Safety Of Atrovent((R)) Cfc-Free Inhaler: Respiratory Events Reported From An Observational Cohort Study In England

ObjectivesThe aim of the study was to identify any unexpected clinical events associated with starting the new CFC-free formulation of Atrovent((R)) MDI in general practice in England.MethodsAn active surveillance cohort study was conducted with a focus on selected clinical events, including respiratory symptoms, in past users of Atrovent((R)) CFC MDI (switchers') and Atrovent((R)) naive users. Incidence density rate ratios (with 99% confidence intervals) for events occurring in the first 3 months of exposure (risk period-ID1-3) compared to 3 months prior to starting treatment (reference period-IDR) were calculated.ResultsThe cohort consisted of 13 211 patients (median age 70 years, 50.1% female; 63.5% prior users of Atrovent((R)) CFC MDI (switchers')). Common respiratory events occurred at higher rates after starting treatment than before for switchers, for example lower respiratory tract infection (LRTI) [ID1/IDR = 1.45 (99% CI: 1.17, 1.81)] and worsening asthma [ID1/IDR = 1.58 (99% CI: 1.00, 2.51)]. Of these events only LRTI was significant for Atrovent((R)) naive patients [ID1/IDR = 1.42 (99% CI: 1.04, 1.95)].ConclusionsThe results of this study suggest effect modification of risk as a result of prior Atrovent((R)) CFC MDI use. Overall, Atrovent((R)) CFC-free MDI appeared to be reasonably well tolerated in the immediate postmarketing period and the safety profile appeared similar to that of the CFC formulation.