title: A prospective comparative study of ASCA and pANCA in Chinese and Caucasian IBD patients.
abstract: BACKGROUND
  Inflammatory bowel disease manifests throughout all ethnic groups. Antisaccharomyces cerevisiae (ASCA) and antineutrophil cytoplasmic antibodies (pANCA) can aid in the differentiation between Crohn's disease (CD) and ulcerative colitis (UC), but their sensitivity may vary between races.
  
  
  OBJECTIVE
  This study compared the sensitivity, specificity, and positive and negative predictive values (PPV, NPV) of pANCA and ASCA between Chinese and Caucasian IBD populations and identified disease subtype associations.
  
  
  RESULTS
  Three hundred patients were prospectively recruited from Caucasian and Chinese populations (CD, n = 50, UC, n = 50, controls, n = 50 each). pANCA detection was greater in Caucasian than Chinese UC patients (p= 0.046). ASCA IgG detection was similar, but IgA was lower in Chinese CD patients (p < 0.001). Differentiation between UC and CD (+ve pANCA/-ve ASCA) demonstrated a PPV of 92% in isolated colonic disease. Logistic regression in CD identified positive pANCA had a lower association with ileal (OR = 6.8, p= 0.0067) and complicated disease (OR = 5.5, p= 0.015). Caucasian CD patients with positive ASCA IgA/IgG had a greater association with ileal (OR = 6.7, p= 0.022) or complicated disease (OR = 9.4, p= 0.0073) and in Chinese CD patients positive ASCA IgA/IgG was associated with isolated ileal disease (OR = 16.8, p= 0.032). Linear regression demonstrated that higher ASCA titers predicted complicated CD and isolated ileal disease.
  
  
  CONCLUSIONS
  This study identified that pANCA is more sensitive in Caucasian than Chinese UC and that ASCA IgA has a low yield in Chinese CD. pANCA and ASCA are useful for differentiating between UC and CD in both populations, and ASCA IgG and IgA titers have potential use in determining the risk of developing complicated CD.
authors.affiliation: Department of Gastroenterology, University Department of Medicine and Pharmacology, University of Western Australia, Fremantle Hospital, WA, Australia.
authors.forename: Ian Craig
authors.initials: IC
authors.lastname: Lawrance
authors.forename: Kevin
authors.initials: K
authors.lastname: Murray
authors.forename: Anne
authors.initials: A
authors.lastname: Hall
authors.forename: Joseph J Y
authors.initials: JJ
authors.lastname: Sung
authors.forename: Rupert
authors.initials: R
authors.lastname: Leong
mesh_terms: D000328:Adult; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood*; D000908:Antibodies, Fungal / Q000097:blood*; D044466:Asian People; D001323:Autoantibodies / Q000097:blood; D015415:Biomarkers / Q000097:blood; D003093:Colitis, Ulcerative / Q000175:diagnosis* / Q000208:ethnology* / Q000276:immunology; D003424:Crohn Disease / Q000175:diagnosis* / Q000208:ethnology* / Q000276:immunology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D009195:Peroxidase / Q000276:immunology; D011237:Predictive Value of Tests; D012441:Saccharomyces cerevisiae / Q000276:immunology*; D012680:Sensitivity and Specificity; D044465:White People
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D000908:Antibodies, Fungal; D001323:Autoantibodies; D015415:Biomarkers; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D009195:Peroxidase