β-Blockers for the prevention of acute exacerbations of chronic obstructive pulmonary disease (βLOCK COPD): a randomised controlled study protocol

Abstract

Introduction: A substantial majority of chronic obstructive pulmonary disease (COPD)-related morbidity, mortality and healthcare costs are due to acute exacerbations, but existing medications have only a modest effect on reducing their frequency, even when used in combination. Observational studies suggest β-blockers may reduce the risk of COPD exacerbations; thus, we will conduct a randomised, placebo-controlled trial to definitively assess the impact of metoprolol succinate on the rate of COPD exacerbations. Methods and analyses: This is a multicentre, placebo-controlled, double-blind, prospective randomised trial that will enrol 1028 patients with at least moderately severe COPD over a 3-year period. Participants with at least moderate COPD will be randomised in a 1:1 fashion to receive metoprolol or placebo; the cohort will be enriched for patients at high risk for exacerbations. Patients will be screened and then randomised over a 2-week period and will then undergo a dose titration period for the following 6 weeks. Thereafter, patients will be followed for 42 additional weeks on their target dose of metoprolol or placebo followed by a 4-week washout period. The primary end point is time to first occurrence of an acute exacerbation during the treatment period. Secondary end points include rates and severity of COPD exacerbations; rate of major cardiovascular events; all-cause mortality; lung function (forced expiratory volume in 1 s (FEV1)); dyspnoea; quality of life; exercise capacity; markers of cardiac stretch (pro-NT brain natriuretic peptide) and systemic inflammation (high-sensitivity C reactive protein and fibrinogen). Analyses will be performed on an intent-to-treat basis.