Inaccuracy of portable peak flow meters : correction is not needed

This study examined whether correction of peak expiratory flow (PEF) values for the inaccuracy of the meter would affect asthma management in 102 children (7-14 y old). PEF was recorded with a mini Wright meter twice daily for 2 weeks. As expected, measured PEF overestimated PEF level and asthma control in these children on many diary days. The actual numerical differences between measured and corrected PEF on these days were very small(>5% in only five patients, maximum 10%). It is unlikely that such small changes in PEF justify changes in asthma management, even if these changes cause PEF levels to cross arbitrary borders between various levels of asthma control used in self-management plans. The clinical importance of the inaccuracy of portable PEF meters is negligible.