Physician awareness of the cardiac effects of methadone: results of a national survey

BACKGROUND: Levacetylmethadol was withdrawn from the U.S. market as a treatment for opioid-dependent patients in 2003 due to QT prolongation, leaving methadone as the primary therapy for over 200,000 individuals. Methadone was subsequently shown to prolong the QT interval as well. We hypothesized that opioid treatment program physicians are unaware of these safety concerns. METHODS: To assess awareness of methadone's QT-prolonging properties, we conducted a national mail survey of physicians licensed as medical directors for accredited U.S. opioid treatment programs in 2006. The primary outcome was knowledge of methadone's QT-prolonging effects. Awareness of the cardiac effects of levacetylmethadol and buprenorphine were also assessed. RESULTS: The survey response rate was 66% (692 physicians) of whom 35% were family practitioners, 25% internists, 22% psychiatrists, and 8% self-identified as addiction specialists. While 75% (95% CI, 72-78) correctly identified levacetylmethadol as a QT-prolonging drug, only 41% (95% CI, 37- 45) were aware of methadone's QT-prolonging properties. Just 24% (95% CI, 21-27) were aware of methadone's association with torsade de pointes. In addition, 52% (95% CI, 48- 56) correctly reported the absence of an association between buprenorphine and QT prolongation. Larger program census and academic setting tended to predict greater awareness of methadone's QT-prolonging effects; yet even in these subgroups awareness did not exceed 54%. CONCLUSIONS: Scientific publication alone has been inadequate in raising awareness regarding methadone's QT-prolonging properties, even among those who most often prescribe the drug. Universal education initiatives for all accredited opioid treatment programs seem warranted to enhance the safety of this essential therapy.