Illicit drug use and acute kidney injury in patients admitted to hospital with rhabdomyolysis

Background: Severe rhabdomyolysis is associated with acute kidney injury, but it is unclear if patients developing rhabdomyolysis after illicit drug use have a higher risk of acute kidney injury compared to other causes. Aims: To provide a descriptive analysis of patients admitted with rhabdomyolysis, with a focus on illicit drug use, and to determine if illicit drug use was an independent predictor for acute kidney injury or renal replacement therapy. Methods: We conducted a 5-year cohort study of patients admitted to Monash Health, a tertiary referral hospital network. We identified adult patients with muscle injury from ICD-10 AM codes, serum creatine kinase level greater than 1000 U/mL, and a clinical history consistent with rhabdomyolysis. We determined the prevalence and type of illicit drug involved and determined the association between illicit drug use and renal outcomes by logistic regression. Results: Of 643 patients, illicit drug use was identified in 12%. Acute kidney injury developed in 51%, and 5% required renal replacement therapy. Compared to the rest of the cohort, patients who used illicit drugs were younger and had higher peak serum creatine kinase, and developed a higher severity of acute kidney injury. In multivariable analysis, the factors associated with acute kidney injury were illicit drug use, peak creatine kinase, cardiovascular disease, concurrent sepsis and a clinically-evident pressure injury. Chronic kidney disease and need for fasciotomy were additional risk factors for renal replacement therapy. Conclusions: Illicit drug use was associated with acute kidney injury and renal replacement therapy independent of creatine kinase levels.