The level of evidence is downgraded by study limitations (small studies with limited duration).
A Cochrane review [Abstract] 1 included 6 studies with a total of 438 subjects. All studies were double-blinded comparing tramadol with placebo. Participants had experienced moderate or severe neuropathic pain for at least 3 months due to cancer, cancer treatment, postherpetic neuralgia, peripheral diabetic neuropathy, spinal cord injury, or polyneuropathy. In each study tramadol was started at a dose of about 100 mg daily and increased over one to two weeks to a maximum of 400 mg daily or the maximum tolerated dose, and then maintained for the remainder of the study. Study duration for treatments was 4 to 6 weeks, and 2 studies had a cross-over design.
At least 50% pain intensity reduction was reported in 3 studies (265 participants, 110 events). Using a random-effects analysis, 70/132 (53%) had at least 50% pain relief with tramadol, and 40/133 (30%) with placebo; RR 2.2 (95% CI 1.02 to 4.6), NNT was 4.4 (95% CI 2.9 to 8.8). Participants experienced more adverse events with tramadol than placebo. Report of any adverse event was higher with tramadol (58%) than placebo (34%) (4 studies, 266 participants, 123 events; RR 1.6 (95% CI 1.2 to 2.1); NNH 4.2 (95% CI 2.8 to 8.3)). Adverse event withdrawal was higher with tramadol (16%) than placebo (3%) (6 studies, 485 participants, 45 events; RR 4.1 (95% CI 2.0 to 8.4); NNH 8.2 (95% CI 5.8 to 14)).
Primary/Secondary Keywords