Data will be analyzed with Review Manager; version 5.3.5 (RevMan, The Cochrane Collaboration, Oxford, United Kingdom) using random effects models (Mantel-Haenszel for binary outcomes and inverse variance for continuous outcomes). We will represent pooled continuous data as weighted mean differences (WMD) with a 95% confidence interval and pooled dichotomous data as risk ratios (or odds ratio (OR) in the case of rare events if deemed appropriate). We will perform subgroup and sensitivity analyses to evaluate the robustness of our findings and potential sources of heterogeneity. We hypothesize that the following factors may explain heterogeneity: type of funding (pharmaceutical industry or not), type of surgery (overall type and surgery associated with a greater risk of chronic pain), type of follow-up (inpatient or ambulatory surgery), type of population (previous diagnostic of chronic pain condition, addiction to opioids or not, women or others, and geriatric patients or not), type of anesthesia (general, regional, or others), type of drug (gabapentin or pregabalin or both), the dosage regimen (high dose (pregabalin ≥ 300 mg/day and gabapentin ≥ 900 mg/day), low dose (pregabalin < 300 mg/day and gabapentin < 900 mg/day), or both and single or multiple intake), timing of the intervention (preoperative, postoperative, or both), context of pain assessment (rest, dynamic, or unknown), type of comparator (with an analgesic effect or not), type of co-analgesia (regional analgesia or not, opioids or not, and any co-analgesia or not), and the overall risk of bias (low, high, or unclear) [
38,
39]. We will perform all subgroup analyses for our primary outcome. For our secondary outcomes, only type of funding, type of drug, the dosage regimen, the association with an opioid analgesic, and the risk of bias will be carried out. We will assess statistical heterogeneity with the
I2 index [
40]. We will consider an
I2 greater than 50% indicative of significant heterogeneity. If deemed appropriate, we will conduct a meta-regression to analyze the effect of the cumulative dosage of gabapentinoids until 12 h after surgery using
R software [
41]. We will explore the potential presence of publication bias using funnel plots for outcomes reported in more than ten trials. We will also perform a trial sequential analysis to evaluate our primary outcome in order to account for random errors due to sparse data and repeated testing (error alpha 5%; beta 20%) [
42]. To facilitate the clinical interpretation of our primary outcome, we will then calculate the probability of observing an analgesic effect greater than the minimally important difference, defined as 10 points on a 100-point scale, following the OMERACT recommendations [
33]. If appropriate, we will pool results using the inverse variance method and we will calculate relative and absolute effect measures using the
R software [
41,
43]. We will perform sensitivity analyses of this analysis with the thresholds of minimally important difference of 20, 30, and 50 points [
33].