Economic burden of irritable bowel syndrome with constipation: a retrospective analysis of health care costs in a commercially insured population

The prevalence of irritable bowel syndrome with constipation (IBS-C) is estimated to be between 4.3% and 5.2% among adults in the United States. Little is known about the health care resource utilization and costs associated with IBS-C. To (a) evaluate the annual total all-cause, gastrointestinal (GI)-related, and IBS-C-related health care costs among IBS-C patients seeking medical care in a commercially insured population and (b) estimate the incremental all-cause health care costs among IBS-C patients relative to matched controls. Patients aged ≥ 18 years with continuous medical and pharmacy benefit eligibility in 2010 were identified from the HealthCore Integrated Research Database, which consists of administrative claims from 14 geographically dispersed U.S. health plans representing 45 million lives. IBS-C patients were defined as those with ≥ 1 medical claim with an ICD-9-CM diagnosis code in any position for IBS (ICD-9-CM 564.1x) and either ≥ 2 medical claims for constipation (ICD-9-CM 564.0x) on different service dates or ≥ 1 medical claim for constipation plus ≥ 1 pharmacy claim for a constipation-related prescription on different dates of service during the study period. Controls were defined as patients without any medical claims for IBS, constipation, abdominal pain, or bloating or pharmacy claims for constipation-related prescriptions. Controls were randomly selected and matched with IBS-C patients in a 1:1 ratio based on age (± 4 years), gender, health plan region, and health plan type. Patients with diagnoses or prescriptions suggesting mixed IBS, IBS with diarrhea, chronic diarrhea, or drug-induced constipation were excluded. Total health care costs in 2010 U.S. dollars were defined as the sum of health plan and patient paid costs for prescriptions and medical services, including inpatient visits, emergency room (ER) visits, physician office visits, and other outpatient services. The total cost approach was used to assess total all-cause or disease-specific health care costs for patients with IBS-C, while the incremental cost approach was used to examine the excess all-cause costs of IBS-C by comparing IBS-C patients with matched controls. Generalized linear models with bootstrapping were used to assess the incremental all-cause costs attributable solely to IBS-C after adjusting for demographics, Elixhauser Comorbidity Index (ECI) score, and other general and GI-related comorbidities not included in the ECI score. A total of 7,652 patients