Abstract
Ideally, serial measures of lung function should be compared using data from the person when young and healthy. In practice reference equations are the best substitute.
Aim: To compare the natural decline in spirometry in respiratory scientists using measured values and their reference value z-scores.
Methods: Serial measures of FEV1 and FVC from respiratory scientists were obtained. We calculated the annual decline in measured values and compared with z-scores using ECSC/ERS'93, Hankinson and GLI2012 equations.
Results: 2044 data points were available for 26 scientists (13 female) starting from 20-39 years up to 31-60 years. The data time-span was 5 to 33 years. The average fall in FEV1 was 29 mL/year and FVC 23 mL/year.
Age-related FEV1 and FVC z-scores for the equations are shown in Figure 1.
Discussion: The horizontal z-score trends using GLI2012 equations demonstrate they virtually match the rate of decline in FEV1 and FVC in our group of respiratory scientists. ECSC/ERS'93 elevates the z-score, and Hankinson shows a decreasing trend suggesting these equations are a poorer match for our longitudinal data.
Conclusion: This study suggests that the GLI2012 equations are more appropriate for monitoring lung function over time.
- © 2013 ERS