Background: Previous research has reported improved pain after adding methadone to another opioid, but did not quantify this benefit using a validated outcome measure.
Objective: To assess quantitatively the effectiveness of adding methadone to another opioid for moderate to severe cancer-related pain.
Design: All outpatients attending the Oncology Palliative Care Clinic from September 2010-September 2011, who had received methadone, were identified from pharmacy records. Inclusion criteria included: histological diagnosis of malignancy, age >18 years, taking regular opioids and Edmonton Symptom Assessment System (ESAS) pain score ≥ 4.
Measurement: The primary outcome measure was a decrease in pain score of ≥ 2 points from methadone initiation to one-month follow-up (or closest available ESAS).
Results: Twenty patients were available for analysis, 16 of whom had neuropathic pain (80%). Eight patients (40%) had a decrease in pain score of ≥ 2 points at 1 month and a further 7 (35%) had a decrease of ≥ 2 points at the closest available time point. The mean pain score decreased from 7.7 +/- 1.8 to 5.2 +/- 2.4 from time of initiation to time of evaluation. The mean daily routine morphine equivalent, (excluding methadone), was 338 +/- 217.8 mg/day at initiation and 332 +/- 191 mg/day at evaluation; for methadone, mean doses at initiation and evaluation were 4.4 +/- 1.4 mg/day and 15.5 +/- 5.9 mg/day, respectively. Methadone was well tolerated in 17 patients (85%).
Conclusions: The addition of methadone was associated with improved pain control for patients with moderate to severe pain on another opioid and appears to offer a safe, well-tolerated and practical alternative in this situation.