Abstract
INTRODUCTION: Evidence on the association between irritable bowel syndrome (IBS) and mortality is conflicting. In this study, we estimated the association between IBS and all-cause and cause-specific mortality in the NIH-AARP Diet and Health Study. METHODS: IBS diagnoses between 1994 and 2008 were identified from Medicare claims data, and mortality outcomes through 2019 were obtained through linkage to the National Death Index. Using multivariable Cox proportional hazards regression models, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and cause-specific mortality within partitioned follow-up time categories (>2-5, >5-8, >8-11, >11-14, >14-17, and >17 years) with adjustment for confounders, including habitual diet and proxies for personal health advocacy/healthcare access. RESULTS: Of 132,697 individuals with available data, 5,030 (3.8%) had a prevalent IBS diagnosis. During the earliest follow-up interval (>2-5 years), the risk of all-cause mortality among individuals with IBS was 25% lower compared with those without IBS (HR = 0.75, 95% CI: 0.64-0.88), in the fully adjusted model. The inverse association attenuated over time such that during the >17-year follow-up interval, individuals with IBS had only an 8% lower risk of all-cause mortality (HR = 0.92, 95% CI: 0.87-0.98). Individuals diagnosed with IBS also had a lower risk of cancer and cardiovascular disease mortality, which attenuated over time. DISCUSSION: We found time-dependent inverse associations between IBS and all-cause, cancer and cardiovascular disease mortality. Although this association seemed to be strongly confounded by personal health advocacy/healthcare access during very short follow-up, further research is needed to explore the factors contributing to these associations observed after longer follow-up.