Prevalence of Churg-Strauss syndrome, vasculitis, eosinophilia and associated conditions: Retrospective analysis of 58 prescription-event monitoring cohort studies

Purpose - Churg-Strauss syndrome is characterised by hypsreosinophilia, sys temic vasculitis and asthma. The cause is usually unknown, but there have b een reports of an association with particular drugs, including anti-asthma drugs. Our aim was to estimate the prevalence of Churg-Strauss syndrome and related conditions in post-marketing safety studies of new anti-asthma dru gs. Methods - We accessed the prescription-event monitoring (PEM) database of t he Drug Safety Research Unit (DSRU). This database currently has informatio n on 622 294 patients observed during 58 completed PEM studies of individua l drugs, including 35 799 patients in studies of new anti-asthma drugs. Results - Overall, four cases of Churg-Strauss syndrome were identified dur ing these studies, giving a period prevalence rate of 6.8 (95% confidence l imits [CL]: 1.8 17.3) per million patient-years of observation. The period prevalence of Churg-Strauss syndrome was significantly greater in the PEM c ohorts of anti-asthma drugs (63.4 million patient-years of observation: 95% CL: 13.3-188.1), than the other PEM drug cohorts (1.8 per million patient- years of observation; 95% CE: 0.05-10.2) (rate ratio: 35.1; 95% CL: 2.8-183 9.9; p = 0.002). Conclusion - Our data provide estimates of the prevalence of Churg-Strauss syndrome and related conditions in cohorts of asthmatic patients, which may be useful during the pharmacovigilance of new asthma drugs, including the new leukotriene receptor antagonists. Copyright (C) 1999 John Wiley & Sons, Ltd.