Finding the optimal balance between extending limits and achieving outcomes

It has always been the goal of pioneers and innovators to extend the limits of what is currently thought to be possible. This is as true in the field of thoracic surgery as in any field of endeavour. In lung transplantation, it was not long after the initial clinical successes of the University of Toronto group in the 1980s that they and others began to explore possible innovations that would allow more patients to benefit from this ground-breaking procedure [1]. Over the ensuing 30 years, during this first phase of the history of clinical lung transplantation, many research avenues have been explored in this goal to extend the opportunity of lung transplantation to a greater number of patients. These have included improved preservation techniques and solutions, advances in critical care and postoperative management and refinements in immunosuppression strategies [2–4]. The article by Moreno et al. in this issue [5], examines the interface between two important areas for extending the reach of lung transplantation: the utilization of ‘extended’ or ‘marginal’ donor lungs and the broadening of the range of severity of recipient candidates for lung transplantation. Extending the limits of what is considered an acceptable donor lung has been a recurring theme in the on-going efforts to overcome the paucity of donor lungs available for transplantation—So much so that so-called ‘extended’ donors have become almost the norm. Indeed, in the article by Moreno, 37% of donors were classified as ‘extended’. Equally, as experience increases, our collective limits on the severity of potential recipients have also expanded [6, 7]. This has been fuelled as well by donor organ allocation systems, such as the UNOS Lung Allocation Score system in the USA, which distribute organ offers based solely on the severity of illness of potential recipients [8]. The counterbalance, of course, to the extension of clinical boundaries must always be the resultant patient outcomes. This emphasis on appropriate outcomes becomes all the more germane in a discipline with obvious requirements for strict stewardship of rare but shared resources and a relatively high cost of care. Unjustifiably poor results do not only affect the recipient. The standard in transplantation is, therefore, understandably higher. It is for this reason that the research by Moreno et al. is an important effort from an experienced and well-respected lung transplantation programme. In their simplified but clever approach, Moreno et al. have tried to parse out the intersection between extending the limits of both donors and recipients. The endpoints analysed of 30-day mortality, primary graft dysfunction, onset of bronchiolitis obliterans and long-term survival are well chosen as they not only have widely accepted definitions but also are clearly the most relevant. After considering a number of caveats that the researchers themselves recognize and appropriately discuss, the main finding in the study is that the effect of extending the usual clinical boundaries is more hazardous with the extended recipient when compared with the extended donor. Median long-term survival of extended recipients was markedly lower than optimal recipients irrespective of the quality of the donor. Conversely, in the comparison with donors this was not observed; there was no overall difference in long-term survival according to donor quality. This is an important and novel observation as we continue to ‘push the envelope’ in all possible directions. The knowledge that the risks may be higher when extending the recipient criteria should help to guide us on a more secure path as we continue to extend the clinical limits of lung transplantation while trying to maintain acceptable and respectable outcomes. Naturally, there will be some that say that these findings were predictable. Indeed, this may be the sense of many who have been deeply invested in lung transplantation over the past three decades. These are the experts that have the benefit of experience permitting them to successfully prove Malcolm Gladwell’s thesis in Blink that an extensive past experience can allow good judgement, in the absence of hard data and seemingly based solely on intuition [9]. What Moreno’s group provides is the first body of data to support these ‘intuitions’ that recipient severity has a greater impact on outcomes than donor quality. As we enter the next era in lung transplantation, we should endeavour to providemore data-driven refinements to both donor and recipient selection. This will allow us to better define this important interface between the donor and recipient. Moreno’s work makes the correct inference that these determinations can and should be coupled together in each transplant event. On the one hand, identifying recipients who can afford to be transplanted with a ‘specifically extended’ donor while maintaining acceptable outcomes may provide the latitude necessary to allow other more ‘extended’ recipients to be earmarked for a more strictly defined ‘optimal donor’. This Benthamesque utilitarian ideal of achieving the greater good for the greater number of patients will be