The QTc effect of low-dose methadone for chronic pain: a prospective pilot study.

OBJECTIVE: Methadone is associated with QT prolongation and serious cardiac complications, but this has been primarily demonstrated in opioid dependent patients receiving moderate to high doses. This study investigates the effect of low-dose methadone on the QTc interval in a chronic pain population. DESIGN AND SUBJECTS: We conducted a prospective cohort study in a chronic pain clinic including 82 patients receiving methadone and 102 patients receiving non-methadone opioid therapy. METHODS: We analyzed automated QTc calculations from 12-lead electrocardiograms at baseline and during the subsequent 6 months. The primary outcome of interest was the incidence of QTc greater than 470 milliseconds or an increase from baseline of greater than 60 milliseconds. RESULTS: The methadone group did not manifest an overall higher frequency of QTc > 470 milliseconds (6% for the methadone group vs 5% for controls, P = 0.722) or an increase in the QTc of > 60 milliseconds (4% for the methadone group vs 4% for controls, P = 0.94). In the first month after initiating methadone, patients demonstrated an increase in QTc compared to controls (5% for the methadone group vs 0% for the controls, P = 0.073) but the difference disappeared in the third and sixth months. CONCLUSION: Data from our chronic pain clinic support a potential association of QTc prolongation during the initiation of methadone, but this effect is small and short lived. We believe larger scale studies to further characterize the safety profile of low-dose methadone are warranted.

The Initiation of Chronic Opioids: A Survey of Chronic Pain Patients.

This study reports the results of a researcher-administered survey with 115 patients receiving chronic opioid therapy (>90 days) to obtain information regarding how chronic opioid therapy was started. Chronic opioids were started after surgery (27.0%, 95% confidence interval [CI], 18.5-35.5) or for the treatment of acute injury-related pain (27.0%, 95% CI, 18.5-35.5). Many who initiated opioid therapy after surgery reported postoperative complications (61.3%, 95% CI, 50.8-71.8) and many with injury-related pain reported follow-up corrective surgery (58.1%, 95% CI, 47.5-68.7), which led to the continuation of opioids. A large percentage of patients had concurrent depression (43.5%, 95% CI, 34.0-53.0) and anxiety (23.5%, 95% CI, 15.3-31.7). Many participants had a medical history of aberrant drug-related behavior (32.5%, 95% CI, 23.5-41.5) and self-reported history of addiction (21.7%, 95% CI, 13.7-29.7). Almost one-quarter reported taking opioids for a different indication than that for which opioids were started (95% CI, 26.6-45.0). Patients receiving long-term opioid therapy often transitioned to chronic use after starting opioids for the short-term treatment of postoperative or injury-related pain. It is not evident if a clear decision to continue opioids on a chronic basis was made. This survey provides insight as to how chronic opioid therapy is started, and may suggest opportunities for improved patient selection for opioid therapy. PERSPECTIVE: This article explores the reasons why patients using chronic opioid therapy (>90 days) initiated opioid medications. The results of this study may help clinicians better select patients for chronic opioid therapy.