The Use of Low-Dose Methadone as Add-On to Regular Opioid Therapy in Cancer-Related Pain at End of Life: A National Swedish Survey in Specialized Palliative Care

Background: Low-dose methadone in addition to another ongoing opioid therapy is a promising approach for managing complex cancer-related pain and is, despite limited evidence, used in clinical practice. Objective: To investigate the use of low-dose methadone in specialized palliative care in Sweden. Design: Specialized palliative care services in Sweden answered a survey regarding methadone use in individual patients over 12 months. Setting/Subjects: The survey was an add-on to the Swedish Register of Palliative Care's (SRPC) mandatory end-of-life questionnaire (ELQ). Results: Sixty of 133 invited units (45%) participated in the study. A total of 4780 ELQs were registered. Four hundred ten of these patients received methadone (9%). In 96% of these patients, methadone was prescribed as an add-on to ongoing opioid therapy, mostly because of poor pain control due to mixed nociceptive and neuropathic pain (70%). Methadone was used for a median of 21 days, in 86% of cases until death. Mean daily methadone doses increased from 7 mg at start to 21 mg ( p  < 0.005) during the last 24 hours. Corresponding morphine equivalent daily doses of other opioids were 184 and 199 mg ( p  < 0.05), respectively. A pain-relieving effect was reported in 94% of the patients. Adverse effects were seen in 20% of the patients; none of these was severe. Conclusion: The addition of low-dose methadone to an ongoing opioid therapy in patients with complex cancer-related pain is well established in Swedish specialized palliative care. It appears to have good pain-relieving effects and to be safe.