It is a generally accepted fact that many patients are not adhering to their medication regimen as prescribed.16-19 Non-adherence can be intentional (actively choosing not to adhere) or unintentional (e.g., passively inconsistent medication-taking behavior including forgetfulness or carelessness). Determinants of non-adherence include the disease, the patient, the practitioner, the treatment regimen, economic factors, and the interaction of each of these factors.

Patient trust in the clinician and treatment as established during the office visit is important. Patients tend to be adherent if they have a good understanding of the illness and the therapy. Therefore, good communication between clinicians and patients is a major factor affecting adherence. A positive office visit, along with individualized regimens and good follow-up on the part of the clinician, improve adherence.

When an illness is serious or disabling, the patient will likely follow the therapeutic regimen. The longer the duration of treatment, the less likely it is that the patient will adhere to the regimen over time. This is especially true if symptoms are relieved before drug therapy is to be discontinued. The regimen itself may also be discouraging or confusing because of multiple drug use, scheduling of dosages, and side effects. Finally, cost may be a major contributing factor.

In children, the major reason for non-adherence is a dislike for the taste or smell of the medication. If it is frustrating to the parent/guardian to give the medication, they are more likely to skip doses or discontinue the medication with the disappearance of symptoms. If the child is attending school, the regimen should be convenient and coordinated with the school schedule. Consider recommending specific times rather than generalize.

Common causes of non-adherence in elderly patients include failure to fill prescriptions due to transportation problems and expense. Other factors include a lack of trust or confidence in the doctor or therapy and poor comprehension of the regimen. Difficulty in opening packages or swallowing pills, poor memory, visual or hearing impairment may also contribute to non-adherence. Repetition of directions with written instructions and clear labeling are helpful.