Benefit in MI, stroke subgroup?
In the subgroup analysis, patients with a history of MI or stroke who were receiving chlorthalidone had a significant 27% reduction in the primary endpoint (HR, 0.73; 95% CI, 0.57-0.94). Conversely, patients without a history of MI or stroke appeared to do worse while taking chlorthalidone (HR, 1.12; 95% CI, 1.00-1.26).
“We were surprised by these results,” Dr. Ishani said. “We expected chlorthalidone to be more effective overall. However, learning about these differences in patients who have a history of cardiovascular disease may affect patient care. It’s best for people to talk with their health care clinicians about which of these medications is better for their individual needs.”
He added: “More research is needed to explore these results further because we don’t know how they may fit into treating the general population.”
Dr. Ishani noted that a limitations of this study was that most patients were receiving the low dose of chlorthalidone, and previous studies that suggested benefits with chlorthalidone used the higher dose.
“But the world has voted – we had 4,000 clinicians involved in this study, and the vast majority are using the low dose of hydrochlorothiazide. And this is a definitively negative study,” he said. “The world has also voted in that 10 times more patients were on hydrochlorothiazide than on chlorthalidone.”
Commenting on the study at an AHA press conference, Biykem Bozkurt, MD, PhD, Baylor College of Medicine, Houston, pointed out that in all of the landmark National Institutes of Health hypertension trials, there was a signal for benefit with chlorthalidone compared with other antihypertensives.
Catherine Hackett/MDedge News
Dr. Biykem Bozkurt
“We’ve always had this concept that chlorthalidone is better,” she said. “But this study shows no difference in major cardiovascular endpoints. There was more hypokalemia with chlorthalidone, but that’s recognizable as chlorthalidone is a more potent diuretic.”
Other limitations of the DCP trial are its open-label design, which could interject some bias; the enduring effects of hydrochlorothiazide – most of these patients were receiving this agent as background therapy; and inability to look at the effectiveness of decongestion of the agents in such a pragmatic study, Dr. Bozkurt noted.
She said she would like to see more analysis in the subgroup of patients with previous MI or stroke. “Does this result mean that chlorthalidone is better for sicker patients or is this result just due to chance?” she asked.
“While this study demonstrates equal effectiveness of these two diuretics in the targeted population, the question of subgroups of patients for which we use a more potent diuretic I think remains unanswered,” she concluded.
Designated discussant of the DCP trial at the late-breaking trial session, Daniel Levy, MD, director of the Framingham Heart Study at the National Heart, Lung, and Blood Institute, reminded attendees that chlorthalidone had shown impressive results in previous important hypertension studies including SHEP and ALLHAT.
He said the current DCP was a pragmatic study addressing a knowledge gap that “would never have been performed by industry.”
Dr. Levy concluded that the results showing no difference in outcomes between the two diuretics were “compelling,” although a few questions remain.
These include a possible bias toward hydrochlorothiazide – patients were selected who were already taking that drug and so would have already had a favorable response to it. In addition, because the trial was conducted in an older male population, he questioned whether the results could be generalized to women and younger patients.
The DCP study was funded by the VA Cooperative Studies Program. Dr. Ishani reported no disclosures.
A version of this article first appeared on Medscape.com.