Initiation of controller medication in newly diagnosed asthma patients: Impact on economic resource utilization

Introduction: To better understand the economic burden of asthma, we compared asthma-related direct costs among adults prescribed controller regimens. Methods: A cohort of newly diagnosed asthma patients (14-65 y/o), initiating a controller therapy for the first time between 1997 to 2007, was created from the health administrative database of British Columbia, Canada. Five cohorts of patients were created according to the way controller therapy was initiated: inhaled corticosteroid (ICS group), ICS/long-acting beta-agonist combination (ICS/LABA group), ICS+LABA in separate formulations (ICS+LABA group), leukotriene receptor antagonist (LRA group) or ICS+LRA in separate formulations (ICS+LRA group). Index Date (ID) was defined as the date controller medication prescribed. Direct cost of asthma in the post-ID year (2008 Canadian dollars) was calculated from the hospital, physician visits, and prescription records, adjusted for multiple covariates estimated from the pre-ID year. Results: 153,224 patients were included: 109,601 ICS; 34,184 ICS/LABA; 2,249 ICS+LABA; 6,289 LRA; 901 ICS+LRA. The average age was 37.7 and 61.0% were female. The average direct costs of asthma for the post-ID year for the ICS group was 265.2$. All other groups had higher incremental costs: ICS/LABA +$125.9, ICS+LABA +$218.2, LRA +$198.4, and ICS+LRA +$322.4 (all p<0.01). Older age, higher resource, and higher cumulative dose of rescue medicine use in the pre-ID year were predictors of resource use in the post-ID year (p<0.01). Conclusions: Initiation of ICS, as recommended by guidelines, was associated with the lowest costs than initiation of other controller or combination therapies.