Another way to measure process quality is to determine whether care meets evidence-based professional standards. This assessment can be done by creating a list of quality indicators describing a process of care that should (or should not) occur for a particular type of patient or clinical circumstance. Quality indicators are based on standards of care, which are found in the research literature and in statements of professional medical organizations or determined by an expert panel. The performance of physicians and health plans is assessed by calculating rates of adherence to the indicators for a sample of patients (see Chapter 6 for a discussion of quality assurance programs). Current performance can be compared to a physician's or plan's prior performance, to the performance of other physicians and plans, or to benchmarks of performance. Indicators can cover a specific condition (e.g., patients diagnosed with colon cancer who do not have metastatic disease should be offered a wide resection with anastomosis within six weeks of diagnosis), or they can be generic, covering general aspects of care regardless of condition (e.g., patients prescribed a medication should be asked about allergies to medications).
Interpersonal quality refers to whether the clinician provides care in a humane manner consistent with the patient's preferences. It includes such topics as whether the clinician supplied sufficient information for the patient to make informed choices and involved the patient in decision making. It is generally assessed using patient survey data.
Good process measures are based on research studies and supported by professional consensus. They are also flexible with respect to patient preferences. Some patients may not want what most people would consider proper care. Indicators can be constructed so that they are scored favorably if care was offered but declined. However, there has to be some recognition that a perfect score on indicators is not necessarily a feasible or even a desirable goal. For example, although chemotherapy is highly recommended after surgical resection for colon cancer involving the lymph nodes, some patients might decline treatment because they do not wish to experience its associated toxicities. Therefore, 100 percent adherence may not be a reasonable target for an indicator specifying adjuvant chemotherapy for these patients. Furthermore, such a target might also create incentives to ignore patient preferences in making treatment decisions. An alternative approach would be for an indicator to specify that chemotherapy was offered or recommended.
The best process measures are those for which there is evidence from research that better process leads to better outcomes. For example, adjuvant chemotherapy has been shown in several randomized controlled trials to improve survival after surgery for Duke's C colon cancer (NIH, 1990a); performing routine mammography identifies breast cancer at an earlier stage when it is more curable (Kerlikowske et al., 1995); perioperative chemotherapy and radiation therapy have been shown to increase survival for patients with rectal cancer (Krook et al., 1991; Moertel, 1994). Unfortunately, research has not covered all aspects of standard medical practice related to cancer (or other types of disease), so in these cases, expert consensus is used to decide which processes are important measures of quality. If there is not strong consensus supporting the value or superiority of a clinical practice, it generally is not used as a quality measure.
Several studies outside of oncology have tied process measures to outcomes. In a study of five hospitals in Los Angeles County, mortality rates were examined for patients who had coronary angiography and for whom a revascularization procedure was deemed "necessary" by explicit criteria. Those who received necessary revascularization within one year had a mortality of 9 percent, compared to 16 percent for those who did not. Those receiving "necessary" revascularization also had less chest pain at follow-up (Kravitz et al., 1995).