Rarely does tweaking a health guideline double the disease burden. It happened last week when the United States decided to lower the threshold for reading high blood pressure. By lowering it from 140/90 to 130/80, they put nearly half of American adults under the hypertensive bracket. The guideline by the American Heart Association (AHA) and the American College of Cardiology (ACC) is sweeping but has come into effect after a large study showed pretty ‘convincing’ data that markedly lower blood pressure was both beneficial and achievable.