title: 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.
authors.affiliation: Integrium, Orange, California 92868, USA. dsmith@integrium.com
authors.forename: David H
authors.initials: DH
authors.lastname: Smith
authors.forename: Joel M
authors.initials: JM
authors.lastname: Neutel
authors.forename: Yves
authors.initials: Y
authors.lastname: Lacourcière
authors.forename: Joan
authors.initials: J
authors.lastname: Kempthorne-Rawson
mesh_terms: D000959:Antihypertensive Agents / Q000627:therapeutic use*; D018660:Blood Pressure Monitoring, Ambulatory; D004311:Double-Blind Method; D006801:Humans; D006973:Hypertension / Q000175:diagnosis* / Q000188:drug therapy*; D010919:Placebos; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic / Q000379:methods* / Q000706:statistics & numerical data
chemical_list: D000959:Antihypertensive Agents; D010919:Placebos