Second Australian national blood pressure study-ANBP2.

The 2nd Australian National Blood Pressure Study is a 5 year cardiovascular outcome trial (total cardiovascular events) of the treatment of hypertension in patients aged 65-84 years. The study is being conducted in 6000 subjects using a prospective randomised open-label design with blinding of end point assessment. Subjects are eligible if average untreated sitting blood pressure (BP) on the 2nd and 3rd screening visits is ≥ 160 mm Hg systolic or ≥ 90 mm Hg diastolic and there has been no recent cardiovascular event or other serious intercurrent illness. Subjects suitable after screening (conducted by study nurses) are randomised to initial antihypertensive treatment with either an ACE inhibitor (enalapril) or a diuretic. Interim analysis of end points will be reviewed by an independent data monitoring committee at the end of recruitment (2 years) and then annually. In order to determine feasibility, a 6 month pilot study was conducted in South Australia and Victoria. Feasibility was defined as determining, a) whether 20 GPs could be enrolled in both Adelaide and Melbourne, b) whether patients identified through practice records would attend a BP screening program at the general practice, and c) whether patients could be randomised at a rate to ensure the recruitment of 6000 subjects over a two year period. GPs registered with 5 Divisions of General Practice (n=741) were invited by mail to participate. Those expressing interest received a follow-up telephone call and/or a personal visit. 89 GPs have been enrolled to date - 12% of mail invites and 75% of those receiving a personal contact 2583 patients were identified through practice records and attended the pilot study screening program. 55% of participants (n=1424) were hypertensive at the screening visit, either on medication (n=1194) or had elevated BP (n=230). 371 treated hypertensives were withdrawn from antihypertensive therapy and 89 (23%) have remained normotensive. 74 newly diagnosed and 104 previously treated hypertensive subjects have been randomised (7% of the screened population). The ANBP2 pilot study has demonstrated that it is feasible to conduct a cardiovascular outcome trial in general practice in Australia and will be expanded to the 5 mainland state capitals in 1996.