Predicted peak expiratroy flow in human and the clinical implications of differences across related formulae: a proposed guideline standard reference for Asthma

Abstract

In an attempt to examine the differences between Peak Expiratory Flow (PEF) formulae in the literature so as to assess the potential impact of those differences on the interpretation of clinical guidelines for asthma management, the present study was carried out. We calculated 100% PEF values using formula developed by (Gregg, 1973) at 50th percentile for age, height and weight obtained from our study (Salisu et al., 2007) and classified the percent predicted PEF in to severity groups according to national asthma guidelines (NAEPP, 1991 and 1997). Choosing different formulae could give an individual in the age range of 15-19 years a 100% predicted PEF as low as 402 L/min and as high as 412 L/min; and another woman in the age range of 30-34years a classification of severe (47%) using one, but moderate (71%) using another. This indicates that predicted PEF varied widely across formulae and choice of a particular formula may alter guidelinebase care. This work has therefore accepted a recently published population-base equation proposed as the reference standard for future asthma guidelines.

Keywords Peak expiratory flow, Asthma, Practice guidelines, reference values