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ICD Code: 493. Asthma



ICD Code: 493. Article Review
Title: Kelley CF et al; "Asthma Phenotypes, Risk Factors, and Measures of Severity in a National Sample of US Children." Pediatrics; V.115; No.3; 3/05; p726
      STUDY DESIGN: This study examined a nationally representative sample of U.S. children aged 6 to 16 years old and determined whether there are differences in risk factors and measures of severity between children with different asthma phenotypes. Data were obtained from the Third National Health and Nutrition Examination Survey (NHANES III), conducted from 1988 through 1994 by the National Center for Health Statistics of the Centers for Disease Control and Prevention (CDC). To delineate children who had asthma from those who did not have asthma, the authors used a positive answer to the question, "Has a doctor ever told you that your child has asthma?" After exclusions, the analytic sample consisted of 5244 children who represented about 39.6 million U.S. children.
      ASTHMA PHENOTYPES: The authors classified 4.8% of children as having atopic asthma, 1.9% as having nonatopic asthma, 3.4% as having resolved asthma, 4.3% as having frequent respiratory symptoms with no asthma diagnosis, and 85.6% as normal. Children with resolved asthma were, in general, more similar to normal children than those with atopic asthma. They did, however, have significantly lower lung function.
      Children with nonatopic asthma had higher mean body mass index (BMI). Prenatal maternal smoking and child care attendance were associated with resolved asthma phenotype and frequent respiratory symptom phenotype, respectively. Children with atopic and nonatopic asthma share the highest burden of hospitalization, emergency department visits, and school absences. A substantial proportion of all three phenotypes of physician-diagnosed asthma demonstrated lung function impairment.
      Another important finding was that atopic and nonatopic asthma do not differ substantially with respect to most asthma severity measures, with the notable exception of symptom aggravation by dust or animals. This finding was surprising in that the literature documents differences in airway lability in children and risk factors in adults between atopic and nonatopic asthma.
      DISCUSSION: Those who experience frequent respiratory symptoms in the absence of an asthma diagnosis are often classified in the literature as having probable or undiagnosed asthma. In this study, this phenotype was distinctly different from those with a physician diagnosis of asthma, particularly with regard to asthma severity measures and lung function. Therefore, it is possible that many children with frequent respiratory symptoms are not undiagnosed or have probable asthma but represent a process different from that of asthma.
      Asthma, which is an important cause of morbidity in U.S. children, probably represents several different clinical entities with different risk factors and outcomes.

Search Criteria: Text - Pediatrics; V.115; No.3; 3/05; p726