Pulmonary function of healthy Korean children from three independent birth cohorts: Validation of the Global Lung Function Initiative 2012 equation

Abstract

Background and Objective Global Lung Function Initiative (GLI) 2012 equations were developed to resolve the age‐related disparity in interpreting spirometry results. Local validation of the equation is needed, especially in Northeast Asian children. This study evaluated the GLI equation in Korean children. Methods Spirometry indices (FEV1, FVC, FEV1/FVC, and FEF25%–75%) and clinical information were gathered from three population‐based birth cohorts. Predicted GLI reference values and z scores of spirometry results were calculated for 1239 healthy children. The mean, standard deviation of z scores were compared with the expected 0 and 1. Probabilities of falling below the lower limit of normal (LLN) (z score: −1.64) were compared with the expected value 5%. GLI z scores were assessed according to low (<−2), normal (≥−2 and ≤2), and high (>2) BMI z score groups. Results Mean z scores significantly differed from 0 for FEV1/FVC in males (mean [95% confidence interval]: 0.18 [0.08, 0.27]) and forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) in females (−0.23 [−0.31, −0.15] and −0.26 [−0.36, −0.16], respectively). The standard deviation was larger than 1 for all variables in males and FVC and FEV1/FVC in females. The probability of falling below the LLN was significantly larger than 5% for FEV1 (12.13% [9.64, 14.77]), FVC (15.86% [13.06, 18.81]), and forced expiratory flow at 25%–75% of forced vital capacity (FEF25%–75%) (7.31% [5.29, 9.49]) in males and FVC (11.91% [9.40, 14.60]) in females. FEV1 and FVC z scores increased across low to high body mass index (BMI) groups, and FEV1/FVC decreased from low to high BMI groups. Conclusion GLI equations marginally differ from real‐world values, which should be considered by pulmonologists in practice or research.

Age and body mass index affect fit of spirometry Global Lung Function Initiative references in schoolchildren

“…increased dysanapsis) for children considered overweight and obese [ 9 ]. In line with our findings, previous studies have described associations between BMI and GLI-based lung function z-scores in children [ 40 , 41 ].…”

“…This aligns with our findings and may be due to asymmetric lung growth (i.e., increased dysanapsis) for children considered overweight and obese [9]. In line with our findings, previous studies have described associations between BMI and GLI-based lung function z-scores in children [40,41]. P values for a trend in z-scores across ordered categories of BMI were <0.001 for FEV1, 0.014 for FVC, <0.001 for FEV1/FVC, and <0.001 for FEF25-75.…”

Pulmonary function outcomes after tuberculosis treatment in children: a systematic review and meta-analysis

“…As the GLI-2012 equation17 for North East Asian ethnicity was developed using only subjects aged ≥16 years, the spirometry z-scores for young children in this study22 were calculated using extrapolation, which may have inadvertently inflated the effect sizes. This inference was partially supported by a validation study31 which found that South Korean females aged 7–8 years have mean FEV 1 and FVC z-scores lower than the GLI-2012 predictions by −0.23 (95% CI −0.31, –0.15) and −0.26 (95% CI −0.36, –0.16), respectively, suggesting the actual lung function for this subgroup is slightly below established baseline. A secondary analysis which excluded this outlier study22 from the meta-analyses yielded an alternative random-effects model for FEV 1 based on three studies with reduced statistical heterogeneity (red diamond; figure 2).…”

Pulmonary Function Outcomes after Tuberculosis treatment in Children: A Systematic Review and Meta-analysis

“…As the GLI-2012 equation 17 for North East Asian ethnicity was developed using only subjects aged ≥16 years, spirometry z-scores for this study 22 were calculated using extrapolation for young children, which may have inadvertently inflated effects sizes. This inference was partially supported by a validation study 31 which found that South Korean females aged 7-8 years have mean FEV 1 and FVC z-scores lower than GLI-2012 predictions by -0.23 (95% CI: -0.31, -0.15) and -0.26 (95% CI: -0.36, -0.16) respectively, suggesting actual lung function for this subgroup is slightly below established baseline. A secondary analysis which excluded this outlier study 22 from meta-analyses yielded an alternative random-effects model for FEV 1 based on three studies with reduced statistical heterogeneity (red diamond; Figure 2).…”