Background: The use of placebo in clinical trials has been vigorously debated. Placebo control may be useful in disease states, such as stage 1 and stage 2 hypertension as defined by the Sixth Report of the Joint National Committee on Detection, Evaluation and Treatment of High Blood Pressure (JNC VI), in which response rates for placebo are high or close to response rates for effective therapies, or when established interventions have significant adverse effects.
Objective: To compare rates for the control of blood pressure and adverse effects of placebo vs active treatment in patients with stage 1 and stage 2 hypertension.
Methods: This study is a randomized controlled trial evaluating the blood pressure response and adverse effects of placebo vs 6 active treatments administered in 15 Veterans Affairs hypertension centers. The 1292 subjects of the Veterans Affairs Cooperative Study receiving single-drug therapy for hypertension were randomly allocated to receive treatment with 1 of 6 active drugs (n= 1105) or placebo (n=187). Treatment success was defined as maintaining a diastolic blood pressure of less than 95 mm Hg for at least 1 year. We compared treatment success rates for the control of blood pressure and adverse effects of placebo vs active treatment. Using the Kaplan-Meier method, we also compared rates of discontinuation from placebo vs active drug treatment over time as a result of adverse drug effects and blood pressure exceeding safety limits.
Results: At the end of the titration phase, 58 patients who were treated with placebo (31%) achieved a goal diastolic blood pressure lower than 90 mm Hg and 57 (30%) achieved success at 1 year. Older white patients who received placebo had a success rate of 38% vs 23% to 27% for the other age-race subgroups. The rates of discontinuation as a result of adverse drug effects were 13% for patients receiving placebo vs 12% for patients receiving active treatment (P=.40). The rates of discontinuation for blood pressure being too high were 14% for patients receiving placebo vs 7% for patients receiving active treatment (P=.01).
Conclusions: Placebo control provides an important benchmark for both efficacy and adverse effects. It continues to have an appropriate place in certain therapeutic trials, particularly those involving the treatment of stage 1 and stage 2 hypertension.