Chlorthalidone, the guideline-recommended diuretic for lowering blood pressure, causes more serious side effects than hydrochlorothiazide, a similarly effective diuretic, according to a new study led by researchers at Columbia University Irving Medical Center. The findings, published in JAMA Internal Medicine , contrast with current treatment guidelines recommending chlorthalidone over hydrochlorothiazide.
The researchers found that patients taking chlorthalidone had nearly three times the risk of developing dangerously low levels of potassium and a greater risk of other electrolyte imbalances and kidney problems compared with those taking hydrochlorothiazide. Information from the largest individual database studied by the team revealed that 6.3% of patients treated with chlorthalidone experienced hypokalemia (low blood potassium), compared with 1.9% of patients who were treated with hydrochlorothiazide.
Hypokalemia rates remained higher for patients taking chlorthalidone even when given at a lower dose than hydrochlorothiazide.
"Doctors prescribing chlorthalidone should monitor for certain side effects in their patients," says George Hripcsak, MD, MS, chair and Vivian Beaumont Allen Professor of Biomedical Informatics at Columbia University Vagelos College of Physicians and Surgeons and lead author of the study.
The study, which looked at 17 years of data on more than 730,000 individuals treated for hypertension, is the largest multisite analysis directly comparing the two antihypertensive drugs in the general patient population.
The results were generated by the Large-Scale Evidence Generation and Evaluation in a Network of Databases (LEGEND) Hypertension study, a method for analyzing data in millions of electronic health records around the world developed by the Observational Health Data Sciences and Informatics (OHDSI) network, which has a central coordinating center at Columbia University.
An earlier LEGEND Hypertension study, published in The Lancet, found that thiazide diuretics were more effective and caused fewer side effects than ACE inhibitors when used as first-line C.
In the current paper, the researchers found that chlorthalidone and hydrochlorothiazide were similarly effective in preventing heart attack, hospitalization for heart failure, and stroke. However, patients treated with chlorthalidone had a significantly higher risk of side effects, including hypokalemia, which can lead to abnormal heart rhythms; hyponatremia (low sodium), which can cause confusion; kidney failure; and type 2 diabetes.
The difference in the occurrence of side effects was striking. Hypokalemia, hyponatremia, chronic and acute kidney problems, along with other electrolyte imbalances, are all potentially dangerous side effects." George Hripcsak, lead author of the study Related Stories
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