For quite some time, I have been unimpressed with the utility of serologies in distinguishing Crohn’s disease and Ulcerative Colitis. While some of these tests claim some usefulness, when one excludes the obvious cases of Crohn’s disease (eg. perianal disease, fistulizing disease, small bowel disease), these claims seem quite dubious Another study backs up my interpretation: L Birimberg-Schwartz et al. Inflamm Bowel Dis 2016; 22: 1908-14
This longitudinal report from the IBD Porto Group examined a multicenter retrospective cohort of 406 children with isolated colonic disease. These children had a mean age of 10.5 years. 117 had Crohn’s colitis, 143 had ulcerative colitis, and 146 had IBD-unclassified (IBDU).
- Among those with IBDU, the most prevalent serologic profile was pANCA neg/ASCA neg (41%). 34% had pANCA pos/ASCA neg, and 17% and pANCA neg/ASCA pos.
- ANCA+: present in 43% of patients with IBDU, 64% of patients with UC, and 30% of patients with Crohn’s.
- ASCA+ (IgA or IgG): present in 26% of patients with IBDU, 6% of patients with UC, and 40% of patients with Crohn’s.
- pANCA neg/ASCA pos did help differentiate Crohn’s colitis versus IBDU with 83% specificity, 96% positive predictive value; however the sensitivity was only 33% and the negative predictive value was only 13%.
- pANCA neg/ASCA pos also differentiated Crohn’s colitis compared with ulcerative colitis with 97% specificity, and 90% positive predictive value however the sensitivity was only 33% and the negative predictive value was only 40%.
- pANCA pos/ASCA neg did NOT differentiate well. For IBDU versus UC, the specificity was 66%, the positive predictive value was 94%; the sensitivity was 65% and the negative predictive value was 38%.
In short, these tests generally have poor sensitivity. If ASCA antibodies are present, which occurred in only 23%, the serology performs better but still usually not well-enough to help with big decisions. The presence of positive serology was associated with an increased likelihood of more severe disease.
Before you order IBD serology, you may want to consider whether you might use the money for this costly test in a better way.
My take (borrowed from authors): “Serology cannot routinely be recommended for differentiating between IBDU versus CC or UC as a sole diagnostic criterion given its low diagnostic utility.”
Related blog posts:
- ESPGHAN IBD Diagnostic Practice … – gutsandgrowth
- Serology in IBD | gutsandgrowth
- Paris Classification of Pediatric Crohn’s Disease | gutsandgrowth