Can We Stop Waiting for Godot? Establishing Selection Criteria for Simultaneous Liver–Kidney Transplantation

The appropriate selection of candidates for simultaneous liver-kidney transplantation (SLKT) is more complex and less well defined than for liver transplant alone (LTA). The current allocation policy is flexible, providing a kidney to any liver transplant candidate based solely on local physician opinion. This latitude has resulted in tremendous diversity of opinion and practice. SLKT recipients span the gamut from well-compensated cirrhotics with end stage renal disease (ESRD) to severely decompensated chronic liver patients suffering acute kidney injury requiring continuous veno-venous hemofiltration in the intensive care unit. At the first extreme, the indication for kidney transplantation is clear but the indication for liver transplantation is less obvious. The liver transplant is usually not urgent, but prevents hepatic decompensation after kidney transplantation. Moreover, the liver may also facilitate kidney transplantation by shortening waiting time. At the second extreme, the issues are exactly reversed. The kidney transplant is not urgent since dialysis can be maintained indefinitely. However, inclusion of the kidney for these critically ill patients may avert early posttransplant complications related to renal failure and reduce the risk of future ESRD. Nephrologists and ESRD patients may, however, question the equity of bestowing precious renal grafts upon liver recipients to mitigate the risk of future renal dysfunction with three functioning kidneys. Unfortunately, no data currently exists to verify, much less quantify, the short or long-term survival benefit afforded by SLKT over kidney transplant alone or LTA for any of these patients. The increasing prevalence of acute and chronic renal dysfunction among liver transplant candidates, coupled with the burgeoning kidney transplant waitlist has motivated physicians to define and standardize selection criteria for SLKT (1–3). Acknowledging limitations in both quantity and quality of available data, these consensus conferences have nevertheless issued recommendations based on literature review and expert opinion. These guidelines have likely had some effect on practice, but have drawn criticism for insufficient sensitivity and specificity to predict relevant outcomes. As a result, although the debate surrounding SLKT listing criteria continues, policy development remains at a dense stalemate and practice patterns remain erratic.