Objective: To evaluate the efficacy of tramadol as adjunctive therapy in patients with musculoskeletal pain attributed to osteoarthritis (OA) who experienced breakthrough pain while taking a nonsteroidal antiinflammatory drug (NSAID).
Methods: This single center, parallel, placebo controlled, 2 phase study was conducted in adults who experienced breakthrough OA pain while undergoing stable NSAID therapy. In a 24 h open label phase, patients took 100 mg of tramadol followed by 50 mg every 6 h (total 250 mg) in addition to their daily NSAID regimen. Supplemental analgesics were prohibited. Patients who met entry criteria and were willing to continue therapy were randomized to a 13 day double blind phase of adjunctive therapy with tramadol (50-100 mg every 4-6 h as needed for pain) or placebo; NSAID therapy was continued. The primary efficacy endpoint was the time to exit from the study because of therapeutic failure (i.e., insufficient pain relief or an inability to perform activities of daily living).
Results: The time to exit from the study because of insufficient pain relief tended to be longer in the tramadol group (250 mg/day) compared with the placebo group (p = 0.066). At the end of the double blind phase, pain at rest was significantly less severe in tramadol treated patients (p = 0.046). In addition, severity of pain on motion tended to be less severe in tramadol treated patients (p = 0.059). General severity of current pain and ability to perform activities of daily living were not significantly different with tramadol or placebo. Patients' overall assessment of therapy (p = 0.022) and investigator's rating of global improvement (p = 0.004) were significantly better with tramadol than with placebo.
Conclusion: Tramadol may have a role as adjunctive treatment for breakthrough pain in patients receiving NSAID therapy for musculoskeletal pain attributed to OA.