NEW YORK (Reuters Health):

Obese adults with asthma are more likely than their leaner counterparts to have severe, persistent disease, according to a large, new study.

In a telephone interview with Reuters Health, Dr. Brian Taylor of Emory Crawford Long Hospital, Atlanta, said: "A lot of studies have clearly demonstrated that obesity is associated with asthma and we think actually that not only does obesity likely lead to asthma, but it may also lead to a more severe (type of asthma)."

Findings consistent

"Our study does not prove that," he emphasised, "but ... our findings stayed consistent."

Taylor's team classified 3,059 adults with asthma as normal weight, overweight, or obese, based on their body mass index. He reported the findings at the American Thoracic Society's conference in San Francisco.

Obese patients, compared with normal-weight adults, were 47 per cent less likely to have their asthma in remission and were 52 per cent more likely to have severe persistent asthma, Taylor said.

They were also 66 per cent more likely toreport continuous symptoms, and 36 per cent more apt to miss more than 2 days of work per year due to asthma.

Although the reason why obesity increases asthma severity is not entirely clear, evidence suggests that the hormone leptin, which is produced by fat cells and plays a role in weight regulation and asthma-related airway inflammation, may be involved.

Taylor and his associates are now involved in research looking at whether obese patients who undergo weight-loss surgery experience a lessening of their asthma compared with obese patients who do not have the surgery.