Study protocols for the GEPard project: systematic analysis of sex- and gender-specific differences in the efficacy of perioperative pain management - a two-pronged approach.

INTRODUCTION: Postoperative pain is common, with approximately one-third of surgical patients experiencing severe acute pain and 10-20% developing chronic post-surgical pain (CPSP). Evidence shows that female patients are at higher risk of pain after sex non-specific surgery, thus sex- or gender-specific differences in pain treatment efficacy with potential consequences for perioperative pain management are to be expected. Considering the clinical and societal burden of poorly managed postoperative pain, the GEPard project comprises two systematic reviews, GEPard 1: sex- and/or gender-specific differences in efficacy of perioperative pain management for certain (major) surgical procedures in adult patients; and GEPard 2: sex- and/or gender-specific differences in the dosing, efficacy and adverse effects of the most common systemic perioperative non-opioid- and co-analgesics across all sex non-specific surgical procedures in adult patients. METHODS AND ANALYSIS: The reviews will be conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and the Cochrane Handbook. MEDLINE, Embase, Cochrane Library, Web of Science, Scopus, ClinicalTrials.gov and PsycINFO will be searched. We will include randomised controlled trials (RCTs) and systematic reviews/meta-analyses reporting outcomes disaggregated by sex and/or gender in adult surgical patients. For GEPard 1, this applies to selected major surgical procedures; for GEPard 2, to all non-sex-specific surgical procedures. Interventions include regional anaesthesia, systemic analgesics and psychological strategies for GEPard 1 and non-opioid- as well as co-analgesics for GEPard 2. Two reviewers will independently screen and extract the data. Cochrane Risk of Bias Tool 2.0 (RoB 2) and AMSTAR 2 tools will assess study quality. Random-effects or Bayesian meta-analyses will be performed where possible; otherwise, narrative synthesis will be applied. GRADE methodology will assess evidence certainty. ETHICS AND DISSEMINATION: No ethical approval is required for these reviews. Findings will be disseminated via peer-reviewed publications, patient organisations and professional societies. Data will be shared via Zenodo or Open Science Framework (OSF), following FAIR principles. PROSPERO REGISTRATION NUMBER: The systematic review protocols for both reviews have been registered in PROSPERO on 29 August 2025 (Registration-ID: CRD420251121393 (GEPard1), CRD420251121536 (GEPard2).