Getting control of the control group

Scientists face challenges in designing comparison groups for treatment studies

Lifestyles and emotions play important roles in many different medical illnesses, but changing them can be difficult. It also is surprisingly difficult for scientists to evaluate which behavioral interventions are truly effective in helping people to stop smoking, get more exercise, overcome depression or improve their diet.

When scientists study potential treatments for psychological and psychiatric problems, they often compare patients who get a certain treatment to others who don’t.

But researchers, led by Kenneth E. Freedland, PhD, professor of psychiatry at Washington University School of Medicine in St. Louis, say that to accurately measure the effectiveness of a new therapy, it is critical to carefully define the comparison — or control — group.

In a review article in the May issue of the journal Psychosomatic Medicine: Journal of Behavioral Medicine, Freedland and his colleagues examine the complications that arise in trials evaluating behavioral interventions — such as cognitive therapy or stress reduction techniques — to treat problems from smoking to insomnia to depression.

“When people hear about randomized controlled treatment studies, they usually think about drug trials,” Freedland says. “One group gets the active drug. Another gets a placebo sugar pill. Everyone involved is ‘blinded’ so that no one knows who got the real drug until the study is over.”

When scientists like Freedland test behavioral treatments, however, study design gets more complex. For example, it’s not possible to keep patients and researchers in the dark about who is or is not receiving the active therapy.

“If we’re comparing cognitive behavior therapy to medication for insomnia, then it’s pretty obvious who is getting which treatment,” Freedland says. “That‘s important because people tend to be more optimistic about getting better if they happen to receive the treatment they prefer, and that can affect how well the treatment works.”

In many cases, he says scientists may want to study whether a behavioral intervention is better than whatever treatment people would ordinarily get from their own doctor. This kind of study uses a “usual care” comparison group.

“One of the biggest challenges is that usual care can mean very different things in different places,” he says. “I’m testing a behavioral treatment for depression in people with heart failure. Some of our participants receive state-of-the-art usual care at a world-class heart failure clinic. But some of the others come from rural areas where usual care might not even involve seeing a cardiologist. So different people in our usual care group are getting different kinds of usual care.”

Therefore, he says for a researcher to claim that a behavioral treatment is more effective than usual care, it’s important to take the quality of the usual care into account.

Some behavioral treatments are used to help people with problems such as getting too little exercise, for which there are no drugs. Others are used instead of, or in combination with, drugs for problems such as depression, smoking or post-traumatic stress disorder (PTSD).

But determining a behavioral treatment’s effectiveness requires that comparison groups meet high scientific standards. Unfortunately, clear standards haven’t yet been established for clinical trials of behavioral treatments. It is time, he says, for the scientific community to address this.

“There is more consensus around standards for drug trials than for behavioral treatment trials,” Freedland says. “I think we need better guidelines and standards for behavioral scientists if we want to help the field move forward. Behavioral treatments may be very effective for many health-related lifestyle and emotional problems, but it’s up to researchers to prove it.”

Freedland KE, Mohr DC, Davidson KW, Schwartz JE. Usual and unusual care: existing practice control groups in randomized controlled trials of behavioral interventions. Psychosomatic Medicine: Journal of Behavioral Medicine, vol. 73(4): pp. 323-335. May 2011.

This work was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health (NIH).

Washington University School of Medicine’s 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.