Background. The proportion of severe asthma among the asthma population of Estonia is unknown. However, real-life data are necessary for planning resources for treatment of properly pre-phenotyped patients with right biologics to ensure highlevel asthma control.
Objectives. The primary objective was to estimate the number of patients with severe or uncontrolled asthma in Estonia. Secondary objectives included description of treatment and prescription patterns across the continuum of asthma severity.
Study design. This is a descriptive, observational, nationwide, retrospective study that includes data from all adult Estonian residents aged ≥20 years, with asthma who had redeemed asthma medication from October 2015 through September 2017 based on the information extracted from a nationwide prescription database. The inclusion criteria for the search were ATC codes R01, R03, and H02, diagnoses J45.00-J45.99 (asthma by ICD-10), and presence of health insurance provided by the Estonian Health Insurance Fund. Patients whose follow-up time after first prescriptions was <12 months were excluded. For identification of severe asthma by GINA, three criteria were used: 1) continuous or frequent use of oral corticosteroids (OCS), 2) use of high-dosage inhaled corticosteroids (ICS), 3) frequent use/overuse of short-acting beta2-agonists (SABA), and 4) ≥1 prescription for a third asthma controller medicine. Patients were classified as having GINA-defined severe asthma if combinations of 1 and 2 or 2 and 3 were met for ≥12 months and severe asthma by the Estonian criteria for eligibility for treatment with biologics, if the criterion 4 was additionally met.
Results. During the study period, 36,392 patients met the inclusion criteria. GINA defined severe asthma was found in 1,905 patients (5.2%). Of them, 195 (0.5%) met the criteria 1+2 and 1,710 (4.7%) met the criteria 2+3. A total of 524 patients (1.4%) had severe asthma according to the Estonian eligibility criteria for treatment with biologics. Of the latter, 96 patients (18.3%) met the criteria 1+2+4 and 428 patients (81.7%) met the criteria 2+3+4. There were 221 different combinations of 10 groups of asthma medication, whereas 18 most frequent combinations accounted for treatment of 91.0% of patients with the leading combination being ICS/long-acting beta2-agonist (LABA) combination used by 43.5 % of all patients. In severe asthma by GINA, the leading combination was ICS/ LABA + SABA, used by 49.3% of the respective patients. In severe asthma by GINA, the medicines were prescribed most often by primary care physicians (for 40.4% of the patients), followed by prescriptions made alternatingly by primary care physicians and pulmonary specialists (in 36.8% of the patients).
Conclusions. This nationwide, prescription database-derived study could be of value for primary identification of patients with potentially severe asthma. The secondary endpoint data can be usable for improving primary care practices and for designing IT solutions for both decision making in primary care and for ensuring proper patient pathways through the health care system.