Spirometric reference values for advanced age from a South german population

Background: The diagnostic use of lung function using spirometry depends on the validity of reference equations. A multitude of spirometric prediction values have been published, but in most of these studies older age groups are underrepresented.

Objectives: The aim of the present study was to establish new spirometric reference values for advanced age and to compare these to recent prediction equations from population-based studies.

Methods: In the present study spirometry was performed in a population-based sample from the KORA-F4 and KORA-Age cohorts (2006-2009, Augsburg, Germany) comprising 592 never-smoking subjects aged 42-89 years and with no history of respiratory disease. Using quantile regression analysis, equations for the median and lower limit of normal were derived for indices characterizing the expiratory flow-volume curve: forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC, peak expiratory flow (PEF), and forced expiratory flow rates at 25, 50 and 75% of exhaled FVC (FEF25, FEF50 and FEF75).

Results: FEV1 and FVC were slightly higher, and PEF was lower compared to recently published equations. Importantly, forced expiratory flow rates at middle and low lung volume, as putative indicators of small airway disease, were in good agreement with recent data, especially for older age.

Conclusion: Our study provides up-to-date reference equations for all major indices of flow-volume curves in middle and advanced age in a South German population. The small deviations from published equations indicate that there might be some regional differences of lung function within the Caucasian population of advanced age in Europe.