[Characteristics and regional reference standards of peak expiratory flow in children and adolescents in high-altitude regions of Xizang, China: a cross-sectional study].

<b>Objective:</b> To systematically evaluate the applicability of existing peak expiratory flow (PEF) prediction equations from plain area for children and adolescents in high-altitude regions of Xizang, and to establish PEF reference percentiles and prediction regression equations characteristic of high-altitude populations. <b>Methods:</b> A cross-sectional survey was conducted from September to October 2024 in 17 primary and secondary schools in Xizang, covering altitudes of 3 200 to 4 500 m. PEF was measured using a COSMED Micro Quark portable spirometer. Agreement between measured PEF values and those predicted by low-altitude equations was assessed using Bland-Altman analysis. Age-and sex-specific PEF reference percentiles were constructed using generalized additive models for location, scale and shape (GAMLSS), and local prediction regression equations were developed. <b>Results:</b> A total of 3 427 healthy children and adolescents in Xizang aged 7-17 years were included (1 567 boys and 1 860 girls). Plain-area prediction equations generally overestimated PEF in the pediatric population of Xizang. PEF reference percentiles were established based on the Box-Cox power exponential (BCPE) distribution, and local prediction equations were developed with height, weight, and residential altitude (or age) as the main explanatory variables. <b>Conclusions:</b> This study is the first to establish PEF reference percentiles and prediction equations for children on the Xizang plateau, clearly demonstrating the limitations of plain-area prediction equations in high-altitude populations. These findings provide a scientific basis for pediatric respiratory health screening, disease management, and public health policymaking in high-altitude regions.