Any chronic disease is a risk situation for non-adherence to treatment. This results in suboptimal medication, and poor disease control. Adherence and compliance are directly related to therapeutic success, which is further complicated in inflammatory bowel disease patients.

There is a wide array of circumstances that increase the likelihood of non-compliance in a given patient: difficult-to-follow treatment schedules (multiple doses and multiple drugs), insufficient patient information, longer evolution of the disease and inactive disease. Depression, male gender, active employment and living alone are also associated with poorer adherence to therapy.

Monitoring drug intake is possible in many circumstances, directly or indirectly (urinary salicylate levels; erythrocyte metabolites and increased mean corpuscular volume and bilirubin in patients under azathioprine; blood levels of ciclosporin or tacrolimus). However, such measures are probably better utilized for dose adjustment and not for the identification of non-compliant patients. High-risk patients are a target group in which pre-emptive intervention could ensure better compliance.

If the question of non-adherence arises, for instance, as a possible cause of therapy failure, the patient should be carefully approached. This should take into consideration factors that may be corrected and, most importantly, should aim at building a better patient–doctor relationship.