Increased risk of bladder cancer following diagnosis with bladder pain syndrome/interstitial cystitis

Aims Interstitial cystitis/bladder pain syndrome (IC/BPS) is a prevalent disorder that may contribute to bladder cancer (BC). This cohort study set out to investigate the association between IC/BPS and BC by using a population‐based dataset. Methods The data for this study were sourced from the Taiwan National Health Insurance program. The case cohort comprised 7,562 patients with IC/BPS, and 22,686 randomly selected subjects were used as a comparison cohort. A Cox proportional hazards regression model (stratified by age group, geographic location, urbanization level, and the index year) was constructed to estimate the risk of subsequent BC following a diagnosis of IC/BPS. We also ran the analysis utilizing an alternative comparison cohort composed of patients with urinary incontinence (UI). Results In the study sample of 30,248 patients, 96 patients (0.32%) received a diagnosis of BC during the 3‐year follow‐up period; 48 (0.63% of patients with IC/BPS) were from the study cohort; and 48 (0.21% of patients without IC/BPS) were from the comparison cohort. The incidence rate of BC was 2.12 (95% CI: 1.58–2.78) per 1,000 person‐years in patients with IC/BPS and 0.70 (95% CI: 0.52–0.92) per 1,000 person‐years in comparison patients. Cox proportional analysis revealed that the adjusted HR for BC during the 3‐year follow‐up period for patients with IC/BPS was 2.95 (95% CI: 1.97–4.41) that of comparison subjects. When performing the analysis with the alternative UI comparison cohort, the adjusted HR for BC was 1.96 (95% CI: 1.14–3.39). Conclusions This investigation detected a novel association between BC and prior IC/BPS. Neurourol. Urodynam. 32: 58–62, 2013. © 2012 Wiley Periodicals, Inc.