Abstract

Background
The Global Lung Initiative 2012 (GLI‐2012) spirometry equations are multi‐ethnic equations that cover all ages between 3 and 95. However, there is a need to evaluate the suitability of these equations to a sample of Middle Eastern adolescents prior to being applied in clinical practice. The aim of this study is to evaluate the suitability of GLI‐2012 equations and two regional equations to a sample of Jordanian adolescents.

Methods
Spirometric measures were collected from 1036 healthy 14 to 17‐year‐old Jordanian children. z‐scores, predicted values, percent predicted values, and frequency of measures below lower limit of normal (LLN) were calculated for each adolescent using the studied equations.

Results
The means of z‐scores produced by GLI‐2012 equations for Caucasians in forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), FEV1/FVC% and mid forced expiratory flow (FEF25‐75) for boys were 0.12, −0.06, 0.34 and 0.09, respectively, while for girls they were −0.09, −0.16, 0.19 and −0.05, respectively. The mean of z‐scores produced by GLI‐2012 Other or Mixed equations in FEV1, FVC, FEV1/FVC% and FEF25‐75 for boys were 0.74, 072, 021 and 0.33, respectively, and for girls were 0.53, 0.56,0.02 and 0.2, respectively. The frequency of measures below LLN as produced by GLI 2012 for Caucasians were significantly different from the expected 5% in FEV1 and FEF25‐75 in boys only, whereas Other or Mixed produced frequencies significantly different from the expected 5% in most of the parameters.

Conclusion
Spirometry reference equations formulated for Jordanian adolescents may improve the diagnosis and treatment of asthma in Jordan.