Blood pressure targets for hypertension in people with diabetes mellitus
Jose Agustin Arguedas1, Viriam Leiva, James M Wright
1Depto de Farmacologia Clinica, Facultad de Medicina, Universidad de Costa Rica, San Pedro de Montes de Oca, Costa Rica.
Insights
Lowering blood pressure targets for people with diabetes does not reduce mortality or morbidity. Achieving lower systolic blood pressure targets increased serious adverse events, with no significant benefit for overall mortality.
Area of Science:
- Cardiology
- Nephrology
- Endocrinology
Background:
- Elevated blood pressure (BP) management in diabetes often involves targeting lower BP levels (<130/80 mmHg) compared to the general population (<140-160/90-100 mmHg).
- The clinical benefit of these lower BP targets regarding mortality and morbidity in diabetic patients remains unclear.
Purpose of the Study:
- To evaluate if lower blood pressure targets (<130/85 mmHg) reduce mortality and morbidity in individuals with diabetes compared to standard targets (<140-160/90-100 mmHg).
Main Methods:
- Systematic review and meta-analysis of randomized controlled trials (RCTs) comparing lower versus standard BP targets in diabetic patients.
- Searched multiple databases including DARE, Cochrane, MEDLINE, EMBASE, and ClinicalTrials.gov up to October 2013.
- Primary outcomes included total mortality, serious adverse events, myocardial infarction, stroke, congestive heart failure, and end-stage renal disease.
Main Results:
- Five RCTs with 7314 participants were analyzed. One trial on systolic BP (SBP) targets showed a reduction in stroke incidence with lower targets (<120 mmHg vs <140 mmHg) but increased serious adverse events and no significant mortality benefit.
- Four trials on diastolic BP (DBP) targets showed a trend towards reduced total mortality with lower targets (<128/76 mmHg vs <135/83 mmHg) but no significant differences in stroke, myocardial infarction, or heart failure.
- Evidence quality was generally low, with a high risk of selection bias favoring lower targets in DBP analyses.
Conclusions:
- Current evidence from RCTs does not support the use of lower blood pressure targets than standard ones for individuals with elevated blood pressure and diabetes.
- Further high-quality RCTs are necessary to investigate the effects of different BP targets on mortality, serious adverse events, and cardiovascular/renal outcomes in this population.
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.
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