Watch CBSN Live

Study questions quality of medical evidence found in clinical trials

research, clinical trials

(CBS News) Most major medical studies that guide doctors and lead to new treatment advice are not as sound as patients might expect, a new study finds.

Got cancer? 10 secrets for better decisions
First of controversial bird flu papers published

The largest analysis of clinical trials to date looked at nearly 41,000 studies and found many fall short when it comes to producing meaningful evidence that should guide medical decision-making.

"Our analysis raises questions about the best methods for generating evidence, as well as the capacity of the clinical trials enterprise to supply sufficient amounts of high quality evidence to ensure confidence in guideline recommendations," study author Dr. Robert Califf, vice chancellor for clinical research at Duke University Medical Center and director of the Duke Translational Medicine Institute in Durham, N.C. said in a university news release.

For the study, published in the May 2 issue of the Journal of the American Medical Association, Califf and colleagues reviewed studies found on the website that were downloaded in September of 2010. The site is a database managed by the National Library of Medicine to maintain past, current and planned clinical research studies and contains specifics on the study's methodology.

The impact of results found in clinical trials range from changing treatment guidelines for diseases such as cancer or heart disease, or determining how medical devices may help people with certain conditions. Ideally they are randomized controlled trials (RCTs) that randomly assign participants to receive a treatment or an alternate treatment (often a placebo) and control for factors that could bias the study.

The researchers looked specifically at trials related to cardiovascular, mental health, and cancer studies, and found 96 percent of the trials had 1,000 or fewer participants, while over 60 percent had 100 or fewer participants. What's more 66 percent of studies were conducted on a single site as opposed to at multiple research locations, the researchers found.

"There are 330 new clinical trials being registered every week, and a number of them are very small and probably not as high quality as they could be," Califf told HealthDay.

Cancer trials in particular were flagged by the researchers. They found cardiovascular trials, for example, were typically twice as large as cancer trials, with mental health trials falling in the middle. Additionally, a majority of cancer trials don't randomize their patients. Califf questioned to HealthDay if 65 percent of cancer studies don't randomize their participants compared with 26 percent of heart studies, should cancer research be done differently?

Dr. Kay Dickersin, a professor of epidemiology at Johns Hopkins Bloomberg School of Public Health and Drummond Renie, deputy editor of JAMA, commented on the findings in an accompanying editorial, saying more engagement is needed among everyone involved with clinical trials - including the test subjects, who should ask for a copy of the results.

"If all trial investigators and sponsors, as well as the regulators, were equally engaged, this might help further the universal adoption of trial registration," they wrote. It might "restore the public's confidence in investigators, sponsors, and the clinical trial enterprise."