Effectiveness and tolerability of the buprenorphine transdermal system in patients with moderate to severe chronic pain : A multicenter, open-label, uncontrolled, prospective, observational clinical study

A new transdermal delivery system (TDS) for the rate-controlled systemic delivery of buprenorphine is available in 3 patch strengths, with release rates of 35, 52.5, and 70 microg/h over 72 hours, delivering daily amounts of 0.8, 1.2, and 1.6 mg, respectively. Randomized, double-blind, placebo-controlled, Phase III clinical trials in >400 patients with severe pain of malignant or nonmalignant origin have shown the analgesic efficacy of buprenorphine TDS. This study investigated the effectiveness and tolerability of buprenorphine TDS for the relief of chronic pain in routine clinical practice. This was a multicenter, open-label, uncontrolled, prospective, observational, 3-month follow-up study in patients who were beginning buprenorphine TDS treatment for moderate to severe cancer or noncancer pain that had not responded to nonopioid analgesics. Patches were to be changed every 72 hours. Patients were evaluated at 1 and 3 months after the start of treatment. Those who dropped out were considered treatment failures. Pain relief was assessed on a 5-category verbal rating scale, and quality of life was assessed using the European Quality of Life 5D (EQ-5D) questionnaire. Tolerability was determined based on adverse events recorded during the follow-up period. The study recruited 1223 patients, most of whom were outpatients. Of the 1212 patients for whom sex data were available, 820 (67.7%) were women. In the 1188 patients with age data, the mean (SD) age was 64.9 (12.9) years. In the 1175 patients with data on the etiology of pain, 82.4% had noncancer pain. Six hundred eighty-eight (56.3%) patients completed the 3-month follow-up period. The median daily amount of buprenorphine TDS received at the beginning of the study was 0.8 mg (corresponding to 35 microg/h). Over the study period, there was a significant increase in the proportion of patients reporting very good or good pain relief (P < 0.001), from 3.6% (43/1205) at baseline to 63.2% (762/1205) after 1 month and 56.8% (685/1205) after 3 months. Quality of life also improved, from a mean (SD) EQ-5D score of 40.6 (20.5) at baseline to 56.8 (23.5) at 3 months (P < 0.001). Five hundred seventeen (42.3%) of the original 1223 patients experienced adverse events; the investigator judged 397 (32.5%) of these events possibly or probably related to study drug. The likelihood of experiencing a drug-related adverse event was greater in noncancer patients than in cancer patients. The most common adverse events were na