The Bronchitis Randomized On NAC Cost-Utility Study (BRONCUS): hypothesis and design

Abstract

Chronic obstructive pulmonary disease (COPD) is an irreversible disorder characterized by airflow obstruction and a progressive decline in forced expiratory volume in one second (FEV₁). At present, no treatment except quitting smoking appears to affect the progression of the disease. Oxidative stress has been implicated in its pathogenesis.The Bronchitis Randomized on NAC Cost-Utility Study (BRONCUS) is a phase III, randomized, double-blind, placebo-controlled, parallel group, multicentre study designed to assess the effectiveness of the antioxidant agent N‐acetylcysteine (NAC) in altering the decline in FEV₁, exacerbation rate, and quality of life in patients with moderate to severe COPD. In addition, cost-utility of the treatment will be estimated. Patients will be followed for 3 yrs and evaluated every 3 months. The necessary sample size to demonstrate an effect on the decline in FEV₁of 20 mL·yr⁻¹was estimated to be 478 patients.Five hundred and twenty‐three patients with moderate to severe COPD were recruited from 10 European countries from June 1, 1997–December 31, 1999. They were 63±8 yrs old and consisted of 243 (46%) current smokers and 280 (54%) exsmokers. Patients had on the average 4.9±1.6 exacerbations during the last 2 yrs. Postbronchodilator FEV₁averaged 57±9% and the reversibility after 400 μg of Salbutamol averaged 4±4% predicted.The final results of the trial will be available in about 2 yrs. The study will provide objective data on the effects of N‐acetylcysteine on outcome variables in chronic obstructive pulmonary disease.