Lifetime risks of hypertension quantified by large U.K. database

Blood pressure affects cardiovascular risk differently across different diseases and age ranges, according to a large, new study.

British researchers used electronic health records to gather data on 1.25 million patients who were at least 30 years of age between 1997 and 2010, all initially free of cardiovascular disease. One-fifth were treated with blood pressure medication. The median follow-up was 5.2 years. Results were published in The Lancet on May 31.

Overall, 83,098 patients developed cardiovascular disease. The lowest risk for cardiovascular disease was found in patients with a systolic blood pressure of 90 to 114 mm Hg and a diastolic blood pressure of 60 to 74 mm Hg. This was true across all age groups, and no J-shaped pattern of increased risk at the lower pressures was found. The researchers also looked at what types of cardiovascular disease were most strongly predicted by hypertension and found that high systolic pressure was most strongly associated with intracerebral hemorrhage (hazard ratio [HR], 1.44; 95% CI, 1.32 to 1.58), subarachnoid hemorrhage (HR, 1.43; 95% CI, 1.25 to 1.63), and stable angina (HR, 1.41; 95% CI, 1.25 to 1.63). On the other end of the spectrum, high systolic pressure was not significantly associated with aortic aneurysm at all; high diastolic pressure was a better predictor.

Looking at lifetime risk from age 30 on, the study found that hypertension patients (defined as those having blood pressure over 140/90 mm Hg or those taking antihypertensives) had a 63.3% risk of cardiovascular disease, compared to 46.1% in patients with normal blood pressure. The hypertensive patients developed cardiovascular disease 5 years earlier on average. Stable and unstable angina accounted for the greatest share of cardiovascular disease in younger hypertensive patients, while heart failure had an equal share to angina in patients age 80 and over.

The findings conflict with some widely held assumptions about the associations between hypertension and all cardiovascular diseases as well as the concordance between diastolic and systolic pressures and risk. The evidence of substantial lifetime effects from hypertension offer support for treating mild hypertension in younger patients, a current topic of debate. The results also support a recent shift to focus on systolic, rather than diastolic, pressure. Clinicians could generally use the study's data about specific risks to improve patient counseling and treatment decisions, the authors concluded.

An accompanying comment suggested several targets for improvement in hypertension treatment, including risk assessment, patient education and decision making, caregiver support and education, medication compliance, use of home and ambulatory monitoring, recognition of secondary hypertension, and referral to specialty care.