Validity of the Handheld Expiratory Flowmeter for COPD Screening in the Primary Care Setting of China

The use of simple and affordable screening tools for chronic obstructive pulmonary disease (COPD) is limited. We aimed to assess the validity of a handheld expiratory flowmeter (Vitalograph Ltd., COPD-6^®, Ireland) for COPD screening in Chinese primary care settings.

In our cross-sectional study, subjects were randomly selected in eight primary care settings. Tests with the handheld expiratory flowmeter and the conventional spirometry were sequentially performed on all participants. The correlation between the handheld expiratory flowmeter and the conventional spirometry was determined. Validity was determined by the area under the receiver operator characteristic curve (AUC) of the forced expiratory volume in one second (FEV₁)_/forced expiratory volume in six seconds (FEV₆) that used to detect airway obstruction. The sensitivity, specificity, predictive values, and likelihood ratio were calculated according to different FEV₁/FEV₆ cut-off points.

A total of 229 subjects (15.4%) were diagnosed with airflow limitation by conventional spirometry. FEV₁, FEV₆, and FEV₁/FEV₆ measured by the handheld expiratory flowmeter were correlated with FEV₁, FVC, and FEV₁/FVC measured by the conventional spirometry (r=0.889, 0.835 and 0.647, p<0.001), respectively. AUC of the FEV₁/FEV₆ to determine airflow obstruction was 0.857 (95% CI: 0.826 to 0.888). No significant difference of AUC was observed between the symptomatic group and the asymptomatic group (AUC=0.869 vs 0.843, P=0.425). A similar phenomenon was found in the AUC of smokers and never-smokers (AUC=0.862 vs 0.840; P=0.515). The cut-off point for FEV₁/FEV₆ was 0.77 and the corresponding sensitivity and specificity were 71.2% and 89.8%, respectively.

The handheld expiratory flowmeter might be used as a screening device for COPD in Chinese primary care settings.