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Concerns About Consensus Guidelines for QTc Interval Screening in Methadone Treatment
TO THE EDITOR:
The medical profession has been developing guidelines to improve opioid maintenance treatments for 40 years. The guidelines proposed by Krantz and colleagues (1) could set us back decades because they address only 1 extremely rare side effect with an unproven strategy of serial electrocardiography (ECG) on all patients regardless of risk.
Worse than that, Krantz and colleagues give no alternative clinical strategy to maintain treatment outcomes. Indeed, their current advice may even do the opposite if put into practice. Vague notions of avoiding methadone treatment or using lower doses would be as helpful as saying that patients with diabetes need to avoid insulin and, when unavoidable, should take only small doses. The only licensed alternative to methadone, buprenorphine, is simply not effective in a significant proportion of patients (2).
Justo and colleagues (3) reviewed the literature up to 2006 and found 40 cases of torsade de pointes in association with methadone treatment. None of the cases was fatal, and 85% were associated with a clear precipitant in addition to high-dose methadone treatment. Most patients with torsade de pointes have comedication or electrolyte disturbance contributing to their arrhythmia; therefore, ECG at a remote time could never prevent such cases.
Before recommending effective clinical guidelines, Krantz and colleagues should have gone back to the field and determined an incidence rate for tachycardia. They also need to propose a viable, safe alternative strategy to compare with guideline-based treatment in addiction clinics, which currently reduce the high mortality in the addiction population by approximately 75%.
Torsade de pointes rarely, if ever, occurs in young opioid-dependent patients starting methadone treatment. These guidelines should be taken along with a mountain of other clinical advice, and our patients should be treated individually, according to their needs. In the absence of other indications, patients prescribed methadone at more than 150 mg/d should probably be recommended routine ECG.
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Potential Financial Conflicts of Interest: Dr. Byrne owns a clinic that charges fees for dispensing buprenorphine and methadone in addiction treatment.
