Measuring Quality: Are We Ready To Compare the Quality of Care among Physician Groups?

Americans want high-quality health care, but they are not confident that they are getting it. Nor are Americans confident that they have valid information about the quality of their care. The public, health care purchasers, health system managers, and health policymakers are increasingly interested in getting more, and more accurate, information on the quality of care offered by different health care providers. The gap between the data they want and the data they can get may be widening as the public's expectations exceed what the health system can provide. Information on quality of care has three principal uses: to support accountability, to inform quality improvement efforts, and to guide choice. This editorial focuses on the role of quality measures in guiding choice, although the three uses are entwined at many levels. Forty-two percent of respondents to a consumer survey conducted by the Agency for Healthcare Research and Quality (AHRQ) and the Kaiser Family Foundation stated that high-quality care was their most important concern in choosing a health plan (1). This evidence that consumers and purchasers want information on quality is encouraging to people who still hope that the public will base its purchasing decisions on quality of care rather than simply cost. According to the elusive business case for quality, providers who offer superior care will have more patients and higher payments. Information about quality can improve care at several points of leverage in the health care system. Such information should be able to guide consumers' choices of health plan, hospital, nursing home, or doctor. Having the opportunity to consider data on quality should give patients and their families more confidence that they are making the right choices. Feeding information on quality of care back to clinicians and health care institutions should help them identify areas for improvement. Purchasers of health care should be able to use metrics of quality to implement the principles of value-based purchasing. The prerequisite for action is an interested, demanding public that has access to information and can make real choices, which is possible only if people have more than one plan from which to choose. The proponents of value-based purchasing argue that the opportunity to choose high-performing providers will improve health care by creating competition on the basis of quality. However, the premise of value-based purchasing is accurate measures of value. Absent these, patients may not get the best-quality physicians, and the best-quality physicians may not get the patients. The dearth of accurate quality measures is a major obstacle to value-based purchasing. A second obstacle is access to information about quality, even when such data exist. Few Americans have seen information about the quality of health care providers. In a survey published in 1997, only 27% of Americans reported ever seeing information comparing providers' quality; fewer than 15% had ever used this information (2). However, respondents thought that such information would be useful for decision making (3). Why is it that a public that wants information on the quality of its health care cannot get it, and then, when the information is available, does not often use it? We do not yet know the answer to this question. In this issue, Greenfield and colleagues present the results of a study that illustrates several ways in which one type of quality measure, comparisons of physician groups, can lead the value-based decision maker astray (4). By examining diabetes care in 29 physician practices, the authors showed that an accurate conclusion about whether endocrinologists or general internists provide better care requires adjustment for differences in case-mix. This finding would not surprise most physicians. However, at a far more subtle level, Greenfield and colleagues also found that performance measures could be misleading unless one considered the possibility that physicians gravitate toward practicing with like-minded physicians (clustering). When clustering occurs, individual patients are not entirely independent of one another, which means that more patients are required to make statistically valid comparisons between groups. Without adjustment for clustering, endocrinologists appeared to give better diabetes care. With adjustment, endocrinologists and generalists provided care of comparable quality. This study by Greenfield and colleagues prompts us to ask whether the data that compare physician groupsand, by extension, the data that compare individual physicians, hospitals, or health plansare fair to those being measured and useful to decision makers. Consumers should ask this question, but they should ask it in the form of three related questions. Do the data take into account the case-mixes of the groups' patient panels? Is the number of cases in each group large enough to accurately represent typical practice patterns? Do the performance measures reflect the possibility that patients and physicians cluster into certain types of practices? Value-based decision makers must have access to better measures of quality. Such access has not been available. However, there are now emerging several examples of purchasers who can use reports on physician performance. For example, PacifiCare's Quality Index for California includes rankings of 120 physician groups that are based on a large number of clinical and satisfaction criteria (5). Another California plan, HealthNet, has issued member satisfaction reports that are disease specific and are reported by physician group (6). So, are we ready to compare the quality of care among physician groups? The technical barriers to performance reports remain formidable. As the unit of measurement becomes smaller (an individual physician as opposed to a physician group or a hospital), the sample size challenge worsens. Leveling the playing field between practices by taking account of the types and severity of clinical problems (the case-mix challenge) is difficult. Finding quality indicators that are easy to collect during day-to-day practice represents yet another barrier. The study by Greenfield and colleagues is important because the authors overcame some of these serious methodologic barriers to making fair comparisons of physician groups. In addition, this study points the way to lasting success in providing the public with the information it wants and deserves. As providers and the public become more comfortable with these measures and their fairness, we will probably see them being used not just by purchasers who want to make value-based decisions but also by providers who want to improve the care in their practice; demonstrate that they give excellent care; and provide the public with the accountability and informed, value-based choice that it wants. The emerging demand for comparisons of practices according to the quality of care they provide is gradually leading to better measures and methodologic advances in using the data. These advances are beginning to show up in the form of high-quality data that more closely fit the desires of purchasers, patients, and providers. We are getting close to a historic moment when we can set in motion the upward spiral that can occur when there is a business case for quality.