Efficacy and safety of low-dose transdermal buprenorphine patches (5, 10, and 20 microg/h) versus prolonged-release tramadol tablets (75, 100, 150, and 200 mg) in patients with chronic osteoarthritis pain: a 12-week, randomized, open-label, controlled, parallel-group noninferiority study.

OBJECTIVE
This study compared the efficacy and safety of low-dose 7-day buprenorphine patches and prolonged-release tramadol tablets in patients with chronic, moderate to severe osteoarthritis (OA) pain of the hip and/or knee.


METHODS
Eligible patients were adults with a clinical and radiologic diagnosis of OA of the hip and/or knee and moderate to severe pain, as confirmed by a mean Box Scale 11 (BS-11) score >or=4 while using paracetamol 4000 mg/d for pain during the screening week. Patients were randomized in a 1:1 ratio to receive either low-dose 7-day buprenorphine patches (patch strengths of 5, 10, and 20 microg/h, with a maximum dosage of 20 microg/h) or twice-daily prolonged-release tramadol tablets (tablet strengths of 75, 100, 150, and 200 mg, with a maximum dosage of 400 mg/d) over a 12-week open-label treatment period. Supplementary paracetamol was available as rescue medication throughout the study. The primary end point was the difference in BS-11 scores from baseline to the completion of treatment. Noninferiority was assumed if the treatment difference on the BS-11 scale was -1.5 boxes, indicating a clinically meaningful result. Secondary efficacy variables were rescue medication use, sleep disturbance and quality of sleep, and patients' and investigators' global assessments of pain relief. In addition, patient preference was assessed at the completion visit by asking patients whether, given equal pain relief, they would prefer basic treatment for OA pain with a patch applied once weekly or a tablet taken twice daily. Exploratory variables included investigators' assessments of patients' pain, stiffness, and ability to perform daily activities (Western Ontario and McMaster Universities Osteoarthritis Index); patients' quality of life (EuroQol EQ-5D health states index and EuroQol visual analog scale); and abuse and diversion of study drug.


RESULTS
One hundred thirty-four patients (69 receiving 7-day buprenorphine patches and 65 receiving tramadol tablets) were randomized and received >or=1 dose of study medication. A respective 98.6% and 100% of the 2 treatment groups were white, with mean (SD) ages of 64.4 (11.1) and 64.2 (9.3) years. Both treatments were associated with a clinically meaningful reduction in pain from baseline to study completion. The least squares mean change from baseline in BS-11 scores in the 7-day buprenorphine patch and tramadol tablet groups was -2.26 (95% CI, -2.76 to -1.76) and -2.09 (95% CI, -2.61 to -1.58). The efficacy of 7-day buprenorphine patches was noninferior to that of prolonged-release tramadol tablets. The incidence of adverse events (AEs) was comparable in the 2 treatment groups: 226 AEs were reported in 61 patients (88.4%) in the 7-day buprenorphine patch group, and 152 AEs were reported in 51 patients (78.5%) in the tramadol group. Ten patients (14.5%) in the 7-day buprenorphine patch group and 19 (29.2%) in the tramadol tablet group withdrew from the study due to AEs. The most common AEs in the 7-day buprenorphine patch group were nausea (30.4%), constipation (18.8%), and dizziness (15.9%); the most common AEs in the tramadol tablet group were nausea (24.6%), fatigue (18.5%), and pain (12.3%). Most patients (47/67 [70.1%] in the 7-day buprenorphine patch group and 43/61 [70.5%] in the tramadol tablet group) reported that they would prefer a 7-day patch to a twice-daily tablet for future pain treatment.


CONCLUSIONS
In these patients with chronic, moderate to severe OA pain of the hip and/or knee, 7-day low-dose buprenorphine patches were an effective and well-tolerated analgesic. The buprenorphine patches were noninferior to prolonged-release tramadol tablets. European Union Drug Regulating Authorities Clinical Trials number: 2006-003233-32.