Characterization and burden of severe eosinophilic asthma in New Zealand: Results from the HealthStat Database

BACKGROUND: This retrospective cohort study aimed to characterize epidemiology, medication use and healthcare resource utilization (HCRU) of patients diagnosed with severe eosinophilic asthma (SEA) compared to other patients with asthma in New Zealand. METHODS: Adult patients with asthma with no concurrent diagnosis of Chronic Obstructive Lung Disease (COPD) were identified from the HealthStat primary care database and the National Minimum Dataset using asthma diagnosis, hospital codes and prescriptions. Patients with SEA were identified using a 1-year baseline period (2011) and were those with: inhaled corticosteroid prescription above medium dose (including high dose) plus controller medication, ≥2 exacerbations, and eosinophils ≥300 cells/μl (or ≥150 in 6 weeks prior to index date); patients were followed for 1 year (2012). RESULTS: 160/3,276 (4.9%) asthmatics with available eosinophil counts met SEA criteria. Patients with SEA were more likely to be Māori, former smokers, have more comorbidities, higher mean BMI and higher neutrophil counts compared with other patients with asthma. In the follow up period, SEA patients had over 4 times as many exacerbations; incidence of exacerbations of the same frequency was highest in Māori patients. CONCLUSIONS: Compared with other patients with asthma, SEA patients had over 1.5 times as many respiratory treatment prescriptions and higher all-cause HCRU and total healthcare costs; asthma-related healthcare costs were 3.6 times greater.