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Quality of care has been defined by the Institute of Medicine (IOM) 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 IOM 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 IOM'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 IOM 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 (this tradition is now sometimes called “eminence-based medicine,” with more than a hint of derision). 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 20,000 per year in 2010). 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 the Triad has important advantages and disadvantages3 (Table 3-2). In recent years, as clinical research has established the link between certain processes and improved outcomes, process measures have often been used as proxies for quality. Examples include measuring whether hospitalized patients with pneumonia received influenza and pneumococcal vaccinations, and measuring glycosylated hemoglobin (hemoglobin A1c) at appropriate intervals in outpatients with ...