LONDON, September 4. Clinical trials that use a heart patient's 'quality of life' as the only measure of the success of their treatment may skew results because of a significant placebo effect, according to researchers at the European Society of Cardiology meeting in Amsterdam last week.
James Jollis of the Duke Clinical Research Institute, North Carolina, and his colleagues have studied the endpoint of clinical trials of novel cardiac therapies to determine whether a patient's own assessment of their health, a common 'endpoint' used by clinical researchers, is appropriate in assessing a new therapy.
In a study of 1189 patients with severe coronary artery disease, Jollis and his team found that a patient's sense of well-being was unaffected by the treatment they received. Yet their treatment dramatically affected the actual clinical outcome: mortality rates for patients given drug therapy were twice as high as those for patients undergoing heart bypass surgery or angioplasty to clear blocked arteries.
"Even the sickest patients in this study, those for whom revascularisation wasn't an option, felt better during the time they were being followed by physicians," Jollis says. "When you take care of patients over time and follow their progress, the placebo effect can be strong."
Trials of various novel techniques, such as myocardial laser perforation and the use of vascular growth factors, have relied heavily on general health indicators rather than 'hard' evidence of a clinical endpoint, such as death or use of health resources. Indeed, trials of vascular growth factors have not proved definitive as both test and control group patients showed improvement.
A patient's view of their health can be coloured by many factors, such as other non-cardiac illnesses and social, psychological and economic factors. "Our data suggest that qualify-of-life measures vary little, such that many patients would be required to detect a treatment benefit, while mortality and cost vary greatly, such that fewer patients would be required to detect a benefit," Jollis explains. This could be critical in the assessment of new treatments for 'end-stage' coronary artery disease, for which surgery is not an option. "It's important that these new therapies be tested and measured in such a way that it demonstrates their effectiveness," adds Jollis.