Clinical course of rhabdomyolysis by etiology: Findings from a prospective cohort study

BACKGROUND: Rhabdomyolysis is a complex syndrome with varying severity. Few studies compare outcomes by etiology, and prospective data are limited. We aimed to assess whether the clinical course of rhabdomyolysis differs according to etiology and whether this may aid early risk stratification. MATERIALS AND METHODS: In this prospective multicenter cohort study, 310 adults with creatine kinase ≥ 5,000 U/L and/or myoglobin ≥ 1,000 ng/mL were included. Muscle injury was categorized as traumatic or non-traumatic; the latter further divided into exertional and non-exertional. Primary outcomes were acute kidney injury (AKI), kidney function after 3 months, and in-hospital mortality. RESULTS: AKI occurred in 108 (35%) patients: 82 (60%) in the non-exertional group, 21 (55%) in the traumatic group, and 5 (4%) in the exertional group. The odds of AKI were higher in the non-exertional (OR 39, 95% CI: 13 - 116) and traumatic groups (OR 29, 95% CI: 9 - 89) compared to the exertional group. Stage III AKI occurred in 36 (12%) patients, mainly in the non-exertional group, with increased odds. No significant difference was found between the traumatic and exertional groups. Reduced kidney function after 3 months was observed in 3 patients - 2 in the non-exertional group and 1 in the traumatic group. Seven (2%) patients died, all in the non-exertional group. CONCLUSION: The non-exertional group was associated with the highest risk, followed by the traumatic group, while exertional rhabdomyolysis generally had a milder course. Etiology may help identify patients at increased risk and support early clinical risk stratification.