Adherence to combination antiretroviral therapy: synthesis of the literature and clinical implications.

Adherence to combination antiretroviral therapy has a strong impact on virologic response and emergence of viral resistance. However, monitoring adherence in the clinic is difficult. What a patient says or a clinician believes about a patient's adherence may be misleading. Patients with suboptimal adherence may have reduced or undetectable viral loads. On the other hand, viral load may not decrease in patients with perfect adherence because of pretreatment resistance, poor drug metabolism, or other factors. A multidisciplinary approach involving patients, health care professionals, family, and friends may optimize adherence. This article reviews the literature on adherence to antiretroviral therapy, critiques the various adherence measures used by researchers and clinicians, and discusses the clinical implications of adherence to antiretroviral therapy.