Study looks at treatment link for obesity, asthma

The interplay of obesity, asthma and certain medications highlight an emerging understanding of why some drugs might be more effective for some people, a new study says.

Specifically, inhaled corticosteroids are more effective than leukotriene antagonists in patients with asthma, but the impact of corticosteroids is lessened if a patient is obese. The effect of the leukotriene antagonists also increases as the patient's weight increases, says the March European Respiratory Journal.

"It is increasingly recognized that obese people are more prone to develop asthma, but there is no information about whether obesity influences people's responses to particular asthma medications," says Marc Peters-Golden, MD, lead author and professor of internal medicine in the division of pulmonary and critical care medicine at the University of Michigan Medical School. "Our findings are the first to suggest the possibility that obesity might be a factor that influences how well asthmatics respond to particular medications."

Researchers pooled the results of four double-blind, placebo-controlled studies that randomized more than 3,000 adults to either the leukotriene modifier montelukast or the inhaled corticosteroid beclomethasone. They then analyzed the results, taking into account the participants' body mass indexes.

Beclomethasone nearly doubled the percentage of asthma control days in those who were lean. This impact was less striking in those who were heavier, and the difference between the two drugs was not statistically significant at higher BMIs.

Experts praised the data for suggesting that leukotriene, a mediator of inflammation, is a possible mechanism for the strong, albeit poorly understood, link between asthma and obesity. The study also adds to the body of evidence that, for these heavy patients, asthma may be a different kind of disease than it is for those who are thinner.

"It's such a wonderful area of study. Not just because of what we can learn about montelukast, but what it might tell us about the pathophysiology of a disease that causes such a health burden," said Valerie Flaherman, MD, MPH, a general pediatrics fellow at the University of California, San Francisco.

Creating a new line of questions

But it was generally agreed that this paper, a post-hoc retrospective analysis, was far too preliminary to dictate prescribing decisions.

"This article is hypothesis-generating and raises questions, but it does not really provide the answers," said David Beuther, MD, instructor in pulmonary medicine at National Jewish Medical and Research Center in Denver.

There also are many areas of inquiry surrounding why obese asthmatics would not do as well on a medication that has a reasonable track record. Those who treat these patients questioned whether these differences in responses were actually caused by differences in their means of delivery rather than by differences in how these medications work.

Leukotriene modifiers are taken in pill form, which can be simpler than inhaled corticosteroids, which tend to be more difficult to use correctly. Physiology also might come into play.

"Maybe the obese are not able to get their medication to the right place when they use their inhaler," said Glennon O'Grady, MD, family physician and medical director of the Greater Lawrence Family Health Center in Lawrence, Mass.

But experts say this demonstrates that, no matter what the nature of the link might be, a recommendation for weight loss could be appropriate for obese asthmatics. This study found that not only was this patient group different in its response to medication, but also their disease tended to more severe. Symptoms also were less responsive to the placebo.

"We need to work on [patients] in terms of their weight. They might do better with their asthma," said Michael Rosenthal, MD, clinical professor and vice chair of academic programs in the Dept. of Family and Community Medicine at Thomas Jefferson University in Philadelphia.