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Background: Severe asthma outcomes in primary care are poorly documented. This study characterizes adults with severe uncontrolled asthma and evaluates modifications of prescribed inhalation therapy and exacerbations over 12 months.

Methods: Adult primary care asthma patients, with visits recorded in the Swedish National Airway Register from July 2017 to February 2019 (index date), were included. Data were linked to National Prescribed Drug Register. Severe asthma was defined by adherence to high dose inhaled corticosteroids (ICS) ± long-acting beta-agonists (LABA) or ICS+LABA+long-acting muscarinic antagonists. Inhalation therapy was assessed 12 months pre- and post-index. All other variables were collected up to 24 months pre-index and 12 months post-index. Uncontrolled asthma was defined as Asthma Control Test ≤19.

Results: Severe asthma was identified in 2789 patients, of which, 1261 had uncontrolled disease. Severe uncontrolled asthma associated with regular OCS use 24 months pre-index (OR 1.77, 95% CI 1.42–2.20), obesity (1.63, 1.32–2.02), primary school education (1.55, 1.22–1.96) and inversely associated with asthma management education (0.77, 0.66–0.90). Post-index, 5%, 55% and 45% increased, maintained or reduced their inhalation therapy, respectively. Patients increasing inhalation therapy had lower mean FEV1% predicted (67.8 vs. 80.9 and 79.4), more regular OCS uses pre-index (34.8% vs. 17% and 21.9%), and high SABA use (33.3% vs. 27.3% and 21.3%). Post-index asthma exacerbations in severe uncontrolled asthma associated with rhinitis (1.46, 95% CI 1.14–1.88), cardiovascular disease (1.38, 1.06–1.80), high SABA use (1.79, 1.38–2.34), and treatment increase (1.83, 1.08–3.10).

Conclusion: In primary care, severe uncontrolled asthma was among other factors associated with regular OCS use, obesity, lower educational level and absence of asthma management education. Uncontrolled patients already adhering to high dose ICS medication and further increased inhalation therapy were at greater risk of exacerbations, indicating the need for referral to secondary care.