Simulated waiting list prioritization for equitable allocation of donor lungs

In lung transplantation (LTx), allocation of donor lungs is usually based on blood group, height and waiting time. Long waiting times favor patients with a slowly progressive end-stage lung disease and make the current allocation system the subject of discussion. In an attempt to equalize the chances for transplantation for every patient, irrespective of diagnosis, we investigated the effect of diagnosis-dependent prioritization on the waiting list, using a simulation model.

For the main disease categories on the waiting list, the relative risks of dying while on the waiting list were calculated using empirical data from the Dutch LTx program gathered over a period of 10 years. In a microsimulation model of the Dutch LTx program based on data from the actual situation, patients with diagnoses associated with a statistically significant increased risk of death while on the waiting list were prioritized by multiplying the time on the waiting list by the relative risk.

Relative risks of death on the waiting list were increased significantly in patients with cystic fibrosis, primary pulmonary hypertension and pulmonary fibrosis. Prioritization resulted in an increased chance of transplantation for the prioritized diagnoses and a decreased chance for the non-prioritized diagnoses. The distribution of diagnoses after LTx was almost equal to the distribution of diagnoses on the waiting list.

The simulated method of prioritization on the waiting list is a step forward to a more equitable allocation of donor lungs. Moreover, this method is clinically feasible, as long as the waiting list is updated frequently.