Troponin, a predictor of mortality in methadone exposure: An observational prospective study

Abstract

BACKGROUND: Methadone poisoning/overdose is a global public health problem. We aimed to determine whether methadone poisoning increased cardiac troponin and whether high-sensitivity cardiac troponin I (hs-cTnI) levels predicted the need for intensive care unit admission, intubation, and mortality. METHODS AND RESULTS: This observational, prospective single-center study was done at Loghman-Hakim Hospital (Tehran, Iran) from June 2018 until February 2019. Patients aged >14 years admitted with a diagnosis of methadone exposure were included. Patients were excluded if they had coexisting conditions associated with elevated hs-cTnI levels. An ECG and hs-cTnI levels were obtained on emergency department presentation. Patients were followed up on their need for intubation, intensive care unit admission, and in-hospital mortality. Of 245 included patients (186 [75.9%] men; median age, 33 years), most referred to loss of consciousness (210 cases, 89%). Nineteen (7.7%) patients had hs-cTnI levels of >0.1 ng/mL (positive), and 41 (16.7%) had borderline levels of 0.019 to 0.1 ng/mL. Twenty-three (9.3%) cases were admitted to the intensive care unit, 21 (8.5%) needed intubation, and 5 (2%) died during hospitalization. An hs-cTnI cutoff value of 0.019 ng/mL independently predicted mortality. For optimal concomitant sensitivity and specificity, receiver operating characteristic curve analysis was conducted and showed that hs-cTnI had an independent significant association with mortality, with a cutoff value of 0.0365 ng/mL (odds ratio, 38.1; 95% CI, 2.3–641.9; P<0.001). CONCLUSIONS: Methadone exposure/toxicity is a newly identified cause of elevated hs-cTnI. Values >0.019 ng/mL, and particularly >0.0365 ng/mL, of hs-cTnI predicted mortality in our sample. Future studies should measure troponin levels in methadone maintenance treatment clients to assess the risk of myocardial injury from long-term exposure.