title: Total serum IgE in a population-based study of Asian children in Taiwan: reference value and significance in the diagnosis of allergy.
abstract: BACKGROUND
  Total serum immunoglobulin (IgE) test is usually performed to aid in the diagnosis of allergic diseases, but its reference values may vary among people of different ethnic backgrounds.
  
  
  OBJECTIVE
  To establish reference values of total IgE in Asian children and to assess their significance in the diagnosis of atopy and allergic diseases.
  
  
  METHODS
  1321 Asian children aged 5-18 years in the Prediction of Allergies in Taiwanese CHildren (PATCH) study, a population-based cohort, were evaluated for total and specific IgE by ImmunoCAP and Phadiatop Infant, respectively.
  
  
  RESULTS
  Male, atopy, allergic diseases, recent symptoms of upper respiratory infection, and lower FEV1/FVC, were associated with higher total IgE levels in univariate analyses. Multivariate analysis revealed that atopy was the single most important determinant explaining 66.1% of the variability of total IgE levels in this population. The area under the receiver-operator characteristic (ROC) curve of total IgE for diagnosing atopy, asthma, rhinitis, and eczema were 0.92, 0.72, 0.70, and 0.70, respectively. The sensitivity, specificity, and positive and negative predictive values of total IgE at the optimal cutoff of 77.7 kU/L on the ROC curve for diagnosing atopy were 82.3%, 87.1%, 89.5%, and 78.6%, respectively. The corresponding values using the upper 95% CI of total IgE (164.3 kU/L) in non-atopic children were 61.2%, 95.0%, 94.3%, and 64.6%, respectively; whereas a customary cutoff (100 kU/L) provided accuracy between that of the aforementioned two cutoffs. Total IgE at the cutoff of 77.7 kU/L provided modest sensitivity and specificity (49.0%-78.3%) for diagnosing allergic diseases, but had high negative predictive values (84.2%-97.9%).
  
  
  CONCLUSIONS
  Total serum IgE discriminates Asian children with and without atopy independent of allergic symptoms, with an optimal cutoff of 77.7 kU/L. The study confirms the insufficient diagnostic accuracy of total IgE alone to detect allergic diseases, but low total IgE levels may help exclude allergic diseases.
authors.affiliation: Division of Allergy, Asthma, and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan ; Community Medicine Research Center, Chang Gung Memorial Hospital at Keelung, Keelung, Taiwan ; Graduate Institute of Clinical Medical Sciences, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Yu-Ling
authors.initials: YL
authors.lastname: Tu
authors.forename: Su-Wei
authors.initials: SW
authors.lastname: Chang
authors.forename: Hui-Ju
authors.initials: HJ
authors.lastname: Tsai
authors.forename: Li-Chen
authors.initials: LC
authors.lastname: Chen
authors.forename: Wen-I
authors.initials: WI
authors.lastname: Lee
authors.forename: Man-Chin
authors.initials: MC
authors.lastname: Hua
authors.forename: Ju-Hui
authors.initials: JH
authors.lastname: Cheng
authors.forename: Liang-Shiou
authors.initials: LS
authors.lastname: Ou
authors.forename: Kuo-Wei
authors.initials: KW
authors.lastname: Yeh
authors.forename: Jing-Long
authors.initials: JL
authors.lastname: Huang
authors.forename: Tsung-Chieh
authors.initials: TC
authors.lastname: Yao
mesh_terms: D000293:Adolescent; D000485:Allergens / Q000276:immunology; D000918:Antibody Specificity / Q000276:immunology; D044466:Asian People; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology*; D008297:Male; D011159:Population Surveillance; D012372:ROC Curve; D012016:Reference Values; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology
chemical_list: D000485:Allergens; D007073:Immunoglobulin E