[Non-specific effects of a drug study in hypertensive patients]

During the first phase of a drug study, 33 hypertensive patients received 2 placebo tablets daily for 2 weeks as the sole treatment. Analysis of the blood pressure readings during this placebo phase shows that the study in itself creates a psychological climate which tends to decrease blood pressure. This effect should be taken into account when analyzing results of drug studies; only in studies with a double blind design is drug effect adequately judged.