Association between asthma control test, pulmonary function tests and non-specific bronchial hyperresponsiveness in assessing the level of asthma control

Introduction: Global Initiative for Asthma (GINA) reports emphasize the use of validated and simple tools in order to assess the level of asthma control, as the Asthma Control Test (ACT). However, an ACT does not include assessment of airway inflammation, which is better reflected when measuring nonspecific bronchial hyperresponsiveness (BHR). The authors aimed to find out if the level of asthma control quantified by an ACT correlates with BHR and pulmonary function tests.

Material and methods: 118 asthmatics participated in the study. All patients completed an ACT. The scores of the ACTs were compared with pulmonary function tests and BHR assessed with the methacholine challenge test and expressed as a provocative concentration of methacholine, inducing a 20% decline in the FEV1 (PC20 M in mg/ml).

Results: Patients with controlled asthma amounted to 52 (44%) while those with uncontrolled asthma amounted to 66 (56%). In patients with controlled asthma (ACT score ≥ 20) the mean geometric value of PC20M was 2.72 mg/ml (range from 0.25 to > 8.0), whereas 0.94 mg/ml (range from 0.28 to 8.0) (p = 0.02) was observed in patients with uncontrolled asthma (ACT score < 20). Almost 64% (21/33) of uncontrolled asthmatics achieved normal lung function (FEV1 > 80% pred. value) while 19% (5/26) patients with controlled asthma presented an FEV1 < 80% predicted value. Asthma duration in years in controlled asthmatics was significantly shorter than in uncontrolled patients (6.2 ± 8.9 vs. 12.0 ± 11.4, p = 0.005) CONCLUSION: In determining the most accurate level of asthma control it is reasonable to use an ACT in conjunction with BHR, which provides more accurate assessment of bronchial inflammation than ventilatory parameters alone.