[The problems of compliance and adherence, using the example of chronic inflammatory bowel disease].

To what extent do patients comply with their doctor's treatment recommendation, i.e. show "compliance" and "adherence" ?. The treatment of chronic diseases in particular is associated with enormous problems of adherence. Patients often take only 40 to 80% of their prescribed dosage of medication. This issue affects not only the course of the disease in the particular patient, but also has considerable impact on the health care system. Great difficulties still exist in recognizing poor adherence, because doctors depend on the information given by their patients. The reasons for adherence problems can be attributed to disease-related, treatment-related or patient-related factors, as well as to the quality of the doctor-patient relationship. Improving adherence is difficult due to its numerous and individually different causes. This has been emphasized by a recent Cochrane review, in which only 5 out of 21 randomized and controlled studies concerning the improvement of adherence demonstrated significant success. However, half of the studies displayed methodological errors that weakened the statistical detection of improvement because of the low numbers patients. Overall, enormous efforts will be required of doctors, patients and health care policies to achieve substantial alterations in the problems associated with adherence.