Lung function reference values in children and adolescents aged 6 to 18 years in Galicia

OBJECTIVE: it is well known that lung function reference values differ between populations, hence the apparent importance of establishing such values. The aim of this study was to develop prediction equations for spirometry for healthy children and adolescents in Galicia, Spain. POPULATION AND METHODS: We studied children and adolescents aged 6 to 18 years from randomly selected schools in 14 municipalities in Galicia. Spirometric values were measured following the protocols established by the American Thoracic Society in 1987, with real-time monitoring of flow-volume curves. The prediction equations were derived using multivariate linear regression. RESULTS: We developed equations to predict the main spirometry parameters for this age group according to sex, height, and weight. Mean spirometry values in relation to height were higher for boys than for girls, except in the 140-160 cm range, where they were higher for girls. Equations published in other studies in similar populations gave different predictions, ranging from an underestimation of forced midexpiratory flow rate (FEF25%-75%) by 16% in comparison to ours to an overestimation of peak expiratory flow (PEF) rate by 15% for an average boy. For a girl, the corresponding differences ranged from an underestimation of FEF25%-75% by 17% to an overestimation of PEF by 19%. CONCLUSIONS: These results support the importance of using population-specific prediction equations to establish lung function reference values.