[Example of a phase IV trial involving several physicians and aiming at answering a scientific question: EOL]

The aim of this trial was to test the hypothesis that a reduced number of doses improves compliance in current medical practice. Compliance with twice a day dosage was compared with compliance with three doses a day. Two bioequivalent presentations of nicardipine were used, the regular presentation (t.i.d.) and the slow-release (b.i.d.). The trial was controlled, randomized, open, in two parallel groups: (1)'t.i.d.' group: one tablet of regular nicardipine, 20 mg, three times a day, three months; (2) 'b.i.d.' group: one capsule of slow-release nicardipine, twice a day, three months. 2651 general practitioners randomized 7274 hypertensive patients. The primary criterion was documented in 93.7 per cent of the cases at the end of the trial. The remaining 6.3 per cent comprised treatment withdrawal (2.8 per cent) and patients lost to follow-up (3.5 per cent). The primary criterion study was compliance, assessed by a self-questionnaire filled in by the patient and a standardised interview by the physician. Compliance was slightly better in the b.i.d. group than in the t.i.d. group (p < 0.001). Remaining pill count was also used but it was a failure. A random sample of investigators made on-site visits. Discordant data were infrequent and were limited to dates of visits. Difficulties with on-site visits were mostly due to a rather frequent lack of source records.