The single most powerful standard of care measurement today is customary care. “Customary care” is that care which would customarily be given by other physicians under the same or similar circumstances. Customary care standards are meant to be empirical; they come from doctors asking a significant sample of their peers what they would do if they were faced with the same set of circumstances. In the best light, customary care or “eminence-based medicine,” is a collaborative effort to create the care standard through collective evaluation of actual practices.
The concept of customary care as a measurement for quality originated in the past when accepted practices for clinical problems were more straightforward than those that face today’s clinicians. Physicians simply made subjective, intuitive decisions about what worked based on what they observed. Today, with the chaotic array of clinical choices, ambiguities and uncertainties, customary care has come under criticism.
The strongest criticism highlights the unwarranted variation in diagnosis and treatment choices for patients with the same clinical conditions. The choices physicians make when treating the identical clinical conditions vary widely from region to region. For example, a patient living in Provo, Utah is ten times more likely to receive a shoulder replacement than someone living in Syracuse, New York. Studies indicate that what constitutes customary care can be based on local practice styles, highly dependent on the region in which the physician practices.
These variations were also evident between providers within the same locale. Physicians looking at the same thing will disagree with each other and even themselves from 10 to 50 percent of the time during virtually every aspect of the medical-care process. A telling series of studies conducted in the 1990s concluded, “Physician agreement regarding quality of care is only slightly better than the level expected by chance.”
Critics of the customary standard believe that physicians employing old or outdated techniques may feel immunized against liability as long as the profession still predominantly uses those techniques. Customary practices have been routinely linked to a negative impact on quality of care and may reflect physician preference, not objective, scientific evidence. According to Dr. David Eddy, a leading medical scientist, physicians rely on preference because, “[p]ractical clinical judgment is woefully outmatched by the complexities of medicine.” Research has documented a phenomenon of decreasing quality of clinical performance with increasing years in practice. The customary care standard includes physicians whose years of practice experience only demonstrate out-of-date practice patterns.
In spite of many studies revealing regional and individual variation, the very low level of agreement among physicians, and the real questions of care quality, physicians are aware that the most powerful scrutiny they will face, both in practice and the courtroom, is the customary standard of care. When regional variations leave physicians wondering which custom is standard, treatment defaults to a liability risk balancing equation approach to healthcare where patients are likely underserved. As a result, custom may contribute to the tremendous delay between discovery of effective therapies and their routine use.
As a standard of care measurement, the concept of customary care can, and perhaps should be saved. Physicians have been allowed the historical privilege of self-governance precisely because they should have the greatest likelihood of knowing which treatment is best. To save customary care, and ultimately self-governance, will require physicians to establish their leadership in the field by giving customary care some teeth, basing care on “what other physicians would do” only as long as the act itself can be tied to a rational basis.
 Katharine A. Van Tassel, Blacklisted: The Constitutionality of the Federal System for Publishing Reports of “Bad” Doctors in the National Practitioner Data Bank, 33 Cardozo L. Rev. 2031, 2079 (2012).
 The Locality Rule and the Physician’s Dilemma – Local Medical Practices vs. the National Standard of Care, Lewis, et al., JAMA. 2007;297(23):2633-2637.
 Sanjaya Kumar and David Nash, “Health Care Myth Busters: Is There a High Degree of Scientific Certainty in Modern Medicine?”, http://www.scientificamerican.com/article/demand-better-health-care-book/. (Last visited March 4, 2015) In one study, a group of cardiologists were given high-quality coronary angiograms (a type of radiograph or x-ray) of typical patients. These cardiologists disagreed on the diagnosis for almost half of the patients. The cardiologists in the test were even shown to disagree with their own original finding 33% of the time when making two successive readings of the same angiograms.
Another study required a group of experts to estimate the effect of colon-cancer screening on colon-cancer mortality. The answers provided by the experts ranged from five percent to 95 percent.
A third study required cardiovascular surgeons to estimate the probabilities of various risks associated with xenografts (animal-tissue transplant) versus mechanical heart valves. The answers to the same question ranged from zero percent to 50 percent. When asked about the 10-year probability of valve failure with xenografts, these same cardiologists estimated a range of three (3) percent to 95 percent.
A final example resulted from a study of surgical prevalence. Surgeons were provided with a written description of a surgical problem. Half of the group recommended surgery, while the other half did not. When the same doctors were surveyed again two years later, 40 percent of the same surgeons disagreed with their previous opinions and changed their recommendations.
 ELLIOT S. FISHER ET AL., REGIONAL AND RACIAL VARIATION IN HEALTH CARE AMONG MEDICARE BENEFICIARIES: A BRIEF REPORT OF THE DARTMOUTH ATLAS PROJECT 24 (Kristen K. Bronner ed., 2008), available at http:// www.dartmouthatlas.org/downloads/reports/AF4Q_disparities_Dec2008.pdf.
 Katharine Van Tassel, Harmonizing the Affordable Care Act with the Three Main National Systems for Healthcare Quality Improvement: The Tort, Licensure, and Hospital Peer Review Hearing Systems, 78 Brook. L. Rev. 883, 895 (2013).
 Katharine Van Tassel, Hospital Peer Review Standards and Due Process: Moving from Tort Doctrine Toward Contract Principles Based on Clinical Practice Guidelines, 36 Seton Hall L. Rev. 1179, 1219 (2006). The most recent studies describing the disparity in treatment choices shows that doctors and hospitals “fail with alarming frequency to deliver essential life-saving treatments for some of the most common causes of death–heart attack, pneumonia and heart failure….” For example, patients who are given aspirin within the first twenty-four hours after a heart attack may have up to a thirty percent increase in the rate of survival. Of 3500 hospitals studied, physicians in those hospitals failed to give aspirin to one out of every sixteen patients. There is a wide variation, from state to state, from hospital to hospital and from physician to physician within the same hospital, in whether it is customary to provide this life saving treatment or whether it is customary not to provide the treatment. For example, the data showed that the hospitals studied in Massachusetts provided this treatment ninety-seven percent of the time, whereas the hospitals in Arkansas provided the treatment only eighty-five percent of the time. In most states, some hospitals provided the treatment one-hundred percent of the time, while other hospitals in the same community provided it only fifty percent of the time.
 E. Haavi Morreim, A Dose of Our Own Medicine: Alternative Medicine, Conventional Medicine, and the Standards of Science, 31 J.L. Med. & Ethics 222, 223-25 (2003).
 Haya R. Rubin et al., Watching the Doctor Watchers: How Well Do Peer Review Organization Methods Detect Hospital Care Quality Problems, 267 J. Am. Med. Ass’n 2349, 2349 (1992).
 Sokol AJ, Molzen CJ. The Changing Standard of Care in Medicine. J Legal Med. 2002; 23:485.
 James N. Weinstein et al., Trends and Geographic Variations in Major Surgery for Degenerative Diseases of the Hip, Knee, and Spine, Health Aff., Oct. 2004, at 81, 82.
 V. Prasad, et al. “A Decade of Reversal: An Analysis of 146 Contradicted Medical Practices”, http://www.mayoclinicproceedings.org/article/S0025-6196(13)00405-9/fulltext. (Last visited March 4, 2015)
Medical experts reverse course on certain practices and procedures when science dictates a change in the standard of care. One study found 146 reversals of previously established practices, treatments and procedures over the past 10 years. Many new medical treatments gain popularity over older standards of care due to clever marketing more than solid science.
 Sanjaya Kumar and David Nash, “Health Care Myth Busters: Is There a High Degree of Scientific Certainty in Modern Medicine?”, http://www.scientificamerican.com/article/demand-better-health-care-book/. (Last visited March 4, 2015). In one study, underuse of recommended services was actually more common than overuse: about 46 percent of patients did not receive recommended care, while about 11 percent of participants received care that was not recommended and was potentially harmful.