Improvements in an oral aspirin challenge protocol for the diagnosis of aspirin hypersensitivity

Abstract

Oral aspirin challenge (OAC) is used to confirm aspirin hypersensitivity (AHs) but there is no consensus on a standardized protocol. As a prior clinical history of adverse reactions to aspirin is poorly predictive of a positive result from formal aspirin challenge, many patients have an OAC performed. We retrospectively identified and prospectively validated how a 1-day OAC protocol could be modified, and patient selection improved, to deliver a safe and more efficient service. In a retrospective audit of 45 OACs using a 2 h dose interval, all reactions occurred within 90 min of the threshold dose. Forty OACs were then performed using a 90-min dose interval. This reduced the mean duration of a positive and negative OAC from 6 to 5 h and from 8 to 6 h, respectively. Histories of multiple manifestations of AHs were found in 91.6% (11) of those with asthma, 87.5% (7) with angiooedema, 70.6% (12) with rhinosinusitis, 63.6% (7) with chronic non-vasculitic urticaria and all with anaphylaxis, who developed a positive OAC. None of those with anaphylaxis, 8.3% (1) with asthma and 12.5% (1) with angiooedema, with a positive OAC, had a history of a single manifestation of AHs. The efficiency of an OAC service can safely be improved by reduction of the dose interval from 2 to 1 (1/2) h, and more targeted patient selection, as the likelihood of a positive OAC increases among patients with a history of asthma, angiooedoema or anaphylaxis with multiple manifestations of AHs.