Liver Transplantation for Hepatopulmonary Syndrome (HPS): What Is the MESSAGE?
Article first published online: 4 MAR 2008
©2008 The Authors Journal compilation © 2008 The American Society of Transplantation and the American Society of Transplant Surgeons
American Journal of Transplantation
Volume 8, Issue 5, pages 911–912, May 2008
How to Cite
Krowka, M. J. and Fallon, M. B. (2008), Liver Transplantation for Hepatopulmonary Syndrome (HPS): What Is the MESSAGE?. American Journal of Transplantation, 8: 911–912. doi: 10.1111/j.1600-6143.2008.02190.x
- Issue published online: 14 APR 2008
- Article first published online: 4 MAR 2008
- Received 31 December 2007, revised 20 January 2008 and accepted for publication 27 January 2008
In this issue of the Journal, Sulieman et al. describe an analysis of 2002–2005 UNOS data from the Scientific Registry of Transplant Recipients (SRTR) that compares liver transplant (LT) outcomes between patients granted model for end-stage liver disease (MELD) exception for a reported diagnosis of hepatopulmonary syndrome (HPS) and all others transplanted without ‘MELD exception’ (1). The authors conclude that the current policy of MELD exception favors HPS patients over others in terms of overall survival, an unintentional outcome of the policy. We would like to highlight key aspects of the process of evaluating MELD exception policies and place these aspects in perspective for HPS (2).
LT Data Collection
The most critical aspect of defining the effectiveness of MELD exception policies for liver transplantation is obtaining data relevant to the process for which patients may receive exception points. In this regard, the current analysis of the SRTR database related to HPS is provocative and of interest. Are HPS patients favored over others for organ allocation? Should the current policy be revised based on these findings? One might assume so based on the current report. However, it is of fundamental importance to recognize the fact that the SRTR data contain no specific information relevant to the diagnosis or severity of HPS, most importantly co-existent cardiopulmonary disease, chest imaging, arterial blood gases, contrast echocardiography and pulmonary function tests. Therefore no documentation exists as to who actually had HPS. Accordingly, the current study simply does not have sufficient information to help us refine or change the current MELD exception policy for HPS. Of specific concern is that prior studies where HPS and controls were well characterized have found diminished survival in HPS patients, in part related to the degree of hypoxemia, both in those who undergo LT (4–8) and those who do not (3–8). The lack of such data in the SRTR database is a serious deficiency and underscores the importance of capturing data relevant to HPS in rationally assessing both clinical outcomes and MELD exception.
One might also argue that it does not matter whether all the HPS or control patients actually had HPS in the current report, because the findings show that those who received MELD exception for HPS were favored over the others with regard to pretransplant outcomes; thus the policy is flawed. This argument is simply scientifically unsound as it confuses an attempt to optimize MELD exception for HPS (in the absence of data on HPS) with defining whether HPS patients have different outcomes from those without HPS. Because the current study does not contain data that allow us define whether patients with documented HPS have different outcomes from patients documented not to have HPS, we will not advance patient care or improve the MELD exception policy by making changes now.
The original MELD allocation policy included the Regional Review Board (RRB) consideration of ‘exceptional diagnoses’ in which MELD scores did not accurately correlate with death from liver disease (2). In the current report, Sulieman et al. have concluded that the HPS-MELD exception policy may not be justified based on the observation that waitlist survival was better in HPS patients. It is important to recognize that the MELD exception policy addresses more than waitlist survival and includes, among others, decreasing the risk of disease recurrence after LT, preventing disease progression (nonneoplastic) that might preclude LT and improving survival after LT (2). Thus, even if one assumes that the current data accurately identifies HPS patients with advanced hypoxemia and non-HPS patients, then the observation that survival was similar in HPS and controls after LT may be viewed as a success for HPS-MELD exception. Why success? Both HPS progression was prevented and survival improved relative to findings in prior studies. The ‘cost’ of this success may be a small increase in pre-LT survival in HPS patients relative to others. To clearly define the benefits and costs of MELD exception for HPS, data regarding the presence and severity of HPS are important in all patients that are listed for LT.
The Message from MESSAGE
The MELD Exceptional Case Study Group (MESSAGE) was convened by UNOS due to the lack of guidelines for exceptional cases and RRB differences in assessment for such cases (2,9). Specific HPS-related recommendations included standardizing methods for intrapulmonary vascular dilatation assessment and hypoxemia (arterial blood gases in sitting position breathing room air every 3 months) (9). The important issues raised regarding MELD exception for HPS by Sulieman and colleagues clearly highlight the fundamental deficiencies in the SRTR. Moving forward, we must collect key data regarding HPS in patients being cared for under the existing system and then use these data to regularly re-assess the utility of the MELD exception policy. This is the message from MESSAGE.