Recent guidelines on hypertension have relaxed blood pressure targets in elderly subjects i.e. 150mmhg systolic, but the SPRINT trial (published in NEJM Nov 2015) on contrary has come up with results showing, a reduction in cardiovascular events with aggressive blood systolic pressure control i.e less than 120 mmHg, in non-diabetic elderly with increased cardiovascular risk. This is has generated debate even to modify guidelines. in this article, we will discuss why one should not go aggressive .
In SPRINT trial 9351 subjects were randomly assigned for standard arm systolic BP less than 140 mmHg and intensive arm systolic BP less than 120 mmHg. These were non-diabetic subjects with increased cardiovascular risk. The trial was stopped prematurely for a mean duration of 3.26 years owing to a lesser incidence of the primary outcome (myocardial infarction, other acute coronary syndromes, stroke, heart failure, or death from cardiovascular causes.).
Guidelines have recommended 150 mmHg systolic targets because most trials have shown the benefit of a systolic reduction up to less than 150 mmHg although cardiovascular risk increases with increase of systolic BP more than 115 mmHg.
Points for treating physicians against SPRINT trial.
1. Benefit in limited group.
SPRINT trial has shown benefit in elderly non-diabetic patients with higher risk of cardiovascular events so extrapolating to lower cardiovascular event individual is not justified.
In SPRINT a mean number of drugs used was 1.8 versus 2.8 in standards versus intensive arms, i.e. one drug extra. This was because included subjects were not severely hypertensives. But, in practice in order achieve systolic BP to less than 120 mmHg physicians may end up giving 4 to 5 medicines. So, before adding many medicines, drug side effects and compliance has to be considered.
3. Kidney injury
Kidney Injury was more frequently seen in subjects in intensive arm whose baseline kidney function was normal . In individuals with baseline kidney disease, the difference was not obvious.
Assessment of kidney worsening was defined differently in individual with normal and abnormal baseline kidney disease. eGFR reduction needed to demonstrate the difference in individual with baseline normal kidney function was 30% as opposed to 50% in individual with abnormal kidney function.
4.Technique of BP measurement
In SPRINT trial Blood pressure measurement was done by automated machines in absence of attending physician. This would lead to lower BP values. But, in most clinical practice and also in other clinical trials attending physician is usually present while measuring BP, this tends to produce a higher reading. This kind of measurement makes SPRINT results uncomparable
5. Syncope and hypotension
Although orthostatic hypotension was not more in the intensive group but syncope and hypotension was more frequent in the intensive group i.e 3.5% vs. 2.4%, P=0.003) and (3.4% vs. 2.0%, P<0.001) respectively .