People with difficult-to-control asthma are often not taking their anti-asthma medication as prescribed by their doctor, new study findings indicate.

Even when prescribed high doses of steroids, about 5 percent of adults with asthma remain difficult to control, with persistent symptoms and frequent flare-ups, Dr. Liam G. Heaney at Queen’s University of Belfast, Northern Ireland, and colleagues have found.

They thus remain at high risk for fatal or near-fatal asthma attacks. While not taking medication as prescribed is believed to contribute to this problem, its prevalence is unknown.

To find out, Heaney’s group studied 182 patients referred to the Northern Ireland Regional Difficult Asthma Service. Nonadherence to anti-asthma therapy was not suspected as a major issue, and all patients denied not taking their medicine at their first visit to the clinic.

Nonetheless, it was found that 35 percent of these patients had filled no more than half their prescriptions for inhaled steroids, and these patients were more likely to have been hospitalized at least 3 times in the previous year.

Women were most apt to be lax in taking their asthma controller medication as prescribed, the researchers note in the latest issue of the American Journal of Respiratory and Critical Care Medicine.

Among 51 asthma patients who were supposed to be using oral prednisolone, blood tests showed that 45 percent were nonadherent.

After being confronted about their prescription data, 88 percent admitted their poor compliance.

“One could speculate that if (patients) took regular preventative therapy (as prescribed) their asthma would probably improve substantially,” Heaney and colleagues conclude.

SOURCE: American Journal of Respiratory and Critical Care Medicine, November 1, 2009.