Abstract
AbstractBackgroundReferences from the Global Lung Function Initiative (GLI) are widely used to interpret children’s spirometry results. We assessed fit for healthy schoolchildren.MethodsLuftiBus in the school (LUIS) is a population-based cross-sectional study done from 2013-2016 in the canton of Zurich, Switzerland. Parents and children aged 6-17 years answered questionnaires about respiratory symptoms and lifestyle. Children underwent spirometry in a mobile lung function lab. We calculated GLI-based z-scores for FEV1, FVC, FEV1/FVC, and FEF25-75 for healthy White participants. We defined appropriate fit to GLI references by mean values ±0.5 z-scores. We assessed if fit varied by age, body mass index, height, and sex using linear regression models.ResultsWe analysed data from 2036 children with valid FEV1 measurements of which 1762 also had valid FVC measurements. The median age was 12.2 years. Fit was appropriate for children aged 6-11 years for all indices. In adolescents aged 12-17 years, fit was appropriate for FEV1/FVC (mean: -0.09; SD: 1.02) z-scores, but not for FEV1 (mean: -0.62; SD: 0.98), FVC (mean: -0.60; SD: 0.98), and FEF25-75 (mean: -0.54; SD: 1.02). FEV1, FVC, and FEF25-75 z-scores fitted better in children considered overweight (means: -0.25, -0.13, -0.38) than normal weight (means: -0.55, -0.50, -0.55; p-trend: <0.001, 0.014, <0.001). FEV1, FVC, and FEF25-75 z-scores depended on both age and height (p interaction: 0.034, 0.019, <0.01).ConclusionGLI-based FEV1, FVC, and FEF25-75 z-scores do not fit White Swiss adolescents well. This should be considered when using reference equations for clinical decision making, research and international comparison.Take home messageOur study suggests GLI-based FEV1, FVC, and FEF25-75 z-scores over detect abnormal lung function in Swiss adolescents, and more so among slimmer adolescents, which has important implications for clinical care, research, and international comparisons.
Publisher
Cold Spring Harbor Laboratory