Effectiveness and dose stability of opioids in patients with restless leg syndrome: 5-year findings from the National Restless Legs Syndrome Opioid Registry

STUDY OBJECTIVES: Large long-term assessments of opioid effectiveness and dose stability for those with dopamine agonist augmentation of restless legs syndrome (RLS) are lacking. We present 5-year longitudinal findings from the National RLS Opioid Registry. METHODS: Five-hundred participants taking opioids for RLS were interviewed at baseline about RLS symptoms, opioid medications and doses, sleep, and mental health. Participants subsequently completed online surveys every 6 months. Changes from baseline to 5-year follow-up in morphine milligram equivalents (MMEs), excluding those taking buprenorphine, were evaluated by group-based trajectory modeling. Independent associations with opioid dose changes were determined using multiple logistic regression. RESULTS: At 5 years of follow-up, 410 (364 excluding any taking buprenorphine) participants remained for this analysis. Most participants are female (57.1 per cent) and white (98.3 per cent), with an average age of 64.7 (±10.6) and 88.8 per cent had a history of dopamine agonist augmentation. The median daily MME at 5 years was 37.5 (equivalent to methadone 8.0 mg or oxycodone 25.0 mg), an increase of 7.5 MME from baseline. Opioid doses increased from baseline to 5 years in 49.5 per cent of participants and decreased in 20.0 per cent of participants. Group-based trajectory analysis identified four distinct groups: decrease (3.4 per cent of participants; average MME change = -15.7 ± 12.4), no/little change (66.1 per cent of participants; average MME change = 1.5 ± 8.0), small increase (23.9 per cent of participants; average MME change = 22.0 ± 11.6), and large increase (3.4 per cent of participants; average MME change = 49.2 ± 18.7). RLS severity was stable from baseline (13.3 ± 9.6) to 5 years (13.1 ± 9.0) according to the International Restless Legs Syndrome Study Group Severity Scale. CONCLUSIONS: Opioid doses in augmented RLS remain largely stable over 5 years of follow-up. Low-dose opioids provide an effective long-term option for augmented RLS.