Relationship of the Arabic version of the asthma control test with ventilatory function tests and levels of exhaled nitric oxide in adult asthmatics

OBJECTIVE: To determine the relationship between the asthma control test (ACT) score using the Arabic version, fractional exhaled nitric oxide (FENO), and lung functions, and to derive the cutoff points for the ACT score with the American Thoracic Society recommended FENO standard levels of inflammation control.

METHODS: We recruited 59 adult asthmatics out of which 53 subjects completed the study between July 2011 and June 2012 at King Saud University, Riyadh, Saudi Arabia. The FENO levels were measured by NIOX MINO (Aerocrine AB, Solna, Sweden), and ventilatory functions were recorded by standard techniques.

RESULTS: The FENO values were significantly higher in patients with an ACT score <20 (65.5+/= 35.4) compared with those patients with an ACT score >/= 20 (27.4+/=10.5, p<0.001). Among the well-controlled group based on the ACT score criteria, 6 (25%) cases had high FENO levels, while among the poorly controlled group, 23 (79.3%) cases had high FENO levels (odds ratio: 11.5; p<0.0001; confidence interval: 3.16-41.72). There was a significant negative correlation between FENO and ACT score (r=-0.581, p<0.0001). At the international cutoff point of 20, the sensitivity was 95.2, and the specificity was 68.8. The receiver operating curve (ROC) showed that maximum sensitivity and specificity were observed at an ACT score cut off point of 19 (sensitivity: 90.5, and specificity: 81.2).

CONCLUSION: The FENO levels correlate negatively with ACT scores however, the relationship between FENO and lung function is not significant. A significant relationship between ACT score and FENO levels indicate that there is an ongoing inflammatory state in patients with poor asthma control.