Analysis of agreement between peak expiratory flow meters and comparison of reference values

Abstract Introduction: The peak expiratory flow (PEF) is a practical method that evaluates the caliber of the proximal airways. The ease in handling and the low cost of portable PEF meters made their use frequent. However, few studies have examined the correlation between the different equipment and compared their reference values. Objective: Analyze the correlation of three portable meters of PEF and check if the reference values are applicable in the studied population. Methods: 168 healthy individuals, of both genders, ranging in age from 20 to 80 years, had their PEF measured in Mini-Wright®, Assess® and AirZone® and the values obtained were compared to those predicted by Leiner et al. (1963) and Nunn and Gregg (1989). Statistical analysis was performed by the Kolmogorov-Smirnov tests, ANOVA, Wilcoxon test, Spearman correlation and analysis of agreement of Bland-Altman (p< 0.05). Results: There was significant difference in the values of PEF obtained between the Mini-Wright® and Assess® meters in both genders, between the AirZone® and Assess® only in men and between the Mini-Wright® and AirZone® only in women. The predicted values in the three meters have overestimated the obtained in both genders; there was no correlation between the values obtained from three meters due to the great variation of agreement limits and large interindividual variation. Conclusion: The values obtained in the three meters are not interchangeable and the predicted values were unsuitable for the sample.