Researchers have identified a new problem associated with childhood obesity: failure to finish high school.

A new study from Sweden finds that teens who received medical treatment for obesity were far less likely to graduate from upper secondary school than their slimmer peers. The gap in the graduation rate was startling — 56 percent of the obese students finished all 12 years of schooling, compared with 76 percent of their classmates.

“The differences are much larger than we predicted,” the study authors said in a statement. They presented their results this week at the European Congress on Obesity meeting in Prague.

The research team, from the Karolinska Institute in Stockholm, conducted their study by tapping into a national registry of people who were treated for childhood obesity. They selected 1,061 adults who were at least 20 years old, giving them enough time to have finished the Swedish equivalent of high school. People were excluded if they had an intellectual disability.

To form a comparison group, the researchers randomly selected 7,780 people who matched the obesity patients for age, gender and living area. Then, using information from Sweden’s national education registry, they checked to see how many people in each group had reached certain milestones in their schooling.

Almost everyone in both groups finished secondary school, the Swedish version of junior high. But then the two groups diverged quickly, the researchers found.

About 24 percent of the obese teens did not enroll in upper secondary school, or gymnasium. These high school years are optional, but students may enroll free of charge and most teens do attend, according to the Swedish government. Indeed, only 12 percent of teens in the comparison group chose not to enroll in high school, according to the study.

The drop-out rate was also higher for obese students. Nearly 19 percent of the people in this group started high school but didn’t finish. That compares with 12 percent of people in the comparison group.

The end result was that just 56 percent of the obese teens graduated upper secondary school, a figure significantly lower than the 76 percent graduation rate for students who did not have issues with obesity.

“The differences between the groups do not seem to depend upon gender, ethnicity or socioeconomic status based on living area,” according to the study.

The researchers looked for other factors that might explain the lower graduation rate among obese teens. They found that students who were not Swedish were less likely than Swedish citizens to complete upper secondary school — but that was true only in the larger comparison group, not in the smaller group of people with a history of obesity. They also noticed that in both groups, women were more likely than men to finish high school.

“We will now continue our analysis by investigating factors in this obese group that might affect the observed associations in this study,” the authors said. “Hopefully this will result in an action plan making it possible to help this vulnerable group.”

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