Global Lung Function Standardisation: Finally Making Our Dream a Reality?

Abstract

age, sex, height and ethnic group. Until now, it has been difficult to interpret spirometry, particularly in geriatric patients and in different ethnic groups. Crucially, the main advantage of the GLI2012 equations is that they are applicable over a wider age range (3–95 years of age) than any other published reference data and, in addition, robust predicted values for multiple ethnic groups are available. As we are consulted by increasingly ageing populations [6] , in the absence of clear LLN, it is often frustrating to correctly attribute clinical relevance to subtle respiratory symptoms and borderline ventilatory abnormalities in elderly patients who may present with many concomitant co-morbidities that could provide an alternative (and often more plausible) explanation for their symptoms. In addition, spirometry may also be influenced by ethnicity [7] and, as we are practising clinicians in an increasingly cosmopolitan world, this variable is now very relevant. The authors report a change in the prevalence rates of airflow obstruction of up to 32% between the three equations (NHANES III, the Stanojevic equations and GLI2012). Notably, these discrepancies were due to differences in LLN rather than in mean values for FEV 1 /FVC ratios. Switching to the GLI2012 spirometry reference values will impact on the interpretation of spirometry test results, and the magnitude and direction of the change depends upon which reference data are used. In this issue of Respiration , Brazzale et al. [1] investigate the clinical implications of changing from the commonly used current spirometry equations for references values, such as the European Community for Steel and Coal (ECSC) [2] , the National Health and Nutrition Examination Survey (NHANES III) [3] and the Stanojevic all-ages reference equations [4] to the Global Lung Function Initiative (GLI2012) equations. The GLI2012 (http://www.lungfunction.org) equations are the result of a huge international cooperation and have already been endorsed by six international scientific societies (the American College of Chest Physicians, the American Thoracic Society, the Asian Pacific Society of Respirology, the Australian and New Zealand Society of Respiratory Science, the European Respiratory Society and the Thoracic Society of Australia and New Zealand) and incorporated into the software equipment of many spirometers. Data from 74,187 healthy nonsmoker (57.1% females) subjects, aged 3–95 years, from 72 centres in 33 countries, were studied to derive multiethnic reference equations and age-dependent lower limits of normal (LLN) [5] . The authors of this Herculean effort should be congratulated by the scientific community for providing us with these long-awaited reference values. Lung function tests provide us with vital information in our everyday clinical practice. However, spirometric indices vary with Published online: August 16, 2013