EVIDENCE-BASED ANSWER:
There is no simple answer; the risk/benefit picture is complicated. Controlling blood pressure to a target of 130/80 mm Hg or lower produces mixed results in patients with diabetes and coronary disease equivalents (chronic kidney disease [CKD], coronary artery disease, peripheral arterial disease, and previous stroke).
No evidence indicates that patients with diabetes or most patients with CKD have better outcomes if their blood pressure is controlled below 140/90 mm Hg. Patients with diabetes controlled to lower systolic blood pressure targets (below 120 mm Hg) have fewer strokes, but more serious adverse events. Achieving diastolic blood pressure targets below 80 mm Hg doesn’t reduce mortality, strokes, myocardial infarction, or congestive heart failure (strength of recommendation [SOR]: A, systematic review of randomized controlled trials [RCTs]).
Tight blood pressure control (approximately 130/80 mm Hg or lower) reduces the risk of kidney failure by 27% in CKD patients with proteinuria at baseline. In patients without proteinuria, it doesn’t add benefit over standard blood pressure control (140/90 mm Hg) for reducing kidney failure, mortality, or cardiovascular events (SOR: A, meta-analysis of RCTs).
Controlling hypertension to 130/80 mm Hg or lower in patients with coronary artery disease reduces heart failure (27%) and stroke (18%) but increases the incidence of hypotensive episodes (220%) when compared with standard 140/90 mm Hg target blood pressure. Lower target pressures don’t affect total or cardiovascular mortality, myocardial infarction, or angina, but do increase the need for revascularization in 6% of patients (SOR: A, meta-analysis of RCTs).
Controlling systolic blood pressure to a target of 120 mm Hg, compared with the standard target of 140 mm Hg, reduces a composite outcome (myocardial infarction, acute coronary syndrome, stroke, congestive heart failure, or cardiovascular death) by 25% and a secondary outcome of all-cause mortality by 27% in patients ages 50 and older with cardiovascular risk factors (but not diabetes or previous stroke).
However, intensive control doesn’t significantly improve the composite outcome in patients who are female, black, or younger than 75 years, or who have systolic blood pressures above 132 mm Hg, previous CKD, or previous cardiovascular disease. Intensive control causes more hypotension, syncope, and electrolyte abnormalities, but not falls resulting in injuries (SOR: B, large RCT).
No evidence-based studies exist to guide BP control in patients with peripheral artery disease or previous stroke. Current guidelines recommend treating hypertension to a target of 140/90 mm Hg in these patients.
EVIDENCE SUMMARY
A Cochrane systematic review of 5 RCTs with a total of 7314 patients evaluated cardiovascular outcomes after 4.7 years follow-up in patients with diabetes who were treated for hypertension to either “lower” or “standard” target blood pressures.1 One trial in the review (ACCORD, 4734 patients) compared outcomes from significantly lower and standard systolic blood pressures (119/64 mm Hg vs 134/71 mm Hg; P<.0001) in patients with diabetes and either cardiovascular disease or 2 risk factors for cardiovascular disease. The authors evaluated outcomes based on achieved systolic blood pressures rather than intention to treat.
They found a reduced incidence of stroke (risk ratio [RR]=0.58; 95% confidence interval [CI], 0.39-0.88; P=.009; number needed to treat [NNT]=91) but no change in mortality (RR=1.05; 95% CI, 0.84-1.30) at lower blood pressures. Achieving the lower systolic blood pressure increased the number of serious adverse effects, however (RR=2.58; 95% CI, 1.70-3.91; P<.0001; absolute risk increase=2%; number needed to harm=50).