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Effectiveness of blood pressure-lowering drug treatment by levels of absolute risk: post hoc analysis of the Australian National Blood Pressure Study


Ho, CLB and Breslin, M and Doust, J and Reid, CM and Nelson, MR, Effectiveness of blood pressure-lowering drug treatment by levels of absolute risk: post hoc analysis of the Australian National Blood Pressure Study, BMJ Open, 8, (3) Article e017723. ISSN 2044-6055 (2018) [Refereed Article]


Copyright Statement

ęThe Author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted. Licensed under Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

DOI: doi:10.1136/bmjopen-2017-017723


Objectives: In many current guidelines, blood pressure (BP)-lowering drug treatment for primary prevention of cardiovascular disease (CVD) is based on absolute risk. However, in clinical practice, therapeutic decisions are often based on BP levels alone. We sought to investigate which approach was superior by conducting a post hoc analysis of the Australian National Blood Pressure (ANBP) cohort, a seminal study establishing the efficacy of BP lowering in 'mild hypertensive' persons.

Design: A post hoc subgroup analysis of the ANBP trial results by baseline absolute risk tertile.

Setting and Participants: 3244 participants aged 35-69 years in a community-based randomised placebo controlled trial of blood pressure-lowering medication.

Interventions: Chlorothiazide500 mg versus placebo.

Primary Outcome Measures: All-cause mortality and non-fatal events (non-fatal CVD, congestive cardiac failure, renal failure, hypertensive retinopathy or encephalopathy).

Results: Treatment effects were assessed by HR, absolute risk reduction and number needed to treat. Participants had an average 5-year CVD risk in the intermediate range (10.5▒6.5) with moderately elevated BP (mean 159/103 mmHg) and were middle aged (52▒8 years). In a subgroup analysis, the relative effects (HR) and absolute effects (absolute risk reduction and number needed to treat) did not statistically differ across the three risk groups except for the absolute benefit in all-cause mortality (p for heterogeneity=0.04). With respect to absolute benefit, drug treatment significantly reduced the number of events in the high-risk group regarding any event with a number needed to treat of 18 (10 to 64), death from any cause with 45 (25 to 196) and major CVD events with 23 (12 to 193).

Conclusion: Our analysis confirms that the benefit of treatment was substantial only in the high-risk tertile, reaffirming the rationale of treating elevated blood pressure in the setting of all risk factors rather than in isolation.

Item Details

Item Type:Refereed Article
Keywords:absolute cardiovascular risk, antihypertensive drug, cardiovascular disease, hypertension, primary prevention
Research Division:Biomedical and Clinical Sciences
Research Group:Cardiovascular medicine and haematology
Research Field:Cardiology (incl. cardiovascular diseases)
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:Ho, CLB (Ms Chau Le Bao Ho)
UTAS Author:Breslin, M (Dr Monique Breslin)
UTAS Author:Nelson, MR (Professor Mark Nelson)
ID Code:125144
Year Published:2018
Web of Science® Times Cited:11
Deposited By:Menzies Institute for Medical Research
Deposited On:2018-03-29
Last Modified:2018-12-11
Downloads:76 View Download Statistics

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