Glucocorticoids, commonly called steroids, were found to be 40% less effective in overweight and obese asthmatic patients than in lean asthmatic patients. The study was conducted by Dr. E. Rand Sutherland, MD, MPH and his colleagues at National Jewish Health. Nearly half of asthmatic patients are classified as either overweight or obese, with a body mass index (BMI) of greater than 25. Studies suggest that since obese people have higher levels of inflammatory molecules in their bodies, and asthma is characterized partly by inflamed airways, asthma is more difficult to control or incidence are higher in overweight or obese cases.

The study’s aim is to understand why glucocorticoids might be less effective in overweight and obese asthma patients. They enrolled non-smoking adults with asthma, and measured cell responses in the blood and lungs to the steroid dexamethasone.

Steroids mainly work by raising the level of a molecule known as MAP kinase phosphatase-1 (MKP-1). This is how it interferes with inflammatory signaling pathways. When the researchers applied dexamethasone to cultures of the participant’s blood cells, they found that steroids did not increase MKP-1 in obese and overweight patients as effectively as in lean patients.

If patients are concerned that their asthma medication is not working, they should discuss it with their physician rather than simply making some adjustments to their prescribed dosage.

From Science Daily:

“This study identifies what could be a significant issue for the 20 million Americans with asthma; specifically, the main controller medication might be less effective if you are overweight or obese,” said Dr. Sutherland. “These findings should spur doctors to carefully evaluate response to treatment in overweight and obese asthmatics and consider optimizing therapeutic regimens as indicated. We also hope they will spur additional research into the treatment of obese patients with asthma.”