Center differences in model for end-stage liver disease exceptions: Fairness, local culture, and norms of practice

Fairness – it seems like a simple concept, understood even by children, but ensuring fairness in resource allocation turns out to be quite difficult. Fairness can be divided into criteria and process. To paraphrase the esteemed philosopher Norman Daniels, we may never agree on the criteria, but we should at least perceive that the process is fair.1 The current primary criterion used for organ allocation in liver transplantation is based upon the principle of urgency, operationalized as the patient’s probability of dying from liver disease in the near future. In most patients, this is measured by the Model for End-stage Liver Disease (MELD) score. Like any prognostic index, MELD only works to predict a specific thing (death from liver disease) in a specific population (cirrhosis with impaired synthetic function). It does not correlate well with quality of life,2 nor does it do a good job of predicting death from miscellaneous complications of liver disease such as hepatopulmonary syndrome, or from other conditions that would benefit from transplantation such as amyloidosis. Thus, the transplant community has had to develop a process for prioritizing such patients. Some of these complications are common enough that a standardized exception score has been set, such as with hepatocellular carcinoma. However, other various complications such as cholangitis, called non-standardized exceptions or non-recognized exceptional diagnoses (non-REDs), are reviewed on a case-by-case basis by Regional Review Boards (RRBs). Is the MELD exception process fair? New information provided by Goldberg et al in this issue of Liver Transplantation suggests that the answer is, unfortunately, not really. The authors reviewed 58,641 candidates for liver transplantation, among whom 4,356 (7.4%) had at least one non-RED exception applied for on their behalf. Hierarchical regression techniques were used to investigate reasons for variation in exception applications, and to understand the extent to which variation occurred at the patient, transplant center, and regional levels. In other words, if rates of exceptions vary by center, is this due to between-region differences in strictness of RRBs, thus exerting feedback regulation of center behavior? Or, could it just be that some centers have sicker patients than others? The authors found that while exception applications did vary by region, as previously documented, there was 3-fold more variation by center – independent of the region where the centers were located. Despite adjusting for between-center differences in patient characteristics, rates of exception applications varied by more than 4-fold between centers in the same region. As might be expected, since approval decisions occur at the regional level, between-center differences in approval rates were much smaller. These data provide compelling evidence that centers differ in the behavior regarding submitting exception applications on behalf of their patients, and that this behavior is not driven by variations in severity of patient illness or the whims of the local RRB. Concerns about fairness in MELD exceptions are further heightened by Dr. Goldberg and colleagues’ finding that on multivariable analysis, women, African-Americans, Hispanics, and those with Medicaid insurance were all statistically significantly less likely to have an exception application, as shown in Table 6 of the manuscript. These are traditionally vulnerable populations, all of whom have been shown to be underserved by the transplant system in various ways.3–5 On the positive side, minorities and patients with Medicaid insurance seem to fare slightly better at the RRB level as shown in Table 7. Women, however, are not only 21% less likely to have an exception applied for (p=0.001), but are also 14% less likely to have their exception approved (p=0.07). This is somewhat surprising, since it is common knowledge that women tend to have slightly lower MELD scores than men at a given severity of liver disease, since their serum creatinine levels are lower.4 Further study is needed to understand the reasons behind these disparities. Why are physicians at one center much more likely to submit exception applications than physicians at another center? This finding could not be explained by center-level differences in volume or competitiveness of the local environment. Only median match MELD was associated with likelihood of higher submission rate, and the magnitude of this association was small. I would theorize that these differences are primarily due to differences in local culture and norms of practice. Most transplant physicians spend the majority of their career practicing at one center, and many practice in the same center where they completed their training. At national meetings, few of us spend time comparing our rate of exception applications with our colleagues at other centers – in fact, most of us can only guess at our own personal rate. When deciding whether to apply for an exception on a patient’s behalf, we habitually behave as we have always done, and similarly to how colleagues at our own center behave. Such center-level differences have been shown for other behaviors in liver transplantation, such as organ utilization practices.6 In summary, the process for determining MELD exceptions does not fully adhere to the accepted criterion of urgency. A given patient’s probability of receiving a MELD exception is determined not just by his or her probability of dying from liver disease, but also by race/ethnicity, gender, socioeconomic status, and geographic location. What, then, are some possible solutions? Since most of the variation is at the center level, a national review board would not solve the problem. One solution is improved prognostic models. It is possible that the upcoming incorporation of serum sodium into the MELD score (MELD-Na) will reduce the need for non-RED exceptions in some patients, though this remains to be seen. Another solution would be to delineate formal criteria for the RRBs to follow. One hypothesis to partially explain center differences is that centers with a representative on the RRB have inside knowledge about what types of applications are likely to receive a favorable review – which makes these centers more likely to submit applications. The 2006 consensus guideline on MELD exceptions was developed as a review of the available evidence, not as a working document for RRBs.7 Perhaps it is time for the liver transplant community to develop a more granular set of protocols and standards. Finally, the most powerful tool to reduce center-level variability would be to provide each center with feedback about their practices in relation to national averages. Normative feedback has long been recognized as a crucial component of physician behavior change,8 and I have argued that it is underutilized in transplantation.6 Feedback would at least promote consistency, which is an important –and measureable – aspect of fairness.