An Aspirin a Day Keeps the Doctor at Bay
An Aspirin a Day Keeps the Doctor at Bay
Abstract & Commentary
By Barbara A. Phillips, MD, MSPH, Professor of Medicine, University of Kentucky; Director, Sleep Disorders Center, Samaritan Hospital, Lexington. Dr. Phillips reports no financial relationship to this field of study.
Synopsis: Aspirin, 325 mg every other day, reduced the risk of developing asthma by 25% (compared with placebo) over a 5-year period in a large group of healthy male physicians.
Source: Garr RG, et al. Aspirin and decreased adult-onset asthma. Randomized comparisons from the Physician's Health Study. Am J Respir Crit Care Med. 2007; 175:120-125.
This report is a secondary analysis of a cohort of 22,040 physicians (mean age 54 years) who were free of asthma at enrollment, and who were randomized to take either aspirin 325 mg every other day or placebo. The study was terminated at 4.9 years of follow-up because the primary outcome measure (risk of first myocardial infarction) was very statistically and clinically reduced (by 44%!) in the group that was randomized to take aspirin. The onset of asthma was ascertained by self-report in this group of physicians, who are, as the authors put it, "unlikely to misrepresent their own medical diagnoses." At the termination of the study, there were 258 new cases of asthma altogether, but only 113 of them were in the aspirin group. This was statistically significant (p = 0.045), even after controlling for body mass index (BMI), age, and smoking. Aspirin's benefit in reducing asthma was greatest for those who were younger at enrollment and who had never smoked.
This report comes from a very large and very old dataset, the Physician's Health Study, which was actually begun in 1982 to test the hypotheses that aspirin or beta carotene prevent cardiovascular disease or cancer.1 The aspirin arm of this study was terminated early in 1988 (because of the ethical need to allow all participants to take aspirin, given its benefits in reducing cardiovascular risk), and the beta carotene arm was terminated at its scheduled end in 1995. So these are old data, but still quite relevant and important.
The biologic basis by which aspirin might reduce asthma risk is that it might reduce COX-1, which blocks prostaglandin E2, which in turn inhibits Th1 lympocytes from releasing evil substances such as IFN-gamma.2-4 There are several other proposed mechanisms as well, but frankly, I don't understand them. The background evidence that aspirin might reduce asthma risk includes the increase in asthma in the United States coincident with the reduction in aspirin use because of concerns about Reyes Syndrome.2 Earlier work with a large cohort of women demonstrated a reduced rate of newly-diagnosed asthma in those who self-selected to take aspirin, as compared with other analgesics.5 However, that kind of study does not have the power of a randomized controlled trial, such as is presented here. Other benefits of aspirin include the reduction in cardiovascular risk also demonstrated by the PHS, and a reduction in head and neck cancer.6
On the other hand, asthma is known to precipitate bronchospasm in as many as 10% of asthmatics.7 Once asthma has developed, the horse is out of the barn, so to speak, and use of aspirin must be carefully considered in those with well-documented asthma.
Aspirin is an under rated drug, perhaps at least in part because it is cheap, unpatented, and over the counter; direct-to-consumer marketing and physician detailing simply don't occur for aspirin. It's a good thing we can read journals!
References
1. Steering Committee of the Physician's Health Study Research Group. N Engl. J Med. 1989:321:129-135.
2. Varner AE, et al. Ann Allergy Asthma Immunol. 1998; 81:347-351.
3. Betz M, Fox BS. J Immunol. 1991;46:108-113.
4. Snijdewing FGM, et al. J Immunol. 1993;150:5321-5329.
5. Barr RG, et al. Am J Respir Crit Care Med. 2004;169:836-841.
6. Jayaprakash V, et al. Arch Otolaryngol Head Neck Surg. 2006;132:1231-1236.
7. Vally H, et al. Thorax. 2002;57:569-574.
Aspirin, 325 mg every other day, reduced the risk of developing asthma by 25% (compared with placebo) over a 5-year period in a large group of healthy male physicians.Subscribe Now for Access
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