title: A systematic review of the economic and humanistic burden of illness in irritable bowel syndrome and chronic constipation.
abstract: BACKGROUND
  Irritable bowel syndrome (IBS) and chronic constipation (CC) are common functional gastrointestinal disorders affecting 14% and 20% of the U.S. population, respectively. Reviews of the evidence on the burden of illness associated with IBS and CC have not been comprehensive in scope and have not provided an assessment of the distribution of health care costs across categories of resource use.
  
  
  OBJECTIVE
  To (a) identify studies from any geographic region or country perspective that measure the economic burden of the disease; (b) analyze the direct (medical, drug, and other components) and indirect costs of illness; and (c) assess published evidence of the humanistic burden as measured by quality of life (QOL).
  
  
  METHODS
  An electronic literature search was conducted using journal databases, including MEDLINE, The Cochrane Library, EconLit, CINAHL, and Digestive Disease Week meeting abstracts. Specific search terms used were "irritable bowel syndrome" and "chronic constipation." In databases that accommodated Boolean searches, terms related to economic and quality of life outcomes were incorporated. Studies were included if they evaluated patients with an IBS or CC diagnosis and quantitatively measured the economic or humanistic burden of disease. Results were descriptively analyzed.
  
  
  RESULTS
  The search identified a total of 882 unique publications. Thirty-five articles and abstracts met the inclusion criteria. Studies included 1,706 IBS-C, 2,264 IBS-D, 2,892 IBS-A, 15,830 IBS unclassified, and 1,278 CC patients. Nineteen of 35 studies assessed cost-of-illness endpoints, and from the U.S. perspective, the direct cost per-patient for IBS ranged from $1,562 to $7,547 per year, while direct costs of CC ranged from $1,912 to $7,522 per year. From the U.S. perspective, the indirect costs of IBS ranged from $791 to $7,737 per year, and no study assessed the indirect costs of CC. For IBS, data on the distribution of costs attributable to categories of resource use varied widely, particularly outpatient costs (12.7% to > 50% of total costs), inpatient costs (6.2% to 40.8%), and pharmacy or drug costs (5.9% to 46.6%). Comparable data on CC were not identified. Nineteen studies of IBS patients measured the humanistic burden of disease; 14 studies utilized SF-36; and within-study domain scores were significantly lower in IBS patients compared with non-IBS controls. Only 1 study of CC patients reported humanistic burden of disease.
  
  
  CONCLUSIONS
  The studies identified in the systematic review varied in the method used to identify patients with IBS and CC. Results were not typically reported by IBS subtype. We observed a large variation in attributable direct and indirect costs and drivers of these costs. Future research should refine burden of illness estimates to subtypes so that estimates associated with IBS-C and CC are differentiated.
authors.affiliation: 1010 El Camino Real, Ste. 310, Menlo Park, CA 94025, USA. dnellesen@analysisgroup.com.
authors.forename: Dave
authors.initials: D
authors.lastname: Nellesen
authors.forename: Kimberly
authors.initials: K
authors.lastname: Yee
authors.forename: Anita
authors.initials: A
authors.lastname: Chawla
authors.forename: Barbara Edelman
authors.initials: BE
authors.lastname: Lewis
authors.forename: Robyn T
authors.initials: RT
authors.lastname: Carson
mesh_terms: D002908:Chronic Disease; D003248:Constipation / Q000175:diagnosis / Q000191:economics* / Q000453:epidemiology*; D017281:Cost of Illness; D017048:Health Care Costs / Q000639:trends; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000175:diagnosis / Q000191:economics* / Q000453:epidemiology*