Use of a Microprocessor-Equipped Tablet Box in Monitoring Compliance with Antihypertensive Treatment

Abstract

Summary: 

Compliance with antihypertensive therapy is usually monitored by questionnaire, tablet counts, or estimation of drug levels in blood or in urine. The aim of this study was to examine patient compliance by means of an “electronic monitor.” After 2 weeks of run-in on placebo, 34 moderately hypertensive patients were included in an open, randomized, crossover trial examining the efficacy and tolerance of nitrendipine, 20 mg as a single daily dose (morning or evening) for 1 month. We analyzed the results in 26 patients. Patients were supplied with tablet boxes equipped with a microprocessor (MENS) that registered the timing and duration of opening of the box over both the placebo and nitrendipine periods. Compliance (%) was calculated as the ratio of the number of days that the pill box was opened to the number of days between visits. The compliance was analyzed for each treatment group, namely placebo and nitrendipine morning and evening, over 1 month. Compliance (mean + SD) was 96.5 ± 7.4% on placebo and 94.4 ± 10.7% in the morning and 90.6 ± 15.4% in the evening. Nitrendipine was taken in the morning at 0700 h ± 2 h and in the evening at 1859 h ± 2 h 12 min. The frequency of 24 h ± 1 h intervals between medication was 83.5% on placebo. This frequency was 72.6% for morning dosage and 71.8% for evening dosage on nitrendipine. There were no differences in compliance between the morning and evening groups when analyzed according to age and sex. There was a negative correlation with time (r = −0.57, ρ < 0.001). Compliance was not influenced by the day of the week. This technique is thus useful in the conduct of phase III trials. In this study, compliance with nitrendipine treatment once daily (morning or evening) was good. It was found, however, that strict compliance decreases over time.