The authors reply:

Asthma drug use and the development of Churg–Strauss syndrome (CSS)

“…DuMouchel et al apply the EBGM statistical adjustment in an attempt to correct for the role of chance in producing spurious associations and they found impressively large EBGM signal scores; however, their method is still subject to the caveats of adverse event reporting. 5,13,14 In contrast to the preceding classes of studies, our study was based on a large population of asthma drug users and entailed identification of incident cases, validation of each CSS diagnosis by two experts, and ascertainment of a large number of asthma drug user controls-elements the other studies lacked. 1,2,5,10 For the cases, we relied on expert diagnosis rather than ACR criteria as the 'gold standard,' recognizing the fact that ACR criteria are a classification rather than a diagnostic system and based on the current thinking about diagnosis of eosinophilic and vasculitic diseases in general.…”