Isolated high systolic blood pressure is strongly associated with risk for intracerebral hemorrhage, subarachnoid hemorrhage, and stable angina, whereas isolated high diastolic blood pressure is associated with risk for abdominal aortic aneurysm, according to findings published in the Lancet.
The observations debunk widespread assumptions that isolated systolic and diastolic blood pressures are similarly and consistently associated with cardiovascular diseases, wrote Dr. Eleni Rapsomaniki and associates of the Farr Institute of Health Informatics Research in London (Lancet 2014;383:1899-1911).
©American Heart Association
The results suggest blood pressure functions through different biological mechanisms for different diseases.
"Our data support the possibility that blood pressure functions through different underlying biological mechanisms for different diseases," the researchers wrote. These data can be considered when counseling patients.
The results "also emphasize the limitations of existing blood pressure–lowering strategies," they added. Better implementation of existing blood pressure–lowering treatments and better management of other cardiovascular risk factors as part of global risk estimation could help to mitigate excess risk.
The researchers studied 1.25 million patients, aged 30 years or older, who had no previous history of cardiovascular disease. Baseline blood pressures were recorded during primary care consultations. Patients were classified as having hypertension with a baseline blood pressure reading of 140/90 mm Hg or greater, a previous diagnosis of hypertension, or repeat prescriptions for blood pressure–lowering medications.
Isolated systolic hypertension was defined as a value of 140 mm Hg or higher with a diastolic level of lower than 90 mm Hg. Isolated diastolic hypertension was defined as systolic blood pressure of less than 140 mm Hg and a diastolic level of 90 mm Hg or higher.
Endpoints were defined as the initial presentation of any of 12 cardiovascular diseases.
The primary analysis reported associations of outcomes with a 20/10 mm Hg increase in systolic/diastolic blood pressure by age group (30-59 years, 60-79 years, and 80 years or older), and estimated risks and years of life lost associated with hypertension for the index ages of 30, 60, and 80 years. The secondary analysis reported associations of blood pressure with cardiovascular outcomes, after adjusting for smoking status, diabetes, cholesterol, body mass index, and baseline treatment with hypertension drugs.
Isolated systolic hypertension was strongly associated with intracerebral hemorrhage (hazard ratio, 1.44; 95% confidence interval, 1.32-1.58), subarachnoid hemorrhage (HR, 1.43; CI, 1.25-1.63), and stable angina (HR, 1.41; CI, 1.36-1.46).
Isolated diastolic hypertension was associated with abdominal aortic aneurysm (HR, 1.45; 95% CI, 1.34-1.56).
Peripheral arterial disease had the strongest association with pulse pressure (HR, 1.23; CI, 1.20-1.27).
The lifetime risk of total cardiovascular disease at 30 years of age was 63.3% in people with hypertension and 46·1% in those with healthy blood pressure, with stable and unstable angina as the most frequent outcomes. The mean number of cardiovascular disease–free life years lost in those with hypertension was 5 years at 30 years of age, 3.4 years at 60 years, and 1.6 years at 80 years.
The study was funded by the National Institute for Health Research, the Wellcome Trust, the Medical Research Council Prognosis Research Strategy Partnership, and numerous other sources. The researchers had no competing interests.