Acute Kidney Injury in Acute Respiratory Distress Syndrome: Association with Mortality, Prevalence, and Risk Factors – A Systematic Review and Meta-analysis

Introduction: Acute kidney injury (AKI) frequently complicates acute respiratory distress syndrome (ARDS) and leads to poor outcomes. Although prone ventilation in moderate-to-severe ARDS improves oxygenation and survival, AKI may offset these benefits and contribute to mortality. Furthermore, multiple factors have been implicated in AKI risk in ARDS, but have not been comprehensively synthesized. Methods: This review followed Preferred Reporting Items for Systematic reviews and Meta-Analyses 2020 guidelines. PubMed, Embase, Scopus, and the Cochrane Library were searched. Observational studies reporting AKI prevalence and mortality in ARDS patients were included. Risk ratios (RR), prevalence estimates, and mean differences were pooled using random-effects models. Results: Twenty-one studies ( n = 5631) were included with 13 supine-and 8 prone-ventilated cohorts. AKI was associated with increased mortality (RR 2.40, P < 0.00001), with a numerically higher risk observed with prone than supine ventilation. Subgroup analysis revealed a significantly higher mortality risk in coronavirus disease 2019 (COVID-19)-ARDS compared to non-COVID-19 (RR 2.88 vs. 1.72; P < 0.0001). The AKI-mortality association remained robust regardless of ECMO ( P < 0.0001) or vasopressor use ( P < 0.0001), with no significant subgroup differences. AKI prevalence was high in both prone (47%) and supine (43%) groups. Meta-analysis identified older age, diabetes, obesity, higher serum lactate levels, lower PaO 2 /FiO 2 , and ECMO use as risk factors for AKI. Conclusion: AKI is highly prevalent in ARDS and is associated with a more than two-fold increase in mortality risk, irrespective of prone or supine ventilation. This association is consistent across COVID-19 and non-COVID-19 patients, as well as those requiring ECMO or vasopressors, highlighting AKI as a critical prognostic indicator in ARDS care.