There is a reasonably strong relationship between high blood pressure (hypertension) and cardiovascular events such s strokes and heart attacks. As a result, conventional wisdom (as expressed here by WHO) suggests preventative treatment:
Since publication of the WHO/ISH Guidelines for the Management of Hypertension in 1999, more evidence has become available to support a systolic blood pressure threshold of 140 mmHg for even 'low-risk' patients. ... There is evidence that specific agents have benefits for patients with particular compelling indications, and that monotherapy is inadequate for the majority of patients. For patients without a compelling indication for a particular drug class, on the basis of comparative trial data, availability, and cost, a low dose of diuretic should be considered for initiation of therapy. In most places a thiazide diuretic is the cheapest option and thus most cost effective, but for compelling indications where other classes provide additional benefits, even if more expensive, they may be more cost effective.
but in a recent opinion piece, British GP Iona Heath suggests that we are currently overtreating low risk patients and actually making their health worse:
...antihypertensive drugs used in the treatment of otherwise healthy adults with mild hypertension (systolic blood pressure [BP], 140–159 mm Hg, and/or diastolic BP, 90–99 mm Hg) have not been shown to reduce mortality or morbidity in randomized clinical trials.
The controversy is discussed by Forbes concluding:
While Dr. Heath raises some interesting points, her call for significantly raising the treatment threshold (to 160/100) should be discarded until stronger evidence supports her ideas.
Who is right? Do we have good evidence that preventative treatment to lower blood pressure improves health outcomes? What is the balance of benefit and harm?