Predictive Factors for the Diagnosis of Irritable Bowel Syndrome in a Large Cohort of 440,822 Young Adults

Background: The prevalence of irritable bowel syndrome (IBS) in the community has been reported in numerous cross-sectional surveys. However, little is known about the incidence and predictive factors for the clinical diagnosis of IBS. Methods: We examined the association of socioeconomic, anthropometric, and occupational factors with the incidence of IBS in a cohort of 440,822 young Israeli adults aged 18 to 39 who served in active military service during the years 2005 to 2011. Results: During the follow-up of 1,925,003 person-years, IBS was diagnosed de novo in 976 patients, giving an incidence rate of 221:100,000 (0.2%) person-years for the diagnosis of IBS. On multivariable Cox analysis, higher socioeconomic status [hazard ratio (HR) 1.629; 95% confidence interval (CI), 1.328-1.999; P < 0.0001], Israeli birth (HR 1.362; 95% CI, 1.084-1.712; P = 0.008), Jewish ethnicity (HR 2.089; 95% CI, 1.344-3.248; P = 0.001), education Zthan 11 years (HR 1.674; 95% CI, 1.019-2.751; P = 0.042), and a noncombat military position (HR 1.196; 95% CI, 1.024-1.397; P = 0.024) were found to be risk factors for the diagnosis or for the worsening of IBS. Overweight (HR 0.744; 95% CI, 0.589-0.941; P = 0.014), obesity (HR 0.698; 95% CI, 0.510-0.95; P = 0.025), living in a rural settlement (HR 0.705; 95% CI, 0.561-0.886; P = 0.003), and Middle Eastern (HR 0.739; 95% CI, 0.617-0.884; P = 0.001,) or North African and Ethiopian origin (HR 0.702; 95% CI, 0.585-0.842; P < 0.001) were found to be protective for the diagnosis or the worsening of IBS. Conclusions: This study provides novel data on the socioeconomic, anthropometric, and occupational factors predictive for IBS development. The predictive factors for IBS diagnosis may point to the fact that stress had a lower impact on IBS incidence in our study cohort.