Does asthma control as assessed by the asthma control test reflect airway inflammation?

The treatment of asthmatic patients is particularly focused on the control of symptoms as well as functional and inflammatory parameters. In our study, we investigated the relationship between the asthma control test (ACT) which evaluates symptoms and airway inflammation and functional parameters.

Stable asthmatic patients admitted to our pulmonary outpatient clinic were enrolled in the study consecutively and underwent the ACT, pulmonary function tests and methacholine bronchial provocation test (MBPT). Additionally, fractional exhaled nitric oxide level (FeNO) and induced sputum cell distribution were assessed. All these parameters were re-evaluated at the third month after adjusting medications of the patients according to baseline ACT scores.

Of the 101 patients screened, we analyzed 83 who proceeded to the follow up visit. At the baseline visit, 8 were totally controlled, 36 partially controlled and 39 uncontrolled according to ACT. At the follow up visit, 10 were totally controlled, 39 partially controlled and 34 uncontrolled. Comparison of the two visits in terms of all parameters revealed significant reductions only in the percentages of patients with MBPT positivity (p = 0.029) and FeNO levels > 20 ppb (p = 0.025) at follow up. The percentages of patients with FeNO > 20 ppb, MBPT positivity, induced sputum eosinophilia or induced sputum neutrophilia did not show significant differences between totally controlled, partially controlled and uncontrolled groups at both baseline and follow up visits.

Although the ACT scores did not show significant correlations with the airway inflammation parameters tested in this study, a marked reduction in the percentage of patients with MBPT positivity and FeNO > 20 ppb at follow up may suggest the importance of the control concept in the management of asthma.