Pharmacotherapy and non-invasive neuromodulation for neuropathic pain: a systematic review and meta-analysis

There remains a substantial unmet need for effective and safe treatments for neuropathic pain. The Neuropathic Pain Special Interest Group aimed to update treatment recommendations, published in 2015, on the basis of new evidence from randomised controlled trials, emerging neuromodulation techniques, and advances in evidence synthesis.

For this systematic review and meta-analysis, we searched Embase, PubMed, the International Clinical Trials Registry, and ClinicalTrials.gov from data inception for neuromodulation trials and from Jan 1, 2013, for pharmacological interventions until Feb 12, 2024. We included double-blind, randomised, placebo-controlled trials that evaluated pharmacological and neuromodulation treatments administered for at least 3 weeks, or if there was at least 3 weeks of follow-up, and which included at least ten participants per group. Trials included participants of any age with neuropathic pain, defined by the International Association for the Study of Pain. We excluded trials with enriched enrolment randomised withdrawal designs and those with participants with mixed aetiologies (ie, neuropathic and non-neuropathic pain) and conditions such as complex regional pain syndrome, low back pain without radicular pain, fibromyalgia, and idiopathic orofacial pain. We extracted summary data in duplicate from published reports, with discrepancies reconciled by a third independent reviewer on the platform Covidence. The primary efficacy outcome was the proportion of responders (50% or 30% reduction in baseline pain intensity or moderate pain relief). The primary safety outcome was the number of participants who withdrew from the treatment owing to adverse events. We calculated a risk difference for each comparison and did a random-effects meta-analysis. Risk differences were used to calculate the number needed to treat (NNT) and the number needed to harm (NNH) for each treatment. Risk of bias was assessed by use of the Cochrane risk of bias tool 2 and certainty of evidence assessed by use of GRADE. Recommendations were based on evidence of efficacy, adverse events, accessibility, and cost, and feedback from engaged lived experience partners. This study is registered on PROSPERO, CRD42023389375.