Clinical trial participants fare no better, no worse than other patients

01/18/05

People who participate in randomized controlled studies to test new therapies seem to fare no better or no worse than those who receive the same care outside of such studies, a new review of research has found.1

The finding was published against a backdrop of debate about drug trials for popular pain-relievers and about whether trial results can be safely applied to an entire population. "These results challenge the assertion that the results of RCTs (randomized controlled trials) are not applicable to usual clinical practice," report the authors, who say this review is the most comprehensive of its kind conducted to date.

A randomized clinical trial is considered the "gold standard" of medical research because it is the best way to make sure that the only difference between the groups that are compared is the treatment they receive. Patients are assigned to each group randomly in order to increase the probability that differences between the groups can be attributed only to the treatment under study.

Critics, however, say the rigorous standards for inclusion in trials and the nature of those who conduct and participate in them mean that when a new drug or treatment is applied to a general population, the results might be different.

A recent article in the prestigious journal The Lancet suggested that clinical trials cannot be expected to be relevant to all patients with the same conditions for a number of reasons, such as selecting trial participants who are in better overall health, excluding people who have conditions in addition to the one being studied and the reality that in a general population patients will not always act according to doctors' instructions.

In the new study, researchers led by Gunn Elisabeth Vist of the Norwegian Health Services Research Centre, systematically identified and reviewed 55 studies involving a total of more than 31,000 patients who were treated in randomized clinical trials and more than 20,000 patients who were treated outside of them.

"The bottom line is that the effects of treatments appear most of the time to be similar inside and outside of trials, and participation in trials doesn't appear to be associated with greater risk than getting the same treatment outside of a trial," reports Andrew Oxman, one of the review authors."

The review appears in the January issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.

What is new in this review is that the researchers compared outcomes of study participants with those who did not participate in studies but received similar treatments.

In 91 comparisons, the researchers found no statistically significant differences. Ten comparisons showed better outcomes for patients within the trial, and four comparisons showed worse outcomes for them. One important limitation of the review is that the results are based mainly on "cohort comparisons" that fall short of the most rigorous randomized controlled trials, but Vist says patients similar to the controlled trial participants can expect similar outcomes if given the same treatment outside of a trial.

Oxman himself believes that clinical trials frequently may offer the benefit of better care, despite their finding that there usually is no difference in outcomes. "Typically, when you're cared for in a trial, you're cared for according to a protocol and you often get better follow-up than you get in routine practice," he says. "In addition, health care professionals who participate in trials may be more up-to-date and practice more in accordance with best evidence."

According to a December 2004 survey of 1,000 adults conducted by the non-profit Center for Information and Study on Clinical Research Participation and Opinion Dynamics Corporation, two-thirds of Americans believe that clinical research studies are "very safe" or "somewhat safe." More than half of respondents also said they would have greater trust in clinical research information if the results were disclosed on a public Web site.

"The primary reason people participate in clinical trials is to gain access to new therapies that may offer treatment where none exists currently, or that offers benefits over currently available treatments," says CISCRP chairman Ken Getz. "Another top reason people participate is to help advance medical knowledge. . . . They participate because they feel doing so may have an impact on other people's lives."

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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Two roads diverged in a wood, and I--
I took the one less traveled by,
And that has made all the difference.
-- Robert Frost