Cardiothoracic Transplantation Kozower et al The impact of the lung allocation score on short-term transplantation outcomes: A multicenter study Benjamin D. Kozower, MD,a Bryan F. Meyers, MD,b Michael A. Smith, MD,c Nilto C. De Oliveira, MD,d Stephen D. Cassivi, MD,e Tracey J. Guthrie, RN,b Honkung Wang, PhD,f Beverly J. Ryan, ACNP,a K. Robert Shen, MD,a Thomas M. Daniel, MD,a and David R. Jones, MDa Objective: The lung allocation score restructured the distribution of scarce donor lungs for transplantation. The algorithm ranks waiting list patients according to medical urgency and expected benefit after transplantation. The purpose of this study was to evaluate the impact of the lung allocation score on short-term outcomes after lung transplantation. Methods: A multicenter retrospective cohort study was performed with data from 5 academic medical centers. Results of patients undergoing transplantation on the basis of the lung allocation score (May 4, 2005 to May 3, 2006) were compared with those of patients receiving transplants the preceding year before the lung allocation score was implemented (May 4, 2004, to May 3, 2005). Results: The study reports on 341 patients (170 before the lung allocation score and 171 after). Waiting time decreased from 680.9 Ϯ 528.3 days to 445.6 Ϯ Dr Kozower 516.9 days (P Ͻ .001). Recipient diagnoses changed with an increase in idiopathic pulmonary fibrosis and a decrease in emphysema and cystic fibrosis (P ϭ .002). Postoperatively, primary graft dysfunction increased from 14.1% (24/170) to 22.9% (39/171) (P ϭ .04) and intensive care unit length of stay increased from 5.7 Ϯ 6.7 days to 7.8 Ϯ 9.6 days (P ϭ .04). Hospital mortality and 1-year survival were the same between groups (5.3% vs 5.3% and 90% vs 89%, respectively; P Ͼ .6) From the Department of Surgery, Univer- sity of Virginia Health System, Charlottes- ville, Vaa; Department of Surgery, Wash- Conclusions: This multicenter retrospective review of short-term outcomes supports ington University School of Medicine, St the fact that the lung allocation score is achieving its objectives. The lung allocation Louis, Mob; Department of Cardiothoracic Surgery, University of Southern California, score reduced waiting time and altered the distribution of lung diseases for which Los Angeles, Calif c; Department of Sur- transplantation was done on the basis of medical necessity. After transplantation, gery, University of Wisconsin, Madison, recipients have significantly higher rates of primary graft dysfunction and intensive Wisd; Department of Surgery, Mayo Clinic, Rochester, Minne; and Department of Pub- care unit lengths of stay. However, hospital mortality and 1-year survival have not lic Health Sciences, University of Virginia been adversely affected. Health System, Charlottesville, Va.f Read at the Eighty-seventh Annual Meeting TX of The American Association for Thoracic Surgery, Washington, DC, May 5–9, 2007. Received for publication May 3, 2007; re- he lung allocation score (LAS) was implemented in May 2005 by the Organ visions received Aug 13, 2007; accepted for 1 publication Aug 15, 2007. Procurement and Transplantation Network (OPTN).The LAS dramatically changed lung allocation from a system based purely on waiting time to an Address for reprints: Benjamin D. Kozo- T wer, MD, University of Virginia Health algorithm based on survival probability on the waiting list and after transplantation. System, General Thoracic Surgery, PO Box The impetus for change was the scarcity of suitable donor lungs and the increasing 800679, Charlottesville, VA 22908-0679 2-4 (E-mail: [email protected]). number of deaths for patients on the waiting list. The OPTN began allocating lungs in 1990 on the basis of blood type and the J Thorac Cardiovasc Surg 2008;135:166-71 amount of time candidates had spent on the5 In waiting1995, list.a minor change 0022-5223/$34.00 was made to this system when 90 days of waiting time were added for patients with Copyright © 2008 by The American Asso- ciation for Thoracic Surgery idiopathic pulmonary fibrosis to offset the increased risk of mortality on the waiting doi:10.1016/j.jtcvs.2007.08.044 list. In 1998, the Department of Health and Human Services published the Final Rule.6 This required the OPTN to emphasize the broader sharing of organs, reduce 166 The Journal of Thoracic and Cardiovascular Surgery ● January 2008 Kozower et al Cardiothoracic Transplantation variables available close to the time of transplant. Primary graft Abbreviations and Acronyms dysfunction was defined according to the International Society of ICU ϭ intensive care unit Heart and Lung Transplantation definition: arterial oxygen tension/ LAS ϭ lung allocation score inspired oxygen fraction less than 300 and a chest radiograph with OPTN ϭ Organ Procurement and Transplantation a characteristic diffuse bilateral infiltrate.8 The human studies Network committees at each institution granted approval for this research. Waiting List Estimates Data from the waiting lists at the five institutions were gathered for the use of waiting time as an allocation criterion, and create the same two groups. To calculate the percentage of patients dying an allocation system based on objective medical criteria and on the waiting list, we estimated the size of the waiting list for both measures of medical urgency. groups. Because the waiting lists are dynamic, this is not a straight- The LAS was developed by multivariate modeling and forward process. We identified the actual number of patients on the was approved by the OPTN in 2004. The three main objec- waiting lists at 4 interval time points for both cohorts (May 15, tives were as follows: (1) reduce the number of deaths on August 15, November 15, and February 15). These numbers were the lung transplant waiting list, (2) increase transplant ben- averaged (total number divided by 4) to estimate the size (denom- efit for lung recipients, and (3) ensure the efficient and inator) of the waiting list. The numerator was the actual number of patients who died on the waiting lists. equitable allocation of lungs to active transplant candi- dates.7 The LAS assigns a score to all candidates over the Statistical Analysis age of 12 years ranging from 0 to 100. It is a weighted Categorical variables were compared by the ␹2 test. Continuous combination of predicted risk of death during the following variables were compared with the Student t test or Kruskal–Wallis year on the waiting list and the predicted likelihood of test where appropriate. Estimates of the cumulative death rate at 1 survival during the first year after transplantation. year were calculated by the Kaplan–Meier method, and the sur- The purpose of this study was to evaluate the impact of vival differences between the pre-LAS and LAS groups were the LAS system on the waiting list and short-term outcomes assessed by the log–rank test. Short-term results were controlled after lung transplantation. Many lung transplant surgeons for diagnosis by the Mantel–Haenszel test. All data analysis was have the impression that the LAS has increased the com- performed with SAS 9.1.3 software (SAS Institute, Inc, Cary, NC). plexity of the cases and their complication rates. Our hy- pothesis was that the LAS would decrease waiting time for Results recipients but would also increase morbidity and mortality Patient Characteristics after transplantation. There were 170 patients in the pre-LAS group and 171 in the LAS group. The numbers of patients per group from Patients and Methods each institution were as follows: Washington University 59 Transplant Recipients and 52, University of Southern California 37 and 38, Uni- A multicenter retrospective cohort study was performed with data versity of Virginia 31 and 35, University of Wisconsin 34 from five academic medical centers: University of Virginia, Wash- and 33, and Mayo Clinic 9 and 13. The baseline character- ington University, University of Southern California, University of istics are listed in Table 1. The pre-LAS group had fewer Wisconsin, and the Mayo Clinic. The two cohorts were patients retransplants and a lower calculated LAS (P Ͻ .05). The undergoing transplantation the year preceding the introduction of the LAS (May 4, 2004, to May 3, 2005) (pre-LAS group) and recipient diagnoses changed significantly with the initiation patients undergoing transplantation the year after the LAS was of the LAS (Table 2). There were an increase in the number implemented (May 4, 2005, to May 3, 2006) (LAS group). In an of patients with idiopathic pulmonary fibrosis and a de- effort to compare the severity of illness between the groups, the crease in patients with chronic obstructive pulmonary dis- TX LAS was calculated for the pre-LAS group using the appropriate ease and cystic fibrosis (P ϭ .002). TABLE 1. Baseline characteristics P value (171 ؍ LAS (n (170 ؍ Pre-LAS (n Age (y) 49.2 Ϯ 14.0 51.2 Ϯ 13.0 .16 Gender (female) 80 (47.1%) 80 (46.8%) .96 Procedure (bilateral lung transplant) 111 (65.3%) 106 (62.0%) .2 Retransplantation 3 (1.8%) 10 (5.8%) .05 Ischemic time (first lung in minutes) 285.2 Ϯ 97.9 271.0 Ϯ 99.4 .20 LAS 35.4 Ϯ 8.2 42.5 Ϯ 15.2 Ͻ.001 LAS, Lung allocation score. The Journal of Thoracic and Cardiovascular Surgery ● Volume 135, Number 1 167 Cardiothoracic Transplantation Kozower et al TABLE 2. Recipient diagnosis P value (171 ؍ LAS (n (170 ؍ Pre-LAS (n Etiology of end-stage lung disease COPD 78 (45.9%) 58 (33.9%) Cystic fibrosis 39 (22.9%) 22 (12.9%) Idiopathic pulmonary fibrosis 25 (14.7%) 42 (24.6%) .002 Pulmonary hypertension 7 (4.1%) 4 (2.3%) Other 21 (12.4%) 45 (26.3%) LAS, Lung allocation score; COPD, chronic obstructive pulmonary disease.