Prospective, randomized, open-label, blinded-endpoint (PROBE) designed trials yield the same results as double-blind, placebo-controlled trials with respect to ABPM measurements

Abstract

Objective: This meta-analysis aimed to determine whether ambulatory blood pressure monitoring (ABPM) results from double-blind, placebo-controlled (DBPC) and prospective, randomized, open-label, blinded-endpoint (PROBE) hypertension trials are statistically comparable.

Methods: Two DBPC and three PROBE parallel-group studies were selected from an angiotensin II receptor blocker clinical programme. These were fixed-dose studies involving similar mild to moderate hypertensive patient populations. All used SpaceLabs 90207 ABPM devices, and each comprised a 4-week placebo period and a 4-8-week treatment period. Data from patients receiving telmisartan 80 mg were used to compare the results of DBPC (126 patients) and PROBE (734 patients) trials. The analysis had approximately 87% power to show equivalence between the two design types in terms of ruling out differences of >or= 3 mmHg in SBP and >or= 2 mmHg in DBP. Office blood pressure was also compared.

Results: The change from baseline in mean 24-h ambulatory SBP was -12.2 mmHg in DBPC trials and -12.3 mmHg in PROBE trials, a rounded difference of 0.2 mmHg [95% confidence interval (CI): -1.8, 2.1]. The change from baseline in mean 24-h ambulatory DBP was -7.7 mmHg in DBPC trials versus -7.9 mmHg in PROBE trials, a difference of 0.2 mmHg (95% CI: -1.1, 1.5). Ambulatory pulse pressure results were identical.

Conclusions: Thus, changes in mean 24-h ambulatory blood pressure from the DBPC and PROBE trials in this meta-analysis are statistically equivalent in terms of ruling out a difference of >or= 3 mmHg in SBP and >or= 2 mmHg in DBP. This supports the validity of the PROBE design in assessing antihypertensive efficacy based on blinded ABPM measurements.