Patient compliance with peak flow monitoring in chronic obstructive pulmonary disease

The factors affecting patient compliance with peak flow monitoring in advanced chronic obstructive pulmonary disease (COPD) were examined using a prospective, blinded study.

Twenty-eight male veterans were instructed in the use of an electronic, hand-held peak flow meter and the modified Medical Research Council dyspnea scale. They then entered a 6-month monitoring phase in which they recorded a dyspnea score once daily and peak expiratory flow rates twice daily, before and after bronchodilator use. The meter displays were disabled so that the patients were blinded to their values. Medical care was provided in the customary manner. Compliance was defined as the ratio of recorded values to all values specified by the protocol, exclusive of those missing due to circumstances beyond the patient's control.

Of 40 patients who met the entry criteria for this study, 8 refused to participate and 4 could not master the technique. The remaining 28 patients were enrolled. Overall, 25 (63% of those eligible) adhered to the protocol until its conclusion or until they became unable to comply because of medical or social problems. Compliance was 89.8+/-15.0%. Of those followed for longer than 150 days, linear regression showed that only one patient had a decline in compliance over time (r=0.84, P=0.04). Compliance was lower in the afternoons (P < 0.001) and on days with higher dyspnea scores (P < 0.001). No other clinical factors had an effect on patient measurements.

A substantial proportion of patients with advanced COPD can be trained in the technique of peak flow monitoring. Compliance is high if patients are enrolled in a long-term, structured program of supervision and periodic retraining.