Singleton 1989.

Methods	1‐week washout; 2‐week single‐blind placebo run‐in period; inclusion criteria=sitting DBP 95‐105 mm Hg for 2 consecutive weeks; 7‐week double‐blind treatment, consisting of 3‐week dose titration period (to preassigned dose group) followed by 4‐week "maintenance" period at preassigned fixed dose unless limited by side effects
Participants	All patients: n=220 (166 prazosin GITS, 54 placebo); n=205 patients included in efficacy analysis; Prazosin GITS 2.5 mg: n=49 (32 males, 17 females); 35 white, 12 black, 2 other; mean age=54.4(11.3) years; baseline sitting SBP=150.3(14.1) mm Hg, DBP=99.4(3.2) mm Hg, HR=76.5(8.8) bpm; baseline standing SBP=150.6(13.6) mm Hg, DBP=100.5(5.8) mm Hg, HR=80.1(9.0) bpm Prazosin GITS 10 mg; n=56 (38 males, 18 females); 44 white, 10 black, 2 other; mean age=54.1(12.2) years; baseline sitting SBP=150.0(13.2) mm Hg, DBP=100.6(3.0) mm Hg, HR=76.0(9.1) bpm; baseline standing SBP=149.5(14.1) mm Hg, DBP=101.8(5.4) mm Hg, HR=77.5(8.8) bpm Prazosin GITS 20 mg; n=52 (32 males, 20 females); 40 white, 10 black, 2 other; mean age=57.1(10.5) years; baseline sitting SBP=155.6(16.1) mm Hg, DBP=100.1(3.0) mm Hg, HR=75.7(8.8) bpm; baseline standing SBP=154.6(16.5) mm Hg, DBP=101.8(5.0) mm Hg, HR=78.6(8.7) bpm Placebo: n=48 (28 males, 20 females); 42 white, 5 black, 1 other; mean age=55.0(10.6) years; baseline sitting SBP=151.9(14.8) mm Hg, DBP=99.5(3.2) mm Hg, HR=77.6(8.0) bpm; baseline standing SBP=150.8(17.1) mm Hg, DBP=101.3(5.9) mm Hg, HR=81.2(8.4) bpm
Interventions	Prazosin GITS 2.5 mg once daily Prazosin GITS 10 mg once daily Prazosin GITS 20 mg once daily Placebo
Outcomes	Change from baseline in trough sitting SBP/DBP using sphymomanometer Change from baseline in trough standing SBP/DBP using sphymomanometer Change from baseline in trough sitting HR Change from baseline in trough standing HR WDAE
Notes	GITS=gastrointestinal therapeutic system; BP change reported, SD of change not reported, endpoint BP and SD not reported; baseline BP and SD reported; imputed baseline SBP SD for SBP SD of change, imputed overall trial mean DBP SD of change; trough BP data from Table IV, p. 47S
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Not described.
Incomplete outcome data (attrition bias) All outcomes	Low risk	15/220 patients (9/166 receiving prazosin GITS; 6/54 receiving placebo) who were lost to follow‐up or withdrew prematurely not included in efficacy analysis.
Selective reporting (reporting bias)	Low risk	BP lowering efficacy was primary outcome. HR and safety/tolerability data reported.
Other bias	High risk	Funding source is manufacturer of prazosin GITS (Pfizer).