Tuesday, February 16, 2016

Results of the SPRINT trial

Not sure what the hullabaloo is all about. Some doctors seem to be jubilant that the SPRINT trial shows lower blood pressure than what is currently recommended is better. But I looked at the data and I'm scratching my head.

A general picture of the trial: Participants were non-diabetic hypertensives aged 50 and older. About half (over 4,600) were randomized to therapy that would reduce their blood pressure to less than 140mm Hg. The other half had more intensive pharmacotherapy to get their bp to less than 120mm Hg. The former group averaged 2.8 medications per day, the latter 1.8 meds. Primary outcome was a composite of cardiovascular events including heart attack, stroke, and CV death.

Results: Here's where the rubber meets the road. And frankly the winner zipped past the finish line just a fraction of second earlier than its competitor. Media reported a 25% drop in cardiovascular events in the intensive therapy group. However, the sober truth behind the lurid reporting is that the absolute risk dropped from 2.19% to 1.65% (after 3 years of treatment). That's a measly one half percent. All-cause mortality dropped even lower--just over a third of a percent.

But given the number of hypertensive patients even in the US alone, such a small reduction could potentially prevent a huge number of CV events--even if the data shows that we'd need to give 185 patients an additional pill daily to save one patient from suffering a heart attack, heart failure, stroke, or some other CV event (after a few years of treatment).

But then the trial also discovered a few worms--big ones which should make doctors wary. The NEJM quick take doesn't provide the numbers, but it does tell us that there were more adverse events in the intensive therapy group, events such as syncope (loss of consciousness from hypotension) and kidney failure.

So you have greater benefits, on the one hand, but then greater risks for adverse events as well. So is it really beneficial for hypertensives to bring their bp down to less than 120? Perhaps it would eventually become a judgement call--a decision that doctor and patient will have to arrive at after taking into account the patient's lifestyle, other medical conditions, goals in life, risk aversion level, etc.