Commentary on some studies on the quality of care.

This essay is a personal commentary on general aspects of quality assessment that are either illustrated or challenged by the articles presented in this volume. It is not a critique of the individual papers in the collection; papers are mentioned in order to illustrate or clarify a point, without implication of either merit or demerit. This article addresses the definitions of quality, the relationship of cost to quality, approaches to assessing quality, the use of case fatality as an indicator of quality, measures of post-hospital morbidity, case-mix adjustment, sources of information, selection of referents, criteria and standards, quality assurance, the role of consumers, the prevalence of quality, the effects of prospective payment, and a research agenda.