Background and objectives: Applicability data of the Global Lung Function Initiative (GLI)-2012 prediction equations for Asian children are limited. We aimed to assess the applicability of the GLI-2012 prediction equations to Hong Kong children and to develop new prediction equations.

Methods: Healthy Chinese children aged 6-17 years old were recruited from randomly selected schools to undergo spirometric measurements, which were transformed to z-scores according to the GLI-2012 South East (SE) Asian equations to evaluate the fitness of the equations. Prediction equations for spirometric index were developed based on Generalised Additive Models for Location, Scale, and Shape (GAMLSS) modelling. 

Results: 886 children (477 boys, mean age: 12.5 years; standard deviation (SD): 3.3 years) were included. In both sexes, positive mean z-scores for spirometric indices according to GLI-2012 were observed in FEV1 (boys: z-score ± SD: 0.138 ± 0.828, p<0.001; girls: 0.206 ± 0.823, p<0.001), and FVC (boys: 0.160 ± 0.930, p<0.001; girls: 0.310 ± 0.895, p<0.001). However, a negative mean z-score was observed in FEV1/FVC ratio in girls (-0.223 ± 0.897, p<0.001). By GAMLSS models, age and height were significant predictors for all four spirometric indices, while weight was an additional predictor for FVC and FEV1. Our GAMLSS models showed better predictions for spirometry than the GLI-2012 equations.

Conclusion: GLI-2012 SE Asian prediction equations underestimated FEV1 and FVC in Hong Kong children, reflecting the potential secular trends of improved spirometric function over time. Besides age, sex and height, weight was also a factor contributing to the variability of lung function in children.