[The cutoff value of FEV(1)/FVC as the criteria of airway obstruction in children].

To explore the cutoff value of FEV(1)/FVC for evaluating obstructive ventilation dysfunction in children. Three hundred and eighty-three healthy children (190 boys and 193 girls) aged 6-14 years in primary and middle school in Beijing, who were enrolled from May 2010 to June 2011, had their spirometry done with the Jaeger lung function instrument, and the lower limit of normal (LLN) of FEV(1)/FVC was calculated. Two hundred and thirteen asthmatic children (151 boys and 62 girls) aged 6-14 years from the outpatient Department of Allergy, Capital Institute of Pediatrics were enrolled consecutively from June to July 2018, whose clinical history and pulmonary function parameters were collected. The expected value of spirometric parameters of asthmatic children was calculated according to Zapletal prediction equations. And the LLN of FEV(1)/FVC in healthy children was used as the gold standard to calculate the sensitivity, specificity, Youden index and Kappa value of FEV(1)/FVC<80% and FEV(1)/FVC< 92% predicted. In healthy children, the FEV(1)/FVC and the LLN were 91%±5% and 82% respectively, while 90%±6% and 81% in boys, and 92%±5% and 84% in girls. There were 27 (12.7%) asthmatic children whose FEV(1)/FVC<80% but FEV(1)/FVC≥92% predicted (χ(2)=123.7, 0.01). The sensitivity, specificity, Youden index and Kappa value of FEV(1)/FVC<80% were 80.3%, 100%, 0.803 and 0.787 respectively when FEV(1)/FVC<80% was used as the criteria to assess lung function, while they were 57.3%, 100%, 0.573 and 0.547, respectively, when FEV(1)/FVC<92% predicted was used as criteria. The 80% of FEV(1)/FVC has a better consistency with the LLN of FEV(1)/FVC than 92% of FEV(1)/FVC% predicted. It is more accarate to use FEV(1)/FVC<80% as the diagnostic criteria for airway obstruction.