Background: The recent consensus reports on asthma management emphasize the importance of using peak flowmeters to accurately assess the degree of airflow obstruction. However, the optimal way to use those devices has not yet been determined.
Objectives: To assess compliance with peak expiratory flow (PEF) measurements in the long-term management of asthma, and identify the characteristics of patients with poor compliance.
Setting: Asthma clinics from three tertiary-care hospitals.
Design: A descriptive and prospective study of 1-year duration.
Patients: Twenty-six patients with moderate to severe asthma taking part in an asthma education program.
Main outcome measures: Patients were asked to measure morning and evening PEF using an electronic peak flowmeter with a 3-month memory; they were unaware that PEF values were being recorded by this device.
Results: Compliance with PEF measurements was relatively good during the first month (63% of the measurements done) but even with regular reinforcement, fell to 50% at 6 months and to 33% at 12 months. Right from the beginning, 8 of 26 subjects (30%) never or almost never (<5% of the readings done) measured PEF, with seven of these subjects writing fabricated results in their diaries most of the time. At 12 months, 60% of the subjects were measuring PEF <25% of the time, and most of them continued writing fabricated PEF values in their diaries. None of the subjects' characteristics helped us to identify those who had poor compliance with these measurements.
Conclusions: While short-term compliance with PEF measurements is fairly good, most patients with moderate to severe asthma are not interested in measuring PEF twice daily over a prolonged period. In the current management of asthma, PEF measurement devices can be suggested to those showing a strong personal interest in using them, but should be limited to short periods of time. Furthermore, this study outlines the usefulness of electronic peak flowmeters when doing clinical research where PEF improvement is an important outcome.