The study--co-funded by the National Institute of Allergy and Infectious Diseases (NIAID) and the National Institute of Environmental Health Sciences (NIEHS), two NIH Institutes--appears in the September 9th issue of The New England Journal of Medicine.
"The burden that childhood asthma places on our society is enormous," says Anthony S. Fauci, M.D., director of NIAID. "For the millions of children living with asthma, this important research demonstrates that taking practical steps can achieve long-term benefits in the form of better quality of life, fewer emergency room visits and lower healthcare costs."
"These study results are exciting because they show that changes made in the home environment can produce a reduction in symptoms comparable to that achieved with asthma inhalers," notes Kenneth Olden, Ph.D., director of NIEHS.
Asthma, a chronic lung disease characterized by coughing, wheezing and difficulty breathing, affects roughly 20 million Americans. Children who live in the inner city--in particular African-American and Hispanic children--suffer disproportionately from the disease. Increased asthma symptoms in this population may stem from exposure to high levels of multiple indoor allergens and tobacco smoke.
More than 900 children ages 5 to 11 with moderate to severe asthma participated in the study. Each participant had to be allergic to at least one common indoor environmental allergen, such as cockroach allergen or house dust mite allergen. The children, most of whom were African American or Hispanic, lived in low-income sections of seven major metropolitan areas--the Bronx, Boston, Chicago, Dallas, Manhattan, Seattle/Tacoma and Tucson. Once accepted into the study, they were randomly assigned to either the intervention group or a control group.
Based on the child's sensitivity to the selected indoor allergens and evidence of exposures at home to known asthma triggers, investigators designed an individualized environmental intervention, carried out by the child's mother or another caretaker. The intervention focused on educating the family about ways to reduce or eliminate all allergens to which the child was allergic, as well as to reduce exposure to tobacco smoke, and motivating them to pursue these steps. The investigators developed separate interventions tailored to tobacco smoke and to the following allergens--house dust mite, cockroach, pet, rodent and mold.
In addition, families were given specific allergen-reducing measures, such as allergen-impermeable covers for children's bedding and air purifiers with HEPA (high efficiency particulate air) filters, to be placed in key locations within their homes, including the children's bedrooms. Cockroach extermination visits were provided for children who were allergic to cockroach allergens. During the first year of the study, the investigators conducted educational home visits with the families in the intervention group. Throughout the yearlong study and the one-year follow-up, researchers closely monitored all participants' asthma symptoms and home allergen levels.
Children who participated in the intervention had significantly fewer asthma symptoms compared with those in the control group: an average of 21 fewer days of symptoms in the first year and an average of 16 fewer days during the second, or follow-up, year. In addition, the benefits of the intervention occurred rapidly: Investigators noted significant reductions in symptoms just 2 months after the study began.
The levels of cockroach and dust mite allergens in the children's bedrooms in the intervention group were substantially lower than in the control group. Furthermore, the researchers noted a direct correlation between allergen levels and asthma symptoms for the children in the intervention group: The greater the drop in cockroach or house dust mite allergen levels, the greater the reduction in asthma symptoms, suggesting that the allergy-reducing measures made the difference.
Most previous environmental intervention studies focused on controlling a single allergen or tobacco smoke, and met with limited success.
"Children with asthma are usually sensitive to more than one allergen," says Daniel Rotrosen, M.D., director of NIAID's Division of Allergy, Immunology, and Transplantation. "By taking a multifaceted, home-based approach, this new study demonstrates the promising results families can achieve when they incorporate the recommended practices of allergen reduction into their everyday lives."
This project is part of the Inner City Asthma Study, a cooperative multicenter initiative comprising seven asthma study centers across the country and a statistical center. The principal investigators are Wayne J. Morgan, M.D., University of Arizona College of Medicine, Tucson, first author on the paper; Ellen F. Crain, M.D., Ph.D., Albert Einstein College of Medicine/Jacobi Medical Center, Bronx, NY; Richard Evans III, M.D., Children's Memorial Hospital, Chicago, IL; Rebecca S. Gruchalla, M.D., Ph.D., University of Texas Southwestern Medical Center at Dallas, TX; Meyer Kattan, M.D., Mount Sinai School of Medicine, New York, NY; Herman Mitchell, Ph.D., Rho, Inc., Chapel Hill, NC; George T. O'Connor, M.D., Boston University School of Medicine, Boston, MA; and James Stout, M.D., University of Washington School of Medicine and Public Health, Seattle, WA.
NIAID and NIEHS are components of the National Institutes of Health, an agency of the U.S. Department of Health and Human Services. NIAID supports basic and applied research to prevent, diagnose and treat infectious diseases such as HIV/AIDS and other sexually transmitted infections, influenza, tuberculosis, malaria and illness from potential agents of bioterrorism. NIAID also supports research on transplantation and immune-related illnesses, including autoimmune disorders, asthma and allergies. NIEHS conducts and supports research to reduce the burden of human illness and dysfunction from environmental causes by understanding environmental factors, individual susceptibility and age, and by discovering how these influences interrelate.
Reference: W Morgan et al. Results of a home-based environmental intervention in urban children with asthma--The Inner City Asthma Study. The New England Journal of Medicine 351(11):1068-80 (2004).
News releases, fact sheets and other NIAID-related materials are available on the NIAID Web site at http://www.niaid.nih.gov.
Journal
New England Journal of Medicine