Impact of asthma severity on long-term asthma control

Background: Asthma is a common childhood disease with significant morbidity. Severe asthma accounts for just 4-6% of patients, but this group is more difficult to treat and is responsible for up to 40% of asthma expenses.Objective: The relationship between asthma severity and control is not well characterized. The main objective of this study was to determine impact of asthma severity on asthma control over time.Methods: This was a three year, prospective observational cohort study at a tertiary care children's hospital. Results were compared over time and between patients with severe and non-severe persistent asthma. Intervention included therapy based on severity and control, accompanied by a NAEPP (EPR-3) guidelines based structured asthma education program.Results: The sample included 471 children referred from primary care offices with the diagnosis of persistent asthma, mean age 6.4 ± 2.4 years. Forty-one children (8.7%) had severe persistent asthma and 430 (91.3%) children had non-severe persistent asthma (mild-moderate persistent). Our sample size decreased over the three-year period and the number of patients completing the third year were 176 (38%) and among them 20 (11.4%) had severe asthma. At the initial visit, children with severe persistent asthma had significantly more acute care needs, more daily symptoms, and lower mean Asthma Control Test™ scores compared to children with non-severe persistent asthma. Differences between groups decreased within six months with significant improvements in most indicators persisting throughout three-year follow up in both groups (p < 0.05).Conclusion: Asthma control improves independent of severity if asthma guidelines are followed.