Spirometry: A Comparison of Prediction Equations Proposed by Lubiński for the Polish Population with Those Proposed by the ECSC/ERS and by Falaschetti et al.

Introduction: Prediction equations proposed by the European Community of Steel and Coal (ECSC) and the European Respiratory Society (ERS) or those proposed by Falaschetti et al. for the English population are currently recommended for use in Poland. The aim of the present study was to compare these equations with those developed by Lubiński and Gólczewski for the Polish population—both in terms of methodological correctness and appropriateness to the present Polish population. Materials and methods: The ECSC/ERS prediction equations, the Falaschetti equations, and the Polish equations (developed on the basis of data on healthy, non-smoking Poles aged 18 to 85 years [1120 men and 1625 women] who underwent spirometry in accordance with the American Thoracic Society [ATS]/ERS recommendations) were compared in terms of methodological correctness. Results: The main flaws in the ECSC/ERS equations include: (a) the a priori assumption that the age from which a given pulmonary function parameter (PFP) begins to decline is the same for all the PFPs and is equal to 25 years; (b) the fact that a single linear equation may not correctly describe age-related changes beyond the age of 25 years; (c) the fact that the lower limits of normal are defined by equations for the mean values minus 1.645 × SD (where SD is the standard deviation for differences between the observed and the expected values); and (d) the fact that the equations were developed a long time ago for previous generations and old spirometry procedures. The main flaws in the Falaschetti equations include: (a) excessive and unnecessary non-linearity of the equations; and (b) inadequate selection of the general population sample (insufficient number of elderly subjects) causing overestimation of forced expiratory volume in one second (FEV₁) to forced vital capacity (FVC) ratio in elderly subjects. The equations proposed by Lubiński and Golczewski are free from these flaws. In particular, age distribution in the sample was uniform. Moreover, with reference to each of the PFPs: (a) the age from which a given PFP began to decline was mathematically determined together with the other coefficients of the equations; and (b) the statistical significance of the non-linearity of the relationship between age and each of the individual PFPs was analysed. What is more, in the case of the oldest subjects, the Lubiński equations yielded identical results to those obtained by other authors who had thoroughly analysed PFPs in the elderly. Conclusions: The comparison presented in this paper suggests that the equations proposed by Lubiński and Gólczewski should be used in Poland rather than those proposed by ECSC/ERS or Falaschetti et al.