We are delighted that our article has captured the attention of our colleagues and we appreciate the comments and additional data. Petrosillo et al describe QT interval prolongation (QTc >0.44 seconds½) in 29 (29%) of 99 HIV-positive injection drug users; similar proportions have been reported by others.1 In our study, 76 (46%) of 167 methadone maintenance patients and 16 (20%) of 80 controls without methadone use presented with a QTc greater than 0.44 seconds½. It is interesting that Petrosillo et al also found a significantly increased risk of QTc prolongation with methadone treatment and a trend for increased risk with the use of cytochrome 3A4 inhibitors. It is important to note, however, that their prospectively examined outpatients differ from the inpatients in our study, notably in that only 29 (29%) of their patients are methadone maintenance patients and in our methadone group only 67 (40%) were HIV positive. The 2 groups of patients are therefore not unequivocally comparable, but both findings underline the possibility of multiple simultaneous risk factors for QT prolongation with methadone treatment.
Ehret GB, Shah D, Dayer P, Desmeules JA. QTc Prolongation Among Hospitalized Patients Receiving Methadone—Reply. Arch Intern Med. 2006;166(20):2289-2290. doi:10.1001/archinte.166.20.2289-b