Benefits and safety of gabapentinoids in chronic low back pain: A systematic review and meta-analysis of randomized controlled trials

Chronic Low Back Pain (CLBP) is very common, with a lifetime prevalence between 51% and 80%. In majority, it is nonspecific in nature and multifactorial in etiology. Pregabalin (PG) and Gabapentin (GB) are gabapentinoids that have demonstrated benefit in neuropathic pain conditions. Despite no clear rationale, they are increasingly used for nonspecific CLBP. They necessitate prolonged use and are associated with adverse effects and increased cost. Recent guidelines from the National Health Service (NHS), England, expressed concerns on their off-label use, in addition to the risk of misuse. We aimed to assess the effectiveness and safety of gabapentinoids in adult CLBP patients. Electronic databases of MEDLINE, EMBASE, and Cochrane were searched from their inception until December 20th, 2016. We included randomized control trials reporting the use of gabapentinoids for the treatment of CLBP of >3 months duration, in adult patients. Study selection and data extraction was performed independently by paired reviewers. Outcomes were guided by Initiative on Methods, Measurement and Pain Assessment in Clinical Trials guidelines, with pain relief and safety as the primary outcomes. Meta-analyses were performed for outcomes reported in 3 or more studies. Outcomes were reported as mean differences (MDs) or risk ratios (RRs) with their corresponding 95% confidence intervals (CIs), and I2 in percentage representing the percentage variability in effect estimates that could be explained by heterogeneity. GRADE (Grading of Recommendations Assessment, Development, and Evaluation) was used to assess the quality of evidence. Out of 1,385 citations, eight studies were included. Based on the interventions and comparators, studies were analyzed in 3 different groups. GB compared with placebo (3 studies, n = 185) showed minimal improvement of pain (MD = 0.22 units, 95% CI [-0.5 to 0.07] I2 = 0%; GRADE: very low). Three studies compared PG with other types of analgesic medication (n = 332) and showed greater improvement in the other analgesic group (MD = 0.42 units, 95% CI [0.20 to 0.64] I2 = 0; GRADE: very low). Studies using PG as an adjuvant (n = 423) were not pooled due to heterogeneity, but the largest of them showed no benefit of adding PG to tapentadol. There were no deaths or hospitalizations reported. Compared with placebo, the following adverse events were more commonly reported with GB: dizziness-(RR = 1.99, 95% CI [1.17 to 3.37], I2 = 49); fatigue (RR = 1.85, 95% CI