Forced oscillation technique as a predictor for loss of control in asthmatic children

Abstract

Background A reliable objective tool using as a predictor of asthma control status could assist asthma management. Objective To find the parameters of forced oscillation technique (FOT) as predictors for the future loss of asthma symptom control. Methods Children with well-controlled asthma symptom, aged 6-12 years, were recruited for a 12-week prospective study. FOT and spirometer measures and their bronchodilator response were evaluated at baseline. The level of asthma symptom control was evaluated according to Global Initiative for Asthma. Results Among 68 recruited children, 41 children (60.3%) maintain their asthma control between 2 visits (group C-C), and 27 children (39.7%) lost their asthma control on the follow-up visit (group C-LC). Baseline FOT parameters, including the values of respiratory resistance at 5 Hz (R5), respiratory resistance at 20 Hz (R20), respiratory reactance at 5 Hz, area of reactance, %predicted of R5 and percentage of bronchodilator response (%∆) of R5 and R20 were significantly different between C-C and C-LC groups. In contrast, only %∆ of forced vital capacity, forced expiratory volume in 1 second (FEV1), and FEF25%-75% (forced expiratory flow 25%-75%) were significantly different between groups. Multiple logistic regression analysis revealed that %predicted of R5, %∆R5, %predicted of FEV1 and %∆FEV1 were the predictive factors for predicting the future loss of asthma control. The following cutoff values demonstrated the best sensitivity and specificity for predicting loss of asthma control: %predicted of R5=91.28, %∆R5=21.2, %predicted of FEV1=89.5, and %∆FEV1=7.8. The combination of these parameters predicted the risk of loss of asthma control with area under the curve of 0.924, accuracy of 83.8%. Conclusion Resistance FOT measures have an additive role to spirometric parameter in predicting future loss of asthma control.