Background: Severe and uncontrolled asthma is associated with increased risk of exacerbations and death. A substantial proportion of asthma patients have poor asthma control, and a concurrent COPD diagnosis often increases disease burden. The objective of the study was to describe the prevalence and managemant of severe asthma in a Swedish asthma popuöation.
Methods: In this observational cohort study, primary care medical records data (2006-2013) from 36 primary health care centers were linked to data from national mandatory Swedish health registries. The studied population (>18 years) had a record of drug collection for obstructive pulmonary disease (ATC code R03) during 2011-2012, and a physician diagnosed asthma (ICD-10 code J45-J46) prior to drug collection. Severe asthma was classified as collection of high dose inhaled steroid (> 800 budesonide or equivalent per day) and leukotriene receptor antagonist and/or long-acting beta-agonist. Poor asthma control was defined as either collection of ≥600 doses of short-acting beta-agonists, and/or ≥1 exacerbation(s) during the year post index date.
Results: A total of 18,724 asthma patients (mean 49 years, 62.8% women) were included, of whom 17,934 (95.8%) had mild to moderate and 790 (4.2%) had severe asthma. Exacerbations were more prevalent in severe asthma (2.59 [2.41-2.79], Relative Risk [95% confidence interval]; p < 0.001). Poor asthma control was observed for 28.2% of the patients with mild to moderate asthma and for more than half (53.6%) of the patients with severe asthma (<0.001). Prior to index, one in five severe asthma patients had had a contact with secondary care and one third with primary care. A concurrent COPD diagnosis increased disease burden.
Conclusion: Severe asthma was found in 4.2% of asthma patients in Sweden, more than half of them had poor asthma control, and most patients had no regular health care contacts.
Keywords: Asthma prevalence; Severe asthma; Uncontrolled asthma.