[Agreement between reference values for spirometry recommended by the pneumology Spanish and European societies]

To determine whether spirometric reference values (RV) recommended by the Spanish Society of Pneumology and Thoracic Surgery (SEPAR) and the European Respiratory Society (ERS) are equivalent, and if the interpretation of these two RV leads to the same conclusions. A retrospective study of 3,690 spirometric readings (from 2,468 men and 1,222 women, ranging in age from 20 to 70 years old) of FVC, FEV1 and FEV1/FVC. Both quantitative (difference between RV obtained using the two sets of predictive equations) and qualitative (agreement of spirometric classifications using the two RV systems, by the method of standardized residuals, for FVC [non obstructive ventilatory defect] and FEV1/FVC [obstructive ventilatory defect], by calculating the kappa value). The difference in RV estimated by the two sets of equations is -0.544 l for FVC, -0.185 l for FEV1 and 2.36% for FEV1/FVC. In each case the agreement limits are not acceptable and bias is significant. Classifying patients by FVC, kappa was 50.03%. Classifying by FEV1/FVC, kappa was 93.66%. Bias is present for both parameters. The RV of SEPAR and ERS are not equivalent and this should be taken into consideration by manufacturers and distributors of equipment for lung function analysis. Each laboratory should be able to apply the RV most appropriate to the characteristics of the equipment used and the population studied.