Efficacy of N-acetylcysteine on idiopathic or postinfective non-cystic fibrosis bronchiectasis: a systematic review and meta-analysis protocol

INTRODUCTION: Non-cystic fibrosis (non-CF) bronchiectasis is a chronic pulmonary disorder that causes destruction and permanent dilatation of the airways, resulting in excessive sputum production, repeated infection and inflammation. A need for high-quality and specialised care has been highlighted in recent years. N-acetylcysteine (NAC) is a widely used mucolytic agent in respiratory diseases that not only possesses a property to enhance secretion clearance, but also exhibits antioxidant and anti-inflammatory effects. However, the efficacy and safety of NAC are not well described in idiopathic or postinfective non-CF bronchiectasis. OBJECTIVE: This study aims to evaluate the efficacy and safety of NAC in patients with idiopathic or postinfective non-CF bronchiectasis. METHODS AND ANALYSIS: PubMed/Medline, Embase, Web of Science, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials will be searched from inception to 1 March 2022 for eligible randomised controlled trials that investigating the effects of NAC on exacerbations, health-related quality of life, lung functions, sputum volume and colour, inflammation markers, exercise capacity and adverse events in patients with idiopathic or postinfective non-CF bronchiectasis, with ongoing trials being identified by searches on the websites of Chinese Clinical Trial Registry and ClinicalTrials.gov. Two independent reviewers will identify eligible studies, two will fulfil the data extraction and three will perform the quality appraisal. To generate more accurate analyses, the Grading of Recommendations Assessment, Development and Evaluation will be used to grade the evidence. χ(2) test and I(2) statistic will be used to assess heterogeneity. Subgroup analyses and meta-regression will be used to explore potential sources of heterogeneity. The potential publication bias will be examined using funnel plots. ETHICS AND DISSEMINATION: No research ethics approval is required in this study because it is a systematic review. The results of this study are expected to be disseminated through peer-reviewed journals and conferences. TRIAL REGISTRATION NUMBER: CRD42021239438.