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An NIH study of treatments for high blood pressure, called the ALLHAT trial, shows some of the strengths and limitations of comparative effectiveness research to improve patient care. More...
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For journalists and other media professionals
In December of 2002, the National Institutes of Health (NIH) published a study in the Journal of the American Medical Association (JAMA) that sought to compare the relative benefits of three popular hypertension medicines. The study known by its abbreviated title, ALLHAT, garnered significant media attention because of its large sample size, government sponsorship, and seemingly novel results. While the majority of media reports on the study contained accurate information, the study‚ outcomes and implications were over-simplified and over-interpreted. The study was widely reported as proving that older, cheaper medicines were "best" in treating high blood pressure. Experience with the ALLHAT trial illustrates the value of comparative effectiveness studies, and also some of the pitfalls. It also shows why it often is very difficult for policy-makers to use CER study findings to decide which treatments should be available to patients.
ALLHAT does not give a single answer for all individuals with hypertension.
The ALLHAT study provided valuable additional information for physicians and patients about their treatment options. For example, it identified concerns about potential risks with one type of treatment (a drug called an alpha-blocker). However, it also illustrates how conclusions about the comparative effects of treatments based on large population averages can overlook the needs of individual patients. They can serve as one of many useful sources of information to help guide treatment, but should not be used by government agencies to dictate medical decisions.
More recent studies yield results that differ from ALLHAT findings.
According to the ALLHAT Fact Sheet on the web site of the National Heart Lung and Blood Institute, Results show that diuretics work best to both lower blood pressure and prevent stroke and some forms of heart disease, including heart attack and heart failure. However, recent developments underscore the danger of over-relying on this type of simplified conclusion.
In the two years following publication of ALLHAT, three separate studies involving a total of about 30,000 patients all had results that differed from ALLHAT findings, and ALLHAT compared only a few of the many medicines that are used to treat hypertension. Commenting on the results of one of the subsequent trials (called the "ASCOT" study), Dr. Franz Messerli and Dr. Tine Sichrovsky said: "Clearly, these [ALLHAT] headlines will need to be amended in view of the recent premature termination of the ASCOT trial."
In addition, Dr. Mark Houston, Hypertension Institute Director, Vanderbilt University Medical Center, and ALLHAT investigator, states, ‚"The ALLHAT study results have been misinterpreted and misquoted and are contradictory to the enormous number of scientific publications on hypertension." Dr. Michael Weber from State University of New York, also an ALLHAT investigator, also has voiced concern, saying the lead researchers "pushed beyond what the data allowed them to say."
Just three months after ALLHAT was published, an Australian study published in the New England Journal of Medicine had contradictory results. In the Australian study, researchers compared a different ACE inhibitor with a diuretic commonly prescribed by physicians in the U.S., and concluded that anti-hypertension treatment using ACE inhibitors in older patients, particularly in men, appears to lead to better primary and secondary outcomes than treatment using diuretics, despite similar reductions in blood pressure. These findings contradict the reported findings of ALLHAT.
The ALLHAT study was outpaced by medical science.
ALLHAT took over $100 mil. and 8 years to complete. During the years the study was going on, medical care for people with hypertension evolved. By the time the study was done, the results reflected "an outdated question that doesn't have huge relevance to the majority of people's clinical practice," according to Dr. John Flack, chairman of medicine at Wayne State University.
ALLHAT shows strengths and limitations of CER.
Experience with the ALLHAT trial illustrates the value of comparative effectiveness studies, providing valuable additional information for physicians and patients about their treatment options.
However, it also illustrates how conclusions about the comparative effects of treatments based on large population averages can overlook the needs of individual patients. Such studies often yield results that are unclear and complex, can be contradicted by other studies, and are open to misinterpretation. As a result, there is a very real risk that such research will be misapplied by policy-makers in ways that impede the ability of physicians to provide optimal care to individual patients.