Safety of Atrovent® CFC-free inhaler: respiratory events reported from an observational cohort study in England

Abstract

Abstract Objectives The aim of the study was to identify any unexpected clinical events associated with starting the new CFC-free formulation of Atrovent® MDI in general practice in England. Methods An active surveillance cohort study was conducted with a focus on selected clinical events, including respiratory symptoms, in past users of Atrovent® CFC MDI (‘switchers’) and Atrovent® naïve 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. Results The cohort consisted of 13 211 patients (median age 70 years, 50.1% female; 63.5% prior users of Atrovent® 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® naïve patients [ID1/IDR = 1.42 (99% CI: 1.04, 1.95)]. Conclusions The results of this study suggest effect modification of risk as a result of prior Atrovent® CFC MDI use. Overall, Atrovent® 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.