Update in Pediatric Lung Disease 2011
Authors: Susanna A. McColley, Rory E. Morty
Journal: American Journal of Respiratory and Critical Care Medicine (2012)

Asthma is the most prevalent chronic illness, and a major cause of hospitalization, in children. A large body of research is enabling physicians and researchers to better understand genetic factors, environmental factors, comorbidities, and health care factors associated with asthma symptoms and severity. Acetaminophen use has been associated with the development of asthma in numerous epidemiologic studies. Beasley and colleagues (2) surveyed 13and 14-year-olds participating in the International Study of Asthma and Allergies in Childhood (ISAAC) study to assess current symptoms of asthma, rhinoconjunctivitis, and eczema and various risk factors during the prior year. Multivariate analysis showed that recent use of acetaminophen was associated with an exposure-dependent increased risk of asthma, rhinoconjunctivitis, and eczema. Amberbir and colleagues (3) studied a birth cohort of Ethiopian children at age 1 and 3 years to assess the relationship between the use of acetaminophen and presence of geohelminth infection with the development of wheeze and eczema. Acetaminophen use was associated with a dose-dependent increase in the risk of wheeze, but not eczema. The postulated reduction in wheeze with geohelminth infection could not be evaluated because of low population prevalence. These studies are large and are consistent with other epidemiologic studies associating prenatal or direct exposure to acetaminophen with asthma symptoms. However, it is difficult to separate the effects of confounding by other factors that influence the risk of asthma, especially febrile lower respiratory tract viral infection (4). Thus, prospective, placebo-controlled studies will be needed to establish causation. The prevalence of both obesity and asthma are increasing. Cottrell and colleagues studied a cohort of 4to 12-year-olds inWest Virginia. After controlling for sex and smoking exposure, children with asthma had higher fasting triglyceride levels and a higher rate of acanthosis nigricans, a marker of abnormal glucose metabolism, regardless of body mass index (5). Although these results suggest that abnormal lipid and glucose metabolism may be associated with asthma, study limitations included classification of asthma by parental report, use of body mass index to designate obesity, and lack of adjustment for comorbidities such as sleep-disordered breathing (6). The relationship between swimming pool attendance and asthma has been inconsistent. Font-Ribera and colleagues studied a prospectively enrolled birth cohort in the United Kingdom to assess the relationship between swimming, wheezing, and allergic disease. More than half the cohort swam once or more weekly. Those who swam more frequently had a lower prevalence of asthma than those who swam less frequently; they also had an increase in forced midexpiratory flow (7). Although these data are reassuring for recreational swimmers, and suggest that pool chlorine poses a low risk overall (7, 8), there are numerous other reports that chlorination products can cause respiratory problems in elite swimmers and swimming pool workers (9). Identifying infants at high risk for allergies and asthma could be valuable in planning epidemiologic studies and in counseling families. Turner and colleagues reported the relationship between fetal size and respiratory symptoms, pulmonary function, and atopy at 10 years of age. Eachmillimeter increase in first-trimester size was associated with a 6% reduced risk of later asthma; reduced firsttrimester size was associatedwith asthma at 5 and 10 years. Low fetal growth in both the first and second trimesters was associated with an increased risk of asthma and lower lung function, and increasing fetal size between the first and second trimesters was associated with risk of eczema and hay fever (10). Chawes and colleagues evaluated biomarkers that might predict allergic disease in asymptomatic 1month-old infants. Eosinophilic protein X was associated with the development of allergic sensitization, nasal eosinophilia and eczema, but not with allergic rhinitis, blood eosinophilia, or asthma (11). Effective asthma treatment requires adherence to controller therapy. Bruzzese and colleagues (12) reported results of a schoolbased intervention, Asthma Self-Management for Adolescents (ASMA), in a randomized study comparing ASMA participants with control subjects who were placed on a wait list for the intervention. ASMAparticipants reported more confidence in managing asthma, more steps taken to prevent symptoms, better controller medication use, fewer nocturnal symptoms and activity limitations, better quality of life, and fewer acute care visits and hospitalizations. Interestingly, ASMA participants showed no improvement in managing daytime episodes, in daytime symptoms, or in school absences. Ducharme and colleagues (13) randomized children seen in the emergency room for asthma exacerbations to receive a written asthma action plan plus fluticasone and albuterol inhalers or unformatted prescriptions only. Patients who received the written action plan increased adherence to oral and inhaled steroids and to medical follow-up.