Annual Change of Peak Expiratory Flow Rate in Asthma and COPD

Background: Peak Expiratory Flow Rate (PEFR) is a useful measurement for the follow-up examination in a chronic airway disease because it has the advantage of simple measuring and repetitive examination. The aim of this study is to examine the annual decrease of PEFR in asthma and COPD patients and to confirm the factors which influence the annual decreasing rate of PEFR.

Methods: From May, 2003 to September, 2010, the annual decreasing rate of PEFR is obtained from the asthma and COPD patients attending an outpatient pulmonary clinic. PEFR was measured using Mini-Wright (Clement Clarke International Ltd. UK), we conducted an analysis of the factors to influence on the change of PEFR and the average of it. 

Results: The result indicate decrease of 3.72±12.55 L/min annually in the asthmatic patient and decrease of 8.69±8.87 L/min annually in the COPD patient. In the asthma, age and FEV1 are the predictive factor to influence on the change, on the other hand, age, FEV1, smoking and the number of aggravation are the factors in the COPD.

Conclusions: We could confirm the annual decreasing rate in patients of chronic airway disease and similar factor with FEV1 to influence on the change.