Dr. Kohli On The DCP Trial

A recent study called the DCP trial showed that compared with hydrochlorothiazide, chlorthalidone failed to reduce major cardiovascular outcomes or non-cancer related deaths in elderly veterans with hypertension. The results were presented last month at AHA 2022.

DocWire News Medical Leader Dr. Payal Kohli spoke in detail about the study design, and findings, and provided some key takeaways on this important trial.

Overview of The DCP Trial

Yeah, so the DCP trial was another trial that challenged some of our old friends. And so I really loved the AHA this year because they had all these trials looking at what we’ve been doing for decades and asking, are we really doing the right thing? So here the clinical question was, is chlorthalidone versus hydrochlorothiazide any different with respect to major adverse cardiovascular events?

So this was a VA trial, and what they did is they looked through the VA electronic medical record and they found patients that were already on hydrochlorothiazide and then they did a washout and kind of switched them over. This was also an open label design as well, and they recruited patients through the electronic medical record from their providers.

And interestingly, also another null trial that gives us a lot of clinical insight. We really found no difference with respect to clinical outcomes with hydrochlorothiazide versus chlorthalidone, and that included blood pressure control. It was interesting that more patients in the chlorthalidone arm had more hypokalemia that was severe, so lower potassium levels. If you broke it down by subgroups, most of the subgroups also came out negative, but there was one subgroup, the one that did not have a prior MI, that seemed to do worse with chlorthalidone. Now, I don’t put a lot of stock into subgroups when the parent trial itself is negative, but again, a very interesting study that I do think has some clinical implications.

What are the key takeways of DCP?

I really like the fact that, again, we challenged something we’ve been doing for a while. It was 97% men and it was all older men by design, so all greater than 65 years of age. So the generalizability to other subgroups, younger patients as well as female patients, that’s still a bit of a question mark. It does tell us that we can pretty much use kind of either thiazide diuretic, doesn’t really necessarily impact outcomes all that much.

I do like the idea of having an electronic medical record driven recruitment design, because I think that’s kind of going to be the clinical trials of the future. But one of the criticisms of the trial is that because it screened people that had already been on hydrochlorothiazide, could there have been a bit of a selection bias where we kind of favored the results or biased the results to words hydrochlorothiazide because we picked people who were already tolerant of that medication as opposed to picking people who are either on both medications or patients who are on neither of those thiazide diuretics.
So again, very interesting science. Doesn’t change a whole lot of what I’m doing, but in a way reinforces that we can really pick sort of either thiazide diuretic in our patient care protocol. And we do know from prior trials that treating hypertension aggressively does reduce cardiovascular events. So that continues to remain the ultimate goal.