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Seth Noar, PhD, a UNC Lineberger member and professor in the UNC School of Media and Journalism.

A review of nearly three dozen international studies found cigarette smokers tried to quit more and smoked less overall when countries implemented new policies replacing text warnings with graphic images on cigarette packs or strengthened pack warnings in other ways, report University of North Carolina Lineberger Comprehensive Cancer Center researchers.

In the analysis published in the journal Social Science & Medicine, researchers summarized and pooled the results of 32 studies that had looked at the impact of strengthening pack warnings on smokers’ behavior in 20 countries. Two-thirds of the studies looked at the impact of replacing text pack warnings with graphic warnings that include text and pictures, while the other studies strengthened existing text or picture warnings in other ways, such as changing their size, content, or position on the pack.

“One of the responsibilities of governments is to educate the populace about the many negative health effects of smoking. Our review clearly demonstrates that stronger warnings – particularly graphic warnings – achieve this in a more effective way than text-only warnings,” said the study’s first author Seth Noar, PhD, a UNC Lineberger member and professor in the UNC School of Media and Journalism. “When combining this review with other research evidence that’s continuing to emerge, we see that warnings clearly have a real-world impact on knowledge, attitudes, and, importantly, perhaps on behavior itself.”

The researchers found that calls to smoking quit-lines increased in four of six studies, cigarette consumption decreased in three of eight studies, and quit attempts increased in four of seven studies. Smoking prevalence decreased in six of nine studies.

This was also the first study to pool data from thousands of participants across multiple studies and estimate the size of population-wide effects of strengthening cigarette pack warnings. Results indicated a 10 percent relative increase in knowledge about the health effects of smoking, which grew to 32 percent when countries added new warning content; a 9 percent relative increase in quit attempts; and a 13 percent relative reduction in smoking prevalence after countries strengthened their cigarette pack warnings.

When they examined the impact of replacing text with graphic warnings without including other types of studies, they found virtually identical results – increased knowledge of the health effects of smoking, increased quit attempts, and a decline in smoking prevalence.

“Our review focused on studies that analyzed smoking behavior and other outcomes conducted in the real world where countries had implemented new warning policies,” Noar said.

While Noar said the studies looked at the impact of the warnings in countries around the globe, the United States was used as a control. That’s because the United States still has decades-old Surgeon General’s text-only warnings on the side of cigarette packs.

In 2011, the U.S. Food and Drug Administration issued a rule requiring cigarette packs sold in the United States include color graphic images aimed at depicting the negative health effects of smoking cigarettes along with one of nine new text warnings. Although the U.S. Court of Appeals for the District of Columbia Circuit blocked the specific graphic warnings selected by the FDA from moving forward in response to a legal challenge from tobacco companies, the agency is expected to try again to implement graphic warnings.

Noar said one limitation of the analysis was that since these studies examined the impact of strengthened cigarette pack warnings in the real world, other factors could have contributed to the declines in smoking behavior observed in the review. For example, he said that countries that strengthened their warnings sometimes made other changes, such as implementing media campaigns, raising taxes on cigarettes or implementing advertising restrictions.

Despite this limitation, an independent commentary published along with the article by Joseph Cappella, PhD, of the University of Pennsylvania, concluded that putting this review in the context of other recent controlled studies about cigarette warnings, “an emerging picture of the causal effectiveness of warning labels emerges that is difficult to ignore.”

The study was funded by the National Cancer Institute and FDA Center for Tobacco Products.

In addition to Noar, other authors included: Diane B. Francis, Christy Bridges, Jennah M. Sontag, Kurt M. Ribisl, and Noel T. Brewer.