Background: Ulcerative colitis (UC) can be maintained in remission with 5-aminosalicylic acid (5-ASA) medications, but frequent non-adherence by patients who are feeling well has been associated with more frequent flares of colitis.
Aim: To perform a systematic review of the published literature and unpublished randomized clinical trials (RCTs) regarding the impact of non-adherence with 5-ASA medications on the incidence of UC flares and costs of care.
Methods: A search of MEDLINE, EMBASE and the Cochrane databases was performed. Prospective studies of UC maintenance with 5-ASAs in adults were selected if they included data on adherence and disease flares. Studies using insurance claims data to estimate the impact of non-adherence on cost of care were included. Data from unpublished RCTs were obtained from the FDA with a request under the Freedom of Information Act.
Results: The relative risk for flare in non-adherent vs. adherent patients ranged from 3.65 to infinity. Data were obtained from six unpublished 5-ASA RCTs, but none measured the impact of adherence on disease activity. The comorbidity-adjusted annual costs of care in adherent patients were 12.5% less than in non-adherent patients, despite increased medication expenditures.
Conclusions: A substantial proportion of UC flares and medical costs of UC are attributable to 5-ASA non-adherence. As non-adherence to 5-ASA medications is common, cost-effective strategies to improve adherence are needed. The impact of adherence on disease activity should be measured in RCTs of all inflammatory bowel disease treatments.