Protocol for a systematic literature review and network meta-analysis of the clinical benefit of inhaled maintenance therapies in chronic obstructive pulmonary disease

INTRODUCTION: Chronic obstructive pulmonary disease (COPD) exacerbations progress the course of disease and impair lung function. Inhaled maintenance therapy reduces exacerbations. It is not yet established which inhaled therapy combination is best to reduce exacerbations, lung function decline and symptom burden. METHODS AND ANALYSIS: MEDLINE, EMBASE and the Cochrane Library will be searched for articles between January 2011 and May 2018 using a pre-specified search strategy. Conference proceedings will be searched. Systematic reviews (with or without meta-analysis), randomised controlled trials (RCTs), cohort studies and case controlled studies comparing six interventions comprising different combinations of long-acting bronchodilators and inhaled corticosteroids in unison or on their own. The primary outcome is the reduction in moderate-to-severe exacerbations. Secondary outcomes include: lung function, quality of life, mortality and other adverse events. Titles and abstracts will screened by the primary researcher. A second reviewer will repeat this on a proportion of records. The Population, Intervention, Comparator, Outcomes and Study framework will be used for data extraction. A network meta-analyses of outcomes from RCTs and real-world evidence will be integrated if feasible. The 95% credible interval will be used to assess the statistical significance of each summary effect. Ranking of interventions will be based on their surface under cumulative ranking area. ETHICS AND DISSEMINATION: COPD exacerbations are burdensome to patients. We aim to report results that provide clinicians with a more informed choice of which inhaled therapy combinations are best to reduce exacerbations, improve disease burden and reduce lung function and exercise capacity decline, compared with the potential harms, in certain populations with COPD. PROSPERO REGISTRATION NUMBER: CRD42018088013.