Figure 74-1 Graphic display of cost-effectiveness of a theoretical treatment that adds additional cost but is effective in extending quality-adjusted life. A quality-adjusted life-year (QALY) is a year of life gained for which the quality of life is judged to be acceptable. The lines represent cost per QALY. Cost per QALY depends on the patient population that receives the intervention. For example, patients with low severity of illness receiving activated protein C have a much higher cost per QALY than those with higher severity of illness.