Overview of partial compliance.

A substantial proportion of patients with psychiatric and nonpsychiatric chronic illnesses fail to take their medications as prescribed. A number of studies suggest that 50% or more of individuals with schizophrenia are noncompliant with medications at some time during their illness. In most cases, patients are partially compliant, taking only a portion of their prescribed medications. Noncompliance is probably the most important element contributing to relapse in schizophrenia. Factors contributing to the rate of noncompliance include medication side effects, the severity of psychotic symptoms, impaired cognition, and an inadequate understanding of the role of medication for preventing relapse. In addition, both patients and clinicians overestimate patients' compliance. Strategies for managing partial compliance include the treatment of medication side effects, the education of patients about their illness, and the use of long-acting antipsychotic formulations.