| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Guest Access | Sign In via User Name/Password
|
|
|
|||||||
Guest Access | Sign In via User Name/Password |
|||||||||
Durham, NC
Drs. Snyder and Palmer are affiliated with the Division of Pulmonary and Critical Care, Department of Medicine, Duke University.
Correspondence to: Scott M. Palmer, MD, MHS, Division of Pulmonary and Critical Care, Department of Medicine, Duke University, Box 387, 128 Bell Building, Erwin Road, Durham, NC 27710; e-mail: palme002{at}mc.duke.edu
Within the past 20 years, lung transplantation has evolved as an effective therapy in the treatment of patients with advanced lung diseases. Unfortunately, long-term lung transplant outcomes remain disappointing compared to those in other solid organ transplant populations.1 The primary reason for the decreased lung transplant patient survival rate is the development of bronchiolitis obliterans syndrome (BOS), which is a condition of progressive airflow obstruction that is generally thought to reflect chronic lung rejection. Because of this limited survival of patients posttransplant, a greater understanding of the health-related quality of life (HRQOL) of lung transplant recipients is critical to evaluate the utility of this therapy. Both cross-sectional studies and prospective studies2345 have confirmed that recipients’ experience improved HRQOL after lung transplantation on a variety of validated instruments. In fact, improvements in HRQOL are a major consideration in the decision to offer lung transplantation to patients with several end-stage lung diseases, such as emphysema, in which the actual survival benefit of transplant has been questioned.6
While it is clear that lung transplantation can improve HRQOL, the specific factors that influence quality of life posttransplant have not been well-evaluated. Several studies278 have shown an association between objective measurements of posttransplant pulmonary function and HRQOL. The correlation of declining pulmonary function with the development of BOS is associated with decreased HRQOL.278 What is not clear, however, is the extent to which bilateral transplantation offers improved HRQOL compared to single-lung transplantation. We have previously shown910 that single-lung transplant recipients develop BOS at an earlier time compared to bilateral lung transplant recipients and that single-lung recipients are at risk for a number of unique complications, including native lung hyperinflation, malignancy, or infections. Thus, one might expect that single-lung transplant recipients should have a lower HRQOL compared to bilateral lung transplant recipients, which is consistent with results from a 2001 cross-sectional study11 of HRQOL in 255 lung recipients posttransplant.
This is why the findings of Gerbase et al,12 which are presented in this issue of CHEST (see page 1371), are surprising. They compare posttransplant HRQOL among 44 lung transplant recipients (single lung transplants, 14; bilateral lung transplants, 30) who survived at least 2 years of posttransplant follow-up. Despite the improved FEV1 and lower incidence of BOS in bilateral transplant recipients compared to single-lung transplant recipients, respiratory disease-specific HRQOL was not significantly different in the two transplant groups. However, there is a trend toward a difference favoring the bilateral transplant group when comparing the absolute mean difference between the two groups.
The strengths of the study include the use of validated quality-of-life measurements for general well-being (visual analog scale) as well as the respiratory disease-specific St. George Respiratory Questionnaire (SGRQ), prospective measurements before and after transplantation, appropriate statistical methodology, and a median follow-up time of > 5 years. The findings of Gerbase et al12 raise the following important medical and ethical question: should single-lung transplantation be the standard of care for all diseases in which either single-lung or bilateral transplantation would be appropriate?
The advantage of single-lung transplantation is obvious. With the limited donor lung supply, the prospect of offering single-lung transplants to two recipients, as opposed to one bilateral lung recipient, is appealing. However, before this question can be fully answered, we also need to consider the limitations of the work by Gerbase et al.12 First, the study was relatively small and included relatively few single-lung transplant recipients (n = 14). Second, there is a trend toward improved SGRQ scores in bilateral lung transplant recipients compared to single-lung transplant recipients at later time points (mean score at 5 years, 87 vs 71, respectively). The negative statistical results of the study could be a type II error related to underpowering (details regarding a formal power calculation were not provided). Third, the study only considers HRQOL but not quality-adjusted life years (QALYs). International registry data would suggest that long-term survival is superior among bilateral transplant recipients compared to single-lung transplant recipients. The results of the study by Gerbase et al12 would be consistent with this observation in that 3 of 14 single-lung transplant recipients (21%) died during follow-up, while only 10% of bilateral transplant recipients died (3 of 30 patients). A formal QALYs evaluation in bilateral lung transplant recipients is not possible in the study by Gerbase et al12 because 18 transplant recipients who died within the first 2 years were excluded from analysis. Based on the data available in the article, bilateral transplantation appears to be superior in terms of QALYs. Furthermore, if there were a significantly greater number of single-lung transplant recipients among those early deaths, then bilateral lung transplantation would offer a striking advantage in evaluations of QALYs.
The study by Gerbase et al12 also raises an important point that HRQOL is not simply a function of physical condition. Consistent with this observation, FEV1 proved to correlate poorly with SGRQ, particularly in single-lung transplant recipients. We have observed13 that psychological disorders, including anxiety and depression, are common among individuals with end-stage lung disease awaiting transplantation. Furthermore, perceived HRQOL was lower in individuals with a psychological disorder, even controlling for a degree of pulmonary function impairment and disease diagnosis.13 Others14 have also found that the presence of psychological disorders pretransplant or posttransplant can negatively impact HRQOL in lung transplant recipients.
In summary, Gerbase et al12 contribute to our understanding of HRQOL after lung transplantation. The study clearly demonstrates a significant and sustained increase in HRQOL after lung transplantation compared to pretransplant values. Posttransplant HRQOL is an important factor in the decision to undergo lung transplantation, particularly in light of the median posttransplant survival time of approximately 5 years. The study also demonstrates that HRQOL is not simply a product of objective measures of lung function as the authors found no significant difference in HRQOL in single-lung transplant recipients compared to bilateral lung transplant recipients. Unfortunately, the study by Gerbase et al12 does not consider the QALYs benefit of lung transplantation, which is critical to any analysis of the overall effectiveness of single-lung vs bilateral lung transplantation. Even if HRQOL was found to be identical between single-lung and bilateral lung transplantation, the superior long-term survival time among bilateral lung transplant recipients would lead to an improved long-term QALYs benefit. Moreover, the work of Gerbase et al12 shows a trend toward improved HRQOL after bilateral lung transplantation compared to that after single-lung transplantation. Thus, one could make a compelling argument that bilateral lung transplantation should be pursued whenever possible because of far greater QALYs benefit compared to single-lung transplantation.
References
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
