JAMA : the journal of the American Medical Association
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Health systems play a central role in the delivery of health care, but relatively little is known about these organizations and their performance. ⋯ In 2018, health system physicians and hospitals delivered a large portion of medical services. Performance on clinical quality and patient experience measures was marginally better in systems but spending and prices were substantially higher. This was especially true for small practices. Small quality differentials combined with large price differentials suggests that health systems have not, on average, realized their potential for better care at equal or lower cost.