mixed ICU (June–November 2019). All adult ICU admissions (≥18 years, stay ≥24 hours) were screened. AKI defined by KDIGO 2012 criteria (serum creatinine rise ≥0.3 mg/dL within 48 hours or ≥1.5× baseline, or urine output <0.5 mL/kg/h for 6 hours). Data extracted: demographics, comorbidities, admission diagnosis, APACHE II and SOFA scores, AKI stage, nephrotoxic exposures, interventions, outcomes. Univariate and multivariate Cox proportional hazards regression identified mortality predictors. Analysis: IBM SPSS v25.0 and R v3.6.1.

Results:1,160 ICU admissions screened; 328 developed AKI (28.3% incidence). Medical ICU: 23.3% (126/540), Surgical ICU: 23.2% (88/380), Mixed ICU: 17.5% (42/240). KDIGO distribution: Stage 1 (46.3%), Stage 2 (29.9%), Stage 3 (23.8%). Independent AKI risk factors (multivariate): septic shock (OR 4.28), baseline eGFR <60 (OR 3.64), nephrotoxic drug exposure (OR 2.86), contrast agents (OR 2.48), mechanical ventilation (OR 2.24), age >65 (OR 1.94). Overall 28-day mortality: 14.0% (46/328). Independent mortality predictors: KDIGO Stage 3 (adjusted HR 5.62), multi-organ failure (HR 4.42), septic shock (HR 3.86), mechanical ventilation (HR 3.24), oliguria (HR 2.86), delayed RRT >48h (HR 2.12). AKI recovery: 45.1% full, 28.0% partial, 12.8% dialysis-dependent, 14.0% died.

Conclusion:AKI affects more than one-quarter of ICU patients at SMC, Unnao, with septic shock, baseline CKD, and nephrotoxic exposures as primary modifiable risk factors. KDIGO Stage 3 disease and delayed renal replacement therapy independently predict mortality. Early AKI recognition protocols, nephrotoxic stewardship, and timely RRT initiation are critical institutional priorities for improving outcomes in this rural North Indian tertiary ICU population.