Despite the extensive evidence underpinning treatment of high blood pressure, important questions remain. Morris Brown, Kennedy Cruickshank, and Thomas MacDonald argue that assumptions in recent treatment guidelines are based on insufficient evidence

The treatment of hypertension is arguably the most evidence based and cost effective medical intervention ever.1 Not only is there a greater choice of drug classes than for other common diseases but there are more long term data that establish their efficacy in reducing risks from strokes, heart attacks, and heart failure. Uniquely, a prospective meta-analysis was planned by the leaders of the long term trials before their completion to avoid the post-hoc selection of questions and answers that can confound meta-analyses and guidelines.2 The drugs concerned are now off-patent and inexpensive. The benefits are evident: treating patients saves money as well as reducing morbidity and mortality.3

However, the population attributable risks of raised blood pressure in those not currently classified as hypertensive are large. The prize for public health is to extend the benefits of blood pressure reduction to all those who would benefit. Two such groups exist. One is people whose blood pressure is below current definitions of hypertension (which are based on proved benefit of treatment in outcome trials) but above the threshold where epidemiological studies show a log-linear increase in risk with blood pressure.4 The other is young patients with stage 1 (mild) hypertension, who paradoxically have higher relative and lifetime risk of complications than older people but are not treated in the UK for reasons of cost effectiveness. If we wait for patients to reach a blood pressure >160/100 mm Hg, or absolute cardiovascular risk >2% a year, before starting treatment we cannot be confident that a return to “normal blood pressure” can normalise risk. In outcome …

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