Newswise — Using data from the landmark trial, ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial), scientists today presented results showing that, despite a more favorable effect on metabolic factors defining the metabolic syndrome (MetS) with the alpha-blocker doxazosin, this agent was less effective in preventing hypertensive complications in patients with MetS than the diuretic chlorthalidone.
In their study, Clinical outcomes by race in participants with the metabolic syndrome in the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial on doxazosin vs chlorthalidone, Jackson T. Wright, Jr., MD, PhD and colleagues for the ALLHAT Collaborative Research Group, assessed first-step drug therapy outcomes for 13,209 Blacks and nonBlacks with MetS. Hypertensive participants were defined as having MetS if they also had two or more of the following: fasting glucose >100 mg/dL, BMI>30, fasting triglycerides >150 mg/dL, HDL cholesterol <40 mg/dL for men and <50mg/dL for women.
Of the ALLHAT participants meeting the criteria for MetS, almost 4200 were Black. All were 55 years of age and older.
Participants were randomly assigned either chlorthalidone (diuretic) or doxazosin (alpha-blockers) to control blood pressure. Physicians could also provide other drugs of different types if needed. After 36 months of treatment, both Blacks and nonBlacks in the chlorthalidone group had significantly lower levels of serum glucose and cholesterol than those in the doxazosin group.
"Hypertensive patients with MetS are at especially high risk for complications of cardiovascular disease," said Dr. Wright. "A primary health management strategy for MetS includes lifestyle changes to control blood pressure and other CV risk factors. Drug therapy is added when lifestyle changes alone are not able to control elevated blood pressure or other risk factors associated with MetS."
Racial differences in presentation of the MetS are well-documented.(1,2) Although overall incidence of MetS has been found to be lower in African Americans compared to Caucasians and Mexican Americans,(3) other studies demonstrate that African Americans are at higher risk than Caucasians for several individual cardiovascular risk factors. For example when compared to Caucasians, African Americans have a higher prevalence of elevated blood pressure, type 2 diabetes, and obesity but higher HDL ("good" ) cholesterol and lower triglycerides.(4)
To treat hypertension, the use of drugs with favorable metabolic profiles such as alpha-blockers (ABs), angiotensin converting enzyme inhibitors (ACEIs), and calcium channel blockers (CCBs) has been advocated over other classes of antihypertensive drugs with a less favorable profile (eg, beta-blockers and thiazide-type diuretics [THZ]), despite the lack of clinical outcome data in this population.
However, more recent reports disagree with this approach. "Reports from ALLHAT in 2002 showed that neither an AB, nor an ACEI, nor a CCB was superior to a THZ in preventing cardiovascular or renal events, and a THZ is superior for preventing heart failure " Dr. Wright explained. "For this study, we wanted to test the efficacy of AB vs THZ to see if it performed as well for those with MetS as it did for those with high blood pressure or kidney disease."
With the release of the ALLHAT findings in December 2002, the ALLHAT investigators recommended that, in addition to lifestyle changes, diuretics should be the drug of choice for first-line blood pressure treatment, especially in Black hypertensive patients.
Now, with the findings of this study, investigators are recommending diuretics for controlling cardiovascular risk factors for those with MetS. In addition to improved health outcomes, Wright cites another advantage of diuretics. "They are less expensive than the other classes of drugs. For those on fixed incomes or tight budgets, using a medicine that costs less than $100 a year is an important consideration."
The ALLHAT blood pressure study was funded by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health. It compared the effects of four major classes of medications to treat high blood pressure. More than 42,000 patients, ages 55 and older, participated.
Jackson T. Wright, Jr., MD, PhD, FACP is professor of medicine, and director of the General Clinical Research Center at Case Western Reserve University (CWRU) and director of the Clinical Hypertension Program at the Case Medical Center. In addition, he is chief of the Hypertension Section at the Louis Stokes Cleveland VA Medical Center.
These scientific findings were presented as a blue ribbon presentation today at the 21st International Interdisciplinary Conference on Hypertension and Related Cardiovascular Risk Factors in Ethnic Populations as Abstract 016. The abstract appears below. Additional conference information and news from the conference can be found at http://www.ishib.org/ISHIB2006.
References1. Hall WD, Clark LT, Wenger NK, Wright JT Jr, Kumanyika SK, Watson K, Horton EW, Flack JM, Ferdinand KC, Gavin JR 3rd, Reed JW, Saunders E, O'Neal W Jr. For the patient. What is the metabolic syndrome and why is it important? Ethn Dis. 2003; 13(4):546.2. Ford ES, Giles W, Dietz WH. Prevalence of the metabolic syndrome among US adults: findings from the third National Health and Nutrition Examination Survey. JAMA.2002;287-356-359.3. Park Y-W, Zhu S, Palaniappan L, Heshka, S, Carnethon MR, Heymsfield SB. The metabolic syndrome: prevalence and associated risk factor findings in the US population from the Third National Health and Nutrition Examination Survey, 1988-1994. Arch Intern Med. 2003;163:427-436.4. American Heart Association. Heart Disease and Stroke Statistics " 2006 Update. Dallas, Texas: American Heart Association; 2006.
ISHIB2006 is jointly sponsored by ISHIB and the American Society of Hypertension (ASH). ISHIB (The International Society on Hypertension in Blacks) is a nonprofit, professional medical membership organization devoted to improving the health and life expectancy of ethnic populations. ISHIB was founded in Atlanta, Georgia, in 1986 to respond to the problem of high blood pressure among ethnic populations. Each year, its international interdisciplinary conference presents advancements in the treatment and prevention of cardiovascular diseases to reduce health disparities among ethnic minority populations. In addition to US conference locations, other sites for the conference have included Toronto, London, the US Virgin Island, Kenya, Cameroon, and Brazil.
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