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Kidney Paired Donation and Optimizing the Use of Live Donor Organs
RENAL TRANSPLANTATION AND RENOVASCULAR HYPERTENSION
ogists, who increased their annual volume 3.9-fold. More than a threefold difference in rates of use of renal artery interventional procedures across CMS regions was found. In the Southeast region, the volume of renal artery interventions by cardiologists increased more than 15-fold. CONCLUSION: Among Medicare beneficiaries, the volume of percutaneous renal artery interventions is increasing rapidly, whereas the volume of renal artery surgery is declining. Most growth in percutaneous renal artery revascularization is attributed to increased performance by cardiologists; explosive growth in annual procedure volume by cardiologists occurred in some regions. Marked disparity in use among CMS regions was found. Editorial Comment: This article chronicles the changes in how renal artery disease is treated using data collected from the CMS. The data show that renal artery interventions increased by 62% between 1996 and 2000 but that conventional open renal revascularization decreased by 45%. There was a 2.4-fold increase in endovascular interventions in 2000. Information was also obtained regarding the medical specialty of the provider and the region of the country where service was provided. This information proved interesting. The provider type accounting for the largest increase in use during this period was cardiology, which had a 287% increase from 1996 to 2000. There was wide regional variation in performance of renal artery interventions but the Keystone region (Pennsylvania and New Jersey) and Southeast had the highest increase. During the last 10 years intervention for renal artery disease has increased overall but has clearly shifted from open surgical intervention to endovascular management. The sharp increase in renal artery interventions by cardiologists is a recent phenomenon. This procedure may be performed as part of the cardiac catheterization (the so-called “drive-by” renal angiogram), and the indications for intervention in this setting are less well defined. This practice has created some concern in the nephrology community. Nonetheless, the article highlights the significant changes in practice related to renal artery interventions. Similar analyses of CMS data may be useful to track practice trends for other urological diseases. David A. Goldfarb, M.D. Kidney Paired Donation and Optimizing the Use of Live Donor Organs D. L. SEGEV, S. E. GENTRY, D. S. WARREN, B. REEB AND R. A. MONTGOMERY, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland JAMA, 293: 1883–1890, 2005 CONTEXT: Blood type and crossmatch incompatibility will exclude at least one third of patients in need from receiving a live donor kidney transplant. Kidney paired donation (KPD) offers incompatible donor/ recipient pairs the opportunity to match for compatible transplants. Despite its increasing popularity, very few transplants have resulted from KPD. OBJECTIVE: To determine the potential impact of improved matching schemes on the number and quality of transplants achievable with KPD. DESIGN, SETTING, AND POPULATION: We developed a model that simulates pools of incompatible donor/recipient pairs. We designed a mathematically verifiable optimized matching algorithm and compared it with the scheme currently used in some centers and regions. Simulated patients from the general community with characteristics drawn from distributions describing end-stage renal disease patients eligible for renal transplantation and their willing and eligible live donors. MAIN OUTCOME MEASURES: Number of kidneys matched, HLA mismatch of matched kidneys, and number of grafts surviving 5 years after transplantation. RESULTS: A national optimized matching algorithm would result in more transplants (47.7% vs 42.0%, P⬍.001), better HLA concordance (3.0 vs 4.5 mismatched antigens; P⬍.001), more grafts surviving at 5 years (34.9% vs 28.7%; P⬍.001), and a reduction in the number of pairs required to travel (2.9% vs 18.4%; P⬍.001) when compared with an extension of the currently used first-accept scheme to a national level. Furthermore, highly sensitized patients would benefit 6-fold from a national optimized scheme (2.3% vs 14.1% successfully matched; P⬍.001). Even if only 7% of patients awaiting kidney transplantation participated in an optimized national KPD program, the health care system could save as much as $750 million. CONCLUSIONS: The combination of a national KPD program and a mathematically optimized matching algorithm yields more matches with lower HLA disparity. Optimized matching affords patients the flexibility of customizing their matching priorities and the security of knowing that the greatest number of high-quality matches will be found and distributed equitably. Editorial Comment: The central dilemma of solid organ transplantation remains a shortage of organs. Many potential kidney recipients have willing and medically suitable living donors. However, ABO blood type mismatch or a positive donor specific crossmatch makes the pair incompatible. In the United States there is a 35% chance that any given pair will be ABO incompatible, while 30% of patients on waiting lists are sensitized and may have significant crossmatch incompatibility. There are 2 methods to deal with these dilemmas. One is immunological desensitization, which is resource intensive with the possibility of a compromised outcome. The second is paired donation programs (PDPs), or donor “swap,” to identify donor/recipient pairs with greater immune compat-
1911
1912
RENAL TRANSPLANTATION AND RENOVASCULAR HYPERTENSION
ibility. There is increasing interest throughout the country in such PDPs. Nonetheless, there are relatively few operational programs at present. To increase the number of transplants, there needs to be a critical mass of donor/recipient pairs to facilitate matching, which will make it difficult for individual centers to do this alone. The preferred model would be a regional consortium or a national system. Operating PDPs across a wider geographic area increases logistic, but real, barriers regarding donor (or recipient) travel. The current study uses United Network for Organ Sharing data on patients presently on waiting lists to develop a model that simulates a national PDP. The authors created a model that optimizes HLA concordance to enhance the number of grafts surviving at 5 years. While it is a theoretical construct, they suggest that 48% of incompatible pairs may ultimately be matched through such a system. In a cost analysis this outcome represents significant financial savings over maintaining such patients on dialysis or using desensitization protocols. Such PDPs are likely to increase in the near future, and there will be considerable discussion regarding nationalization of such an effort. David A. Goldfarb, M.D.
ogists, who increased their annual volume 3.9-fold. More than a threefold difference in rates of use of renal artery interventional procedures across CMS regions was found. In the Southeast region, the volume of renal artery interventions by cardiologists increased more than 15-fold. CONCLUSION: Among Medicare beneficiaries, the volume of percutaneous renal artery interventions is increasing rapidly, whereas the volume of renal artery surgery is declining. Most growth in percutaneous renal artery revascularization is attributed to increased performance by cardiologists; explosive growth in annual procedure volume by cardiologists occurred in some regions. Marked disparity in use among CMS regions was found. Editorial Comment: This article chronicles the changes in how renal artery disease is treated using data collected from the CMS. The data show that renal artery interventions increased by 62% between 1996 and 2000 but that conventional open renal revascularization decreased by 45%. There was a 2.4-fold increase in endovascular interventions in 2000. Information was also obtained regarding the medical specialty of the provider and the region of the country where service was provided. This information proved interesting. The provider type accounting for the largest increase in use during this period was cardiology, which had a 287% increase from 1996 to 2000. There was wide regional variation in performance of renal artery interventions but the Keystone region (Pennsylvania and New Jersey) and Southeast had the highest increase. During the last 10 years intervention for renal artery disease has increased overall but has clearly shifted from open surgical intervention to endovascular management. The sharp increase in renal artery interventions by cardiologists is a recent phenomenon. This procedure may be performed as part of the cardiac catheterization (the so-called “drive-by” renal angiogram), and the indications for intervention in this setting are less well defined. This practice has created some concern in the nephrology community. Nonetheless, the article highlights the significant changes in practice related to renal artery interventions. Similar analyses of CMS data may be useful to track practice trends for other urological diseases. David A. Goldfarb, M.D. Kidney Paired Donation and Optimizing the Use of Live Donor Organs D. L. SEGEV, S. E. GENTRY, D. S. WARREN, B. REEB AND R. A. MONTGOMERY, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland JAMA, 293: 1883–1890, 2005 CONTEXT: Blood type and crossmatch incompatibility will exclude at least one third of patients in need from receiving a live donor kidney transplant. Kidney paired donation (KPD) offers incompatible donor/ recipient pairs the opportunity to match for compatible transplants. Despite its increasing popularity, very few transplants have resulted from KPD. OBJECTIVE: To determine the potential impact of improved matching schemes on the number and quality of transplants achievable with KPD. DESIGN, SETTING, AND POPULATION: We developed a model that simulates pools of incompatible donor/recipient pairs. We designed a mathematically verifiable optimized matching algorithm and compared it with the scheme currently used in some centers and regions. Simulated patients from the general community with characteristics drawn from distributions describing end-stage renal disease patients eligible for renal transplantation and their willing and eligible live donors. MAIN OUTCOME MEASURES: Number of kidneys matched, HLA mismatch of matched kidneys, and number of grafts surviving 5 years after transplantation. RESULTS: A national optimized matching algorithm would result in more transplants (47.7% vs 42.0%, P⬍.001), better HLA concordance (3.0 vs 4.5 mismatched antigens; P⬍.001), more grafts surviving at 5 years (34.9% vs 28.7%; P⬍.001), and a reduction in the number of pairs required to travel (2.9% vs 18.4%; P⬍.001) when compared with an extension of the currently used first-accept scheme to a national level. Furthermore, highly sensitized patients would benefit 6-fold from a national optimized scheme (2.3% vs 14.1% successfully matched; P⬍.001). Even if only 7% of patients awaiting kidney transplantation participated in an optimized national KPD program, the health care system could save as much as $750 million. CONCLUSIONS: The combination of a national KPD program and a mathematically optimized matching algorithm yields more matches with lower HLA disparity. Optimized matching affords patients the flexibility of customizing their matching priorities and the security of knowing that the greatest number of high-quality matches will be found and distributed equitably. Editorial Comment: The central dilemma of solid organ transplantation remains a shortage of organs. Many potential kidney recipients have willing and medically suitable living donors. However, ABO blood type mismatch or a positive donor specific crossmatch makes the pair incompatible. In the United States there is a 35% chance that any given pair will be ABO incompatible, while 30% of patients on waiting lists are sensitized and may have significant crossmatch incompatibility. There are 2 methods to deal with these dilemmas. One is immunological desensitization, which is resource intensive with the possibility of a compromised outcome. The second is paired donation programs (PDPs), or donor “swap,” to identify donor/recipient pairs with greater immune compat-
1911
1912
RENAL TRANSPLANTATION AND RENOVASCULAR HYPERTENSION
ibility. There is increasing interest throughout the country in such PDPs. Nonetheless, there are relatively few operational programs at present. To increase the number of transplants, there needs to be a critical mass of donor/recipient pairs to facilitate matching, which will make it difficult for individual centers to do this alone. The preferred model would be a regional consortium or a national system. Operating PDPs across a wider geographic area increases logistic, but real, barriers regarding donor (or recipient) travel. The current study uses United Network for Organ Sharing data on patients presently on waiting lists to develop a model that simulates a national PDP. The authors created a model that optimizes HLA concordance to enhance the number of grafts surviving at 5 years. While it is a theoretical construct, they suggest that 48% of incompatible pairs may ultimately be matched through such a system. In a cost analysis this outcome represents significant financial savings over maintaining such patients on dialysis or using desensitization protocols. Such PDPs are likely to increase in the near future, and there will be considerable discussion regarding nationalization of such an effort. David A. Goldfarb, M.D.