Diuretics can hurt lean patients, researchers say
THURSDAY, Dec. 6 (HealthDay News) -- Taking a patient's weight into account when choosing blood pressure medications might help prevent strokes, heart attacks and death, a new study suggests.
Lean and obese people react differently to different blood pressure medications, said the researchers, who believe their findings could change the way high blood pressure (hypertension) is treated.
"Unexpectedly, people who have high blood pressure and are fat actually have a better prognosis than people who have high blood pressure and are thin," said lead researcher Dr. Michael Weber, a professor of medicine at Downstate Medical Center of the State University of New York in New York City.
"You can now choose blood pressure medication as a means of compensating for this difference between obese and thin people, so that it's possible to treat everybody with a medicine that maximizes the outcome regardless of how much you weigh," he said.
Weber recommends starting all patients with high blood pressure on a class of drugs called calcium channel blockers, regardless of weight. One such drug is Norvasc (amlodipine).
Although diuretics, which reduce excess water in the body, are effective in obese patients, they can harm thin patients, and should be relegated to a third-line therapy, Weber said.
Obese people respond better to diuretics, Weber explained, because their hypertension is often caused by a combination of excess weight, too much fluid and too much salt. Thin hypertensive patients, he said, may have underlying circulatory problems that are causing their high blood pressure and placing them at increased risk for cardiovascular disease.
For the study, published in the Dec. 6 online edition of The Lancet, Weber's group analyzed data on more than 11,000 individuals in an international high blood pressure trial.
That trial compared treatment with a diuretic and Lotensin (benazepril), which is known as an ACE inhibitor, with a regimen of Lotensin plus the calcium channel blocker Norvasc.
The goal of the study was to see which combination better controlled high blood pressure in people at high risk for heart disease and to see if weight had an effect on blood pressure control.
Participants were grouped into three categories -- normal weight, overweight and obese -- based on their body mass index (BMI). BMI is a body fat calculation based on height and weight.
Normal-weight people taking the diuretic fared the worst, the investigators found. This group was 68 percent more likely to have a heart attack, stroke or die than obese patients taking a diuretic.
People taking the Lotensin-Norvasc combination did well regardless of weight, they found. This drug duo reduced stroke, heart attack and death by 43 percent in normal-weight people and 24 percent in overweight people, according to the study.
Among obese people, both drug regimens worked well with no significant differences between them, the researchers found.
However, some doctors argue against giving obese patients diuretics.
"We disagree that diuretics are a reasonable choice for the obese patient," said Dr. Franz Messerli, a cardiologist and director of the hypertension program at St. Luke's-Roosevelt Hospital and Columbia University College of Physicians and Surgeons in New York City.
Obesity is a reason not to use diuretics, he said. Diuretics should be used only when certain types of heart disease, including heart failure, exist, said Messerli, co-author of an accompanying journal editorial.
In obese patients, diuretics can trigger poor blood sugar control and gout, Messerli said.
Messerli agreed that calcium channel blockers should be first-line treatment for all patients with high blood pressure whether they are fat, thin or in between.
Dr. Gregg Fonarow, a spokesman for the American Heart Association and a professor of cardiology at the University of California, Los Angeles, said the study findings may be an example of the "obesity paradox." This theory holds that obesity is a well-established risk factor for developing hypertension, heart disease and heart failure, while "among individuals with established hypertension, coronary heart disease, and heart failure, obesity has been unexpectedly associated with lower cardiovascular event rates and mortality."
These new findings suggest that an individual's BMI should be considered when selecting anti-hypertensive medications, he said.
"Treatment with calcium channel blockers appears preferable to treatment with diuretics in non-obese men and women with hypertension," Fonarow said.
The study was funded by Novartis Pharmaceuticals, maker of Lotensin.
For more information on high blood pressure, visit the American Heart Association (http://www.heart.org/HEARTORG/Conditions/HighBloodPressure/High-Blood-Pressure_UCM_002020_SubHomePage.jsp ).
SOURCES: Michael Weber, M.D., Downstate Medical Center, State University of New York, New York City; Franz Messerli, M.D., cardiologist, and director, hypertension program, St Luke's-Roosevelt Hospital, Columbia University College of Physicians and Surgeons, New York City; Gregg Fonarow, M.D., spokesman, American Heart Association, and professor, cardiology, University of California, Los Angeles; Dec. 6, 2012, The Lancet, online