ABSTRACT
Although attention has been given to identifying and intervening on poor adherence to treatment regimen for more than 35 years, the problem remains a signifi cant one in health care. In an environment struggling to contain health care costs, billions of dollars are wasted treating the consequences of poor adherence. This chapter will address the impact of poor adherence on health care costs as well as on clinical outcomes and will update information on the magnitude of the problem as well as the efforts to predict, remediate, or prevent it. The confounding infl uence of multiple defi nitions and measurement methods will also be addressed.
