May 1997
SAN FRANCISCO — Asthma mortality is disproportionately high for poor, urban black children. During the 1980s, asthma mortality rose at an annual rate of 6.2%, and from 1980 to 1990 there was as a 60% increase in black deaths, said H. James Wedner, MD, during a presentation on the National Cooperative Inner City Asthma Study, sponsored by the National Institute of Allergy and Infectious Diseases.
This high increase in asthma mortality has been seen in cities nationwide, said Wedner, of the allergy and immunology department at Washington University School of Medicine in St. Louis.
Air pollution is one asthma risk factor. "Air pollution affects asthma by being a direct irritant; by provoking airway inflammation; by direct toxicity, particularly to the respiratory epithelium; and by altering the immune response to allergens," Wedner said.
Another environmental risk factor is passive tobacco smoke. Children of smoking mothers have 47% more symptoms and a four-fold greater airway response to histamines, Wedner said.
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A number of allergens also play an important role, including cockroaches, dust mites, cats and rodents. The more allergens a child is sensitive to the more asthma will occur, he said. The extent of exposure to allergens is also important. A child who is sensitive and exposed is more likely to have problems than one that is just sensitive or just exposed.
Another concern is the lack of adequate health care for inner-city children. Poor, inner-city families are less likely to have health insurance, and uninsured poor children make 38% fewer visits to physicians than do those with insurance, Wedner said. Often these families are relying on emergency departments (EDs) for routine care. Data collected in Baltimore show that 52% of first graders and 45% of sixth graders received all of their asthma care in EDs, Wedner said.
"Breakdown of family function leads to increased hospitalizations due to lack of symptom recognition and poor episode management," Wedner said. Family dysfunction is, therefore, an important risk factor for asthma and asthma mortality, he added.
These factors were studied in phase 1 of the National Cooperative Inner City Asthma Study, which took place at eight sites in seven cities. The study followed 1,528 inner city children, ages 4 to 9. The population was 19.6% Hispanic, 73% black and the remainder white. They were recruited over one year from EDs and clinics. A baseline interview was done with follow-ups at three, six and nine months. At the nine-month visit, 95% of the children were still participating.
Hospitalizations were seen in about one-third of the study children over two months. ED visits were about two per child. Symptoms over a two-week period included wheezing for 3.3 days on average, slow play for two days and sleep loss for two days. Skin tests were also done, with 35% of the children being allergic to mites, and 36% being allergic to roaches. Cat, dog, rat and Alternaria however, had the highest levels of sensitivity.
Skin-test positivity correlated with hospitalizations and ED visits. Indoor allergens also correlated with the same two outcomes, along with loss of sleep and missed school days. Age correlated with hospitalizations and school missed. Race correlated with ED visits, wheezing, school missed and caretakers' changed plans. Smoking mothers correlated with ED and clinic visits as well as slow play. Social support correlated with all of the symptoms' measurements.
The psychosocial well being of the child, as measured by the behavior checklist, showed high correlation in terms of severity due to hospitalizations, clinic visits and days of symptoms. "What emerged was that no single or small group of factors merged as related to childhood asthma," he said. "Rather, for each child, there was one or a limited number of important factors, and the challenge, therefore, is to evaluate each child as an individual and discover which areas are important."
Phase 2 of the study was an intervention to impact on these various factors to analyze how changes in the environment and other areas of the children's lives might affect their asthma.
For more information:
- Wedner HJ. Epidemiology of inner city asthma. Presented at the Joint Meeting of the American Academy of Allergy, Asthma and Immunology, the American Association of Immunologists and the Clinical Immunology Society. Feb. 21-26. San Francisco.
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[Search]Copyright 1997, SLACK Incorporated. Revised 8 May 1997.