title: Atopic phenotypes identified with latent class analyses at age 2 years.
abstract: BACKGROUND
  Atopic sensitization (ie, atopy) is the most commonly reported risk factor for asthma. Recent studies have begun to suggest that atopy, as conventionally defined, might be an umbrella term that obfuscates more specific allergic disease types.
  
  
  OBJECTIVE
  We sought to determine whether distinct and meaningful atopic phenotypes exist within a racially diverse birth cohort using 10 allergen-specific serum IgE (sIgE) measurements from children aged 2 years.
  
  
  METHODS
  Using the Wayne County Health, Environment, Allergy and Asthma Longitudinal Study (WHEALS) birth cohort (62% black), we analyzed sIgE data on 10 allergens (Dermatophagoides farinae, dog, cat, timothy grass, ragweed, Alternaria alternata, egg, peanut, milk, and German cockroach) obtained from 594 children at age 2 years. Conventional atopy was defined as at least 1 sIgE level of 0.35 IU/mL or greater.
  
  
  RESULTS
  A 4-class solution (latent class model) was the best fit. Class types were labeled "low to no sensitization" (76.9% of sample), "highly sensitized" (2.7%), "milk and egg dominated" (15.3%), and "peanut and inhalant(s)" (5.1%). Almost one third (32.2%) of the low to no sensitization group met the criteria for conventional atopy. The highly sensitized group was significantly associated with a doctor's diagnosis of asthma after age 4 years (odds ratio [OR], 5.3; 95% CI, 1.6-17.4), whereas the milk and egg dominated and peanut and inhalant(s) groups were not (ORs of 1.6 [95% CI, 0.8-3.0] and 1.8 [95% CI, 0.6-4.9], respectively). Children of black race were more likely to be in the 3 multisensitized groups (P = .04).
  
  
  CONCLUSIONS
  Classification by sIgE patterns defined groups whose membership is more strongly associated with atopic dermatitis, wheeze, and asthma compared with conventional atopy.
authors.affiliation: Department of Public Health Sciences, Henry Ford Hospital, Detroit, Mich. Electronic address: shavsta1@hfhs.org.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Havstad
authors.affiliation: Department of Public Health Sciences, Henry Ford Hospital, Detroit, Mich.
authors.forename: Christine Cole
authors.initials: CC
authors.lastname: Johnson
authors.affiliation: Department of Internal Medicine, Division of Allergy, Henry Ford Hospital, Detroit, Mich.
authors.forename: Haejin
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Public Health Sciences, Henry Ford Hospital, Detroit, Mich.
authors.forename: Albert M
authors.initials: AM
authors.lastname: Levin
authors.affiliation: Department of Internal Medicine, Division of Allergy, Henry Ford Hospital, Detroit, Mich.
authors.forename: Edward M
authors.initials: EM
authors.lastname: Zoratti
authors.affiliation: Department of Public Health Sciences, Henry Ford Hospital, Detroit, Mich.
authors.forename: Christine L M
authors.initials: CL
authors.lastname: Joseph
authors.affiliation: Department of Pediatrics, Georgia Regents University, Augusta, Ga.
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Ownby
authors.affiliation: Department of Public Health Sciences, Henry Ford Hospital, Detroit, Mich.
authors.forename: Ganesa
authors.initials: G
authors.lastname: Wegienka
mesh_terms: D000485:Allergens / Q000276:immunology* / Q000302:isolation & purification; D001249:Asthma / Q000145:classification / Q000276:immunology*; D002675:Child, Preschool; D015331:Cohort Studies; D003876:Dermatitis, Atopic / Q000276:immunology*; D005260:Female; D006801:Humans; D007114:Immunization; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D008894:Milk Proteins / Q000276:immunology*; D010641:Phenotype; D044469:Racial Groups
chemical_list: D000485:Allergens; D008894:Milk Proteins; D007073:Immunoglobulin E
keywords: Atopy; birth cohort; latent class analysis; phenotype