Relationship of the asthma control test with pulmonary function and exhaled nitric oxide

The Asthma Control Test (ACT) is a short, simple, patient-based tool for identifying patients with poorly controlled asthma; however, its value in practice has yet to be demonstrated.

To clarify the relationship of ACT scores and clinical parameters, including pulmonary function tests, peak expiratory flow (PEF) indices, and exhaled nitric oxide (eNO) levels.

The study included 105 patients with asthma who underwent routine checkups by asthma specialists since September 1, 2006, through January 31, 2007. All patients had been taking inhaled corticosteroids with or without other medications for asthma for at least 3 months. The patients completed the ACT questionnaire and underwent testing for eNO and spirometry. PEF indices, including PEF percentage of predicted value (%PEF), lowest PEF during 1 week expressed as a percentage of the highest PEF (Min%Max PEF), and PEF variability, were also analyzed in patients undergoing PEF monitoring.

The ACT scores ranged from 8 to 25 (median, 24), and total control was obtained in 45 patients (42.8%). The PEF indices and eNO values in the total control group were significantly better than those in the less controlled groups. However, the ACT scores were weakly correlated with percentage of predicted forced expiratory volume in 1 second (r = 0.219), %PEF (r = 0.387), Min%Max PEF (r = 0.354), PEF variability (r = -0.351), and eNO values (r = -0.310). Total control of ACT included uncontrolled conditions in physiologic and inflammatory parameters.

ACT should be used in combination with pulmonary function tests and/or eNO measurements.