Prevalence and predictors of bronchiectasis in children and adults with inborn errors of immunity: protocol for a systematic review and meta-analysis

Abstract Background Bronchiectasis is a debilitating chronic lung condition to which patients with inborn errors of immunity (IEI) are highly susceptible. Despite its clinical significance, few studies describe the burden of bronchiectasis in this vulnerable population. The primary objective of this study is therefore to systematically describe the prevalence and predictors of bronchiectasis among children and adults with IEI globally. Methods We will search PubMed, Embase, Scopus, and Web of Science: Core Collection for studies published in English after 2014. We will include studies of children and adults of any age, sex, and ethnicity with IEI and bronchiectasis. We define bronchiectasis as bronchial dilatation assessed on chest computed tomography, and IEI according to the 2024 International Union of Immunological Societies (IUIS) classification. Although cystic fibrosis (CF) is an IEI, patients with CF will be excluded unless they have a concurrent non-CF IEI, since CF-associated bronchiectasis has been extensively studied. The prevalence and predictors of bronchiectasis in IEI patients will constitute the primary outcomes. Covidence will be used for screening and data extraction. Two authors will screen articles, extract data, and assess risk of bias. We will collect data on IEI patients with bronchiectasis, patient and study characteristics, and measures of association for predictors of bronchiectasis. Risk of bias will be assessed using multiple validated tools, including the Joanna Briggs Institute (JBI) checklist for prevalence studies and other standardized study design–specific instruments. If study data are sufficiently homogeneous, we will conduct a meta-analysis using random-effects models to estimate the prevalence and predictors of bronchiectasis in IEI patients, and conduct subgroup analyses by age, sex, country income level, IUIS class, and risk of bias. Discussion Previous systematic reviews on bronchiectasis prevalence and predictors have focused on rheumatoid arthritis, vasculitis, and infections. Understanding the global burden and predictors of bronchiectasis among IEI patients has significant implications for patient care, healthcare expenditure, and the adoption of specialized diagnostics. This systematic review aims to address this gap by providing robust, contemporary, and comprehensive estimates of bronchiectasis prevalence and predictors among children and adults with IEI worldwide. Systematic review registration CRD420251056451. Registered 14th May 2025.