Implications of the Transition From Zapletal to GLI Reference Values for Spirometry

The current standard for monitoring lung function in children with asthma is spirometry. In Europe, results of these lung function tests have been related to Zapletal reference values published in 1977. Recently, the Global Lung Function Initiative (GLI) published predicted values of spirometry for 5 ethnic groups, valid over an age range from 3 to 95 years. These reference values have been approved by many international lung societies, and the algorithms are increasingly being implemented globally. This report describes the consequences of the transition from Zapletal reference values to GLI reference values for 2 pediatric asthma patients, which include unexpected declines in lung function and the ability to take advantage of newly approved reimbursement for advanced therapy. The Zapletal and GLI reference values cannot be used interchangeably, and transition to the GLI values might lead to better treatment in the future.