NEW YORK CITY—The Harlem Children’s Zone Asthma Initiative (HCZAI), an ongoing, intensive effort to test and treat for asthma every child living within a 24-block area of Harlem, has revealed an unprecedented asthma prevalence of 25.5%. Although several factors could contribute to this childhood asthma “epidemic,” clinicians and public health researchers are focusing on how to reduce the shockingly high rate.

One of the researchers, Benjamin Ortiz, Jr, MD, Clinical Instructor of Pediatrics at Columbia University College of Physicians and Surgeons in New York City, said that he and his colleagues were “overwhelmingly surprised” to find a prevalence rate double the previous 12% estimate. Asthma prevalence was expected to be fairly high in the low-income, predominantly black and Hispanic community they are serving.

As another of the investigators, Robert B. Mellins, MD, explained, “There is a history, going back 10 to 15 years at least, which recognizes that in populations of color, especially in the urban cores, asthma prevalence rates are two and three times the national average.” Dr. Mellins, Professor of Pediatrics at Columbia, added, “Those estimates were generally based on smaller samples, but here we had the opportunity to see the estimates validated.”

Nevertheless, the investigators did not expect to find that one in every four children has asthma nor that disease is so severe in this population. “It’s not just the prevalence of asthma but also the severity,” stressed Mary E. Northridge, PhD, MPH, Associate Professor of Sociomedical Sciences at the Columbia University Mailman School of Public Health. “Out of the 25.5% of children who have asthma, 56% of them have been to an emergency room in the last year because of their disease. That is a pretty high indicator of just how severe their asthma is.” The number of missed school days is another indicator of the extent of the asthma problem. “When we ask the parents of children who have asthma in our program if these children missed school in the last two weeks due to their asthma, a quarter of them say yes,” Dr. Northridge added.

Initially, said Dr. Mellins, asthma cases among Harlem children may not be more severe than those found among other populations of children, but they may worsen without appropriate treatment. “A mild case today, if not taken care of, becomes a severe case next week,” he noted. Therefore, improvement in the care given to the asthma patients in the study population is a primary goal of the HCZAI.

EVALUATING EVERY CHILD

HCZAI is unusual in that it attempts to assess every child in the target neighborhood. “When we’re done … we will have screened every child ages 0 to 12 within this 24-block area,” said Dr. Northridge, who is also Deputy Director of the Harlem Health Promotion Center. “We have screened more than 1,400 children to date, but we still have about 800 left to screen.” She and her colleagues anticipate finishing their screening within the year. Dr. Northridge noted, “Having a lead community partner, Harlem Children’s Zone, Inc, who was already working in the three elementary schools … in this area of Harlem was absolutely essential” for this comprehensive survey of childhood asthma.

“We actually borrowed and modeled our screening tools, survey devices, and assessments from what has been previously done … with the National Cooperative Inner-City Asthma Study,” acknowledged Dr. Ortiz. After parents were surveyed for their children’s health history, some children received physical examinations by participating clinicians; children 6 or older were also tested with a peak flow meter. Said Dr. Mellins, “Doing this screen as thoroughly as we’re doing it—at first with a questionnaire, but then following it up with a physical examination—will bring out things that we didn’t appreciate before.” Indeed, emphasized Dr. Ortiz, 4% of the children with no history of asthma were found to have symptoms of the disease during the physical examination, which suggests that the disease is seriously underdiagnosed in this population.

WHY IS ASTHMA PREVALENCE SO HIGH?

A number of environmental factors may contribute to elevated asthma prevalence in this neighborhood. Diesel trucks and buses and apartment building furnaces may produce high ambient concentrations of diesel particles and other pollutants, which have been linked with increased asthma incidence and exacerbation rates. Low-income housing is typically in poor repair and infested with cockroaches, rats, and mice, all of which can generate allergens that may exacerbate asthma. Additionally, fear of crime or violence may prompt closure of doors and windows, leading to poor ventilation of heating and cooking exhaust; it may also dissuade parents from going out to seek care. Said Dr. Mellins, “I don’t think any one of these things is the cause, but I think the sum total probably contributes to the increased prevalence and severity.”

Another possible factor is that an unusually high proportion of cohabiting adults may be smokers. “We did a survey about a decade ago showing that the prevalence of smoking in Harlem was about 44%,” said Dr. Northridge. Among the homes screened in the present intervention, 23.6% had an adult smoker; 31.9% of homes where children with asthma live had an adult who smoked, as compared to only 20.5% of homes with no asthmatic children, she noted. In another urban population, high levels of environmental tobacco smoke (ETS) were linked with a threefold increase in risk for nocturnal asthma symptoms. “Smoking may be a contributor to the children’s symptoms,” Dr. Northridge concluded. And, while no statistics were available to establish how many asthmatic children had been subjected to smoke in utero, data that such exposure can promote permanent structural changes predisposing an individual to asthma underscore the threat that widespread smoking poses to these children’s respiratory health.

Genetic factors could also contribute to the high prevalence. “This 24-block area happens to be one where we have a lot of West African immigrants as well as Caribbean immigrants,” said Dr. Northridge. “The large majority of our enrolled children are African-Americans and Caribbean blacks, but we also have a large number of Latinos.” Previous work indicates that, independent of other socioeconomic and environmental factors, African ancestry is associated with an elevated asthma risk. Additionally, particular gene variants more common among African-American populations are linked with a predisposition for asthma and atopy.

TAKING STEPS TO ELIMINATE ASTHMA TRIGGERS

After identifying children with asthma, the program addresses home and family risk factors. Initially, community workers are assigned to get an in-depth understanding of the children’s family history, social history, medication use, and recent asthma symptoms, as well as their access to care and health coverage status. They also review children’s asthma action plans and educate families about medication. In the next step, said Dr. Ortiz, the community workers “return to do a home-based environmental assessment: They actually do a walk-through with the parents in each of the rooms in the home and identify what they can see as asthma triggers.” Providing such information is important, Dr. Mellins emphasized, “so that families will take the steps to minimize the triggers and to try to make it possible for their children to live healthy lives.”

Once contributing factors in a child’s home are identified, families also receive assistance in addressing these problems. “Some families get the HEPA [high-efficiency particulate air] filters,” said Dr. Ortiz; they may also receive HEPA vacuums to reduce allergens in the home. Additionally, he said, “we give them allergy-free bedding covers and mattress covers and food containers to help limit vermin infestation.” Families may also receive help in repairing structural problems and in cleaning the home to reduce allergen levels. Given the potential for ETS to worsen asthma, said Dr. Northridge, “we’re hoping to do some smoking cessation work with the families, because education alone, or [asking parents to do] it just ‘for the good of your kids,’ hasn’t proven effective.” The American Legacy Foundation recently awarded project partner Harlem Children’s Zone, Inc a grant to develop a smoking cessation program for the family members of children with asthma.

—Mimi Zucker, PhD