Kaiser Permanente Los Angeles Medical Center Los Angeles, CA
Christine Yu, MD1, David Yi, MPH2, Bechien Wu, MD, MPH1; 1Kaiser Permanente Los Angeles Medical Center, Los Angeles, CA; 2Kaiser Permanente, Pasadena, CA
Introduction: Irritable bowel syndrome (IBS) is a chronic disease characterized by abdominal pain, altered bowel habits, bloating and gas. With a rising incidence of colorectal cancer (CRC) among younger age groups, we aimed to evaluate the incidence of CRC in patients with IBS and identify key risk factors for CRC in this patient population. Methods: Retrospective cohort study using data from 2008-2018 in a diverse, community-based integrated healthcare system in Southern California. We included members over age 18 with an International Classification of Diseases 9 or 10 code for IBS. Exclusions included pregnancy and history of prior gastrointestinal disease (i.e. inflammatory bowel disease, celiac disease, etc). We collected demographic and clinical data (age, sex, race/ethnicity, marital status, body mass index (BMI). Diagnosis of CRC was identified based on internal cancer registry. We calculated the crude incidence rate of CRC. Using Chi-square and Wilcoxon Rank Sum tests, we compared demographic and clinical characteristics between patients who did and did not develop CRC during the study period. We used Cox regression analysis to calculate adjusted hazard ratios including age, sex, race/ethnicity for risk of CRC. Results: Among 41,775 IBS patients (Mean age 45.8 +/- 17.1, 73.3% female, 49.6% non-Hispanic white, 34.3% Hispanic, 7.1% non-Hispanic black, 9.1% other/unknown), we identified 152 cases of CRC during a combined follow-up period of 282,242 person-years (IR 54 per 100,000 person-years). IBS patients with CRC were predominantly female (104/152, 68.4%) with a mean age of 63.4 +/- 15.2 years as compared to those without CRC, age 45.7 +/- 17.0 (p< 0.0001). Results of univariate and multivariate analyses are presented in Table 1. Although racial/ethnic differences were observed in univariate analysis, age (age >/= 45 HR 1.1, 95% CI 1.0-1.1) and gender (female HR 0.7, 95% CI 0.5-1.0) were the only independent risk factors in multivariable analysis. An age threshold >/= 39 years had a 95% sensitivity for CRC (145/152). Discussion: CRC in patients with IBS is rare but the risk significantly increases in males and patients over age 45.
CRC: colorectal cancer; HR: hazard ratio; SD: standard deviation; BMI: body mass index; NS: not significant. * Multivariate analysis including age, gender, race/ethnicity **Age of >/= 45 used ***Reference level for multivariate analysis for race/ethnicity is ‘Non-Hispanic White’
Disclosures: Christine Yu indicated no relevant financial relationships. David Yi indicated no relevant financial relationships. Bechien Wu indicated no relevant financial relationships.