Exploring the evidence for the use of protein biomarkers of muscular damage and disease progression in Duchenne and Becker muscular dystrophy: a systematic review and meta-analysis protocol.

introductionDuchenne and Becker muscular dystrophies (DMD and BMD) are devastating conditions characterised by progressive muscle degeneration and weakness. Despite advances in understanding their pathogenetic processes, there is a critical need for reliable biomarkers to aid in patient stratification and inform clinical decision-making, predict disease progression and evaluate therapeutic responses. Several promising protein biomarkers have been investigated as potential diagnostic/prognostic tools, but, to date, this evidence has not been systematically synthesised. We aim to comprehensively and critically review and summarise published studies reporting the use of protein signatures of muscular damage in DMD and BMD. METHODS AND ANALYSIS: We will systematically search Ovid MEDLINE (PubMed), OVID Embase, OVID Evidence-Based Medicine Reviews and Cochrane Library to retrieve all relevant articles. For ongoing trials, we will search WHO International clinical trials registry and ClinicalTrials.gov registry. We will include studies that measure circulating and urine levels of established and/or promising protein biomarkers associated with skeletal muscular damage and disease progression, such as creatine kinase, myoglobin, skeletal troponin I fast-twitch (type II), myostatin, creatine/creatinine ratio, creatinine and titin. We will consider randomised controlled trials, observational studies and longitudinal cohort studies with serial sampling, without restrictions on sample size, geographic location or language, while excluding animal and in vitro studies. Two independent reviewers will screen articles for inclusion using predefined eligibility criteria and extract data of retained articles. A third author will be consulted in case of disagreement. The approach recommended by the Agency for Healthcare Research and Quality's Methods Guide for Effectiveness and Comparative Effectiveness Reviews will be used. The risk of bias and reporting quality will be assessed with standardised scales. The analysis will involve a structured narrative synthesis and evidentiary tables. If a meta-analysis is possible, biomarker data for each outcome will be pooled using random effects models. Subgroup analyses have been planned as a function of age, genetic mutation, disease severity, imaging and clinical assessment, length of the observation and risk of bias. ETHICS AND DISSEMINATION: Ethics approval is not required for this study as no original data will be collected. The findings will be shared through peer-reviewed publications and conference presentations. Additionally, this systematic review will guide the recommendations of the Duchenne Regulatory Science Consortium. This work will provide a rigorous, exhaustive and accessible evidence synthesis to identify candidate biomarkers of potential clinical value. Furthermore, it is expected that these results could be used to facilitate the development of future research strategies and guidelines, inform resource allocation decisions and accelerate the route towards clinical implementation of biomarkers for DMD and BMD. PROSPERO REGISTRATION NUMBER: CRD42024549471. Available from: