Impact of asthma severity on long-term asthma control.

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. 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. 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. 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 ( < 0.05). Asthma control improves independent of severity if asthma guidelines are followed.