Bottom line
Moderate-quality evidence shows that oral pregabalin at doses of 300 mg or 600 mg daily has an important effect on pain in some people with moderate or severe neuropathic pain after shingles, or due to diabetes. Low-quality evidence suggests that oral pregabalin is effective after trauma due to stroke or spinal cord injury. Pregabalin appears not to be effective in neuropathic pain associated with HIV. Very limited evidence is available for neuropathic back pain, neuropathic cancer pain, and some other forms of neuropathic pain.
Background
Neuropathic pain comes from damage to the nervous system. It is different from pain messages that are carried along healthy nerves from damaged tissue (for example, from a fall or a cut, or from an arthritic knee). Neuropathic pain is often treated by different medicines (drugs) from those used for pain from damaged tissue, which we often think of as painkillers. Medicines that are sometimes used to treat depression or epilepsy can be effective in some people with neuropathic pain. One of these is pregabalin. Our definition of a good result was a high level of pain relief and ability to keep taking the medicine without side effects making people stop.
Study characteristics
In April 2018, for this update we searched for clinical trials that used pregabalin to treat neuropathic pain in adults. We found 31 new studies with 8045 participants. In total, we included 45 studies randomising 11,906 participants to treatment with pregabalin, placebo, or other drugs. Studies lasted 2 to 16 weeks. Most studies reported beneficial outcomes that people with neuropathic pain think are important. Results are available mainly for pain after shingles and pain resulting from nerve damage in diabetes.
Key results
For pain after shingles, 3 in 10 people had pain reduced by half or more with pregabalin 300 mg or 600 mg daily, and 2 in 10 with placebo. Pain was reduced by a third or more for 5 in 10 with pregabalin 300 mg or 600 mg daily, and 3 in 10 with placebo. For pain caused by diabetes, 3 or 4 in 10 people had pain reduced by half or more with pregabalin 300 mg or 600 mg daily, and 2 or 3 in 10 with placebo. Pain was reduced by a third or more for 5 or 6 in 10 people with pregabalin 300 mg or 600 mg daily, and 4 or 5 in 10 with placebo. Pregabalin also helped people with a mixed diagnosis (probably mainly pain after shingles and with diabetes) and people with pain after stroke. It did not work in people with HIV with neuropathic pain. There was no reliable evidence for any other type of neuropathic pain.
Side effects were more common with pregabalin (6 in 10) than with placebo (5 in 10). Dizziness and sleepiness occurred in about 1 to 3 in 10 people who took pregabalin. Serious side effects were uncommon and were not different between pregabalin and placebo. About 1 in 10 people taking pregabalin stopped taking it because of side effects.
Pregabalin is helpful for some people with chronic neuropathic pain. It is not possible to know beforehand who will benefit and who will not. Current knowledge suggests that a short course of treatment (perhaps four weeks) is the best way of telling.
Quality of the evidence
We rated the quality of the evidence using four levels: very low, low, moderate, and high. Very low-quality evidence means that we are very uncertain about the results. High-quality evidence means that we are very confident in the results. We judged that most evidence was of moderate quality, which means that even though research provides a good indication of the likely effect, effects may be substantially different. The main issues were small size for some studies and inadequate reporting of important methodological information. Results have not changed substantially since the 2009 review.
Evidence shows efficacy of pregabalin in postherpetic neuralgia, painful diabetic neuralgia, and mixed or unclassified post-traumatic neuropathic pain, and absence of efficacy in HIV neuropathy; evidence of efficacy in central neuropathic pain is inadequate. Some people will derive substantial benefit with pregabalin; more will have moderate benefit, but many will have no benefit or will discontinue treatment. There were no substantial changes since the 2009 review.
This review updates part of an earlier Cochrane Review titled "Pregabalin for acute and chronic pain in adults", and considers only neuropathic pain (pain from damage to nervous tissue). Antiepileptic drugs have long been used in pain management. Pregabalin is an antiepileptic drug used in management of chronic pain conditions.
To assess the analgesic efficacy and adverse effects of pregabalin for chronic neuropathic pain in adults.
We searched CENTRAL, MEDLINE, and Embase for randomised controlled trials from January 2009 to April 2018, online clinical trials registries, and reference lists.
We included randomised, double-blind trials of two weeks' duration or longer, comparing pregabalin (any route of administration) with placebo or another active treatment for neuropathic pain, with participant-reported pain assessment.
Two review authors independently extracted data and assessed trial quality and biases. Primary outcomes were: at least 30% pain intensity reduction over baseline; much or very much improved on the Patient Global Impression of Change (PGIC) Scale (moderate benefit); at least 50% pain intensity reduction; or very much improved on PGIC (substantial benefit). We calculated risk ratio (RR) and number needed to treat for an additional beneficial (NNTB) or harmful outcome (NNTH). We assessed the quality of the evidence using GRADE.
We included 45 studies lasting 2 to 16 weeks, with 11,906 participants - 68% from 31 new studies. Oral pregabalin doses of 150 mg, 300 mg, and 600 mg daily were compared with placebo. Postherpetic neuralgia, painful diabetic neuropathy, and mixed neuropathic pain predominated (85% of participants). High risk of bias was due mainly to small study size (nine studies), but many studies had unclear risk of bias, mainly due to incomplete outcome data, size, and allocation concealment.
Postherpetic neuralgia: More participants had at least 30% pain intensity reduction with pregabalin 300 mg than with placebo (50% vs 25%; RR 2.1 (95% confidence interval (CI) 1.6 to 2.6); NNTB 3.9 (3.0 to 5.6); 3 studies, 589 participants, moderate-quality evidence), and more had at least 50% pain intensity reduction (32% vs 13%; RR 2.5 (95% CI 1.9 to 3.4); NNTB 5.3 (3.9 to 8.1); 4 studies, 713 participants, moderate-quality evidence). More participants had at least 30% pain intensity reduction with pregabalin 600 mg than with placebo (62% vs 24%; RR 2.5 (95% CI 2.0 to 3.2); NNTB 2.7 (2.2 to 3.7); 3 studies, 537 participants, moderate-quality evidence), and more had at least 50% pain intensity reduction (41% vs 15%; RR 2.7 (95% CI 2.0 to 3.5); NNTB 3.9 (3.1 to 5.5); 4 studies, 732 participants, moderate-quality evidence). Somnolence and dizziness were more common with pregabalin than with placebo (moderate-quality evidence): somnolence 300 mg 16% versus 5.5%, 600 mg 25% versus 5.8%; dizziness 300 mg 29% versus 8.1%, 600 mg 35% versus 8.8%.
Painful diabetic neuropathy: More participants had at least 30% pain intensity reduction with pregabalin 300 mg than with placebo (47% vs 42%; RR 1.1 (95% CI 1.01 to 1.2); NNTB 22 (12 to 200); 8 studies, 2320 participants, moderate-quality evidence), more had at least 50% pain intensity reduction (31% vs 24%; RR 1.3 (95% CI 1.2 to 1.5); NNTB 22 (12 to 200); 11 studies, 2931 participants, moderate-quality evidence), and more had PGIC much or very much improved (51% vs 30%; RR 1.8 (95% CI 1.5 to 2.0); NNTB 4.9 (3.8 to 6.9); 5 studies, 1050 participants, moderate-quality evidence). More participants had at least 30% pain intensity reduction with pregabalin 600 mg than with placebo (63% vs 52%; RR 1.2 (95% CI 1.04 to 1.4); NNTB 9.6 (5.5 to 41); 2 studies, 611 participants, low-quality evidence), and more had at least 50% pain intensity reduction (41% vs 28%; RR 1.4 (95% CI 1.2 to 1.7); NNTB 7.8 (5.4 to 14); 5 studies, 1015 participants, low-quality evidence). Somnolence and dizziness were more common with pregabalin than with placebo (moderate-quality evidence): somnolence 300 mg 11% versus 3.1%, 600 mg 15% versus 4.5%; dizziness 300 mg 13% versus 3.8%, 600 mg 22% versus 4.4%.
Mixed or unclassified post-traumatic neuropathic pain: More participants had at least 30% pain intensity reduction with pregabalin 600 mg than with placebo (48% vs 36%; RR 1.2 (1.1 to 1.4); NNTB 8.2 (5.7 to 15); 4 studies, 1367 participants, low-quality evidence), and more had at least 50% pain intensity reduction (34% vs 20%; RR 1.5 (1.2 to 1.9); NNTB 7.2 (5.4 to 11); 4 studies, 1367 participants, moderate-quality evidence). Somnolence (12% vs 3.9%) and dizziness (23% vs 6.2%) were more common with pregabalin.
Central neuropathic pain: More participants had at least 30% pain intensity reduction with pregabalin 600 mg than with placebo (44% vs 28%; RR 1.6 (1.3 to 2.0); NNTB 5.9 (4.1 to 11); 3 studies, 562 participants, low-quality evidence) and at least 50% pain intensity reduction (26% vs 15%; RR 1.7 (1.2 to 2.3); NNTB 9.8 (6.0 to 28); 3 studies, 562 participants, low-quality evidence). Somnolence (32% vs 11%) and dizziness (23% vs 8.6%) were more common with pregabalin.
Other neuropathic pain conditions: Studies show no evidence of benefit for 600 mg pregabalin in HIV neuropathy (2 studies, 674 participants, moderate-quality evidence) and limited evidence of benefit in neuropathic back pain or sciatica, neuropathic cancer pain, or polyneuropathy.
Serious adverse events, all conditions: Serious adverse events were no more common with placebo than with pregabalin 300 mg (3.1% vs 2.6%; RR 1.2 (95% CI 0.8 to 1.7); 17 studies, 4112 participants, high-quality evidence) or pregabalin 600 mg (3.4% vs 3.4%; RR 1.1 (95% CI 0.8 to 1.5); 16 studies, 3995 participants, high-quality evidence).