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sS1182

Serum Protein Signatures Determined By Mass Spectrometry (SELDI-ToF)Accurately Distinguishes Crohn's Disease (CD) from Ulcerative Colitis (UC)Venkataraman Subramanian, Devika Subramanian, Richard C. Pollok

Background: Accurate diagnosis of UC or CD is essential to guide patient management.Current tests are invasive and carry risks. A meta analysis suggested that diagnosis of CDby ASCA (Anti-Saccharomyces cerevisiae antibodies) has a sensitivity of 54.6%. pANCApositivity has a sensitivity of 55.3% in the diagnosis of UC. Aim: We aimed to detectnovel serum biomarkers by protein fingerprinting using surface-enhanced laser desorptionionization time-of-flight (SELDI-ToF) mass spectrometry to differentiate CD from UC.Methods: Serum was collected prospectively from 62 patients with UC and 48 with CD andstored at -80 0C. Samples were applied to CM10 protein chip arrays and time-of- flightspectra were generated using a PBS-II mass spectrometer (Ciphergen, Freemont, CA, USA).The mass spectrometry data was extracted and preprocessed prior to analysis. The spectrawere analyzed using support vector machine (SVM) analysis utilizing recursive featureelimination (RFE) techniques with radial basis function and 5-fold cross validation. We thendeveloped a boolean pattern classifier on the thresholded peaks (based on median value)detected by SVM. The identity of the selected peaks was confirmed using immunodepletionmethods. ASCA and ANCA were determined by ELISA and indirect immunofluorescencerespectively. Results:12 key peaks were identified using SVM with RFE (RBF kernel widthof 0.00075 and C of 100) in a five-fold cross validation setting. These peaks were thenthresholded to being above or below the median value. We clustered the data using k-means with two clusters. Using 8 of these thresholded peaks two well separated clusterswere identified. A boolean pattern classifier was developed on the 12 thresholded peaks.The specificity and sensitivity of this boolean classifier was 96% for the first cluster and94% for the second cluster. ASCA had a sensitivity of 70.8% in detecting CD and overallaccuracy of 80.9%. p ANCA had a sensitivity of 64.5% for detecting UC. The peaks identifiedas important had m/z values of 2.7, 4.1, 4.2, 5.6, 6.4, 6.8, 7.8, 7.9, 8.6, 8.7, 9.3, 1.6 kDa.These were confirmed to be fragments of inter alpha trypsin inhibitor 4 (2.7 and 4.2),Apolipoprotein C1 and probably its SPA adduct (6.4 and 6.8), Platelet activated factor 4variants (7.8 and 7.9). Conclusions: Using protein signatures of patients with UC and CDwe have developed a classification model which is accurate, sensitive and more informativethan currently available serological tests. There seem to be distinct proteome based clustersof CD and UC patients. The clinical, pathogenic and prognostic significance of these clustersneeds to be further characterized

S1183

A Combination of Serum Adiponectin, Pepsinogen I and Anti-SaccharomycesCerevisiae Antibody (ASCA) Levels Can Accurately Distinguish Patients withCrohn's Disease Involving the Small Bowel from Colonic Crohn's DiseaseVenkataraman Subramanian, Geetha Balarajah, Richard C. Pollok

Background: Serum Pepsinogen I (PG I) level reliably correlates with the number of chiefcells in the gastric corpus mucosa. Gastric heterotopia of the small intestine in Crohn'sdisease (CD) has been well described and PG I & II noted on immunohistochemisty in themetaplastic pyloric and oxyntic glands in the ileum. Adiponectin levels are known to beelevated in patients with CD with mesenteric adipose tissue hypertrophy and not in patientswith UC. ASCA has been associated with more proximal involvement rather than colonicCD. Diagnosis of small intestinal involvement in patients with CD has major implicationson patient management. Aim: The aim of this pilot study was to use serum PG I , serumadiponectin and IgA and IgG ASCA levels to develop an algorithm that distinguishes patientswith colonic CD from those with CD involving the small intestine. Methods: Serum wasprospectively collected and stored at -80 0C from patients with histologically proven CD.PG I levels (Biohit plc, Finland) and Adiponectin levels (B-bridge International, USA), IgAand IgG ASCA (Aesku Lab, Germany) were determined in duplicate by ELISA. Patients weregrouped into those with small intestinal involvement and those with colonic CD. Differencesbetween groups were tested using Mann-Whitney U test of significance. Results: Mean PGI levels in the small bowel CD group (n=18) was 97.89 ± 33.07 µg/l. Mean PG I levels inthe colonic CD group (n=14) was 83.25 ± 29.74 µg/l (p=0.08). Mean Adiponectin levelsin the small bowel CD group was 3.89 ± 1.87 ng/ml and in the colonic CD group was 2.65± 1.50 ng/ml (p=0.02). Area under the Receiver operating curve for Adiponectin was 0.74and for Serum PG I was 0.68. A cut off value of more than 1.58 ng/ml for serum Adiponectinand more than 78 µg/l for serum PG I with either a positive IGA or IgG ASCA had asensitivity of 88.9 %, specificity of 85.7 % and overall accuracy of 87.5% in detecting smallbowel involvement in CD. Only 2 patients each with colonic and small intestinal CD weremisclassified. Conclusion: Adiponectin levels are significantly higher in CD patients withsmall bowel disease. This could be because patients with colonic CD alone are less likelyto have mesenteric fat hypertrophy. Serum PG1 levels showed a trend towards significanceamong patients with small intestinal CD. This could reflect both gastric heterotropia in thesmall intestine as well as inflammation due to CD in the stomach. Further studies arerequired to confirm these findings. A combination of Adiponectin , PG I levels and ASCAserology could help in non-invasive diagnosis of small bowel involvement in patients with CD.

S1184

The Manitoba Index: Psychometric Evidence for a New and Simple Indicatorof IBD ActivityIan Clara, Lisa M. Lix, John Walker, Lesley A. Graff, Norine Miller, Linda Rogala, PatriciaRawsthorne, Charles N. Bernstein

Many indicators of disease activity for IBD can be time consuming or difficult to administer,as they require invasive procedures (endoscopy), clinical evaluation (CDAI), or completionof multiple-item scales (IBDQ). Simpler indices such as the Harvey-Bradshaw (HB) andPowell-Tuck (PT) provide only a brief cross-sectional account of disease activity at the timeof a clinic visit and do not adequately characterize disease activity over an extended period.A single-item indicator of disease activity, the Manitoba Index (MI) is proposed, and compared

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against several standard measures for assessing IBD disease activity. Methods: Participantsenrolled in the Manitoba IBD Cohort Study, a population based longitudinal cohort (n=356) were assessed periodically by survey, clinical interview, and blood sample. The MI isbased on patient report of symptom persistence for the previous 6 mos, using a 6-levelresponse format: active (a) constantly (daily symptoms) (b) often (symptoms most days) (c)sometimes (symptoms some days e.g.,1-2 days/wk) (d) occasionally (symptoms 1-2 days/mo) (e) rarely (symptoms few days past 6 mos) and (f) inactive (absence of symptoms).Disease was defined as active if respondents answered any of a-d and inactive if answerede or f. Physical symptoms (GI and systemic), clinical disease indices (HB, PT), IBD medicationuse, daily productivity loss, and psychological functioning (e.g. health anxiety, distress) wereall assessed. Biological markers included hemoglobin and CRP. Sensitivity analyses anddiscriminant function analyses were used to validate the MI, using data from baseline (i.e.,month 0), 12 and 24 months points. Results: The MI had good sensitivity when comparedto HB, PT, and IBDQ scores (range 0.84 to 0.90). It correlated well with all these measures(0.39 to 0.62, p<0.01) and individual symptom measures (e.g., abdominal, joint, diarrhea,bowel movement urgency; 0.27 to 0.62, p < 0.01), despite the different assessment timeframes. In separate discriminant analyses for CD and UC, common discriminating variablesincluded clinical indices (HB for CD, PT for UC), IBDQ subscales of bowel and systemicsymptoms, and symptom ratings (e.g., abdominal and joint pain, tiredness, diarrhea). Conclu-sions: A single-item patient-defined disease activity measure, the Manitoba Index, showeda high degree of sensitivity for classifying individuals with active disease compared to existingdisease activity measures, and strong convergent validity with expected proxy measures ofdisease. These relationships were consistent across a two-year period. Thus, the MI showspromise as a valid brief tool for measuring disease activity.

S1185

Faecal Calprotectin's Utility in the Prediction of Inflammatory Bowel Disease(IBD) RelapsesJavier P. Gisbert, Fernando Bermejo, Jl Perez-Calle, Carlos Taxonera, Isabel Vera, YagoGonzalez-Lama, Alicia Algaba, P. Lopez-Serrano, N. López-Palacios, Marta Calvo, AdrianG. McNicholl, Ja Carneros, M. Velasco, José Maté-Jiménez

BACKGROUND: IBD activity flares are usually unpredictable. If we had an available andreliable marker to estimate the risk of relapse, we could prescribe early medication to preventor treat the relapse. Inflammation is a continuous process, so a biological marker able toestimate the intensity of inflammation might provide us a pre-symptomatic quantitativemeasure of the risk of imminent clinical relapse AIM: To determine faecal calprotectin'sutility in the prediction of IBD relapses. METHODS: Prospective multicenter study includingCrohn's Disease (CD) and Ulcerative Colitis (UC) patients who had been in clinical remission(based on Truelove and CDAI scores) during the preceding 6 months. Disease and treatmentdata collection and calprotectin's basal levels measurements were done during screening.Follow up period was 12 months in those patients showing no relapse and until activityflare in relapsed patients. RESULTS: Seventy-seven patients, 44 with CD and 35 with UC,have completed the study so far. Treatments: oral 5-ASA (62%), topical 5-ASA (7%), AZA/MP (39%), and infliximab (4%). 25% of the patients had suffered a flare the year precedingthe study. Seventeen patients (22%) relapsed during follow up (after an average of 20 weeks).Average levels of faecal calprotectin were 179±157 µg/g (ranging from 9 to 851 µg/g).Calprotectin concentrations in those patients who suffered a relapse were higher than inthose who maintained remission (255±143 vs. 157±154 µg/g; p<0.05). This difference wasonly demonstrated in CD patients (317 vs. 162 µg/g; p<0.05) but not in UC patients (200vs. 151 µg/g). The percentage of IBD patients relapsing was significantly different betweenthose having calprotectin concentrations <100 µg/g and those with higher concentrations(10% vs 30% relapses respectively, p<0.05). These differences were even clearer in CDpatients (6% for calprotectin <100 µg/g and 28% for >100 µg/g). Faecal calprotectin's (>100µg/g) sensitivity and specificity to predict relapses in CD were 82% and 47% (positive andnegative predictive values of 30% and 90% respectively). The area under the ROC curveto predict IBD relapse using calprotectin determination was 0.72, and considering only CDdata was 0.81%. The best global cut-off point was 166 µg/g (sensitivity 82%; specificity67%), but in CD patients it was 170 µg/g (sensitivity 88%; specificity 68%). Consideringonly the prediction of relapse during the first 6 months of follow up, results were better (areaunder the ROC curve in CD was 0.91) CONCLUSIONS: High calprotectin concentrations infaeces are associated with a higher risk of clinical relapse in IBD patients.

S1186

The Diagnostic Accuracy of Faecal Calprotectin in Inflammatory BowelDisease (IBD): A Systematic ReviewJavier P. Gisbert, Adrian G. McNicholl

BACKGROUND: The presence of calprotectin in faeces is directly proportional to neutrophilmigration towards the intestinal tract. The potential strength of faecal calprotectin assessmentis that it is a direct measure of mucosal inflammatory activity, and levels in the stool seemto be unaffected by a variety of non-intestinal conditions, which may result in an elevationof the systemic inflammatory markers. AIM: To review the diagnostic accuracy of faecalcalprotectin determination 1) to distinguish organic from functional disorders in symptomaticpatients, and 2) for the diagnosis of IBD. METHODS: Bibliographical searches were performedin MEDLINE up to 2007 looking for the following words (all fields): (“inflammatory boweldisease” OR “Crohn's disease” OR “ulcerative colitis”) AND (calprotectin OR faecal marker).The mean sensitivity and specificity of faecal determination was calculated and expressedas weighted mean (and corresponding 95% confidence interval; 95% CI) to make dueallowance for the number of patients included in each study. Subanalyses were performeddepending on the IBD type: ulcerative colitis (UC) vs. Crohn's disease (CD). RESULTS: 1)Thirteen studies, including a total of 2475 patients, measured faecal calprotectin concentra-tions aiming to distinguish organic from functional intestinal disease in symptomatic patients.Mean sensitivities and specificities of 83% (95% CI, 81-84%) and 84% (95% CI, 82-85%),respectively, were calculated. 2) Fourteen studies, including a total of 754 patients, evaluatedthe diagnostic precision of faecal calprotectin for the diagnosis of IBD. In most of thesestudies, symptomatic patients with IBD or irritable bowel syndrome, in addition to controls,