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* From the Inova Heart and Lung Transplant Center (Drs. Nathan, Ahmad, Burton, and Barnett), Falls Church; and the United Network for Organ Sharing (Dr. Edwards), Richmond, VA.
Correspondence to: Steven D. Nathan, MD, FCCP, Medical Director, Lung Transplant Program, Inova Heart and Lung Transplant Center, Inova Fairfax Hospital, 3300 Gallows Rd, Falls Church, VA 22042; e-mail: steven.nathan{at}inova.com
| Abstract |
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Design: Retrospective analysis of the United Network for Organ Sharing transplant database over the period between October 25, 1999, and December 31, 2002.
Patients: All COPD patients who were listed and underwent transplantation during the time period were analyzed and categorized according to who did and did not have a history of LVRS. The two groups were compared for demographics, severity of illness, and various measures of outcomes after transplantation, including survival.
Results: There were 791 COPD patients who underwent transplantation, of whom 50 had a history of LVRS. The two groups had similar demographics and severity of disease. There was no difference in the need for reoperation, hospital length of stay, or survival between the groups.
Conclusion: A history of LVRS does not impact on outcomes after lung transplantation and should not influence a patients candidacy for transplantation. Similarly, a patients potential need for lung transplantation should not impact on the decision-making process for undergoing LVRS.
Key Words: chronic obstructive lung transplantation cohort studies mortality pneumonectomy pulmonary disease pulmonary emphysema surgery survival analysis
| Introduction |
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An unanswered question, however, is what impact the one procedure may have on the outcomes of the other. Specifically, does a history of LVRS impact on the outcomes of COPD patients who ultimately require transplantation? With this as our objective, we performed an analysis of the United Network for Organ Sharing (UNOS)/Organ Procurement and Transplantation Network (OPTN) database to assess the outcomes of COPD lung transplant recipients who had a history of LVRS.
| Materials and Methods |
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Comparisons were made between those COPD patients with a history of LVRS who had undergone transplantation and those COPD patients who had undergone transplantation during the same period, but who had not undergone LVRS. Demographic measures, including age, sex, race, gender, and type of transplant procedure, were compared for the two groups. They were also compared for disease severity based on pretransplant pulmonary function test results and pulmonary artery pressures. Their waiting times on the transplant list were contrasted, as was their incidence of pneumothoraces while waiting. Postoperative outcomes were compared for incidence of prolonged graft ischemia, prolonged graft dysfunction, bronchopleural fistulas, the need for reoperation, hospital length of stay, and survival. Comparisons of categoric factors were made using the
2 test or the Fisher exact test. Comparisons of continuous factors were made using the Wilcoxon test. Survival rates were computed using the Kaplan-Meier method and were compared using the log-rank test.
| Results |
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Survival times for the two groups of patients are shown via Kaplan-Meier curves in Figure 3 . There was no significant difference in survival within 1 month, 3 months, or 1 year (p = 0.5, p = 0.4, and p = 0.4, respectively). The 1-year survival rate of the cohorts was 88.1% for the LVRS patients and 82.4% for the non-LVRS transplant recipients. For an overall comparison of survival for the entire follow-up period, the p value was 0.1, with the LVRS group having a higher survival rate at all time points. There was no significant differences in cause of death between the two groups (p = 0.8), but as there were only six deaths in the LVRS patient group, the sample size may have been too small to draw any definitive conclusions.
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| Discussion |
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LVRS gained popularity in the mid-1990s as a potential palliative surgical option for some patients with advanced COPD.345 However, since the efficacy of the surgery was thought to be uncertain, Medicare discontinued reimbursing for the procedure, and most private payers followed suit. In a follow-up to this, a large multicenter study, the NETT, was undertaken. From January 1998 until July 2002, 3,777 patients were screened and 1,218 patients were randomized to either LVRS or standard medical care. The outcomes of this landmark study have now been published in two reports.79 Aside from the initial high-risk group of patients identified, two independent risk factors (ie, exercise capacity after pulmonary rehabilitation and upper lobe-predominant distribution of disease) were found to be predictive of outcome. Based on these factors, four groups of patients were identified. One group (with low exercise capacity and upper lobe-predominant disease) had the most benefit with improvements in QOL, exercise tolerance, and survival compared to their medically managed counterparts. Two of the groups had more patients (ie, those with upper lobe-predominant disease/high exercise capacity and those with non-upper lobe emphysema/low exercise capacity) who showed an improvement in their exercise capacity and/or symptoms, but there was no difference in their survival times. The last group constituted by those patients with predominantly non-upper lobe emphysema and a high exercise capacity had a deleterious response with a worse survival compared to their medical treatment counterparts.7
With these groups and their characteristics now identified, it appears likely that there will be a focused resurgence in popularity of the procedure. Some patients who are appropriate lung transplant candidates may also be suitable for LVRS, and it is possible that the need for transplantation might be deferred in such patients, provided that they obtain a successful outcome from LVRS.10111213
The expected duration of benefit from LVRS is yet to be determined. In the NETT, it appeared that most of the benefit was maintained for at least the 2 years of follow-up. In addition, there are reports1011 attesting to a duration of benefits for as long as 5 years in most patients. However, not all patients maintain the benefit for this long, and once they do deteriorate, LVRS patients might still remain good lung transplant candidates.
The issue that we attempted to address was whether a history of LVRS would have any impact on the postoperative course and prognosis of lung transplant patients. There are theoretic reasons as to why this might be the case. Any surgical instrumentation of the chest cavity results in the subsequent formation of adhesions. This might result in difficulty in removing the native lung during the explant phase of the transplant procedure. The dissection of the adhesions can result in excess bleeding, the need for blood products, hypotension, and hemodynamic instability. Therefore, patients with a history of LVRS may be at a higher operative risk, and this might impact on their short-term prognosis and, hence, on their long-term prognosis. If this were the case, then their potential transplant candidacy would need to be addressed at the same time that consideration was being given to LVRS.
For any potential transplant or LVRS candidate to make the appropriate choice, the outcomes that need to be weighed are what their QOL and life expectancy might be with or without the procedure. Furthermore, for LVRS the heterogeneity of response needs to be considered since individual patients might not have a significant improvement. For those patients with COPD, who might be eligible for both LVRS and transplantation, not only does their QOL and life expectancy with LVRS need to be considered, but also what their life expectancy and course is likely to be posttransplant if they first undergo LVRS and subsequently undergo lung transplantation.
This last consideration may be moot since, contrary to our hypothesis, there does not appear to be any statistical difference in outcomes between patients who have previously undergone LVRS and their non-LVRS counterparts. If there were any significant increased perioperative risk, we would have expected a difference in mortality at 1 month, which was not seen. Further supportive evidence of a lack of increased morbidity in the LVRS group is the similarity in the posttransplant hospital length of stay between the two groups. It also appears that intermediate-term outcomes are no different, with similar survival rates seen at 12 months. The OPTN does not collect any data that reflect the difficulty of surgery, so differences in the explant part of the procedure could not reliably be distinguished between the two groups. For example, it is possible that the LVRS group required longer operations and more blood products. However, even if either of these were the case, it did not impact on other measures of relevance to the patients postoperative course, including graft ischemic times, the incidence of prolonged graft dysfunction, or the need for reoperation. The latter could possibly be construed as a surrogate for episodes of severe pleural hemorrhage and might therefore indicate that even if this group did have more bleeding, it was not sufficient to require a greater number of reexplorations. Whether there were other differences in their operative and perioperative course that were not captured by the UNOS/OPTN database, remains unanswered.
The two groups of patients that formed our cohorts appeared to be very well-matched by demographics and severity of disease. The one difference between the two groups was the apparent increased incidence of pneumothoraces in the LVRS group while listed. This most likely was related to the fact that 38% of the patients underwent LVRS during this waiting period. The other apparent difference was the longer waiting times in the LVRS group. There are a number of possible reasons for this. It is conceivable, for example, that patients in whom the waiting time was expected to be longer were offered LVRS as a temporizing measure. It is also possible that LVRS patients were more likely to be listed earlier since they were being followed closer. A survival advantage for the LVRS patients appears unlikely to have accounted for the difference since the mortality rate on the waiting list for the two groups was similar, as were their physiologic characteristics at the time of transplantation.
One caution in interpreting these results is that the relatively small sample size of the LVRS group does not provide sufficient power to be able to detect small-to-moderate differences in survival or other outcomes. It is also possible that there was a selection bias in the LVRS group. It is likely that this group of patients was highly motivated and otherwise "pristine" transplant candidates. It is similarly conceivable that some less robust patients who might have otherwise been considered reasonable candidates for lung transplantation were excluded from transplantation because of their prior LVRS. There does not appear to have been a center bias to explain our results as 78% of the procedures were performed at 29 different centers, with the two highest volume centers accounting for the remaining 22%.
With the results of our study, it is enticing to attempt placing LVRS and lung transplantation in context with one another. However, one needs to be cognizant that, as a group, appropriate LVRS candidates have milder disease than lung transplant candidates, which limits the ability to do direct comparisons of outcomes between these two procedures. Patients who present for LVRS may be too early in their course to consider transplantation, and, similarly, the conditions of those who present for transplantation may be too far advanced for LVRS to be an option. However, there is a group of patients who at the time of initial presentation may be candidates for either of the two procedures.12 It is also important to be cognizant of the inclusion criteria of the NETT, as only a minority of all COPD patients were included. The characterization of patients into one of the four groups described depends first on them fulfilling the other inclusion criteria of the study. With these and other caveats in mind, then, in those patients with predominantly upper lobe disease and low exercise tolerance, who choose a surgical option for their COPD, we contend that LVRS should be favored. Similarly, we hypothesize that in the group of patients who have a high exercise capacity with predominantly upper lobe disease, if their symptoms are such that surgery is contemplated, then LVRS should be favored since there are improvements in QOL with a mortality rate of only 16.5% at a median follow-up time of 29 months. This survival time is no different from that seen with medical management and compares very favorably with the expected outcomes after lung transplantation.11 In those patients with predominantly non-upper lobe disease and low exercise tolerance, the mortality rates that can be expected from LVRS and transplantation appear equivalent to 67% of the LVRS patients surviving a mean time of 29 months vs a 2-year survival rate of 66% in our cohort of non-LVRS lung transplant recipients.7 In these situations, other factors such as the likelihood and degree of improvement in QOL as well as financial considerations should be factored into the decision. In the two high-risk groups of patients identified in the NETT study, the decision between transplantation and LVRS is quite clearly weighted in favor of the former.
In summary, it appears that a history of LVRS does not impact negatively on patients subsequent posttransplant course and, hence, on their candidacy for transplantation. If patients are deemed to be suitable LVRS candidates, there is no evidence to suggest that the possibility of transplantation in the future should impact on this decision. Indeed, based on the NETT results and other reports,121314 LVRS may help to defer the need for transplantation in some patients.
| Footnotes |
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Received for publication December 4, 2003. Accepted for publication June 21, 2004.
| References |
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