from analysis. Results: In total, 1377 filled out the questionnaires and 1028 subjects wereincluded in the analysis after applying the exclusion criteria. 311 (30%) subjects sufferedfrom IGE. 15.6% of these subjects developed PI-IBS after 1 year compared to 6.5% in theexposed group who did not develop IGE during the outbreak (OR 2.6; 95% CI 1.4-1.7; p=0.001). The degree of tap water exposure was associated with an increased risk to developIGE, but was not associated with the risk to develop PI-IBS or PI-FD. Severe abdominalcramps and more than 7 days of diarrhea, younger age and increased anxiety/somatizationwere associated with an increased risk to develop PI-IBS in univariate analysis (p ,0.05,table). Inclusion of these parameters in a multivariate logistic regression model identifiedthe duration of diarrhea during IGE (OR 4.8, p=0.023), younger age (OR 0.94, p=0.003)and increased somatization (OR 1.3, p,0.001) as independent risk factors. After one year,FD had developed in 19% of subjects with IGE and in 12% of exposed subjects withoutIGE (OR 1.8; 95% 1.1-3.1 CI, p=0.030). At univariate analysis younger age and somatizationhad a significant association with PI-FD (p ,0.05, table). Both factors were identified asindependent risk factor in the multivariate logistic regression model (age OR 0.91, p=0.002;somatization OR 1.2, p=0.012). Conclusion: Our data confirm that an episode of acutegastroenteritis due to contaminated drinking water is associated with an increased risk todevelop IBS or FD. Somatization, but not anxiety or depression, and younger age wereidentified as independent risk factors for both PI-IBS and PI-FD.Table: subject characteristics in univariate analysis

* p,0,05 and included in multivariate analysis § non significant p-value, included inmultivariate analysis

Su2032

Irritable Bowel Syndrome in the West Bank, Palestine: Its Prevalence andAffect of Location of ResidenceBashar J. Qumseya, Yasin Tayem, Cristina Almansa, Osma Dasa, Kenneth R. DeVault,Michael B. Wallace, Lesley A. Houghton

Background: Irritable bowel syndrome (IBS) affects between 10-20% of Western populations.Life stress and trauma may predispose to IBS. Limited, or often no studies in Non-Westerncountries, such as the Middle East, have been carried out. A study in Palestine offers theopportunity to evaluate the prevalence of these disorders in an ethnically homogeneousArabic society under chronic stress and also investigate whether this varies depending onlocation of residence. Aims: To determine the prevalence of IBS and its sub-types in theWest Bank, Palestine and assess whether living in urban vs. non-urban environment influencesthis. Methods: This was a national, cross-sectional study of Palestinian adults in the WestBank, Palestine. Participants were randomly selected from all districts of the West Bank,including cities, rural areas, and refugee camps and completed the Rome III IBS questionnairealong with demographic data. The questionnaire was translated into Arabic by two bilingualphysicians and validated in a cohort of 50 Palestinians. Participants were interviewed inperson by trained fieldworkers. The primary outcome was the prevalence of IBS reportedas a proportion with 95% confidence intervals (used to infer results on a population level).A multivariable logistic regression model was used to assess the difference in IBS prevalencebased on locality of residence while controlling for potential confounders. Results: 1601people were approached for interview, of which 1352 agreed to participate (response rate84%). 715 (53%) agreed to participate from urban areas, 455 (34%) from rural areas, and182 (13%) from refugee camps. Baseline demographics for the participants are summarizedin Table 1. The prevalence of IBS was 30% [28% - 33%]. Of poeple who had met criteriafor IBS, 21% (85) had IBS with diarrhea, 18% (73) IBS with constipation, 55% (224) hadmixed IBS, and 6% (24) were un-subtyped IBS. In univariate analysis, IBS prevalence was

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higher in non-urban areas (34%) compared with urban areas (27%), p=0.004. There wasno difference in the distribution of IBS subtypes between the two groups (Table 2). In amultivariable logistic regression analysis, residence in urban areas (OR 0.68 [0.54 - 0.87],p =0.0024) was associated with a decreased odds of developing IBS when controlling forage, gender, education, health insurance, number of people per room in household, andemployment status. As expected females had higher odds of having IBS (OR 1.65 [1.28 -2.12], p , 0.0001) when controlling for the above confounders. Conclusions: The prevalenceof IBS in the West Bank, Palestine is somewhat higher than in Western populations, andhigher in individuals residing in non-urban areas (villages or refugee camps) compared withurban areas. Further research addressing the effect of psychopathology, stress, trauma andsanitation is required.

Su2033

Determining the Minimum Duration for Initial Treatment With Linaclotide inIBS-C Patients: Results From Pooled Phase 3 TrialsWilliam D. Chey, Bernard J. Lavins, Steven J. Shiff, James E. MacDougall, Caroline B.Kurtz, Kelvin Shi, Mark G. Currie, Jeffrey M. Johnston

Introduction: Linaclotide is a minimally absorbed guanylate cyclase-C agonist approved forthe treatment of irritable bowel syndrome with constipation (IBS-C) in the United States.A key question for prescribing physicians will be whether to continue linaclotide treatmentin patients who do not experience improvement within 4 weeks of initiating therapy. Aim:To assess whether the response to linaclotide treatment at Week 4 is predictive of responseat Week 12 and to determine whether linaclotide treatment should be continued in IBS-Cpatients who do not respond during the initial 4 weeks of treatment. Methods: Data from2 randomized, double-blind Phase 3 trials of linaclotide in IBS-C were pooled for thisanalysis. For 3 clinical response parameters (Degree of Relief of IBS Symptoms, Degree ofRelief of Abdominal Pain, and Spontaneous Bowel Movement [SBM] frequency), a patient'sclinical status at Week 4 was used to predict improvement at Week 12. For the purposesof determining a patient's Week 4 status, the 7-point balanced scale for Degree of Reliefwas collapsed into 3 categories: Improved (completely, considerably, or somewhat relieved),Unchanged, and Worse (somewhat worse, considerably worse, or as bad as I can imagine)compared with before the trial started. For SBMs, a dichotomous end point was used: SBMsincreased by ≥2/week or SBMs not increased by ≥2/week (from the 2-week pretreatmentbaseline). Results: At Week 4, the proportion of patients who were improved was statisticallysignificantly greater for linaclotide- vs placebo-treated patients: 72% vs 47% for Degree ofRelief of IBS Symptoms, 70% vs 47% for Degree of Relief of Abdominal Pain, and 59% vs33% for SBMs (P,.0001 for all comparisons). For all parameters, most linaclotide-treatedpatients (≥70%) who had improvement at Week 4 were also improved at Week 12 (Table).For linaclotide-treated patients whose symptoms were unchanged at Week 4 for Degree ofRelief of IBS Symptoms and Degree of Relief of Abdominal Pain, 36% and 39%were improvedat Week 12 (P,.05 vs placebo). For SBMs, 30% of linaclotide-treated patients without anincrease in SBMs ≥2 at Week 4 were improved (SBMs ≥2) at Week 12 (P,.05 vs placebo).Conclusions: Patients whose IBS symptoms improved with linaclotide treatment after 4weeks were likely to maintain improvement through 12 weeks. At least 30% of patientswho did not improve in the first 4 weeks of treatment experienced symptom improvementby Week 12. The statistically significant differences between linaclotide and placebo in thepercentage of patients improved at Week 12 who were "Unchanged" at Week 4 indicatesthat, for some patients, more than 1month of linaclotide therapy is required for improvement.As such, an initial course of linaclotide therapy in an IBS-C patient should be a minimumof 4 weeks.Table. Improvement at Week 12 by Week 4 Symptom Status

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