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FEV1/FVC ratio: a surprise

Biphasic course of FEV1/FVC in childrenFig. 1 - Predicted FEV1/FVC in white males.

Analysis of the FEV1/FVC ratio led to an unexpected result. The predicted value fell quickly between 3 and approximately 10 years of age, followed by a small increase up to about 16 year, and then a gradual non-linear decline in adults (figure 1). As this pattern had never been described before the first thought was that we were dealing with an artefact arising from the collation of so many datasets. After all, if one centre would contribute data with an unusually low FEV1/FVC ratio in and around the 10 year age range, this could explain the findings. However, no centre had contributed a group of children limited to this fairly narrow age range.

 


Biphasic FEV1/FVC in children from different parts of the worldFig. 2 - Data from 15 centres, comprised of different ethnic groups, generally display the same pattern: rapid decline of FEV1/FVC ratio until the start of the adolescent growth spurt, then a small increase followed by a decline.

Evidence that the findings were not an artefact came from analysis of data from boys and girls from 15 difference centres, comprising different ethnic groups (figure 2, [1]). As the determinants of the FEV1 and the VC are not the same, it follows that after birth the vital capacity grows proportionally faster than the FEV1, and that this pattern is temporarily reversed during the adolescent growth spurt [1].

Reference

  1. Quanjer PH, Stanojevic S, Stocks J et al., for and on behalf of the Global Lung Initiative. Changes in the FEV1/FVC ratio during childhood and adolescence: an intercontinental study. Eur Respir J 2010; 36: 1391-1399. Manuscript

Acknowledgement: Figure 2 modified and reproduced with permission of the European Respiratory Society. Eur Respir J December 2010 36:1391-1399; published ahead of print March 29, 2010, doi:10.1183/09031936.00164109

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