Discrepancy between severity of lung impairment and seniority on the lung transplantation list
ABSTRACT 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.
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ABSTRACT: Lung transplantation in mechanically ventilated (MV) patients has been associated with decreased posttransplant survival. Under the Lung Allocation Score (LAS) system, patients at greatest risk of death on the waiting list, particularly those requiring MV, are prioritized for lung allocation. We evaluated whether pretransplant MV is associated with poorer posttransplant survival in the LAS era. Using a national registry, we analyzed all adults undergoing lung transplantation in the United States from 2005 to 2010. Propensity scoring identified nonventilated matched referents for 419 subjects requiring MV at the time of transplantation. Survival was evaluated using Kaplan-Meier methods. Risk of death was estimated by hazard ratios employing time-dependent covariates. We found that pretransplant MV was associated with decreased overall survival after lung transplantation. In the first 6 months posttransplant, ventilated subjects had a twofold higher risk of death compared to nonventilated subjects. However, after 6 months posttransplant, survival did not differ by MV status. We also found that pretransplant MV was not associated with decreased survival in noncystic fibrosis obstructive lung diseases. These results suggest that under the LAS, pretransplant MV is associated with poorer short-term survival posttransplant. Notably, the increased risk of death appears to be strongest the early posttransplant period and limited to certain pretransplant diagnoses.American Journal of Transplantation 08/2011; 11(10):2197-204. DOI:10.1111/j.1600-6143.2011.03684.x · 6.19 Impact Factor
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ABSTRACT: The lung allocation score was initiated in May 2005 to allocate lungs on the basis of medical urgency and posttransplant survival. However, the relationship between lung allocation score and candidate outcomes remains poorly characterized. The purpose of this study was (1) to describe outcomes by lung allocation score at the time of listing and (2) to estimate the net survival benefit of transplantation by lung allocation score. The United Network for Organ Sharing provided de-identified patient-level data. Analysis included lung transplant candidates aged 12 years or more and listed between May 4, 2005, and May 4, 2009 (n = 6082). Candidates were stratified according to lung allocation score at listing into 7 groups: lung allocation score less than 40, 40 to 49, 50 to 59, 60 to 69, 70 to 79, 80 to 89, and 90 or more. Outcomes of interest included the risk of death on the waiting list and likelihood of transplantation. The net survival benefit of transplantation was defined as actuarial median posttransplant graft survival minus actuarial median waiting list survival, where the outcome of interest was death on the waiting list or posttransplant; candidates were censored at the time of transplant or last follow-up. In the lowest-priority strata (eg, <40 and 40-49), less than 4% of candidates died on the waiting list within 90 days of listing. The median net survival benefit was lowest in the lung allocation score less than 40 (-0.7 years) and lung allocation score 90+ group (1.95 years) and highest in the 50 to 59 (3.44 years), 60 to 69 (3.49 years), and 70 to 79 (2.81 years) groups. The mid-priority groups (eg, 50-59, 60-69, 70-79) seem to achieve the greatest survival benefit from transplantation. Although low-priority candidates comprise the majority of transplant recipients, survival benefit in this group seems to be less than in other groups given the low risk of death on the waiting list. As expected, both the time to transplant and survival on the waitlist are lower in the higher-priority strata (eg, 80-89 and 90+). However, their net survival benefit was likewise relatively low as a result of their poor posttransplant survival.The Journal of thoracic and cardiovascular surgery 05/2011; 141(5):1270-7. DOI:10.1016/j.jtcvs.2010.12.028 · 3.99 Impact Factor