(P-405) Characteristics of Patients Initiating Spiriva Respimat for Asthma in the UK

Background: In September 2014, Spiriva Respimat (tiotropium) was approved for asthma in the UK. For future comparative studies, it is important to identify characteristics of patients who initiate this treatment as opposed to other treatments.

Objectives: To describe the characteristics of UK asthma patients at initiation of Spiriva Respimat as add on therapy to inhaled corticosteroids (ICS)/long-acting beta agonists (LABA) and to compare their characteristics to asthma patients who initiated leukotriene receptor antagonist (LTRA) as add on to ICS/LABA, or to those who switched to a new ICS/LABA, or alternatively increased the ICS dose of their ICS/LABA.

Methods: This cross-sectional study used data from the UK Clinical Practice Research Database GOLD from September 2014 to December 2017 with linkage to deprivation index and hospital episode statistics for eligible English patients. The baseline clinical and socio-demographic characteristics were described including comorbidities and medications. Absolute standardized difference (ASD) was calculated to compare cohorts’ characteristics. An ASD of 0.1 or above denotes a meaningful difference.

Results: In total, 940 patients initiated Spiriva Respimat, 3,704 initiated LTRA, 1,561 switched to a different ICS/LABA, and 11,135 patients increased their dose. The Spiriva patients were on average older than patients of the LTRA group and dose increasers (mean±SD 54±15.7 ,49±16.3, 52±7.2, respectively, and ASDs 0.32 and 0.14, respectively). The Spiriva group showed higher averages for number of asthma exacerbations and respiratory related hospitalization pre-index as compared to the other groups (mean±SD 1.3±1.86 vs 0.6±1.19, 0.5±1.15, 0.5±1.09, respectively and 0.6±1.07 vs 0.3±0.89, 0.3±0.95, 0.3±0.94). The average Charlson comorbidity index was higher in the Spiriva group (mean±SD 1.1±0.74 vs 0.9±0.63, 1±0.71, 0.9±0.81). Use of other respiratory medications were higher among the Spiriva initiators e.g. 77% had current use of short-acting beta agonists at baseline vs 69%, 63%, 57% in the other groups. The percentage of patients with pre-index cardiac arrhythmias was 1.2% in the Spiriva group, which was not meaningful different as compared to the other groups (0.5%, 0.9%, 1%, respectively, and ASDs 0.08, 0.03 and 0.01, respectively).

Conclusions: During the study period, Spiriva Respimat initiators tended to be older, with more prior asthma exacerbations, more respiratory disease related hospitalizations, more co-morbidities, and more use of other drugs treating asthma compared to the other three groups. These differences in the baseline characteristics need to be considered in comparative studies to reduce channelling bias.