BODY: Introduction: Biological therapy has dramatically changed the management of Crohn's disease (CD). Appropriateness criteria for maintenance treatment after medically-induced remission (MIR) or surgically-induced remission (SIR) of CD have thus been updated. Formal evidence is weak formany therapeutic decisions regardingmaintenance treatment for CD and thus clinically-explicit and situation-tailored criteria made freely available on the internet will be helpful to physicians in daily decision-making in clinical practice. Methods: Multidisciplinary international experts (EPACT II, Geneva, Switzerland) discussed and anonymously rated virtual clinical indications on the basis of evidence in the literature. Median ratings (on a 9-point scale) were stratified according to three assessment categories: appropriate (7-9), uncertain (4-6 and/or disagreement) and inappropriate (1-3). Experts were also asked to rank appropriate medication according to their own clinical practice, without any consideration of cost. Results: 392 specific indications for maintenance treatment of CD were rated (200 for MIR and 192 for SIR). Azathioprine, methotrexate and/ or anti-TNF antibodies were considered appropriate in 42 indications, corresponding to 68% of all appropriate interventions (97% ofMIR and 39%of SIR). The remaining appropriate interventions consisted of mesalazine and a “wait-and-see” strategy. Factors that influenced the panel's voting were patient characteristics and outcome of previous treatments. Results favor the use of anti-TNF agents after one failure of any immunosuppressive therapy, while an earlier use is still controversial. Conclusion: Detailed explicit appropriateness criteria have been updated for maintenance treatment of CD. New expert recommendations for the use of the classic immunomodulators as well as anti-TNF agents are now available (www.epact.ch). The validity of these criteria should now be tested by prospective evaluation. A-173 AGA Abstracts S1029 Clinical Use and Outcomes from IBD Serology Testing in a Tertiary Referral Center Alan C. Moss, Adam Cheifetz, Nabeel Chaudhary, Jahvari Junior Background Testing for a combination of antibodies against ASCA, ANCA, and OmpC has become common-place in IBD practice. Patient selection for testing, and the impact of test results on patient management, remain variable. Aims To describe patient selection for IBD antibody testing in a tertiary referral center. To measure changes in management after test results became available. To compare test results between patient sub-groups. Methods Review of electronic medical records of all patients who completed IBD serology testing (Prometheus) at a single institution. Results Data were available on 213 patients who completed testing. The distribution of pre-testing diagnoses were as follows; no diagnosis 41 (19%), Crohn's disease 49 (23%), ulcerative colitis 60 (28%), IBD unclassified 60 (28%). In those with established IBD, 122 (57%) had colonic disease only, 36 (17%) had small bowel disease only, 13 (6%) had ileo-colonic disease, and 10 (5%) had pouchitis. The prevalence of elevated antibodies to ASCA, ANCA and OmpC in different patient populations can be seen in Table 1. The proportion of patients with a change in diagnosis after antibody testing in each patient sub-group was as follows; no diagnosis 27%, Crohn's disease 48%, ulcerative colitis 20%, IBD unclassified (IBDU) 63%. The odds ratio of a change in diagnosis after testing positive for ASCA, ANCA or OmpC was not statistically significant in any patient sub-group. A cohort of patients also underwent antibody testing for celiac disease antibodies (n=21), but all were negative. Conclusions IBD serology testing was applied to a wide range of patient populations in this center. ASCA antibodies were present in similar proportions across all patient populations. Patients with IBDU were most likely to have a change in diagnosis after antibody testing.