In aspirin-induced asthma, symptoms typically begin 30 minutes to three hours after ingestion of aspirin. These patients usually are sensitive to all nonsteroidal anti-inflammatory drugs (NSAIDs) but not to acetaminophen. Estimates of the percentage of persons with asthma who are aspirin-sensitive range from 4 to 44 percent, depending on the population studied and the criteria used to define sensitivity. Jenkins and colleagues studied the syndrome to better inform these patients and their physicians about the danger of aspirin-induced asthma, given the rising prevalence of asthma and the widespread availability of aspirin and NSAIDs.

They identified articles concerning aspirin sensitivity in patients with asthma and searched the references of these articles for additional relevant studies. Most studies and reports involved patients attending asthma clinics. The analysis was limited to studies that defined patients by use of an aspirin provocation challenge. A positive test was defined as a 20 percent or greater reduction in forced expiratory volume in one second within three to four hours of the challenge.

From the 66 papers initially identified, 21 were found to be suitable for inclusion in the analysis. The pooled incidence of aspirin-induced asthma in adults was 21 percent. One half of these patients responded to doses of aspirin of 80 mg or more. If only the history was used to determine aspirin sensitivity, the overall prevalence was 2.7 percent. In children, the prevalence was 5 percent when provocation testing was used. Rates of cross-sensitivity were 98 percent to ibuprofen (400 mg or less), 100 percent to naproxen (100 mg or less), and 93 percent to diclofenac (40 mg or less). Only 7 percent of adults and children showed cross-sensitivity to acetaminophen.

The authors conclude that about 21 percent of adults and 5 percent of children with asthma have significant aspirin sensitivity and high rates of cross-sensitivity to other common NSAIDs. History alone is insufficient to identify patients with asthma who are at risk of aspirin sensitivity, and some patients are sensitive to extremely low doses of aspirin. Because aspirin and many NSAIDs are available without prescription, the authors call for greater recognition of this condition, better warnings on drug packaging, and implementation of guidelines for analgesic use in patients with asthma.