A team from the University Hospital Gasthuisberg, Leuven, Belgium, evaluated the diagnostic accuracy of perinuclear antineutrophil cytoplasmic (pANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA) for inflammatory bowel disease (IBD).
ASCA and pANCA were studied in a large cohort of 582 consecutive IBD patients. Of these, 407 had Crohn's disease, 147 had ulcerative colitis, and 28 had indeterminate colitis. The antibodies were also investigated in patients with non-IBD diarrheal illnesses (n = 74), and healthy controls (n = 157).
The researchers performed an indirect immunofluorescence technique and a standardized ELISA for detection of pANCA and ASCA, respectively.
|Sensitivity and specificity of antibodies for detecting IBD:|
ASCA+ : 60% and 91%
pANCA+: 50% and 95%
|Am J Gastroenterol |
The team found that the prevalence of ASCA and pANCA was high in Crohn's patients (60%) and ulcerative colitis (50%) patients, respectively.
Positivity for both markers was significantly lower in healthy and non-IBD controls.
The sensitivity and specificity of ASCA+, for differentiating IBD from controls, were 60% and 91%, respectively. For pANCA+, these figures were 50% and 95%.
When both antibodies were measured the sensitivity decreased further. The sensitivity and specificity for ASCA+/pANCA- were 56% and 94%, respectively. For pANCA+/ASCA- they were 44% and 97%.
Researcher M. Peeters said on behalf of the group, "Specificity of serological markers for IBD is high, but low sensitivity makes them less useful as diagnostic tests. The combination of tests is probably more powerful, although clinical subgroups will still need to be defined."
"The usefulness of these markers in indeterminate colitis needs to be studied prospectively," it was concluded.