Study highlights increase in mean lung function over past century in European adults

Mean FEV₁ and FVC increased over time among European adults born from 1884 to 1996, researchers reported in The Lancet Respiratory Medicine.

“These increases appeared to exceed the expected impact of increasing height and have led mean population FEV₁ and FVC to progressively deviate from, and be underestimated by, currently predicted values. By contract, the mean FEV₁/FVC ratio decreased over this period,” James P. Allinson, PhD, respiratory specialist in the department of respiratory medicine at Royal Brompton Hospital and honorary senior clinical lecturer at the National Heart and Lung Institute at Imperial College London, and colleagues wrote. “We believe that these two changes will have resulted in the easier fulfillment of COPD diagnostic criteria and the progressive underestimation of disease severity.”

After adjusting for age, study, height, sex and smoking status, FEV₁ increased by 4.8 mL per birth year (P < .0001) and FVC increased by 8.8 mL per birth year (P < .0001). These findings were corroborated by birth year-related FEV₁ and FVC value increases predicted by 32 reference equations published from 1961 to 2015, the researchers wrote.

According to the researchers, height-independent increases in FEV₁ and FVC over the last century likely caused mean population values that progressively exceeded values predicted previously.

“This finding indicates a changing relationship between height and lung function,” the researchers wrote.

Conversely, the population mean-adjusted FEV₁/FVC ratio decreased by 0.11 per 100 birth years after adjustment (P < .0001).

“Our study highlights the need to update reference equations for populations from high-income European countries to better reflect current normal values and to reevaluate our approach to interpreting longitudinal lung function data,” the researchers wrote.