Spirometry: A Need for Periodic Updates of National Reference Values.

The aim of the study was to assess the need for changes in spirometry reference values in the Polish population with time lapse, as the aftereffect of a radical socioeconomic overturn of the 1990. We retrospectively analyzed data files on forced expiratory volume in 1 s (FEV1), vital capacity (VC), and forced VC (FVC) in healthy, never-smoking Caucasians (731 females and 327 males) obtained in in 1993-1998. We assessed a discrepancy between the then measured values of these variables, on the one side, and the corresponding European Community for Steel and Coal (ECSC) predicted values or the current updated predicted values for the Polish population, on the other side. We found that those old measured values approximately corresponded to the ECSC reference, but they were appreciably lower than the current Polish reference values; the younger the subjects the greater the difference. The current Polish reference values of FVC were much closer to the old measured VC than to the old measured FVC values, which introduces a substantial discrepancy between the past and present FVCs. We conclude that the spirometry reference values may change with time lapse. Thus, accuracy of prediction equations should be periodically updated, which seems to particularly concern the equations elaborated for the nations that undergo rapid economic developments connected with changes in living standards.