Risk factors of developing rhabdomyolysis in cough medicine abusers presented to the accident and emergency departments in Hong Kong during 2008–2023

AbstractIntroductionRhabdomyolysis was observed in cough medicine abusers. This study aimed to identify risk factors that were associated with rhabdomyolysis in cough medicine abusers.MethodsThis was a retrospective cohort study, conducted in the Hong Kong Poison Information Center (HKPIC). Cases of cough medicine abuse captured in the HKPIC database during 1/1/2008–31/12/2023 were recruited. Inclusion criteria were as follows: (1) cough medicine abuser presenting to the accident and emergency department (A&E), (2) documented history of cough medicine abuse in clinical notes or diagnosis code, and (3) positive urine toxicology for cough medicine components (opioid antitussives, antihistamines, and/or ephedrine/pseudoephedrine). Exclusion criteria were as follows: (1) urine toxicology neither available or negative for all 3 components stated above, (2) serum creatine kinase (CK) was level not available, or (3) major trauma. Rhabdomyolysis was defined by the peak serum CK level >1500 U/L or >5 times the upper limit of normal.Results202 patients were included in the final analysis and 28.2% (57/202) developed rhabdomyolysis. Among antitussive opioids detected, codeine was detected in 76.2% (154/202), dextromethorphan in 19.8% (40/202), and both in 8.4% (17/202). Ephedrine/pseudoephedrine (84.7%, 171/202) and antihistamines (92.6%, 187/202), especially promethazine (84%, 157/187), were commonly detected. Other illicit drugs, including stimulants (methamphetamine, MDMA, cocaine), heroin, and ethanol, were detected in 35.6% (72/202). Univariate analysis showed agitation, seizure, Glasgow Coma Scale 8, tachycardia, hyperthermia, anemia, thrombocytopenia, and acute kidney injury (AKI) were associated with rhabdomyolysis. Final multivariate logistic regression analysis found that seizure [adjusted odd ratio (aOR) = 16, 95% confident interval (CI) 4.3–67, and p < 0.001], hyperthermia [aOR = 3.5, 95% CI 1.5–8.1, and p = 0.003], or AKI [aOR = 11, 95% CI 5.0–26, and p < 0.001] were significantly associated with rhabdomyolysis.ConclusionSeizure, hyperthermia, and AKI were significantly associated with rhabdomyolysis in cough medicine abusers.