The study is the first to find an association between adults with asthma and the risk of obesity developing later.
Adults with asthma are more likely to become obese later in life, and the risk is markedly higher for patients with non-allergic asthma, those who have had the disease for a longer period, or those who use corticosteroids, according to findings from an international study published Wednesday.
The results, published in Thorax, are the first to show that asthma is a risk factor for later obesity in adults. Asthma and obesity have several common factors, including socioeconomic, behavioral, and environmental ones. While the link between asthma and obesity is well-known—in that those who are already obese have a higher risk of asthma—the reverse has not been extensively studied, except for some pediatric research, which found children with asthma have a higher rate of obesity 10 years later.
One previous study of adults found an association between asthma and weight gain only in women, but the results released Wednesday found no sex differences.
Researchers used data from the European Community Respiratory Health Survey (ECRHS), a cohort study, where information was collected in 3 waves between 1990 and 2014. Follow-up visits took place about every 10 years. More than 8700 participants from 11 European countries and Australia took part.
The 3 sections of ECRHS had 2 study periods: from ECRHS I (t) to ECRHS II (t+1), and from ECRHS II (t) to ECRHS III (t+1).
Questionnaires collected during the different waves asked whether participants had a doctor diagnose them with asthma; asthma symptoms; and use of asthma medications. They were also asked about their level of atopy, or allergies, as defined as a serum-specific IgE antibody concentration of ≥0.35 kUA/L to at least 1 of 4 common allergens.
At clinical visits, researchers conducted lung function tests and calculated participants' body mass index. In the last 2 waves, participants were also asked about physical activity levels.
Researchers estimated the change in the relative risk (RR) of obesity linked with asthma from 1 study period to the next by multivariable modified Poisson regression (lag) with repeated measurements. They also looked at the association of allergy and asthma medication on the development of obesity.
The first period, ECRHS I-II, had 7576 participants; 51.5% were female with a mean (SD) age of 34 (7) years. The second study period, ECRHS II-III , had 4976 participants, 51.3% of whom were female, but their mean age, 42 (8), was older.
Nine percent of participants became obese in ECRHS I-II and 15% in ECRHS II-III.
Results showed the risk of developing obesity was higher:
Between the first and the second follow-ups, 14.6% of those without asthma developed obesity, while the percentage increased up to 16.9% among those with asthma.
The research was conducted by the Barcelona Institute of Global Health (ISGlobal).
“A potential explanation for the weight gain associated with asthma could be the reduction of physical activity in asthmatic patients. However, our results do not support this hypothesis, since the levels of physical activity in our study did not affect the observed association,” Judith Garcia-Aymerich, PhD, head of the Non-Communicable Diseases and Environment Programme at ISGlobal and senior author of the study, said in a statement. “Regardless of the mechanisms, still unknown, our results have implications for the clinical care of adults with asthma.”
Moitra S, Carsin A-E, Abramson MJ, et al. Long-term effect of asthma on the development of obesity among adults: an international cohort study, ECRHS. Thorax. Published online Apri 28, 2022. doi:10.1136/thoraxjnl-2021-217867