FEV1 is accepted as gold standard of the assessing airway caliber which needs spirometer. Despite of FEV1, PEFR could be evaluated by simple peak flow meter instruments, so it will be very helpful to be able to estimate the amount of FEV1 in a patient by his or her PEFR. The aim of this study is to evaluate the correlation between the predicted values of FEV1 and PEFR in patients underwent methacholin challenge test (MCT) and design regression model of their correlation.
This is a prospective cross-sectional study on 142 young men with respiratory symptoms suggesting asthma which were candidates for MCT. All the patients underwent MCT and spirometery according to American Thorax Society guidelines. The measures of %FEV1 and %PEFR of patients were compared with each other. The normality of distributions was checked by Kolmogorov-Smirnov test. Pearson correlation coefficient was calculated and linear regression used for the statistical analysis.
Mean age of patients was 20.83 (SD, 1.92) years and all were male. Although distribution of %FEV1 was not normal, that’s square was distributed normally. %PEFR and square of %FEV1 were significantly correlated (r=0.758;p=.000) and its regression model was (%FEV1 2 = 99.74 %PEFR –381.05) with R=0.75. The model was not dependent on the %PEFR and the high and low measures did not affect model.
It is believed that assessment of airway caliber through PEFR monitoring may not be valid in some asthmatic subjects; yet, study of FEV1 and PEFR correlation looks like a different subject. In addition, it is first report of assessing correlation of PEFR with square of FEV1 which seems to result in a fit model. Like any regression models lack of plausibility is a major problem though further studies have to be considered.
By the mentioned model %FEV1 can be predicted by %PEFR.
Ali Moghimi, None.