April 27 (UPI) -- Adults with asthma are more likely to become obese later in life, particularly those who have had the disease for longer or those treated with corticosteroids, a study that focused on Europe and Australia and was published Wednesday found.
Among more than 8,700 participants from 11 European countries and Australia, 17% of those with asthma developed obesity, or being severely overweight, data in the journal Thorax showed.
Of those without asthma, just under 15% became obese, the researchers said.
Based on these figures, people with asthma in the study had a 21% higher risk for obesity compared to those who did not have the breathing disorder, according to the researchers.
The risk for obesity was nearly double in asthmatics treated with corticosteroid medications, they said.
"A potential explanation for the weight gain associated with asthma could be the reduction of physical activity in asthmatic patients, [but] our results do not support this hypothesis," study co-author Judith Garcia-Aymerich said in a press release.
Physical activity levels among study participants did not influence their risk for obesity, whether or not they had asthma, she said.
"Regardless of the mechanisms, still unknown, our results have implications for the clinical care of adults with asthma," said Garcia-Aymerich, head of the non-communicable diseases and environment program at the Barcelona Institute for Global Health in Spain.
Lung diseases such as asthma and chronic obstructive pulmonary disorder, or COPD, have become more common globally due to a rise in airborne pollution, among other factors, research suggests.
About 40% of adults and 19% of children in the United States meet the criteria for obesity, while about 8% of adults and children nationally have asthma, according to the Centers for Disease Control and Prevention.
For this study, the researchers used data from the cohort study European Community Respiratory Health Survey, an ongoing assessment of population health funded by the European Commission.
The study was conducted in Australia, Belgium, Estonia, France, Germany, Iceland, Italy, Norway, Spain, Sweden, Switzerland and Britain.
Participants responded to lifestyle questionnaires, underwent lung function tests and were assessed for body weight and asthma status, the researchers said.
Participants with asthma who suffered from the disease for longer periods had a 32% higher risk for obesity compared to those who had the breathing disorder a shorter amount of time, the data showed.
In addition, those with non-allergic asthma, or asthma symptoms not related to allergies, had a 47% higher risk for obesity than those with allergic asthma, according to the researchers.
"Several studies have shown that asthma and obesity share some common socioeconomic, behavioral and environmental risk factors that can lead to the development of both diseases," study co-author Subhabrata Moitra said in the press release.
"Some previous research focused on the mechanisms by which obesity could lead to asthma, but the inverse relationship had not received much attention until recently," said Moitra, formerly of the Barcelona Institute for Global Health and now a post-doctoral research fellow at the University of Alberta in Canada.