Hard choices: Reflections from the tomb of the unknown patient.

Health Technology Assessment (HTA) has always sought to incorporate the evidence of all patients affected in the decision-making process. While health system budgets could increase to cover costs of new technologies, the relevant patients are those benefitting from access to the technology being appraised. More recently, with health system budgets effectively fixed, costs of new technologies are covered by displacing other, currently funded care. This reallocation means the patients affected by the decision include those whose healthcare is displaced. These patients are typically unidentified, however, and so HTA in this instance involves choosing between identified and unidentified patients. We argue that HTA should take account of identifiability bias in this decision-making, to avoid promoting inequitable and inefficient access to healthcare.