A new lung donor score to predict short and long-term survival in lung transplantation

Donor selection criteria are crucial for a successful lung transplant outcome. Our objective was to develop a new donor score to predict short- and long-term survival and validate it with five existing lung donor scores (Oto, Eurotransplant, Minnesota, Maryland-UNOS, Louisville-UNOS).

All 454 adult lung transplants at our center between 1992-2015 were included to develop a new score. Discriminative ability for all scores was calculated by the area under time-dependent receiver operating characteristic curves (time-dependent AUC) at 30-day, 1, 5 and 10-year survival, and their fit compared with Akaike's information criterion. For the new score, five pre-selected donor risk factors were derived: age, diabetes mellitus, smoking history, pulmonary infection, PaO₂/FiO₂-ratio, weighed via simplification of a multiple Cox model, and shrinkage used to avoid overfitting. The score sub-weighting resulted in a total of 17 points.

The existing scores showed predictive accuracy better than chance in prediction of survival of 5-year (AUC 0.58-0.60) to 10-year survival (AUC 0.58-0.64). Our new score had better discriminative ability as the existing scores with regard to 1, 5 and 10-year survival (AUC 0.59, 0.64, 0.66, respectively). Additional adjustment for recipient and surgical procedure variables improved the time-dependent AUC's slightly. For the secondary outcomes primary graft dysfunction and bronchiolitis obliterans syndrome, the new score showed also a good predictive accuracy.

The proposed Zurich Donor Score is simple, well adapted for the current urge of extended donors use, and shows higher discriminative ability compared to preexisting donor scores regarding short- to long-term survival.