Evidence backing effectiveness of community-wide programs is poor, says new review

Programs that encourage communities to get more active are one strategy for stemming the global tide of obesity. Yet, a new review of studies says the evidence backing the effectiveness of these programs is poor.

"When we looked at the available research, we observed that research studies that had been conducted didn't universally work," said Philip R.A. Baker, Ph.D., an adjunct public health professor from Queensland University of Technology, in Australia.

"For example, some research studies claimed that community-wide programs improved physical activity and other studies did not," he added. "It was not possible to identify which components increased the likelihood of program success."

In an effort to combat obesity, communities have tried combining widespread advertising, new walking trails and special partnerships with businesses and schools to promote exercise. So far, Baker and his colleagues write, the interventions available to date have not effectively increased population levels of physical activity.

"Even the most intense interventions and longer-term studies failed to demonstrate consistent improvement" in activity, Baker said.

The general approach of most of the studies reviewed "was to educate and motivate people to change their behavior," said James Sallis, Ph.D., a San Diego State University psychologist who studies and helps design physical activity programs. "However, there is a strong consensus that low levels of physical activity are largely due to environments that make it easy to drive, expensive to join a health club and, in some neighborhoods, hard to find a sidewalk or well maintained park."

Environmental change was the least common strategy in the studies reviewed, he noted, "and most of the time efforts were minor. In the face of environments designed to promote inactivity, a little bit of education is just not effective."

Baker and colleagues' review appears in the latest issue of The Cochrane Library, a publication of the Cochrane Collaboration, an international organization that synthesizes health program research. Systematic reviews draw evidence-based conclusions about health after considering both the content and quality of existing studies on a topic.

The Cochrane researchers analyzed 25 studies of community-wide programs to increase physical activity, which took place in North America, Europe, Iran, China, Australia and Pakistan. The communities ranged in size from small villages of less than 1,000 inhabitants to large regions of nearly 2 million people.

Each program lasted for a minimum of six months and could include at least two "strategies," including advertising on local television, establishing walking clubs and offering exercise counseling. The programs varied in what strategies they used, the researchers noted.

Interventions such as the ones included in the Cochrane report "are typically poorly funded," Sallis said. "They are trying to change daily behavior of most people with a budget of a few cents to perhaps a dollar per person per year."

The studies themselves had "generally weak" tools and questionnaires to measure physical activity in these communities, Baker and colleagues said, making it extremely difficult to tell whether the programs could have been successful.

Population approaches are unlikely to do harm, Baker said, "but we need more information on which are effective and cost-effective. New national programs need to be accompanied by stronger evaluations to understand whether resources are being used effectively."