Blood pressure targets: are clinical guidelines wrong?

Blood pressure targets in adults with hypertension

BACKGROUND

This is the first update of this review first published in 2009. When treating elevated blood pressure, doctors usually try to achieve a blood pressure target. That target is the blood pressure value below which the optimal clinical benefit is supposedly obtained. "The lower the better" approach that guided the treatment of elevated blood pressure for many years was challenged during the last decade due to lack of evidence from randomised trials supporting that strategy. For that reason, the standard blood pressure target in clinical practice during the last years has been less than 140/90 mm Hg for the general population of patients with elevated blood pressure. However, new trials published in recent years have reintroduced the idea of trying to achieve lower blood pressure targets. Therefore, it is important to know whether the benefits outweigh harms when attempting to achieve targets lower than the standard target.

OBJECTIVES

The primary objective was to determine if lower blood pressure targets (any target less than or equal to 135/85 mm Hg) are associated with reduction in mortality and morbidity as compared with standard blood pressure targets (less than or equal to 140/ 90 mm Hg) for the treatment of patients with chronic arterial hypertension. The secondary objectives were: to determine if there is a change in mean achieved systolic blood pressure (SBP) and diastolic blood pressure (DBP associated with "lower targets" as compared with "standard targets" in patients with chronic arterial hypertension; and to determine if there is a change in withdrawals due to adverse events with "lower targets" as compared with "standard targets", in patients with elevated blood pressure.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for randomised controlled trials up to May 2019: the Cochrane Hypertension Specialised Register, CENTRAL (2019, Issue 4), Ovid MEDLINE, Ovid Embase, the WHO International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted authors of relevant papers regarding further published and unpublished work. The searches had no language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing patients allocated to lower or to standard blood pressure targets (see above).

DATA COLLECTION AND ANALYSIS

Two review authors (JAA, VL) independently assessed the included trials and extracted data. Primary outcomes were total mortality; total serious adverse events; myocardial infarction, stroke, congestive heart failure, end stage renal disease, and other serious adverse events. Secondary outcomes were achieved mean SBP and DBP, withdrawals due to adverse effects, and mean number of antihypertensive drugs used. We assessed the risk of bias of each trial using the Cochrane risk of bias tool and the certainty of the evidence using the GRADE approach.  MAIN RESULTS: This update includes 11 RCTs involving 38,688 participants with a mean follow-up of 3.7 years. This represents 7 new RCTs compared with the original version. At baseline the mean weighted age was 63.1 years and the mean weighted blood pressure was 155/91 mm Hg. Lower targets do not reduce total mortality (risk ratio (RR) 0.95, 95% confidence interval (CI) 0.86 to 1.05; 11 trials, 38,688 participants; high-certainty evidence) and do not reduce total serious adverse events (RR 1.04, 95% CI 0.99 to 1.08; 6 trials, 18,165 participants; moderate-certainty evidence). This means that the benefits of lower targets do not outweigh the harms as compared to standard blood pressure targets. Lower targets may reduce myocardial infarction (RR 0.84, 95% CI 0.73 to 0.96; 6 trials, 18,938 participants, absolute risk reduction (ARR) 0.4%, number needed to treat to benefit (NNTB) 250 over 3.7 years) and congestive heart failure (RR 0.75, 95% CI 0.60 to 0.92; 5 trials, 15,859 participants, ARR 0.6%, NNTB  167 over 3.7 years) (low-certainty for both outcomes). Reduction in myocardial infarction and congestive heart failure was not reflected in total serious adverse events. This may be due to an increase in other serious adverse events (RR 1.44, 95% CI 1.32 to 1.59; 6 trials. 18,938 participants, absolute risk increase (ARI) 3%,  number needed to treat to harm (NNTH) 33 over four years) (low-certainty evidence). Participants assigned to a "lower" target received one additional antihypertensive medication and achieved a significantly lower mean SBP (122.8 mm Hg versus 135.0 mm Hg, and a lower mean DBP (82.0 mm Hg versus 85.2 mm Hg, than those assigned to "standard target".

AUTHORS' CONCLUSIONS

For the general population of persons with elevated blood pressure, the benefits of trying to achieve a lower blood pressure target rather than a standard target (≤ 140/90 mm Hg) do not outweigh the harms associated with that intervention. Further research is needed to see if some groups of patients would benefit or be harmed by lower targets. The results of this review are primarily applicable to older people with moderate to high cardiovascular risk. They may not be applicable to other populations.

Effect of Achieved Systolic Blood Pressure on Cardiovascular Outcomes in Patients With Type 2 Diabetes: A Population-Based Retrospective Cohort Study

OBJECTIVE

The objective of this study was to compare the incidence of cardiovascular disease (CVD) among patients with type 2 diabetes mellitus (T2DM) with treated hypertension who achieved systolic blood pressures (SBPs) of <120, <130, and <140 mmHg after an increase in their antihypertensive regimen.

RESEARCH DESIGN AND METHODS

A retrospective cohort study was conducted on 28,014 primary care adult patients with T2DM with no prior diagnosis of CVD and who achieved SBP readings <140 mmHg after an increase in the number of antihypertensive medications prescribed. Using an extension of propensity score matching, a total of 2,079, 10,851, and 15,084 matched patients with achieved SBP measurements of <120, <130, and <140 mmHg were identified. The association between achieved SBP and incident CVD were evaluated using Cox regressions. Subgroup analyses were conducted by stratifying patients' baseline characteristics.

RESULTS

Over a median follow-up period of 4.8 years, the incidence of CVD in patients with achieved SBP measures of <120, <130, and <140 mmHg were 318 (15.3%; incidence rate [IR] 34.3/1,000 person-years [PY]), 992 (9.1%; IR 20.4/1,000 PY), and 1,635 (10.8%; IR 21.4/1,000 PY). Achieved SBP <120 mmHg was associated with a higher risk of CVD compared with achieved SBP <130 mmHg (hazard ratio [HR] 1.75 [95% CI 1.53, 2.00]) and achieved SBP <140 mmHg (HR 1.67 [95% CI 1.46, 1.90]). There was a significant reduction in CVD risk in patients <65 years (HR 0.81 [95% CI 0.69, 0.96]) but no difference for other patients, including patients ≥65 years, who achieved SBP <130 mmHg when compared with the group that achieved SBP <140 mmHg.

CONCLUSIONS

Our findings support a SBP treatment target of 140 mmHg and suspect no risk reduction attenuation on CVD for lower SBP targets (<120 or <130 mmHg) for most patients with uncomplicated T2DM. A randomized control trial is still needed to confirm these findings.

Blood pressure targets for hypertension in people with diabetes mellitus

BACKGROUND

When treating elevated blood pressure (BP), doctors often want to know what blood pressure target they should try to achieve. The standard blood pressure target in clinical practice for some time has been less than 140 - 160/90 - 100 mmHg for the general population of people with elevated blood pressure. Several clinical guidelines published in recent years have recommended lower targets (less than 130/80 mmHg) for people with diabetes mellitus. It is not known whether attempting to achieve targets lower than the standard target reduces mortality and morbidity in those with elevated blood pressure and diabetes.

OBJECTIVES

To determine if 'lower' BP targets (any target less than 130/85 mmHg) are associated with reduction in mortality and morbidity compared with 'standard' BP targets (less than 140 - 160/90 - 100 mmHg) in people with diabetes.

SEARCH METHODS

We searched the Database of Abstracts of Reviews of Effectiveness (DARE) and the Cochrane Database of Systematic Reviews for related reviews. We conducted electronic searches of the Hypertension Group Specialised Register (January 1946 - October 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 9), MEDLINE (January 1946 - October 2013), EMBASE (January 1974 - October 2013) and ClinicalTrials.gov. The most recent search was performed on October 4, 2013.Other search sources were the International Clinical Trials Registry Platform (WHO ICTRP), and reference lists of all papers and relevant reviews.

SELECTION CRITERIA

Randomized controlled trials comparing people with diabetes randomized to lower or to standard BP targets as previously defined, and providing data on any of the primary outcomes below.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed and established the included trials and data entry. Primary outcomes were total mortality; total serious adverse 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

We found five randomized trials, recruiting a total of 7314 participants and with a mean follow-up of 4.5 years. Only one trial (ACCORD) compared outcomes associated with 'lower' (< 120 mmHg) or 'standard' (< 140 mmHg) systolic blood pressure targets in 4734 participants. Despite achieving a significantly lower BP (119.3/64.4 mmHg vs 133.5/70.5 mmHg, P < 0.0001), and using more antihypertensive medications, the only significant benefit in the group assigned to 'lower' systolic blood pressure (SBP) was a reduction in the incidence of stroke: risk ratio (RR) 0.58, 95% confidence interval (CI) 0.39 to 0.88, P = 0.009, absolute risk reduction 1.1%. The effect of SBP targets on mortality was compatible with both a reduction and increase in risk: RR 1.05 CI 0.84 to 1.30, low quality evidence. Trying to achieve the 'lower' SBP target was associated with a significant increase in the number of other serious adverse events: RR 2.58, 95% CI 1.70 to 3.91, P < 0.00001, absolute risk increase 2.0%.Four trials (ABCD-H, ABCD-N, ABCD-2V, and a subgroup of HOT) specifically compared clinical outcomes associated with 'lower' versus 'standard' targets for diastolic blood pressure (DBP) in people with diabetes. The total number of participants included in the DBP target analysis was 2580. Participants assigned to 'lower' DBP had a significantly lower achieved BP: 128/76 mmHg vs 135/83 mmHg, P < 0.0001. There was a trend towards reduction in total mortality in the group assigned to the 'lower' DBP target (RR 0.73, 95% CI 0.53 to 1.01), mainly due to a trend to lower non-cardiovascular mortality. There was no difference in stroke (RR 0.67, 95% CI 0.42 to 1.05), in myocardial infarction (RR 0.95, 95% CI 0.64 to 1.40) or in congestive heart failure (RR 1.06, 95% CI 0.58 to 1.92), low quality evidence. End-stage renal failure and total serious adverse events were not reported in any of the trials. A sensitivity analysis of trials comparing DBP targets < 80 mmHg (as suggested in clinical guidelines) versus < 90 mmHg showed similar results. There was a high risk of selection bias for every outcome analyzed in favor of the 'lower' target in the trials included for the analysis of DBP targets.

AUTHORS' CONCLUSIONS

At the present time, evidence from randomized trials does not support blood pressure targets lower than the standard targets in people with elevated blood pressure and diabetes. More randomized controlled trials are needed, with future trials reporting total mortality, total serious adverse events as well as cardiovascular and renal events.

Diabetes and hypertension: the bad companions

High blood pressure is reported in over two-thirds of patients with type 2 diabetes, and its development coincides with the development of hyperglycaemia. Many pathophysiological mechanisms underlie this association. Of these mechanisms, insulin resistance in the nitric-oxide pathway; the stimulatory effect of hyperinsulinaemia on sympathetic drive, smooth muscle growth, and sodium-fluid retention; and the excitatory effect of hyperglycaemia on the renin-angiotensin-aldosterone system seem to be plausible. In patients with diabetes, hypertension confers an enhanced risk of cardiovascular disease. A blood pressure of lower than 140/85 mm Hg is a reasonable therapeutic goal in patients with type 2 diabetes according to clinical trial evidence. People with controlled diabetes have a similar cardiovascular risk to patients without diabetes but with hypertension. A renin-angiotensin system blocker combined with a thiazide-type diuretic might be the best initial antihypertensive regimen for most people with diabetes. In general, the positive effects of antihypertensive drugs on cardiovascular outcomes outweigh the negative effects of antihypertensive drugs on glucose metabolism.

Epidemiology and prevention of stroke: a worldwide perspective

This paper reviews how epidemiological studies during the last 5 years have advanced our knowledge in addressing the global stroke epidemic. The specific objectives were to review the current evidence supporting management of ten major modifiable risk factors for prevention of stroke: hypertension, current smoking, diabetes, obesity, poor diet, physical inactivity, atrial fibrillation, excessive alcohol consumption, abnormal lipid profile and psychosocial stress/depression.

What should be the optimal levels of blood pressure: Does the J-curve phenomenon really exist?

INTRODUCTION

The blood pressure (BP) J-curve debate has lasted for over 30 years and we still cannot definitively answer all the questions. However, recent studies suggest that BP should be reduced carefully in patients with hypertension and coronary artery disease. BP should not fall below 110 - 115/70 - 75 mmHg, because this may be associated with more cardiovascular events.

AREAS COVERED

A retrospective analysis of the INVEST Trial and the results of the BP arm of the ACCORD Trial shows that care is needed in patients with hypertension and diabetes. Although the ACCORD BP Trial suggests important benefits connected with the significant reduction of stroke in patients being treated intensively, it also shows the lack of advantage of such therapy on each main and other additional endpoints. The ACCORD Trial also confirmed the increased risk of adverse events that might appear when intensive treatment was used in this group of patients.

EXPERT OPINION

Most available studies were observational and randomized trials (BBB, HOT, ACCORD BP), do not have or have lost their statistical power and were inconclusive. Further studies are therefore needed to provide definitive conclusions on the subject. In the meantime, it seems that in high-risk patients with hypertension, it is necessary to carefully select those who might suffer adverse events and those who may benefit from intensive BP lowering.