Benefits of electronic pillboxes in evaluating treatment compliance of patients with mild to moderate hypertension.

OBJECTIVE

This study was designed to assess the compliance of hypertensive patients with a once-daily regimen of the angiotensin converting enzyme (ACE) inhibitor trandolapril and to evaluate the antihypertensive efficacy of the drug in relation to the time interval between taking the final dose and measuring the blood pressure (BP).

DESIGN

After a 2-week wash-out period, hypertensive patients, recruited by cardiologists, received trandolapril 2 mg once daily in the morning for 4 weeks.

METHODS

In order to assess compliance, each patient's supply of trandolapril capsules was presented in a pillbox that incorporated in its lid a microprocessor that recorded the date and time of each occasion that it was opened. BP was measured using validated semi-automatic devices, at the end of both the wash-out and the treatment period.

RESULTS

A total of 590 patients entered the study. Compliance data were evaluable for 501 patients. Overall compliance, defined as the ratio of the number of openings recorded to the number of doses prescribed was less than 80, 80-100, and more than 100% in 17, 63 and 20% of patients, respectively. The average number (+/- SD) of missed doses was 4.5 +/- 8 (median 2). The average interval between successive openings was 25 h 07 min mean +/- 13 h (median 24 h). The average number of delayed doses (a delayed dose being defined as the box being opened 25-36 h after the previous occasion) was 5.6 +/- 3 (median 6). Patients living in the Paris area had more forgotten and delayed doses than those living in the provinces (7.9 versus 3.8 forgotten; P<0.0001 and 6.3 versus 5.5 delayed; P<0.005). Doses were forgotten and delayed more often during weekends than on weekdays. The greatest number of delayed doses occurred in those patients under 60 years of age (6.0 versus 5.2; P<0.01). Decreases in systolic blood pressure (SBP and diastolic blood pressure (DBP) were 20.3/12.8 mmHg, for patients whose final drug was taken on the same day as the BP measurement, and 18.9/11.2 mmHg for patients whose final dose was taken on the previous day.

CONCLUSIONS

Electronic compliance monitoring allows refined analysis of the behaviour of hypertensive patients. In this study doses were missed and delayed frequently during the first month of treatment, depending on the patient's lifestyle.