title: N-acetylcysteine and exacerbations of chronic obstructive pulmonary disease.
abstract: Oxidative stress may play a role in chronic obstructive pulmonary disease (COPD) exacerbations. There is heterogeneity in the literature with regard to the impact of antioxidant therapy on COPD exacerbation frequency. Clinical trials of N-acetylcysteine in COPD were identified in unrestricted searches of MEDLINE, CINAHL, International Pharmaceutical Abstracts and the Cochrane Register. Randomized, controlled trials which reported exacerbations over a treatment period > or =3 months were selected. Two observers independently extracted data regarding exacerbation number over the treatment period in subjects allocated to either N-acetylcysteine or placebo. Data were analyzed using inverse-variance weighted random effects meta-analysis methodology. Meta-analysis of data from 8 trials (randomized n = 2,214) indicated that N-acetylcysteine significantly reduced the odds of experiencing one or more exacerbations over the treatment period (odds ratio = 0.49, 95% confidence interval [0.32-0.74], p = 0.001). Treatment effect was not reduced in studies which enrolled >50% active smokers (odds ratio = 0.36 [0.24-0.55], p < 0.001), although a greater effect was observed with exclusion of subjects using concurrent inhaled corticosteroids (odds ratio = 0.42 [0.32-0.54], p < 0.0001), suggesting that inhaled steroids attenuate the effect of N-acetylcysteine. The use of N-acetylcysteine significantly reduces the odds of exacerbation in patients with COPD, an effect possibly attenuated by inhaled steroids but not smoking. This analysis suggests treatment with N-acetylcysteine may be beneficial in a subset of patients with COPD.
authors.affiliation: Department of Medicine, National Jewish Medical and Research Center, Denver, Colorado, USA. sutherlande@njc.org
authors.forename: E Rand
authors.initials: ER
authors.lastname: Sutherland
authors.forename: James D
authors.initials: JD
authors.lastname: Crapo
authors.forename: Russell P
authors.initials: RP
authors.lastname: Bowler
mesh_terms: D000111:Acetylcysteine / Q000627:therapeutic use*; D016166:Free Radical Scavengers / Q000627:therapeutic use*; D006801:Humans; D018384:Oxidative Stress / Q000502:physiology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000378:metabolism; D016032:Randomized Controlled Trials as Topic; D055502:Secondary Prevention; D016896:Treatment Outcome
chemical_list: D016166:Free Radical Scavengers; D000111:Acetylcysteine