High blood pressure (BP) is linked to an increased risk of heart attack and stroke. High BP has been defined as any number larger than 140 to 160 /90 to 100 mmHg and as a result this range of BPs has become the standard blood pressure target for physicians and patients. Over the last five years a trend toward lower targets has been recommended by hypertension experts who set treatment guidelines. This trend is based on the assumption that the use of drugs to bring the BP lower than140/90 mmHg will reduce heart attack and stroke similar to that seen in some population studies. However, this approach is not proven.
This review was performed to find and assess all trials designed to answer whether lower blood pressure targets are better than standard blood pressure targets. Data from 7 trials in over 22,000 people were analysed. Using more drugs in the lower target groups did achieve modestly lower blood pressures. However, this strategy did not prolong survival or reduce stroke, heart attack, heart failure or kidney failure. More trials are needed, but at present there is no evidence to support aiming for a blood pressure target lower than 140/90 mmHg in any hypertensive patient.
Treating patients to lower than standard BP targets, ≤140-160/90-100 mmHg, does not reduce mortality or morbidity. Because guidelines are recommending even lower targets for diabetes mellitus and chronic renal disease, we are currently conducting systematic reviews in those groups of patients.
When treating elevated blood pressure, doctors need to know what blood pressure (BP) target they should try to achieve. The standard of clinical practice for some time has been ≤ 140 - 160/ 90 - 100 mmHg. New guidelines are recommending BP targets lower than this standard. It is not known whether attempting to achieve targets lower than the standard reduces mortality and morbidity.
To determine if lower BP targets (≤ 135/85 mmHg) are associated with reduction in mortality and morbidity as compared with standard BP targets (≤ 140-160/ 90-100 mmHg).
Electronic search of MEDLINE (1966-2008), EMBASE (1980-2008), and CENTRAL (up to June 2008); references from review articles, clinical guidelines, and clinical trials.
Randomized controlled trials comparing patients randomized to lower or to standard BP targets and providing data on any of the primary outcomes below.
Two reviewers (JAA, MIP) independently assessed the included trials and data entry. Primary outcomes were total mortality; total serious adverse events; total cardiovascular events; myocardial infarction, stroke, congestive heart failure and end stage renal disease. Secondary outcomes were achieved mean systolic and diastolic BP and withdrawals due to adverse effects.
No trials comparing different systolic BP targets were found. Seven trials (22,089 subjects) comparing different diastolic BP targets were included. Despite a -4/-3 mmHg greater achieved reduction in systolic/diastolic BP, p< 0.001, attempting to achieve "lower targets" instead of "standard targets" did not change total mortality (RR 0.92, 95% CI 0.86-1.15), myocardial infarction (RR 0.90, 95% CI 0.74-1.09), stroke (RR 0.99, 95% CI 0.79-1.25) , congestive heart failure (RR 0.88, 95% CI 0.59-1.32), major cardiovascular events (RR 0.94, 95% CI 0.83-1.07), or end-stage renal disease (RR 1.01, 95% CI 0.81-1.27). The net health effect of lower targets cannot be fully assessed due to lack of information regarding all total serious adverse events and withdrawals due to adverse effects in 6 of 7 trials. A sensitivity analysis in diabetic patients and in patients with chronic renal disease also did not show a reduction in any of the mortality and morbidity outcomes with lower targets as compared to standard targets.