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The National Academy of Medicine (NAM, formerly the Institute of Medicine, IOM) defines quality of care as “the degree to which health services for individuals and populations increase the likelihood of desired health outcomes and are consistent with current professional knowledge.” In its seminal 2001 report, Crossing the Quality Chasm, the NAM advanced six aims for a quality healthcare system (Table 3-1): patient safety, patient-centeredness, effectiveness, efficiency, timeliness, and equity.1 Note that this framework depicts safety as one of these six components, in essence making it a subset of quality. Note also that, though many clinicians tend to think of quality as being synonymous with the delivery of evidence-based care, the NAM's definition is much broader and includes matters that are of particular importance to patients (patient-centeredness and timeliness) and to society (equity).
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Although the NAM makes clear that quality is more than the provision of care supported by science, evidence-based medicine does provide the foundation for much of quality measurement and improvement. For many decades, the particular practice style of a senior clinician or a prestigious medical center determined the standard of care, and variation in treatment approach for the same condition was widespread. Without discounting the value of experience and mature clinical judgment, the modern paradigm for identifying optimal practice has changed, driven by the explosion in clinical research over the past two generations (the number of randomized clinical trials has grown from less than 500 per year in 1970 to almost 25,000 per year in 2015). This research has helped define “best practices” in many areas of medicine, ranging from preventive strategies for a 64-year-old woman with diabetes to the treatment of the patient with acute myocardial infarction and cardiogenic shock.
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Health services researcher Avedis Donabedian's taxonomy is widely used for measuring the quality of care. “Donabedian's Triad” divides quality measures into structure (how is care organized), process (what was done), and outcomes (what happened to the patient).2 When used to assess the quality of care, each element of this framework has important advantages and disadvantages3 (Table 3-2). The growth in clinical research has established the link between certain processes of care and improved health outcomes; because of this, process measures have frequently been used as proxies for quality. Examples include measuring whether hospitalized patients with pneumonia received influenza and pneumococcal vaccinations, ...