Discrepancy between severity of lung impairment and seniority on the lung transplantation list

Organ allocation for lung transplantation, based mainly on accrued time on a waiting list, may not be an equitable system of organ allocation. To provide an objective view of the current practice concerning lung allocation, and timing for transplantation, we examined illness severity and list seniority in patients on a lung transplantation waiting list.

Adult patients awaiting lung transplantation underwent testing for mean pulmonary artery pressure (mPpa), maximum oxygen consumption (VO2 max), 6-minute walk distance (6MWD), forced expiratory volume in 1 second, mean partial pressure of carbon dioxide, partial pressure of oxygen/fractional concentration of inspired oxygen, and diffusing capacity of the lung for carbon monoxide. Relationships between physiological variables and waiting list rankings were then determined.

Thirty-four patients were tested and there was no correlation between time spent waiting on the list and mPpa (r=0.01; P=.94), VO2 max percentage predicted (r=0.07; P=.71), or 6MWD (r=0.15; P=.42). Many patients with functional impairments as indicated by low maximum VO2 or by short 6MWD are scheduled to receive their transplant after patients with levels that indicate a lower degree of risk. When compared with a hypothetical reranking based on mean Ppa, 24 of the 34 patients (71%) on our current waiting list were found to be 5 positions higher or lower than this new risk-based ranking. Sixteen patients (47%) were 10 or more positions away from their hypothetical severity-based ranking, and 9 (26%) were at least 15 positions out of place. Sixteen of the 34 patients were ranked lower than they would be based on a severity of illness using the pulmonary artery pressure alone, 17 were ranked higher than "should be" based on pulmonary artery mean, and only 1 patient (ranked in position 15) was appropriately positioned based on seniority and severity of disease based on PA mean.

Rank order for lung transplantation has no relationship with illness severity, and the discrepancy between disease severity and seniority on the lung waiting list may compromise overall outcomes in the lung transplantation population.