Rhabdomyolysis-associated acute kidney injury in a Brazilian tertiary university hospital: a retrospective cohort study

Data on rhabdomyolysis-associated AKI (RML-AKI) in Latin America are scarce. This study aimed to assess the prevalence, etiologies, risk factors, and outcomes of RML-AKI at a Brazilian tertiary hospital. A retrospective cohort study based on an electronic medical record review of adult patients admitted to a tertiary university hospital in São Paulo, Brazil, from 2018 to 2020. We defined RML as a creatine kinase (CK) level at least five times the reference value. AKI was diagnosed using the KDIGO serum creatinine (SCr) criteria. Of 31,845 patients with CK assessment, 822 developed RML, and 290 met exclusion criteria, leaving 532 patients for analysis. RML-AKI occurred in 51.5%, mostly within the first 2 days after RML diagnosis. RML-AKI patients were older, had more comorbidities, and had a higher prevalence of shock, infection, respiratory failure, nephrotoxic drug exposure, and furosemide use before RML. Shock, ischemia, infection, and statin use as RML causes were more prevalent in the RML-AKI group. Admission SCr and peak CK were higher in the RML-AKI group. Patients with RML-AKI had longer hospital and ICU LOS; mortality was 41.0% versus 2.8% in the no RML-AKI group ( p < 0.001). In the logistic regression model, age, admission SCr, shock, any nephrotoxic drug use, and peak CK > 10,000 U/L were independently associated with RML-AKI. Higher admission serum bicarbonate was associated with a lower OR for RML-AKI (aOR 0.89; 95% CI 0.84–0.95). RML-AKI was independently associated with higher mortality (aOR 15.70; 95% CI 6.40–38.52), whereas trauma (as an RML cause) was associated with lower mortality. AKI severity was positively associated with mortality: KDIGO 1 (aOR 6.68; 95% CI 2.45–18.22), KDIGO 2 (aOR 18.42; 95% CI 6.05–56.02), and KDIGO 3 (aOR 36.03; 95% CI 13.40–96.92). RML-AKI was frequent, occurred early, and was independently associated with kidney function at hospital admission and RML severity. RML-AKI was associated with markedly higher mortality, which increased with AKI severity. Moreover, 15.2% of survivors with RML-AKI had not recovered kidney function by discharge, indicating a group potentially at risk of subsequent chronic kidney disease.