The Development of Irritable Bowel Syndrome: A Prospective Community-Based Cohort Study.

Objectives: It remains controversial whether psychosocial burden is an independent predictor of irritable bowel syndrome (IBS) or occurs concurrently as an epiphenomenon. Here we prospectively examine the individual contribution of psychosocial risk factors, demographic factors, somatic symptoms, and gastrointestinal infection within a non-clinical, IBS-free population before infection occurred.

Methods: A prospective community-based cohort study including a consecutive sample of healthy participants with an elevated risk of developing gastrointestinal infection during long-distance travel was conducted. Potential predictive factors were investigated using validated self-report scales pre-travel, 1 week after return, and 7 months post-travel. IBS was assessed using the ROME-III Diagnostic Questionnaire.

Results: Of the 1,964 eligible long-distance travelers, 1,464 responded at follow-up directly after their journey, and 1,190 participants completed the study 7 months post-journey. Fifty-three percent of study completers were female, mean age was 39.9 (s.d.=15.7) years. The mean travel duration was 40.8 (s.d.=52.8) days, and 43.3% (95% confidence interval (CI)=40.4-46.1%) of participants experienced at least moderate infectious travelers' diarrhea. The incidence of newly developed IBS 7 months post-travel was 7.2% (95%CI=5.8-8.6%). In multivariate analyses, female gender, vulnerability to diarrhea under stress, baseline somatic symptom burden, baseline illness anxiety, diarrhea within the 4 months pre-travel, and travelers' diarrhea during the journey significantly predicted IBS post-travel.

Conclusion: This study indicates that gastrointestinal infection as well as predisposing factors such as female gender, vulnerability to diarrhea under stress, illness anxiety, and somatic symptom burden predict the development of IBS. The results indicate the necessity of simultaneously addressing both somatic and psychological needs in patients with IBS as early as possible.