Under-treated asthma in adults – a common problem

Abstract

Background: Patients with under-treated asthma i.e. uncontrolled asthma in treatment step 1-3, remain poorly studied.

Aim: To study factors associated with under-treated asthma in a large adult asthma cohort.

Methods: We studied 28584 asthma patients (≥18yr) registered in the Swedish National Airway Register between 2017 and 2019. We linked the recordings to other national registers to obtain information on prescribed drugs up to a 2-year pre-index period, and education. Patients were classified into treatment step 1-3 and 4-5, and patients in step 1-3 with uncontrolled asthma were further defined as under-treated asthma since treatment escalation is possible. Uncontrolled asthma was defined as: ACT ≤19 and/or previous exacerbations and/or FEV1<80% predicted. Future exacerbations (oral corticosteroids; OCS, or hospitalization) were identified in a 1-year post-index period.

Results: Step 1-3 included; 17318 patients, of which 9586 (55%) were under-treated, and step 4-5; 11266 patients. In adjusted analyses, female sex, older age, overweight, obesity, current smoker, primary education and secondary education were associated with under-treated asthma. Under-treated asthma had similar OR as step 4-5 treatment when analyzing associations with future exacerbations: OCS≥2 (under-treated: ORadj 2.11, 95% CI 1.94-2.30; step 4-5: 2.55, 2.35-2.77), and hospitalization (under-treated: 2.66, 2.26-3.12; step 4-5: 3.79, 3.25-4.41).

Conclusions: Under-treated asthma in step 1-3 is common, and associates with female sex, current smokers, higher BMI, and lower socio-economic status. After evaluation of inhaler technique and adherence, appropriate escalation of treatment is important as these patients have an increased risk for future exacerbations.