Background: 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.
Objectives: 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).
Search strategy: Electronic search of MEDLINE (1966-2008), EMBASE (1980-2008), and CENTRAL (up to June 2008); references from review articles, clinical guidelines, and clinical trials.
Selection criteria: Randomized controlled trials comparing patients randomized to lower or to standard BP targets and providing data on any of the primary outcomes below.
Data collection and analysis: 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.
Main results: 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.
Authors' conclusions: 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.