Life-sustaining therapy. A model for appropriate use.

New strategies are needed to curb the proliferation of life-sustaining therapies that rarely benefit patients. We propose a model for appropriate use of such therapies that incorporates effectiveness, utility, and marginal costs. If a therapy is rarely effective and rarely desirable, it is considered medically inappropriate. If the marginal cost-effectiveness ratio is inordinately high, it is considered economically inappropriate. If a therapy is either medically or economically inappropriate, it should not be automatically offered. The model provides an operational definition of futility and is illustrated with an analysis of out-of-hospital cardiopulmonary resuscitation for chronically ill older people. Advance directives, explicit health care rationing, and defining futile therapy based on survival predictions are alternatives to the appropriate care model, but are insufficient strategies to solve the problem of inappropriate life-sustaining care.