The conceptualization of health.

The meaning of health is complex and subject to change. In this article, four conceptual models of health are presented to summarize the current meanings for health. The medical model is the most widely used definition in the United States, but the World Health Organization model has gained in popularity during the past several decades. In addition, there are other newer models--the wellness model and the environmental model--that are adding new meanings to the definition of health. By understanding and combining these different meanings, the prospects for improving medical outcomes and the quality of care are enhanced. This conceptual work is a prelude to improving health status assessment in a variety of contexts.