title: Characterizing Health Care Utilization, Direct Costs, and Comorbidities Associated with Interstitial Cystitis: A Retrospective Claims Analysis.
abstract: BACKGROUND
  Interstitial cystitis (IC) is a debilitating condition that affects up to 5% of the U.S.
  
  
  METHODS
  This condition is characterized by bladder pain, urinary urgency and frequency, nocturia, and, in some patients, bladder lesions called Hunner's lesions (HL). IC patients who have HL experience a clinical course that is distinct from those without HL and, as a result, respond differently to existing treatments. Without effective and lasting therapeutic options, IC patients are expected to experience a reduced quality of life and be a significant economic burden. Previous research describing the burden of IC is not only outdated but lacks stratification by HL.
  
  
  OBJECTIVE
  To (a) characterize health care utilization, direct costs, and comorbidities associated with IC and (b) elucidate differences between patients with and without HL.
  
  
  METHODS
  A retrospective analysis was conducted using health care claims from the Truven Health MarketScan Research Databases. Adults with an incident IC diagnosis between 2009 and 2014 were identified and matched 1:4 to non-IC patients on age, gender, and geographic region. Health care utilization, direct costs, and comorbidities during the first 12 months after diagnosis were compared between the 2 groups, as well as between IC subgroups with and without HL. Associations were evaluated after adjustment for potential confounders using regression models.
  
  
  RESULTS
  A total of 24,836 IC patients were identified and matched to 99,344 non-IC patients. Patients were predominantly female (92%), with a mean age of 49.0 (SD = 15.3) years. IC patients used significantly more health care resources across all categories compared with non-IC patients. On average, having IC was associated with $7,223 higher total health care costs than not having IC (95% CI = $6,650-$7,796), with outpatient costs contributing to 71% of the difference, after adjusting for baseline age, gender, region, insurance type, plan type, and Charlson Comorbidity Index (CCI) score. The odds of developing select comorbidities were 2.61 times greater in IC patients compared with non-IC patients (95% CI = 2.52-2.70), adjusting for baseline age, sex, region, and CCI score. Among IC patients, the HL subgroup (n = 292) used more health care resources, and having HL was associated with $6,895 higher total health care costs compared with not having HL (95% CI = $3,770-$10,020) after adjusting for baseline age, gender, region, insurance type, and plan type.
  
  
  CONCLUSIONS
  Findings suggest that patients with IC have significantly higher health care utilization, costs, and comorbidities compared with non-IC patients. This economic burden is further amplified in those with HL.
  
  
  BACKGROUND
  Funding for this study was contributed by Allergan. Tung was supported by a training grant from Allergan at the time of this study. Hepp was an Allergan employee at the time this study was conducted. The other authors have nothing to disclose. This research was previously presented, in part, as a poster presentation at the International Society for Pharmacoeconomics and Outcomes Research 21st Annual International Meeting; Washington, DC; May 23, 2016. Study concept and design were primarily contributed by Hepp, along with Tung and Devine. Tung took the lead in data collection, with assistance from Hepp, and data interpretation was performed by Tung, along with Bansal and Devine. The manuscript was prepared primarily by Tung, along with Devine, Bansal, and Hepp.
authors.affiliation: 1 Pharmaceutical Outcomes Research and Policy Program, University of Washington, Seattle.
authors.forename: Amy
authors.initials: A
authors.lastname: Tung
authors.affiliation: 2 Allergan, Irvine, California.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Hepp
authors.affiliation: 1 Pharmaceutical Outcomes Research and Policy Program, University of Washington, Seattle.
authors.forename: Aasthaa
authors.initials: A
authors.lastname: Bansal
authors.affiliation: 3 Pharmaceutical Outcomes Research and Policy Program; Department of Health Services; and Department of Surgery, University of Washington, Seattle.
authors.forename: Emily Beth
authors.initials: EB
authors.lastname: Devine
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D015897:Comorbidity; D018856:Cystitis, Interstitial / Q000191:economics* / Q000453:epidemiology / Q000628:therapy; D016208:Databases, Factual; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006801:Humans; D007345:Insurance Claim Review; D008297:Male; D008875:Middle Aged; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012959:Socioeconomic Factors; D014481:United States / Q000453:epidemiology