2.2 Asthma subgroups
Based on the presence and severity of asthma during baseline and follow-up, patients with CRSwNP were divided into subgroups: no asthma, mild to moderate asthma, severe controlled asthma, and severe uncontrolled asthma. Patients were considered to have asthma if they had an ICD-10: J45 diagnosis at least twice or at least two asthma controller medication purchases (inhaled corticosteroids (ICS) in single inhalers (ATC-codes: R03BA01, R03BA02, R03BA05, R03BA07, R03BA08, R03BA09) or in combination with long-acting beta-2-agonists (R03AK06, R03AK07, R03AK08, R03AK09, R03AK10, R03AK11)). Severe asthma was defined as asthma with a daily use of fluticasone propionate ≥ 800 µg or equivalent (80% adherence to 1 000 µg of fluticasone propionate or equivalent) complemented with at least one other controller (Leukotriene Receptor Antagonists (LTRA), Long-acting beta-agonist (LABA), Long-acting muscarinic antagonists (LAMA), or biologic asthma medication). The daily average ICS use was calculated as fluticasone propionate equivalent based on a sliding window of three consecutive purchases (the total micrograms of ICS at three consecutive purchases were divided by days from the first purchase to the fourth consecutive purchase). The patients with severe asthma were further divided into those with controlled and uncontrolled asthma. Asthma was considered uncontrolled in patients who had been hospitalized for asthma (ICD:10 J45-J46), had a record of emergency room visit for asthma (ICD:10 J45-J46), or had an outpatient visit for acute asthma (ICD-10: J46).