title: Medication non-adherence is associated with increased medical health care costs.
abstract: OBJECTIVE
  Non-adherence to 5-aminosalicylic acid (5-ASA) is associated with adverse outcomes; however, no data exist regarding cost and non-adherence. Our aim was to determine the association between adherence to maintenance therapy and healthcare costs.
  
  
  METHODS
  Patients in the Maryland CareFirst BlueCross BlueShield program with a follow-up of more than 1 month who had been prescribed at least one 5-ASA preparation during the period 1 January 2002 to 31 December 2004 were included. Non-adherence was defined as failure to refill a prescription claim, and a medication possession ratio was calculated. Generalized linear models were built to determine the association between annual average cost per patient.
  
  
  RESULTS
  A total of 4313 patients were included, although only 57% were adherent with their index medication. The mean medication possession ratio ranged from 72% for Azulfidine to 82% for generic sulfasalazine. A twofold difference in gastroenterology-related inpatient cost in non-adherent versus adherent patients (22.8% vs 11.7%, P < 0.01) was observed. Non-adherence also incurred more costs for outpatient services and office visits. In multivariate analysis, patients who were persistent with their medications incurred 12.5% lower medical costs (P = 0.03).
  
  
  CONCLUSIONS
  Adherence remains low over time. Non-adherence was associated with higher health care costs for both in- and outpatient settings. Patients need educated regarding non-adherence and increased costs.
authors.affiliation: Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA. kane.sunanda@mayo.edu
authors.forename: Sunanda
authors.initials: S
authors.lastname: Kane
authors.forename: Fadia
authors.initials: F
authors.lastname: Shaya
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D015331:Cohort Studies; D003093:Colitis, Ulcerative / Q000191:economics / Q000523:psychology / Q000628:therapy*; D005260:Female; D005765:Gastrointestinal Agents / Q000627:therapeutic use*; D017048:Health Care Costs; D006801:Humans; D008297:Male; D008396:Maryland; D008875:Middle Aged; D010349:Patient Compliance; D012189:Retrospective Studies; D016312:Treatment Refusal
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D005765:Gastrointestinal Agents