Validity of peak expiratory flow for assessing the presence of airflow obstruction

Lee, Sang Won; Choi, Won Il; Park, Soon Hyo; Park, Hoon Pyo; Seo, Yong Woo; Lee, Jung Eun; Ku, Duk Hee; Seo, Chang Gyun; Lee, Mi Young; Lee, Choong Won; Jeon, Young June

Abstract

BACKGROUND: Since there has been strong correlation between peak expiratory flow (PEF) and forced expiratory volume in one second (FEV1), assessing the presence of airflow obstruction by PEF measurements would be useful in general practice, but its usefulness has not been well investigated. We hypothesize that PEF would be practicable for assessing the presence of airflow obstruction.
METHODS
PEF measurements were performed mini-Wright peak flow meter in 106 patients (aged 19-82) with a history of asthma or chronic obstructive lung disease. The change in PEF (% predicted value) was compared with the change in FEV1 and forced expiratory volume in one second to forced vital capacity ratio (FEV1/FVC). Airflow obstruction was analyzed according to European Community for Coal and Steel criteria. When defined as an FEV1 and FEV1/FVC ratio both below the 90% confidence interval of predicted values before bronchodilator.
RESULTS
Airflow obstruction was observed in 76.4% (81) of patients. Relative operating characteristic analysis showed that an below in PEF of 60% of predicted value gave optimal discrimination between patients with no airflow obstruction and airflow obstruction (the sensitivity and specificity of below 60% of predicted value in detecting FEV1 and FEV1/FVC ratio both below the 90% confidence interval of predicted values were 86.4% and 83.0% respectively, with a positive predictive value of 94.5%)
CONCLUSION
Percentage of predicted value in PEF could be used to diagnose airflow obstruction.