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Pediatric Asthma: Feature Article
An excerpt of this article was featured in the April 2002 issue of Discover Magazine. Pediatric allergies and asthma: Research, awareness turn tide on disease Asthma affects more than 4.8 million children in the United States under the age of 18, and, worldwide, research indicates that asthma is on the rise, particularly in urban areas. Allergic diseases, which include asthma, are the most frequently reported chronic condition in children. Seeking answers to why asthma is increasing, researchers are further exploring a possible link between allergic diseases and asthma. In the past several decades, physicians began to notice how often allergies and asthma occur in the same patient. A Johns Hopkins School of Medicine survey showed that more than 95% of patients who have allergic asthma also suffer from nasal allergies. Seasonal allergic rhinitis, commonly known as "hay fever," affects nearly 36 million Americans. The condition also affects more than 115 million people worldwide. Besides being impacted by the same allergens, such as pollen, allergic rhinitis and asthma may also be linked by other physiological factors. One possibility links problems between the upper and lower airways. Nerve fibers in the upper airways (nose, mouth) connect to the lower airways (lungs), which could explain how nasal irritation causes the lung and airway inflammation seen in asthma. Other theories focus on mouth breathing due to blocked nasal passages and postnasal drip of inflammatory material from the upper airways as a cause for asthma. The most common form of asthma among children is allergic asthma. In this form, otherwise harmless allergens, such as dust mites, cat and dog dander or other environmental allergens, can trigger an asthma attack. In addition to allergy symptoms brought on by exposure to these allergens—watery eyes, sneezing and itching—asthmatics can experience severe airway constriction. If left untreated, the disease can escalate to dangerous proportions, even resulting in trips to the emergency room to restore normal breathing. The disease also can have a non-allergic component and be triggered by cold, dry air or exercise. The variety of triggers, both allergic and non-allergic, that lurk all around us makes asthma nearly a universal risk for millions of people. Children whose immune systems are not fully developed are most at risk for developing the disease. A global disease Allergic disease has swept across the planet at a rate that shocks today's scientists, affecting both developed and developing countries. Asthma, in particular, is no longer an isolated disease phenomena; it has escalated to epidemic proportions around the globe. The World Health Organization estimates that asthma affects nearly 150 million people worldwide, with more than 180,000 deaths each year are due to asthma. With its sometimes debilitating and life-threatening aspects and growing prevalence, asthma has become a public health emergency in many countries, including the United States. "I believe that the problem of asthma is not limited to developing countries. This problem seems to be universal," said Robert C. Strunk, MD, FAAAAI, Professor of Medicine, Department of Pediatrics, Division of Allergy and Pulmonology, Washington University School of Medicine/St. Louis Children's Hospital in St. Louis, MO. The number of people affected by asthma is climbing dramatically. In St. Louis, health officials saw a 300% increase in hospitalization rates for asthma between 1985 and 1995. The increased hospitalizations seem to be related to the large number of children readmitted, Strunk said. "Reasons for readmissions seem to be family disorganization and the inability of the caregiver(s) to respond to increased symptoms in an effective manner," he said. On a national level, data indicates that the number of children with asthma in the United States has doubled in the past 15 years. The American Lung Association (ALA) reports asthma as the No. 1 cause of hospitalization among children under age 15. According to the ALA, asthma now accounts for one in six of all pediatric emergency visits in the United States. Too clean? According to the theory, first proposed in 1989 by epidemiologist David Strachan of the London School of Hygiene and Tropical Medicine, today's "sterile," Westernized society has led to an increase in allergic diseases. As our society has strived to disinfect its environment and stamp out infectious disease with antibiotics and vaccinations, it has knocked our immune systems out of balance. The National Heart, Lung, and Blood Institute (NHLBI) estimates that asthma is 1.75 times greater in prevalence today than in 1980, and 2.6 times greater for children under age 4. When we limit our exposure to bacteria and infectious diseases, we may be putting ourselves at risk of allergies and asthma, said James E. Gern, MD, FAAAAI, Associate Professor of Pediatrics at the University of Wisconsin-Madison. Children raised in rural environments, especially those with farm animals, have been found to have a lower incidence of allergies. Children enrolled in day care early in life and those raised with multiple siblings also show a lower prevalence of allergic disease, possibly due to their exposure to various germs and viruses. Other studies have found children growing up with pets to have a lower incidence of allergies and asthma. All factors point to the priming of a child's immune system and strengthening of the internal defense system, which could potentially ward off allergic disease. Other research studies have found contradicting evidence to the validity of the hygiene hypothesis. A firm answer for the rising rate of allergic disease still is unknown, Gern said. "One thing that is not explained by the hygiene hypothesis is the current epidemic of asthma in American inner cities. It is generally agreed that the inner city is not a clean environment, and yet allergy and asthma rates are high," Gern said. "This may relate to the fact that asthma is not a single disease and that different factors are driving the asthma trend in this case." Who's at risk? Even more than prevalence, morbidity from asthma is more problematic among inner city children, according to Peyton Eggleston, MD, FAAAAI, Professor of Pediatrics at Johns Hopkins Hospital in Baltimore, MD. Emergency department and hospitalization rates are two to three times higher among inner city children than middle class children. In the National Cooperative Inner-City Asthma Study (NCICAS), a major national study on asthma morbidity, researchers found that on average, inner city children had two visits to the emergency department for asthma annually and a hospitalization nearly every year. Physical environments in the inner city play host to a number of major asthma- and allergy-triggering allergens and pollutants. Mold, cockroach, dust mites and rodent droppings are some of the most common—and the most potent—allergens. Among environmental allergens, cockroach allergen tops the list of potent triggers for asthmatic and allergic children, Eggleston explained. The NCICAS study showed that children sensitized to cockroach allergen and exposed to those same allergens in their home had three times as many emergency department visits, two times the hospitalizations and 50% more wheezing days than non-allergic children or those not exposed to high-allergen concentrations. Dust mites are another common asthma trigger. Beds and carpeting are a particular harbor for mites. Studies of inner city homes have found that such household environments showed a greater likelihood allergen contamination. Housing disrepair and wall-to-wall carpeting in such households are common. Few of these homes have functioning vacuum cleaners. Inner city households also are more at risk for dampness, which can encourage the growth of allergy-inducing molds. Mice are often more prevalent in inner city homes. Mouse urinary protein allergens, due to home infestations, play a role in triggering inner city children's asthma. Studies have shown that mouse allergen was detected in up to 88% of homes studied. Besides indoor allergens, inner city children are exposed to numerous environmental pollutants that put them at risk for allergies and asthma. Topping this list of suspected triggers is tobacco smoke. In the NCICAS study, 59% of families had at least one smoker, with 39% reporting that the primary caretaker smoked. Passive tobacco can inflame the lungs, further constricting the airways for asthmatics. "Smoking rates among inner city families are still above 50% with children from these families reporting 20% higher emergency department visits," Eggleston said. Another pollutant is diesel fuel exhaust. While some studies have found that diesel fuel can increase allergic inflammation and induce airway inflammation, it is not clear if the population is exposed to a high enough concentration to cause asthma, Eggleston added. If it does have an impact, inner city residents are at an increased risk due to the high bus and truck traffic in metropolitan areas. Psychosocial factors, such as social stress, can also have an impact on the development of and morbidity of asthma and allergic disease. "Studies have found that the stress of living in poverty, income issues and concerns about crime play a major role in increasing morbidity from asthma," Eggleston said. The NCICAS study found that stress was associated with a 30% higher emergency department visitation rate. Prevention may be possible While it is not a cure-all, some studies have found exclusive breast feeding for the first year of life, coupled with delayed introduction to potentially allergenic solid foods and cow's milk, to potentially prevent "turning on" an allergic disease circuit in a child's body. Once a person is exposed to an allergen, his or her body's immune system cells "remember" the offending protein, or material. When the allergen is encountered again, whether through breathing or eating, the immune system goes on attack to destroy the invading allergen, which may be as simple as a dust mite or peanut protein. Breast feeding may help protect a child's immune system from overreacting to these potential triggers until it is more fully developed. While several studies have touted the potential benefits of breast feeding in preventing pediatric allergies, other research studies have yielded conflicting results. Debate continues today on the degree to which breast feeding may or may not prevent allergic disease. Breast feeding mothers are often asked to watch what they eat and drink. While their child may not be drinking cow's milk or eating peanuts, allergenic foods mothers ingest may be passed on to their child through their breast milk. Mothers are often asked to avoid such foods as soy, peanuts, eggs and fish to reduce the risk of their child potentially becoming sensitized to the food, as well as tobacco smoke and alcohol. Investigations into the role of food allergens ingested during pregnancy have found that such allergen avoidance during pregnancy did not affect an infant's later development of allergies. Studies have also yet to confirm if ingested allergens (in small quantities and off small molecular size) can prime a child for allergic disease. Therefore, maternal breast feeding diets that exclude certain foods are not recommended at this time. One exception to this is avoidance of peanut ingestion by mothers from highly allergic families during both pregnancy and while nursing. Studies do suggest that peanut ingestion during these times increases the baby's chance of developing peanut allergy. Since peanut allergy is generally a lifelong condition and can be very serious, some health professionals believe avoidance precautions appear warranted in such situations. Besides diet, a child's environment early in life can impact the likelihood of developing allergies and asthma. Several studies have suggested that exposure to high concentrations of indoor allergens is associated with higher rates of asthma in children or an earlier age of disease onset. One study found the relative risk of asthma at age 11 to be 4.8 times greater if the child was exposed to high levels of dust mites in infancy. These children were also found to have asthma symptoms much earlier in life when exposed to the mite allergens. Other studies have found cockroach allergen, commonly found in inner city environments, to relate to the frequency of wheezing in children in their first year of life. Early treatment makes a difference Children miss more than 10 million school days each year due to asthma complications. Asthma symptoms can result in poor academic performance, anxiety and further isolation from peers, which can lead to another health risk—depression, said Bruce G. Bender, PhD, Head of Pediatric Behavior Health at National Jewish Medical and Research Center in Denver, CO. "Chronic illness can take a psychological toll on both the child and the family," Bender said. "Children with severe illness can be traumatized by their illness and sometimes by medical interventions. Depression can be a factor and is more likely in children with severe illness. It is important to remember that many children have emotional problems even in the absence of chronic illness. For these children, the additional burden of an illness can exacerbate the emotional problems." New diagnostic and treatment techniques can help get a child's allergies and asthma quickly under control and potentially prevent a life-threatening allergic reaction or asthma attack. The allergist/immunologist, along with other healthcare professionals, is skilled in diagnosing allergic disease and asthma. Possibly the biggest advocate a child can have in gaining control of their disease is their parent or caregiver. Once pediatric allergies or asthma have been diagnosed, adherence and compliance to a prescribed treatment regimen is essential. Most asthma treatment regimens include a daily dose of inhaled corticosteroids, supplemented by a rescue medication, or bronchodilator, to be used during attacks. The regular daily medication helps to keep airways open and reduce inflammation, avoiding potentially life-threatening asthma attacks when inflammation increases to the point of airway closure. Allergy medication, which can also help to keep allergic asthma in check. Parental involvement and guidance is vital to keep a child actively taking medication and following prescribed control measures. One potential hurdle to a child's adherence to a treatment plan for asthma may be a parent's fear of side effects from oral and inhaled corticosteroids, which are common asthma medications. While steroids are the mainstay medication in asthma treatment, concerns remain about the drugs' potential to impede a child's growth. The latest research indicates that inhaled corticosteroids may produce about a 1 centimeter decrease in growth in the first year they are used. This slight deficit seems to be made up in the child before growth is finished, resulting in an unaffected adult height, said Gail G. Shapiro, MD, FAAAAI, AAAAI President and practicing clinician in Seattle, WA. "This is very positive and comforting information. Oral steroids are usually used for short periods of time and do not cause permanent growth delay when used in this manner," she said. "Overall, the benefits of corticosteroids in controlling asthma and improving a child's quality of life far outweigh any negligible growth risks." Parents need to be involved in a child's health care, including medication programs. How parents can be most effective depends on their child's age. For children under 10, specific direction and medication oversight is required. As a child reaches adolescence, parents may feel tempted to give the child all responsibility for their treatment regimen. This could be a mistake, Shapiro said. "Even adults have adherence problems," Shapiro said. "Medications should be put in a visible spot, like the kitchen table. If the youngster obviously takes the medication, no reminder is needed. If there is no movement towards the medicine, parents need to send a message to the child. Teens require the same. The parent should not abdicate responsibility but should modify the reminder signal to fit the age and level of responsibility of the child." Have a plan Actions like these not only affect a patient's quality of life, but put their life at risk, said Kathleen Harden, RN, BSN, CCRC, Research Coordinator at Kaiser Permanente in San Diego, CA. Compliance with a treatment plan is crucial to gain and retain control of asthma. Poor compliance with asthma treatments and monitoring efforts is a frequent cause of inadequate control of the disease, leading to unscheduled physician visits and hospitalizations. An easy way to take control of asthma is to prepare an Asthma Action Plan with an asthma specialist. The plan also can be shared with a child's school and school personnel to engage them as a partner in the child's health care. "I can't overstate the importance of the Asthma Action Plan in helping families control asthma. I have heard that for many families, the plan actually changed their lives," Harden said. "Before seeing an asthma expert, many families operate in crisis mode regarding their child's asthma. This means hoping things are going well until flares necessitate late-night urgent care or emergency visits. The Action Plan enables the family to develop a sense of control over the disease." Research fosters new, better treatments Further exploration of the human genome has led to a number of breakthroughs in the understanding of disease, including allergic disease. While no single asthma or allergy gene has been identified, many scientists believe that a number of genetic factors may interact with the environment to lead to the development of allergic disease and asthma. Researchers continue to search for the molecules in our environment that may interact with our genetic makeup in order to predict who may develop certain diseases and the severity of those conditions. Another vein of research has concentrated on short-circuiting the allergic reaction in the body before it even begins. A new drug, that is already under review by the Food and Drug Administration (FDA), will mark the first-ever monoclonal antibody available for the treatment of allergic disease. The new treatment regimen, known as anti-IgE, revolves around the theory that an imbalance in the immune system may contribute to the development of allergic disease. Researchers have found that allergic individuals have much larger amounts of the IgE antibody circulating in their blood. Anti-IgE therapy essentially stops the allergic reaction before it starts, allowing the patient to avoid the nasty allergic symptoms, which also often trigger an asthma attack or lead to the development of asthma. Researchers are exploring other targets for new allergic disease treatments. Cytokines, which are thought to be responsible for maintaining the chronic inflammation seen in asthma, have been earmarked as just such a target. New drugs may zero in on cytokines in the body to inhibit or to block antibodies that trigger the allergic cascade. Additional therapeutic research may also lead to the development of new corticosteroids and new nonsteroidal anti-inflammatory drugs, which would retain the anti-inflammatory efficacy but offer fewer systemic side effects. New approaches for monitoring asthma and allergies in children and delivery devices are also on the horizon. A new nebulized corticosteroid was released on the U.S. drug market recently that can be used in children as young as 12 months. Previously, such inhaled corticosteroid therapy was only available for children four years of age and older and typically administered via an asthma inhaler. As the medical community takes greater notice of the growing threat of allergic disease, new research will lead to earlier medical interventions for children suffering from allergies and asthma, said Donald Y.M. Leung, MD, PhD, FAAAAI, Professor and Head, Division of Pediatric Allergy/Immunology at National Jewish Medical and Research Center. "Research will likely lead to more effective and safer therapies for children with asthma and other immune-mediated diseases. It will also provide more awareness of the importance of earlier intervention in these illnesses," Leung said. "It is becoming quite clear that it is important to intervene early in order to prevent consequences that could become even worse later in life." Public health initiatives focus on allergic disease The Managing Pediatric Asthma: Emergency Department Demonstration Program, led by the AAAAI in partnership with The Robert Wood Johnson Foundation, consists of four emergency departments (ED) in pediatric care centers in four states. The program will help the EDs to develop and evaluate four asthma patient tracking systems and educational programs, and may be used as a national model. The U.S. Centers for Disease Control and Prevention (CDC) is working in conjunction with the AAAAI to create a standardized asthma training curriculum for public health department staff and other professionals across the country. The National Asthma Curriculum Initiative will produce a universal curriculum on asthma that will offer direction on topics such as epidemiology, risk factors, physiology, diagnosis and management of the disease. The National Institute of Allergic and Infectious Diseases (NIAID)/National Institute of Environmental Health Sciences (NIEHS) Inner-City Asthma Study and the Inner-City Pollution Study, and the National Heart, Lung, and Blood Institute (NHLBI) Research Program on Management at School both help to establish a broader understanding of asthma in children. Both studies examined the state of inner city environmental conditions in respect to pediatric asthma and potential interventions as methods of enhancing care. Continued discussion about allergic disease and asthma will help to keep the diseases top-of-mind in both the medical and lay communities. This open communication, coupled with cutting-edge research, will help to produce a society that may breathe a little easier, said Stanley J. Szefler, MD, FAAAAI, of the National Jewish Medical and Research Center in Denver. "Research and communication is needed to continually assess the most appropriate use of these medications and formulations. This will lead to new insights for overall disease management and better quality of life for those affected by these conditions," Szefler said. |
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