Predicting the severity of cocaine-associated rhabdomyolysis. STUDY OBJECTIVES: The syndrome of rhabdomyolysis associated with cocaine use has been recently described, but the incidence, severity, risk factors, and complications are unknown. This study sought to describe the spectrum of the syndrome and identify clinical features of patients at risk. DESIGN: Retrospective case series with analysis of common clinical features. SETTING: Medical emergency department of an urban teaching hospital serving an indigent population. TYPES OF PARTICIPANTS: ED patients with acute cocaine intoxication and a serum creatine kinase (all MM) of more than 500 U/L (8.3 ukat/L) who were admitted for in-hospital management. MEASUREMENTS AND MAIN RESULTS: Twenty-nine patients, representing 5% of cocaine-related patient visits, were identified over 20 months. Patients were divided into three groups: mild, characterized by anxiety, tachycardia, diaphoresis, dyspnea, or chest pain; moderate, characterized by delirium, agitation, fever, leukocytosis, or an elevated serum creatinine; and severe, characterized by seizure, coma, hypotension, arrhythmia, or cardiac arrest. There was a significant association between the rating system for level of intoxication and the severity of rhabdomyolysis and its complications (P less than .01). Patients at highest risk for complications of rhabdomyolysis were those in the moderate or severe groups. CONCLUSION: This classification system may be useful for the management of patients with acute cocaine intoxication, predicting those patients in whom aggressive therapy should be initiated in the ED to minimize the complications of rhabdomyolysis. 