Anti-Saccharomyces Cerevisiae (Asca) and Perinuclear Antineutrophil Cytoplasmic Antibodies (Panca) in the Diagnosis of Crohn's Disease and Ulcerative Colitis

A systematic review 1 including 60 studies with a total of 3,841 ulcerative colitis (UC) patients, 4,019 Crohn's disease (CD) patients and 3,748 controls, was abstracted in DARE. Diagnosis of CD. The most sensitive test was ASCA IgG or IgA positive antibodies in sera that were pANCA negative (8 studies, n=1,321). The pooled sensitivity was 55% (95% CI: 52, 59). The specificity for this combination ranged from 87 to 98%; the pooled specificity was 93% (95% CI: 91, 95). The best pooled specificity (100%, 95% CI: 95, 100) was obtained when sera tested positive for ASCA IgG antibody and negative for pANCA (2 studies, 190 patients). Diagnosis of UC. The most sensitive test was positive pANCA with no information on ASCA status (31 studies, 4,054 patients). The sensitivity ranged from 9 to 82%; the pooled sensitivity was 55% (95% CI: 53, 58). The specificity ranged from 28 to 96%; the pooled specificity was 89% (95% CI: 87, 90). There was strong evidence of heterogeneity (p<0.001). The best pooled specificity (94%, 95% CI: 93, 96) was obtained for the combination of pANCA positive and ASCA negative; the pooled sensitivity for this test was 51% (95% CI: 48, 55) (14studies, 2,072 patients). Diagnosis of IBD. The most sensitive test for the diagnosis of IBD was the presence of pANCA or ASCA of any class (5 studies, 839 patients). The pooled sensitivity was 63% (95% CI: 58, 67) and the pooled specificity 93% (95% CI: 89, 95). The most specific test was pANCA alone, which was evaluated in 27 studies (6,117 patients). The pooled specificity was 97% (95% CI: 96, 98) and the pooled sensitivity 33% (95% CI: 31, 34). There was substantial heterogeneity in both sensitivity and specificity (p<0.001). The results were generally similar for studies of paediatric populations

Comment: The quality of evidence is downgraded by limitations in study quality (variable reference standards). The authors conclude that these antibodies may be particularly useful to differentiate CD and UC in paediatric populations.

The following decision support rules contain links to this evidence summary:

• ASCA and pANCA antibodies in the diagnosis of Crohn's disease and ulcerative colitis http://www.ebmeds.org/ebmeds/ebmeds_home.asp?mode=scripts&submode=view&id=scr00611&country=UK

References

• Reese GE, Constantinides VA, Simillis C, Darzi AW, Orchard TR, Fazio VW, Tekkis PP. Diagnostic precision of anti-Saccharomyces cerevisiae antibodies and perinuclear antineutrophil cytoplasmic antibodies in inflammatory bowel disease. Am J Gastroenterol 2006 Oct;101(10):2410-22. [PubMed] [DARE]