Introduction: Definitions, scope, and impact of nonadherence

Abstract

Nonadherence is believed to be the single greatest cause of treatment failure, resulting in substantial morbidity and mortality, much of which could have been avoided. In this chapter we review the scope of the problem of nonadherence, and discuss definitional issues including the distinctions between disease and illness; compliance, adherence, and nonadherence; and intentional and unintentional nonadherence. The multi-factorial nature of nonadherence is highlighted. Barriers inherent in the current healthcare system are then reviewed with an eye toward identifying areas where more improvement could be made.