Collating Spirometry reference values in Asian children and Adolescents; puzzle out the reasons for variations

Abstract

Lung function tests are essential for the diagnosis and management of different respiratory tract diseases; among them the spirometry is the gold standard technique. The accurate diagnosis, management and monitoring require proper interpretation of the results which depends upon the availability of spirometry reference data for that particular region to differentiate the diseased condition from the normal ones. Multiple studies had been done to find out their own area specific reference ranges but it is still lacking. This need was fulfilled by the Global Lung Function Initiative (GLI) in 2012, which reported the first global spirometry equation for all of the age groups. But some of the studies reported difference among GLI reference range and the measured range for that particular region. So here is the review of the reference ranges among 35,603 Asian children and adolescents from the 32 studies done specifically in Asia. The aim was to compare them with the study done by GLI team, along with these, tried to rule out the causal factor that are responsible for the variations in the reference ranges among the children and adolescents of different population. The literature was searched by using Google scholar and PubMed during the month of March up to July 2017.The review of all the articles published in Asia, specifically accounting for normal reference ranges in children and adolescent exhibit a wide variation among the reference ranges. This also suggest involvement of multiple modifiable and non-modifiable risk factors. So it’s necessary to update the reference ranges for spirometry and its prediction equation as well.

Age peculiarities of spirometric indices within the juvenile period of ontogenesis

“…It has been proved that there is a direct relationship between the amount of forced exhalation volume for 1 second (FEV1), forced vital capacity of the lungs (FVC) and the mean expiratory flow (FEF 25-75%) with age, length and body weight [10]. In addition, a higher body mass index had a positive effect on the value of forced exhalation volume for 1 second (FEV1) and forced vital capacity (FVC) in the direction of their increase [15,18,20]. Thus, anthropometric indices are strong determinants of lung function change.…”

Factors affecting spirometry reference range in growing children

“…As there are multiple causal factors including age, sex, height weight, socioeconomic status cultural factors and biomass smoke exposure, that are responsible for significant variations in the range of spirometry variables among the populations. This created a confusion that which of the factor should keep as an independent variable while generating predictive equation15 and the current study developed a regression equation for children and adolescents, by putting age, height and weight as independent variables.…”

“…This created a confusion that which of the factor should keep as an independent variable while generating reference range. The association of age and height with the spirometry variables are established up to some extent but the exact correlation of weight is not yet cleared among Asian children and adolescents 15. So the aims of current study are to find out the association of weight, height and age with the spirometry variables and to generate a regression equation by taking weight as an independent variable beside age and height among children and adolescents of Karachi.…”