#2 SPRINT trial – which blood pressure target is best?

In episode 2 of the Evidence Based Medicine Podcast we delve into the SPRINT trial.
This trial assessed whether targeting systolic blood pressure to less than 120mmHg is better than targeting to less than 140mmHg it terms of harms and reduction in cardiovascular disease.

The trial was conducted in 9,361 patients with very a very high risk of cardiovascular disease but who didn’t have diabetes or a past history of stroke. They were randomised to 2 groups: A standard blood pressure group who were targeted to a systolic BP of less than 140mmHg or an intensive blood pressure group who were targeted to less than 120mmHg systolic. They were followed for an average of 3.3 years

In this episode we go through the results of the trial, it’s impact on hypertension guidelines across the world and how it sits in the face of other similar trials, most notably the ACCORD BP trial. We also discuss some of the controversy about the trial as reported in many commentaries in the literature.

I was a very well done and important trial published in NEJM in November 2015 and stands for “Systolic Blood Pressure Intervention Trial”…I guess SBPRINT trial wouldn’t have sounded as good!

The bottom line is that for patients with hypertension, at high risk of cardiovascular disease, but without diabetes or previous stroke, treating them to a systolic blood pressure target of less than 120, compared to less than 140 will decrease their chance of cardiovascular disease by 1.6% over 3.3 years and will decrease their chance of dying by about 1%. But it comes at a cost, most important of which is an increase in acute renal failure by 1.8%, an increase in worsening renal function by 2.7% and an increase in being seriously harmed by episodes of hypotension, syncope or electrolyte abnormalities by about 3%

Here is a more in depth look at the results:

The benefits of treating blood pressure to 120 versus 140 systolic are as follows:
1. A reduction in cardiovascular disease from 6.8% to 5.2% with an absolute reduction of 1.6% or a Number Needed to Treat (NNT) of 63 over 3.3 years.
2. Death from any cause decreased by 1.2% – It went from 4.5% to 3.3% with a NNT of 83 over 3.3 years
3. Cardiovascular death decreased by 0.6% – It went from 1.4% to 0.8% with a NNT of 167
4. Heart failure decreased by 0.8% – It went from 2.1% vs 2.3% with a NNT 125
5. There was no difference in AMI or stroke

The harms of treating blood pressure to 120 versus 140 systolic are as follows:
1. Worsening renal function increased by 2.7% – it went from 1.1% to 3.8% with a Number Needed to Harm (NNH) of 37
2. – Acute renal failure increased by 1.8% – it went from 2.6% in the 140 systolic group to 4.4% in the 120 systolic group. NNH 56
3. Serious adverse events increased (events that were either fatal or life threatening, or required prolonged hospitalisation, or resulting in significant disability). Episodes of hypotension increased from 2% to 3.4% with a NNH 71
– Syncope increased from 2.4% to 3.5%, with a NNH 91
– Electrolyte abnormality also increased from from 2.8% to 3.8% with a NNH 100
– There was no difference in injurious falls, it was about 2.2% in both groups.

Reference: http://www.nejm.org/doi/full/10.1056/NEJMoa1511939
Music by Polyrhythmics, track titled “El Fuego”

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