Long-term efficiency of opioid medication in patients with chronic non-cancer-associated pain. Results of a survey 5 years after onset of medical treatment

A total of 121 patients with at least a 3-year history of opioid use were evaluated by a standardized interview during a clinical visit or telephone call. Assessed items were the present and former drug medication, daily doses, withdrawals, contentment with the treatment, positive/negative treatment effects, average/maximum pain and others. Statistics: x(2), ANCOVA and survival analysis. Of 121 patients (frequency of withdrawal 14.8% mainly due to lack of efficacy) with an average treatment time of 66 months (37-105 months; 80,264 days; 87% more than 5 years), 103 (85%) still took an opioid step II or III according to the WHO analgesic ladder. Patients further treated in the pain clinic stopped significantly less frequently than patients treated by GPs or other non-specialised physicians (5 versus 23%). Patients with long-term opioid intake revealed significantly lower pain intensity and higher contentment with the pain management and achieved improvement (global, quality of life and physical state). Changes of opioid dosages during the 5 years were inconsistent (no change 33%, decrease 16%, slight increase 27%, high increase 19%). However, the number of patients with high dose increased from 6 to 23 due to significant loss of efficacy (proved in the morphine subgroup, p < 0.05). The survey demonstrates a very low frequency of withdrawal in patients with long-term opioid medication after initial response without evidence for tolerance development, especially if their treatment is controlled in a pain centre.