Chlorthalidone and hydrochlorthiazide yield similar CV benefits to elderly with hypertension

Also, there was no difference in stroke, heart attack, heart failure, or other cardiovascular outcomes. The study findings were presented at the 2022 Scientific Sessions of the American Heart Association (AHA) held in person in Chicago and virtually on Nov. 5-7, 2022.

The study, comprising more than 13,500 study participants, showed that those treated with BP-lowering medication chlorthalidone appeared to have no difference in non-cancer deaths or cardiovascular outcomes versus people treated with hydrochlorothiazide. In a small subgroup having a history of stroke or heart attack, those taking chlorthalidone had lower heart disease and death risk by an average of 27%.

Previous studies have suggested that chlorthalidone is better for controlling blood pressure over 24 hours versus hydrochlorothiazide; many specialists believed chlorthalidone to be more beneficial for reducing risks of heart disease development.

Areef Ishani, University of Minnesota, Minneapolis, and colleagues sought to determine whether chlorthalidone is superior to hydrochlorothiazide for preventing CV events in people with high blood pressure.

In the Diuretic Comparison Project (DCP) as a point-of-care clinical trial -- the researchers allowed participants and healthcare professionals to be aware of the medication being prescribed and to administer the medicine in a real-world setting. The point-of-care aspect imparted several unique features to the trial.

The study enrolled 13,523 U.S. veterans of age least 65 years with a recent systolic B.P. of 120 mm Hg or higher already taking hydrochlorothiazide 25 mg or 50 mg (mean age, 72 years). The participants were examined for stroke, heart attack, heart failure, or non-cancer death rates after a median of about 2.5 years. At baseline, 95% of veterans were on low hydrochlorothiazide doses. For the intervention, veterans either continued hydrochlorothiazide or were switched to chlorthalidone 12.5 mg.

The study led to the following findings:

• The heart disease and death rates were almost similar for the hydrochlorothiazide group (9.3%) and the chlorthalidone group (9.4%).
• Also, there was no difference in secondary outcomes (stroke, heart failure, heart attack, or other cardiovascular outcomes) between the participants taking the two medications.
• In a subgroup analysis, the researchers found differences in the participants who had a history of stroke or heart attack; those taking chlorthalidone reduced the heart disease and death risks by an average of 27%; chlorthalidone tended to exacerbate these outcomes by an average of 12% in patients who did not have a history of stroke or heart attack.

"We were surprised by these findings," Ishani said in a press release. "Chlorthalidone was expected to be more effective overall; however, learning about these differences in patients with a history of cardiovascular disease may affect patient care. People should talk with their healthcare clinicians about which medications are better for their needs.

"More studies are needed to explore these results further because we don't know how they may fit into treating the general population."