Randomised Aspirin Assignment And Risk Of Adult-Onset Asthma In The Women's Health Study

Tobias Kurth ^1*, R Graham Barr ², J Michael Gaziano ¹ and Julie Buring ¹

¹ Brigham and Women's Hospital, United States
² Columbia University Medical Center, United States

^* To whom correspondence should be addressed. E-mail: tkurth{at}rics.bwh.harvard.edu.

Accepted 24 January 2008

Abstract

Rationale: Randomised data in men showed a small but significant reduction in risk of adult-onset asthma among those assigned to aspirin. Results from an observational study in women suggest that frequent use of aspirin decreased the risk of adult-onset asthma. Randomised data in women are lacking.

Objective: To test the effect of 100 mg of aspirin on alternate days or placebo on the risk of adult-onset asthma in the Women's Health Study.

Methods: Post-hoc analyses from a randomised, double-blind, placebo-controlled clinical trial of aspirin and vitamin E in apparently healthy US women with no indication or contraindication to aspirin therapy and free of a history of asthma at study entry.

Measurements: Female health professionals could self-report an asthma diagnosis on yearly questionnaires.

Results: Among 37,270 women without reported history of asthma prior to randomisation and during 10 years of follow-up, there were 872 new reports of asthma diagnosis in the aspirin group and 963 in the placebo group (hazard ratio=0.90; 95% confidence interval=0.82-0.99; P=0.027). This apparent 10% lower relative risk of incident adult-onset asthma among those assigned to aspirin was significantly modified by body mass index, indicating no effect among women with a body mass index of >30 kg/m2. There was no significant effect modification by age, smoking status, exercise levels, postmenopausal hormone use, or randomised vitamin E assignment.

Conclusions: In this large, randomised clinical trial of apparently healthy adult women, assignment of 100 mg of aspirin on alternate days reduced the relative risk of newly reported diagnosis of asthma. Key words: asthma, aspirin, randomised trial.