Should we monitor peak expiratory flow rates or record symptoms with a simple diary in the management of asthma?

Abstract

Background: Various means of monitoring asthma severity have been proposed to reduce morbidity and mortality rates. We compared two means of assessing asthma flare-ups: monitoring peak expiratory flow rate (PEFR) and keeping a symptom diary.

Methods: This was a crossover randomized study. After a 2-week baseline period during which spirometry and PC20 methacholine were assessed, subjects were asked to record either PEFRs or to keep a symptom diary morning and evening for 6 months; a second baseline assessment separated the two periods. Subjects were asked to contact the study coordinator if the following occurred: (1) in the period of PEFR monitoring, daily fluctuations in PEFR were > 20% or the absolute value fell to < 80% of baseline or both occurred; (2) in the period of symptom diary monitoring there were nocturnal symptoms or a persistence of morning dyspnea after inhaled bronchodilator or a reduction in the duration of effect of the bronchodilator or it was impossible to go to work or school or all occurred. In that case they were asked to come to the hospital to confirm the flare-up through investigation for significant changes in FEV1 or PC20 or both. Forty subjects completed a 6-month symptom diary or PEFR recording period respectively, and 20 completed both.

Results: A total of 31 exacerbations were reported in 28 different subjects; three subjects had two flare-ups. Thirteen of 19 (69%) flare-ups were confirmed during the symptom diary period and 9 of 12 (75%) during PEFR monitoring. Nocturnal awakenings and morning falls in PEFR > or = 20% were the most frequent occurrences.

Conclusions: We conclude that a simple symptom diary may be as useful as serial PEFR monitoring in documenting asthmatic flare-ups.