This is the first research to control for the risk factors - smoking, use of oral or inhaled corticosteroid medications, gastroesophageal reflux disorder, and demographics - that might explain the obesity-asthma association.
Earlier studies have shown that obese people are more likely to suffer asthma than non-obese people, and that obese patients often have more severe asthma than their non-obese counterparts.
In the latest study, researchers at Kaiser Permanente Center for Health Research in Portland, Ore., and the Kaiser Permanente Institute for Health Research in Denver surveyed 1,113 patients in Oregon, Washington, and Colorado, age 35 and older, who have persistent asthma.
The researchers asked the patients about their weight, height, smoking habits, other illnesses, treatment and their asthma-specific quality of life, asthma control and asthma-related hospitalizations.
"The big finding here is that even after adjusting for risk factors, obese adults were nearly five times more likely to be hospitalized for their asthma," said study lead author David M. Mosen, Ph.D., MPH, of the Kaiser Permanente Center for Health Research.
The study found that obese people with asthma had significantly worse asthma control, lower asthma-related quality of life, and had 4.6 times higher risk for asthma-related hospitalizations than non-obese asthmatics
Also, obese people with asthma were younger and less educated than non-obese people with asthma.