Angle ß combined with FeNO and FEV1/FVC% for the detection of asthma in school-aged children.

OBJECTIVE: The diagnostic value of angle ß in school-aged children with asthma is unknown. We speculate that angle ß may reflect diversification of the forced expiratory flow (FEF) to some extent. The objective of this study was to assess the diagnostic accuracy of angle ß, FeNO, pulmonary function parameters and their combinations for asthma in school-aged children. METHODS: In total, 248 children participated in this study (140 children with asthma and 108 healthy children). The diagnostic performance of angle ß, FeNO and pulmonary function parameters was determined using receiver operating characteristic (ROC) curves. In the ROC analysis, we used the hold out cross-validation method to avoid overfitting. This study was performed in China and followed the Guidelines for the diagnosis and optimal management of asthma in children (China). RESULTS: 1) In the asthma group, the mean angle ß value was significantly smaller than that in the control group (P < 0.001), but the mean FeNO value was significantly higher than that in the control group (P < 0.001). 2) More acute exacerbation or greater severity corresponded to a smaller angle ß. 3) Among the single indices, the area under the ROC curve of angle ß was the largest (except for FEV1/FVC%). For combined indicators, after cross-verification, the combination of angle ß, FEV1/FVC% and FeNO showed the highest diagnostic accuracy. CONCLUSION: Angle ß combined with FeNO and FEV1/FVC% can improve the diagnostic accuracy for asthma in school-aged children.

Curvilinearity of a Maximum Expiratory Flow-Volume Curve: A Useful Indicator for Assessing Airway Obstruction in Children With Asthma.

BACKGROUND: Lung function parameters are used as signs in the diagnosis and evaluation of asthma; however, their sensitivity and specificity are not ideal. We calculated and combined angle ß with lung function parameters to identify the ideal indicator. OBJECTIVE: We aimed to identify an ideal indicator for evaluating the severity of airway obstruction in children with asthma. METHODS: In total, 151 school-age children diagnosed with asthma were selected as the asthma group, and 106 healthy children were selected as the control group. The subjects were divided into the exacerbation group, chronic persistent group, and clinical remission group. Furthermore, the subjects were classified into mild and moderate groups or severe and critical groups. Angle ß was calculated in each group. A receiver operating characteristic curve analysis was performed to determine the cutoff values of angle ß and lung function parameters that together provided high sensitivity and specificity for airway obstruction evaluation in children with asthma. RESULTS: The mean value of angle ß in the asthma group was significantly smaller than that in the control group (178.18° and 196.72°, respectively, P < .001). More exacerbations or greater severity corresponded to smaller angle ß values (P < .001). The best cutoff value of angle ß was 189.43°, and the area under the receiver operating characteristic curve of angle ß was 0.877, which is greater than the area under the receiver operating characteristic curve of FEV1, forced expiratory flow (FEF) at 75% vital capacity (FEF25%), and FEF at 50% vital capacity (FEF50%), but smaller than the area under the receiver operating characteristic curve of FEF75% and FEV1/FVC%. Interestingly, combining these measures can enhance the sensitivity and specificity in assessing airway obstruction. CONCLUSIONS: Angle ß was a useful indicator for assessing airway obstruction. Furthermore, angle ß combined with FEV1, FEV1/FVC%, FEF25%, FEF50%, and FEF75% can enhance the sensitivity and specificity of airway obstruction evaluations.