Simultaneous Thoracic and Abdominal Transplantation
Simultaneous Thoracic and Abdominal Transplantation
This is a retrospective cohort study using the UNOS database from 1987 through October 2010. Institutional Review Board approval was obtained from the Hospital of the University of Pennsylvania (IRB # 812829).
A total of 1801 STA candidates simultaneously wait-listed for combined thoracic and abdominal organ transplantation were identified in the UNOS thoracic, kidney/pancreas and liver data sets. Our analysis included four dual-organ combinations (SHK = 1420, SHLi = 218, SLuLi = 122, SLuK = 41). Although we identified several other dual (heart–pancreas; N = 5, lung–pancreas; N = 3) and various triple-organ combinations (N = 33), these groupings were excluded due to inadequate number of patients. Among patients with multiple entries in a single data set, only the most recent listing was included, as determined by the wait-list end date. Since a patient listed for a STA may have had slightly different listing and removal dates for each organ, time spent on the thoracic organ wait-list was used to approximate overall STA wait-list time.
Comparison groups comprised of patients wait-listed for a single identical thoracic or abdominal organ (heart-alone = 72 084; lung-alone = 32 393; liver-alone = 163 604; kidney-alone = 441 666). As with STA wait-list cohorts, only the most recent entry was included for those patients with multiple entries.
Eight hundred thirty-six STA recipients (SHK = 684; SHLi = 92; SLuLi = 42; SLuK = 18) who received a thoracic and abdominal organ from the same donor were identified. Comparison groups consisted of all transplant recipients of a single thoracic or single abdominal organ (heart-alone = 47 440; lung-alone = 20 384; liver-alone = 80 332; kidney-alone = 189 038). The first transplant was used as the reference point for control patients who received multiple single-organ transplants. Both single and bilateral lung transplants were included in the controls. Recipients of living donor kidneys and livers, and recipients of small-bowel and multivisceral transplants were excluded from our analyses.
Continuous variables were described with measures of central tendency and categorical variables were listed as percentages of the total cohort. Removal from the wait-list for death or deteriorating health conditions were considered mortality events. Removal for all other reasons, including transplantation, were censored. Patient survival was estimated using Kaplan–Meier survival and compared with log-rank testing. Survival time for candidates was measured from the time of listing and events were measured as removal from the list due to death or deteriorating health. Survival benefit of STA was quantified by comparing risk of death following transplant to the risk of death while remaining on the wait-list for both organs. For this analysis, models were created where candidates contributed time to the wait-list, but were censored at time of transplant, and subsequently accrued time in the transplant risk group. To quantify differences in survival between wait-list and transplant groups, Cox regression models were constructed with age, gender and race entered as covariates. The threshold for statistical significance for all testing was set as p < 0.05. Analysis was performed using SPSS Statistics version 19.
Patients and Methods
Study Design and Patient Population
This is a retrospective cohort study using the UNOS database from 1987 through October 2010. Institutional Review Board approval was obtained from the Hospital of the University of Pennsylvania (IRB # 812829).
A total of 1801 STA candidates simultaneously wait-listed for combined thoracic and abdominal organ transplantation were identified in the UNOS thoracic, kidney/pancreas and liver data sets. Our analysis included four dual-organ combinations (SHK = 1420, SHLi = 218, SLuLi = 122, SLuK = 41). Although we identified several other dual (heart–pancreas; N = 5, lung–pancreas; N = 3) and various triple-organ combinations (N = 33), these groupings were excluded due to inadequate number of patients. Among patients with multiple entries in a single data set, only the most recent listing was included, as determined by the wait-list end date. Since a patient listed for a STA may have had slightly different listing and removal dates for each organ, time spent on the thoracic organ wait-list was used to approximate overall STA wait-list time.
Comparison groups comprised of patients wait-listed for a single identical thoracic or abdominal organ (heart-alone = 72 084; lung-alone = 32 393; liver-alone = 163 604; kidney-alone = 441 666). As with STA wait-list cohorts, only the most recent entry was included for those patients with multiple entries.
Eight hundred thirty-six STA recipients (SHK = 684; SHLi = 92; SLuLi = 42; SLuK = 18) who received a thoracic and abdominal organ from the same donor were identified. Comparison groups consisted of all transplant recipients of a single thoracic or single abdominal organ (heart-alone = 47 440; lung-alone = 20 384; liver-alone = 80 332; kidney-alone = 189 038). The first transplant was used as the reference point for control patients who received multiple single-organ transplants. Both single and bilateral lung transplants were included in the controls. Recipients of living donor kidneys and livers, and recipients of small-bowel and multivisceral transplants were excluded from our analyses.
Statistical Analysis
Continuous variables were described with measures of central tendency and categorical variables were listed as percentages of the total cohort. Removal from the wait-list for death or deteriorating health conditions were considered mortality events. Removal for all other reasons, including transplantation, were censored. Patient survival was estimated using Kaplan–Meier survival and compared with log-rank testing. Survival time for candidates was measured from the time of listing and events were measured as removal from the list due to death or deteriorating health. Survival benefit of STA was quantified by comparing risk of death following transplant to the risk of death while remaining on the wait-list for both organs. For this analysis, models were created where candidates contributed time to the wait-list, but were censored at time of transplant, and subsequently accrued time in the transplant risk group. To quantify differences in survival between wait-list and transplant groups, Cox regression models were constructed with age, gender and race entered as covariates. The threshold for statistical significance for all testing was set as p < 0.05. Analysis was performed using SPSS Statistics version 19.
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