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P179 Serum amyloid A level correlated with endoscopic findings in patients with Crohn's disease - possible biomarker for evaluating mucosal healing

Y. Tada*1, S. Ishihara2, H. Sonoyama2, A. Oka2, N. Fukuba2, N. Oshima2, I. Moriyama2, T. Yuki3, K. Kawashima2, Y. Kinoshita2

1Shimane University School of Medicine, Internal Medicine II, Izumo, Japan, 2Shimane University School of Medicine, Internal Medicine II, Izumo, Japan, 3Shimane University School of Medicine, Gastrointestinal Endoscopy, Izumo, Japan

Background

Mucosal healing (MH) has been proposed as an essential therapeutic goal for treatment of Crohn's disease (CD). Although serum amyloid A (SAA), a major acute-phase inflammatory protein, is a known clinical biomarker of CD, other non-invasive biomarkers for prediction of MH in these patients are lacking. Furthermore, the correlation of SAA in serum with endoscopic disease activity in CD has not been elucidated.

Methods

In this single-center retrospective study, conducted from June 2011 to March 2013 at Shimane University Hospital, Japan, we investigated the correlation of serum SAA level with clinical and endoscopic evidence of CD. Serum samples were obtained at the first visit during the study period and SAA level was assessed in relation to CD activity index (CDAI), defined as 151 or more active phases, as previously reported. SAA was also measured on the day or within 1 week of ileocolonoscopy procedures, with those patients scored according to a simple endoscopic score for CD (SES-CD; inactive 0-3, active >3). MH was defined as an inactive phase of SES-CD. We then assessed the correlation of serum SAA with CDAI and SES-CD findings, and the diagnostic ability of MH correlated with SAA level was evaluated using receiver operating characteristic (ROC) curve analysis.

Results

Sixty-two patients with CD (mean age 36.7 ± 8.8 years; 44 males, 18 females) were enrolled. Mean serum SAA level was significantly higher in the active (n=20, 280.6 ± 491.6 ug/dl) as compared to inactive (n=42, 23.2 ± 34.7 ug/dl) phase (p<0.001) and also significantly correlated with CDAI (Spearman's rank correlation coefficient r=0.45, p<0.001). In addition, the utility of serum SAA level for assessment of MH during the study period was investigated. Mean serum SAA level was significantly higher in the endoscopic active (254.7 ± 481.0ug/dl) as compared to the inactive (8.0 ± 5.2ug/dl) phase (p<0.001), and also significantly correlated with SES-CD (Spearman's rank correlation coefficient r=0.71, p<0.001). The area under the ROC curve for SAA level was 0.83 and the optimal cut-off value for SAA to predict MH was 6.0 ug/dl. SAA level was shown to be associated with MH, with a sensitivity of 93% specificity of 67%.

Conclusion

Our Results demonstrate that serum SAA is elevated during active CD and has a significant correlation with ileocolonoscopy findings. Furthermore, a low concentration of SAA exhibited high sensitivity for MH. Thus, SAA may be a possible biomarker for evaluating MH in CD patients.