Children who have prescriptions for one or more asthma drugs -- which aim to prevent or calm asthma attacks -- have fewer visits to the emergency room for asthma than those who haven't been prescribed such medications, the study finds.
But the research also reveals that asthmatic African-American and urban children rush to the ER more frequently than other kids because of an asthma attack.
U-M pediatric researchers will present the findings at the annual joint meeting of the Pediatric Academic Societies in Seattle on May 6, which by coincidence is also World Asthma Day.
The study is based on data from more than 19,000 children with asthma who were enrolled in Michigan's Medicaid program in the year 2001.
The researchers looked at the frequency of children's asthma-related ER visits, and how rates of ER visits vary by age, gender, race, urban location, disability status and prescriptions for fast-acting "rescue" medications as well as long-term preventive asthma drugs. Sixteen percent of the children had no prescription for a rescue drug.
"We found that use of asthma medications was directly associated with lower rates of ER visits for asthma, and that those kids who have no prescriptions on record are more frequent visitors to the emergency department," says U-M pediatric research investigator and lead author Kevin J. Dombkowski, Dr.PH.
He continues, "Although we couldn't peer into these children's homes to see if they were actually using their inhalers, we hope this study will help prompt increased awareness of how long-term management of asthma can be achieved through appropriate use of medications, and studies to further evaluate the effect of medication use on ER visits."
Dombkowski conducted the study with colleagues from the U-M Child Health Evaluation and Research (CHEAR) unit, part of the Department of Pediatrics and Communicable Diseases in the U-M Medical School, using data provided by the Michigan Department of Community Health. He credits the computerized Michigan Medicaid databases for making it possible to perform the population study, which was funded by the MDCH.
While the results do not directly apply to children who are privately insured, the researchers say, the data provide preliminary evidence of the association between asthma medication use and ER visits. They also document further racial and geographic differences in asthma care, beyond already-known disparities.
Asthma is a chronic, potentially life-threatening lung disease involving inflammation and constriction of the muscles lining the airways. Asthmatic lungs overreact to allergens such as dust and cigarette smoke, exercise, cold and dry air, and other factors -- all collectively known as asthma triggers.
When a trigger sets off a rapid narrowing of the airways, asthmatics cough, wheeze, feel short of breath and experience tightness in their chests -- the symptoms of an asthma attack. Without immediate help, an attack can be fatal, so many people with asthma seek emergency medical care.
Availability of quick-relief asthma medications is important for treating acute asthma attacks, also known as exacerbations, that can otherwise lead to an ER visit. But other, long-term control medications are often used to reduce the overall frequency and severity of asthma symptoms.
More than 4 million children and teenagers under the age of 18 have an asthma attack each year, the Centers for Disease Control and Prevention estimates, and more than 200,000 children under the age of 18 are hospitalized for asthma-related problems each year. Children account for 40 percent of the 1.8 million asthma-related emergency department visits reported in the United States each year, and children under 5 years of age have the highest rates of ER use.
The rate of asthma among children rose dramatically in the 1980s and 1990s, and researchers have documented that the rate is disproportionately high among members of racial and ethnic minority groups, and among children living in inner cities. Asthma is 26 percent more common in African American children than in white children.
"Awareness of asthma's symptoms and triggers, and the availability of effective prescription asthma medications, have both improved in recent years," says Dombkowski. "The National Heart, Lung and Blood Institute recommends that all people with asthma have access to quick-relief medications, such as an albuterol inhaler. But even though these guidelines were published in 1997, we found that 16 percent of kids had no prescription for quick-relief inhalers."
Such inhalers deliver prescription medicines that can either stop an asthma attack while it's happening, or help prevent such attacks in the first place. Corticosteroids and bronchodilators are the most widely used prescription asthma medications, but other drugs are now in common use, such as non-steroidal anti-inflammatory medicines and leukotriene modifiers.
The new U-M research found that 84 percent of the children studied had been prescribed short-acting bronchodilator medications of some kind during 2001. Twenty-nine percent of the entire group used a bronchodilator alone, 33 percent had also received a prescription for a corticosteroid along with their bronchodilator, and 30 percent used other medications, some in conjunction with a bronchodilator. Nine percent of the children had no asthma prescriptions.
"Twenty-two percent of all the children had had at least one ER visit related to their asthma during the year, and ER visits were most common among the children who had no evidence of asthma drug prescriptions," Dombkowski says.
When the researchers performed an analysis that controlled for age, gender, race, urban location and disability status, two statistically significant disparities especially stood out. Black children visited the ER more than twice as often as white children. And urban children visited the ER for asthma-related causes 42 percent more often than non-urban children. Children between the ages of 5 years and 9 years were the most frequent users of the ER for asthma.
The study included 19,116 children ages 5 to 21 years, who had at least one inpatient, outpatient or emergency visit for asthma in 2001, or at least four prescription claims for asthma drugs.
The authors acknowledge their study has several limitations, most notably the fact that they had no way to tell whether children with a prescription for a medication were actually using it as intended, or whether prescriptions made by a physician went unfilled by the patient. They also did not know the severity level of the individual children's asthma.
Dombkowski observes, "Our initial findings provide some important clues regarding asthma ER use, but we really need to follow these kids over a longer period of time to better understand the influence of asthma medications on ER use."
Starting this summer, the authors will take advantage of data from a second year to assess the relationships between prior use of preferred asthma medications and the impact on subsequent asthma ER visit rates. The authors will also examine asthma-related outpatient visits and inpatient admissions.
In addition to Dombkowski, the study's authors are assistant professor Michael D. Cabana, M.D., MPH, and research investigator Sarah J. Clark, MPH, associate director for research.
For Michigan residents, the authors recommend the web site www.GetAsthmaHelp.org, which provides patients and health care professionals with a comprehensive source of information on asthma, medications and achieving long-term control of asthma symptoms. The site is hosted by the Asthma Initiative of Michigan (AIM), a collaborative effort of many individuals and organizations to help decrease the burden of asthma in Michigan.