Misuse of asthma drugs among people with good health insurance is more prevalent than previously thought, according to a new study by Johns Hopkins researchers.

"Contrary to what many people believe, asthma is not just a problem for people in inner cities and the uninsured," says Albert Wu, associate professor of health policy and management in the School of Public Health.

The study, published in the Dec. 13 issue of Archives of Internal Medicine, found that 16 percent of insured individuals who use inhaled beta-agonists for short-term asthma relief overuse their medication. Sixty-three percent of insured individuals who use inhaled corticosteroids for long-term asthma relief underuse their medication.

"The magnitude of corticosteroid underuse is huge, and this is a missed opportunity to control asthma," says Gregory Diette, an instructor in the School of Medicine's Division of Pulmonary and Critical Care Medicine and lead author of the study. "Those who overuse beta-agonists need their treatment regimen intensified or need to pay more attention to whatever triggers their symptoms."

The new study also found that medication misuse has a gender bias. Women are significantly more likely to underuse inhaled corticosteroids, while men are significantly more likely to overuse inhaled beta-agonists. "Only 25 percent of moderately or severely symptomatic female patients, for example, were using at least a modest, regular dose," says Diette.

Inhaled beta-agonists are generally used as asthma-rescue drugs to relieve coughing, wheezing and shortness of breath. They work by opening up the lungs' air passages and increasing air flow. Overusing beta-agonists speeds up heart rate, causes jittery behavior and has been linked to higher than expected death rates. "We don't know whether the overuse is causing harm or whether it is just a marker for people who are very sick," Diette says. "One way or the other, however, the people who are overusing it need more attention."

Inhaled corticosteroids, taken one or two times daily, quiet the inflammation of the lungs, reduce the likelihood of an asthma attack before it begins and help change the course of the disease. Underuse of these drugs increases the chances of having an attack when encountering an asthmatic trigger such as dust, cockroaches, pets, perfume or pollution.

For years, researchers have known that asthmatics misuse their drugs, but they haven't known which people were more apt to do so. Investigators assumed, however, that those with quality health care would be more likely to use medications properly.

To fill the knowledge gap, Diette and his colleagues launched the Managed Health Care Association Outcomes Management System Asthma Project. The doctors gathered and analyzed information from 6,612 sicker-than-average asthmatic individuals on their gender, race, education, asthma symptom severity, medication usage, health care access and satisfaction, and physician specialty. These individuals, employees and dependents of some of the largest U.S. companies, had health insurance coverage through managed care.

The researchers weren't too surprised at the overuse statistics, but they were shocked, they say, at the amount of underuse. "We now know that the magnitude of corticosteroid underuse is huge," Diette says. In addition to being male, overusers of beta-agonists were more likely to have frequent symptoms, use inhaled corticosteroids or visit a doctor other than an allergist. In addition to being female, underusers of corticosteroids were more likely to be younger, nonwhite or getting care from a nonspecialist.

The researchers say doctors need to question their patients, especially those most at risk, about their medication usage. In addition, the findings could have implications for doctor choice or training. "Where there are advantages to specialists, the question is, how do you narrow the gap between specialist and generalist physicians?" Diette says. "It may be worth considering referring more patients to specialists for evaluation and management."

In the United States, between 12 million and 15 million people, including close to 5 million children, have asthma. Asthma is a chronic disease through which airflow in and out of the lungs may be blocked by muscle squeezing, swelling and excess mucus. In 1997, more than 30.5 million prescriptions were filled for asthma medication, and patients had approximately 1.2 million emergency room visits and 445,000 hospitalization days.

Other authors from Hopkins include Albert Wu, Elizabeth Skinner, Rebecca Clark, Maichael Huber and Donald Steinwachs. The study was funded by the Managed Health Care Association and Merck & Co.