Temporal Relationship between Endometriosis and Overactive: A Nationwide Population-Based Cohort Study in Taiwan

Purpose: Both Endometriosis and Over Active Bladder (OAB) are linked with chronic inflammation. We hypothesized that these two diseases may have a temporal relationship due to shared features of chronic inflammation. Methods: A 1:5 matched case-control study using a National Health Insurance Research Databases (NHIRDs) in Taiwan was conducted to investigation whether endometriosis and overactive bladder is positively associated. Two cohorts were constructed (patients with endometriosis (case cohort, n = 5,421) and those without endometriosis (control cohort, n = 27,105) was compared with respect to development of overactive bladder. Results: The Kaplan-Meier survival curves demonstrate significantly higher occurrence of OAB in the case cohort than in the control cohort (p = 0.001, logrank test). Moreover, the incidence density was also higher in the case cohort (2.58 per 1,000 patient-years) than in the control cohort (0.83 per 1,000 patientyears). At the end of one-year follow-up, the results show that the case cohort harbors the highest hazard ratio with 8.82-fold [95% Confidence Interval (CI): 4.10-18.99] higher than the control cohort. The hazard ratios decreased with longer period of follow-up, with 3.97 (95% CI: 2.66-5.93) at the end of thirdyear follow-up, and 2.82 (95% CI: 2.09-3.82) at the end of five-year follow-up, respectively. Conclusions: In conclusion, our data reveal that endometriosis confers higher risk of developing OAB, and this temporal relationship is potentially linked through shared features of chronic inflammation. Chronic inflammation has been demonstrated to play a critical role in the manipulation of a diverse spectrum of disorders, from chronic inflammatory disease to cancer.