Optimal and logical quality: two neglected aspects of the quality of health services.

Many current quality assurance programs aim at maximizing the quality of health services instead of optimizing it, because they rest on the erroneous "best to all" approach, which overemphasizes the scientific and technical aspects of quality. The result is prohibitively expensive "Cadillac care." It is suggested that the optimal qualitative level can be identified by answering a chain of hierarchical questions beginning with the relevance of medical care to the solution of the problem at hand and ending with such detailed questions as what diagnostic procedures should be performed by whom, and with what technique. Using the functional definition of quality applied in industrial quality control, a mathematical model is developed to illustrate the relative nature of the concept of quality and its implications for quality assurance programs. Special attention is paid to logical quality, i.e., the efficacy with which information is used in arriving at decisions.