A27-03 Clinical Validation of GLI-2012 Spirometry Reference Values in 3-11 Year Old Italian Children

Background We previously reported a statistically significant difference between GLI-2012 spirometry reference values [1] and spirometry indices obtained in healthy children from northern and central Italy [2]. In the present study we aimed to evaluate whether this difference was significantly relevant in children referred to our ambulatory. Methods - Reference equations were calculated by linear regression using spirometry data previously obtained in 404 healthy children aged 3.2-11.5 years in Florence and Udine, Italy [2]. The GLI-2012 reference equations [1] were compared with our reference equations in children consecutively referred to our ambulatory in Florence because of a history of cough or wheezing. For GLI-2012, all spirometry indices were considered to be abnormal if the Z-score was <-1.64; when using our reference values, the Forced Expiratory Volume in 1 second (FEV1) was considered to be abnormal if the Z-score was <-1.64, while for the FEV1/Forced Vital Capacity (FEV1/FVC) ratio a value lower than 82% (corresponding to the 5th centile in our healthy children) was considered to be abnormal. Results - A total of 92 children aged 4.3-11.9 years referred to our ambulatory underwent spirometry. FEV1 was found to be abnormal in 15 children when using our reference equations, while only 5 children had abnormal FEV1 when using GLI-2012, and 2 children had abnormal FEV1 with GLI-2012 but not with our reference equations (p = 0.001 by Fisher’s exact test). Similarly, FEV1/FVC was abnormal in 15 children with GLI-2012 and in 24 children with our reference values (Fig.), and none of the children with normal FEV1/FVC with our reference values resulted abnormal with GLI-2012 (p < 0.001 by Fisher’s exact test). Conclusions - The GLI-2012 reference equations for spirometry may underestimate disease in the Italian pediatric population. [1] Eur Respir J 2012;40:1324-1343. [2] Am J Respir Crit Care Med 2019;199:A7448.