[Comparison of the Asthma Control Test (ACT) with lung function, levels of exhaled nitric oxide and control according to the Global Initiative for Asthma (GINA)].

INTRODUCTION

The current goal of asthma treatment is to achieve and maintain control. This study aimed to explore the relationship between the ACT (Asthma Control Test) questionnaire and the levels of control according to GINA (Global Initiative for Asthma) to establish the cut-off points for the ACT and evaluate its relationship with lung function and fractionated exhaled nitric oxide level (FeNO).

PATIENTS AND METHODS

A multi-centre prospective study including 441 patients followed up in an outpatient Chest Clinic. A clinical protocol was followed, and FeNO, spirometry and ACT performed. Disease was classified according to levels of control using GINA. The study analysed sensitivity, specificity and area under the curve (ROC), and the ACT cut-off points. We studied the differences between the functional parameters and FeNO between levels of control.

RESULTS

For controlled asthma the cut-off obtained was ACT> or =21 (area under the curve 0.791) and for uncontrolled < or =18 (AUC 0.774). We found significant differences in FeNO levels and pulmonary function among ACT> or =21 and ACT< or =18, although only 26.3% of patients with ACT< or =18 had a FEV1 <80% and 40% higher FeNO (> or =35 ppb). We found a correlation between baseline FEV1 and ACT (r=0.19, P<0.01) and between ACT and FeNO (r=-0.16, P<0.01).

CONCLUSIONS

The cut-off points would be, for controlled asthma ACT> or =21, partly controlled asthma ACT=19-20 and uncontrolled asthma ACT< or =18. A more complete assessment would require including monitoring operating parameters and FeNO.