Normative Reference Values and Determinants of Pulmonary Function in Healthy Children and Adolescents: A Systematic Review and Meta-analysis

Abstract

Objective: Spirometry is one of the most vital assessment tools for evaluating pulmonary function in
individuals. However, its reference values in various populations are different. This variation is most evident
in children due to various variables like ethnicity, methodological variations, growth spurts, gaps in
understanding and performing PFT, etc. Over or underestimation of normative values can misdiagnose a child
for a pulmonary disorder. Hence, the present study aims to analyze different studies throughout the globe for
reference values of PFT (FEV1, FVC, FEV1/FVC, PEFR) in healthy children as well as adolescents.
Materials and methods: Various studies reporting normative values of PFT in healthy school-going children
between 1990 and 2024 were extracted from Google Scholar, PubMed and CINHAL according to inclusion
criteria through the Rayyan platform. A total of 22 studies (16,754 cildren) were included using PRISMA
guidelines. The required information was extracted by full-text review. Quality of studies was assessed using
the QUADAS scale. A random-effects model and forest plots for pulmonary functions (FVC, FEV1, PEFR
and FEF 25%-75%) were used to estimate heterogeneity and variations between studies in relation to gender.
Results: The pooled mean of FVC, FEV1, PEFR and FEF 25% - 75% was 2.53, 2.16, 4.77 and 2.92 liters for
boys and 2.16, 1.92, 4.43 and 2.56 liters for girls, respectively. The heterogeneity was as high as 97.37 % for
mean values of PEFR to minimum of 87.73 % for mean values of FVC. Multiple factors, including variable
methodological differences, variations in sample size, differing age groups among children, and ethnic
differences, in the included studies, lead to heterogeneity in all pulmonary function values.
Conclusions: Pulmonary function values are determinants of a healthy Pulmonary System. However, the
heterogeneity and variations seen in mean values make the implementation of PFT difficult, especially for
children, globally. Certain variables such as ethnicity, gender, and anthropometric measures, cannot be
modified; however, methodology, procedure of testing, and sampling techniques must follow a generalized
guideline throughout the globe. Furthermore, for clinical implications, predictive values to be considered
should be ethnic-specific.