Virologic and immunologic response, clinical progression, and highly active antiretroviral therapy adherence.

A growing body of evidence suggests that a high degree of adherence is required to achieve and maintain a successful virologic response both in the short and long term. This holds true despite the definition of adherence or how it is measured. Reported differences in the degree of adherence required are likely due to differences in study design, difficulty measuring patient adherence, patient population studied, and the antiretroviral regimen studied. Virologic suppression and immunologic response often go hand in hand, but the impact of adherence on change in CD4 count tends to be delayed and, therefore, less apparent than the impact on HIV viral load. Degree of adherence has also been shown to be associated with AIDS-related morbidity, mortality, and hospitalizations.