Real-world observational study on the characteristics and treatment patterns of allergic asthma patients receiving omalizumab in Canada

Abstract

Background: Omalizumab is a treatment option for pediatric and adult patients with moderate to severe allergic asthma poorly controlled with standard inhaled therapies. Clinical trials and observational studies have demonstrated the efficacy of omalizumab. There is limited real-world evidence on the characteristics and treatment patterns of Canadian asthma patients receiving omalizumab. Objective: We profiled Canadian omalizumab users to estimate time to omalizumab discontinuation and to assess changes in concurrent medication usage before, during, and after therapy. Methods: This was a retrospective, observational, cohort study that analyzed data from Canadian prescription claims databases. An algorithm was used to select naïve users of omalizumab with an inferred diagnosis of GINA 5-asthma who made a claim for omalizumab from February 1, 2007, to June 2, 2015. Demographic and baseline characteristics were assessed at index. Outcomes examined over the analysis period included (i) daily omalizumab dose per patient and per claim; (ii) omalizumab discontinuation (defined as ≥100-day gap in making omalizumab claims) and its potential predictors (ie, age, sex, province of residence, drug insurer; assessed by Cox Proportional Hazards Model); and (iii) for patients who discontinued omalizumab, changes in concurrent medication usage before, during, and 6 months after omalizumab usage. Results: The final study cohort consisted of 1160 patients (mean age: 45.8 ± 15.2 years; 64.7% female). During the first year of omalizumab therapy, 29.5% of patients discontinued treatment. The singular characteristic that predicted omalizumab discontinuation with statistical significance was age group (20-34 years vs 12-19 years; hazard ratio 1.75, 95% confidence interval 1.11-2.76; P<0.05). There were significant reductions in the use of some concurrent inhaled and oral asthma medications during and/or after omalizumab use (P<0.05). Conclusion: Nearly one-third of patients who initiated omalizumab in Canada for refractory, moderate to severe allergic asthma discontinued treatment during the first year.