22 The observation in the present study, of a 4% increase in R2 when adding gender to the analysis, can be explained by the high reproducibility and low variability of parameters.
Other studies found no influence of gender.1 and 3 selleck screening library There was a agreement between the coefficient of determination (R2) of FVC, FEV1, and FEV0.5 with findings in several other important studies carried out in preschoolers.2, 13, 14 and 15 Regarding the regression model, there was significant difference between linear or logarithmic model use in this study, but only for males. Some authors have found a better correlation when using the logarithmic model.1, 3 and 13 For simplification purposes, the use of the linear regression model is suggested in both genders, considering height as the dependent variable.2, 12, 15 and 16 Most previous studies that AZD2281 evaluated RV in preschoolers used z-score measures for these calculations.2, 3, 12, 15 and 16 Stanojevic et al., in a review study on RV in preschool children, showed that there are
differences in the interpretation of spirometry results when using percentage of predicted values or z-scores.11 As in the present study, Piccioni et al. also used measures of percentile of predicted values and lower limits.14 Comparing the predicted values calculated by the present study with the values found by other authors, for FEV1 preschoolers with mean height and weight values corresponding to those observed in this sample values were found of 1.10, (-)-p-Bromotetramisole Oxalate 1.11, 1.08, 1.05 and 1.14, respectively for Burity,
2012; Kjaer, 2008; Nystad, 2002; Zapletal, 2003 and Pesant, 2007. For FEV1 in females, these values were 1.03, 1.06, 1.05, 1.04, and 1.18, respectively. It is observed that, except for the study by Pesant, the values are very similar. In the Pesant study, different statistical models were used to predict values in males and females, which resulted in the finding of much higher values of FEV1 for females. The limitations of this study include the deficit in the spirometric program used, due to lack of millimetric markings on flow-volume curve charts, preventing the identification of maneuvers with early termination. Moreover, the lack of data on weight and height of normal Brazilian preschool children makes it difficult to compare the data on weight and height obtained in this study in order to define its applicability to the Brazilian population. The data on weight and height were consistent with those of the World Health Organization (WHO) for this age group, so this reference equation can be extrapolated to the Brazilian population. The great difficulty in obtaining full expiratory curves in this age group demonstrates the importance of assessing the FEV0.5 in preschoolers. As spirometry quantifies the degree of airway obstruction and aids in the diagnosis of respiratory disease,23 it is necessary that further studies define the usefulness of FEV0.