Interstitial cystitis/bladder pain syndrome (IC/BPS) and irritable bowel syndrome (IBS) are chronic pelvic pain disorders. They often coexist which might be due to “neural cross-talk”. Due to elusive etiology, the diagnosis and treatment outcome are disappointed. These patients often have physical, psychological, social and work influences, and consequently need lots of medical care. Clemens (2008) reported IC/BPS mean yearly medical expense 2.4 times higher than the age and gender controlled non- IC/BPS. The cost differences were mainly due to pharmacy and outpatient expense. In this study, we compared public health insurance reimbursement between IC/BPS and IBS in outpatient perspective to evaluate whether IC/BPS had more reimbursement than IBS.

Through data mining in 2002-2013 Longitudinal Health Insurance Database of Taiwan, we identified IC/BPS and IBS patients. There were 2 models (unmatched and matched) designed to compare outpatient reimbursement for IC/BPS and IBS. In model 1(unmatched), we compared two cohorts before matching. In model 2 (matched), IC/BPS to IBS were matched under 1:1 ratio based on index date, sex, age, income, and 22 co-morbidities (chronic diseases modified from RxRisk model) (Figure 1). Data of expense were compared with Chi-square, ANOVA and multiple linear regressions.

In model 1, IC/BPS had larger female proportion and less income level. No significant ratio difference was noted in comorbidities between two cohorts (Table 1). Before matching, IC/BPS had significantly higher visit times (2.9 vs. 2.5). Pharmacy expense revealed no significant difference. However, significant differences in yearly non-pharmacy expense, yearly total, per-visit non-pharmacy expense and per-visit total claims were noted (Table 2). In model 2, IC/BPS and IBS were matched nearly identically (Table 4). There were significant differences in yearly total non-pharmacy, yearly total, per-visit pharmacy, per-visit non-pharmacy and per-visit total claims, except total visit times and yearly total pharmacy claim (Table 5) . From regression analysis, both models revealed the medical expenses of IC/BPS to IBS were significantly higher in yearly total, yearly non-pharmacy, per-visit non-pharmacy and per-visit total claims. The yearly total pharmacy claim in both models, per-visit pharmacy claim in model 1 and visit times in model 2, all revealed no significant difference (Table 3 and Table 6).

In unmatched model, the larger female proportion and lower income in IC/BPS were compatible with clinical scenario. Patient characteristics of these two cohorts showed no significant difference in ratio of comorbidities. It probably reflected “neural cross-talk” between these 2 patient groups. More IC/BPS outpatient visits might be the result of larger proportion of female gender and easy accessibility to health care with low co-payment in Taiwan. As compared model 1 to model 2, the pharmacy cost per-visit had different significant result. It might be the result of more outpatient visits in matched IBS as compared to unmatched group. It echoed the larger female proportion would increase the medical utilization and resulted in higher visit times. Many studies illustrated IC/BPS had more medical cost than non-IC/BPS patients. Our results demonstrated the outpatient reimbursements of IC/BPS were higher than IBS, mostly from non-pharmacy expense. This might be due to the necessity of non-pharmacy intervention for treatment, including urodynamic survey and cystoscopic interventions such as coagulation or hydrodistension.

IC/BPS has significantly different higher proportion of female and lower income. The outpatient reimbursement for IC/BPS was significant higher than IBS, mainly on the non-pharmacy expenditure. It might be due to IC/BPS patients need more urodynamic survey and cystoscopic interventions. The etiology of IC/BPS and IBS has been considered multifactorial, and it makes diagnosis and efficient treatment difficult. Because of disease chronicity, the expenditure for IC/PBS patient care will increase as time go on. Paying more attention to the disease research and treatment development is encouraged.

Lee MH, Chang KM, Tsai WC. Morbidity rate and medical utilization in interstitial cystitis/painful bladder syndrome. Int Urogynecol J. 2018 Mar 12. doi: 10.1007/s00192-018-3574-x.