Decision Analysis Model for Facial Composite Tissue Allotransplantation

Facial composite tissue allotransplantation (CTA) has been proposed as a potential reconstructive option in severe facial disfigurement, in view of the reported success of hand allotransplantation. In the absence of clinical data, the decision to proceed with facial allotransplantation is dependent on the value or expected utility of the resultant status. Utility is measured by various means, including quality adjusted life years (QALYs). The QALY was developed as an attempt to integrate length of life in a particular health state and quality of life in that state into a single index measure. The change in utility value effected by an intervention multiplied by the duration of the treatment effect provides the number of QALYs gained. Utilities expressed as QALYs can then be fitted into a decision analytic model. Decision analysis enables surgeons to compare the expected consequences of pursuing different strategies (e.g., facial CTA vs. severe facial disfigurement). The purpose of this study was to assist surgeons with the decision of whether to proceed with CTA of the face.

The principal complications associated with facial allotransplantation were identified by a comprehensive review of kidney transplant and hand allotransplant literature. Based on the latter, the probabilities associated with the occurrence of each complication were derived, and fitted into a decision analytic “tree.” The decision analytic tree was constructed illustrating possible health states (pathways) for facial allotransplantation. The QALYs gained with transplantation were obtained from a sample of convenience (n = 60) that included various health care professionals. Utilities were computed from values obtained with the “feeling thermometer” (FG), standard gamble (SG), and time trade-off (TTO) measures.

Quality adjusted life years for severe facial deformity was 11.2, 16.0, and 17.5 with the FT, SG, and TTO measures, respectively. Following facial allotransplantation, QALYs were 37.4, 32.6, and 31.1 with the above listed measures.

The current debate within the medical community surrounding facial CTA has centered on the issue of inducing a state of immunocompromise in a physically healthy individual for a non-life-saving procedure. However, the latter must be weighed against the potential social and psychological benefit transplantation would confer. As demonstrated by a mean gain of 33.7 QALYs, participants' valuation of quality of life is notably greater for facial transplantation and the side effects of immunosuppression than for a state of uncompromised physical health with severe facial disfigurement.