Is TROPHY misleading?
By Elsevier Health Sciences
Oct 27, 2006, 16:39
There may be as many as 70 million Americans with prehypertension. If these people can be treated pharmacologically to avoid or delay progression to clinical hypertension, there would be significant benefits to them and the overall health of the population. The recent TROPHY study seems to lead to that conclusion. However, two editorials published in the November issue of the American Journal of Hypertension emphatically argue that the study is flawed and the conclusions reached are misleading.
Persons with prehypertension, generally defined as having a systolic blood pressure in the range of 120-139 mm Hg or a diastolic blood pressure of 80-89, will usually develop hypertension at the rate of about 10% per year. The recent Trial of Preventing Hypertension (TROPHY) examined whether treating patients with candesartan for two years resulted in a sustained reduction in the incidence of high blood pressure after the drug was discontinued. The TROPHY study concluded that the treatment significantly reduced the risk of incident hypertension over the four year study.
According to Stephen Persell, MD, MPH, TROPHY results are likely invalid. He and co-author David W. Baker, MD, MPH, both of the Feinberg School of Medicine at Northwestern University, argue that the study used an unusual definition of incident hypertension which could not accurately discriminate whether the drug had a sustained effect. They demonstrate that because blood pressure readings taken during active treatment were combined with readings taken after treatment had ended, a difference between treatment and placebo could appear even if blood pressures were identical after the treatment had ended. They also analyze how the results could be misleading due to the methods used to calculate the mean blood pressures.
In the second editorial, Jay I. Meltzer MD, Clinical Specialist in Hypertension in the Nephrology Division of the Columbia College of Physicians and Surgeons, also zeros in on the study endpoint. He argues that clinical practitioners would require a more realistic, classical definition of incident hypertension than was used in TROPHY.
Dr. Meltzer also identifies two other issues in the study. He explains, "Further straining the question of applicability is the confusion between what the authors said they would do and what they actually did. They renamed TROPHY a 'feasibility' study, without specifically defining the term. It usually means a pilot study, but TROPHY was not designed as a pilot…Clinicians rightly suspect bias when the trial language is changed post hoc to allow more accommodation to the data." Finally, he argues that the major conclusion that the drug did prevent the development of hypertension was compromised by the choice of an arbitrary endpoint.
Persell and Baker caution that "the consequences of drawing erroneous conclusions from studies of treatments to prevent progression from pre-hypertension to hypertension are enormous. An expert panel of statisticians and trial methodologists without ties to pharmaceutical companies should be convened to provide consensus recommendations for how future studies addressing the prevention of hypertension should be conducted and reported. Computer models should also be used to confirm that the study methodology would not make it appear that a treatment for prehypertension had sustained benefits when, in fact, none existed."
Dr. Meltzer is equally direct. "What conclusions might actually be appropriate? TROPHY proved that two years of candesartan treatment of patients with 'high normal' or 'prehypertension' did not prevent or delay the development of hypertension, but instead caused a 'slow unmasking.' Reasonable acceptance of the author's own predetermined guidelines for the interpretation of 'slow unmasking' would have necessitated publishing a negative study, which, paradoxically, could have been a great benefit to the hypertension literature. Instead, TROPHY was presented in a way that enables those who want to believe in the original idea despite the evidence against it, still can and still do. Even as the authors trumpet candesartan's success in the paper's conclusions and in public presentations, the conclusion section of TROPHY paradoxically states that they do not advocate treating the 25 million people with prehypertension, but don't explain why."
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