Expanding the Donor Pool: Can the Spanish Model Work in the United States?

Authors


*Corresponding author: John P. Roberts, robertsj@surgery.ucsf.edu

Abstract

Since the creation of the Organizacion Nacional de Trasplantes (ONT) in 1989, the organ donation rate in Spain has doubled. Although often attributed to improved donor recruitment efforts, this increase may also represent higher utilization of marginal donors. Therefore, age-related donor recruitment in Spain and the US was evaluated. Data from the ONT, the US Scientific Registry of Transplant Recipients (SRTR), the US Census Bureau, and the Tempus databank of Spain's Instituto Nacional de Estadistica (INE) were analyzed. Between 1989 and 1999, the number of donors in Spain increased from 14.3 to 33.7 per million population (pmp; 136% increase) compared with an increase in the US from 16.2 to 21.5 donors pmp (33%). The largest difference between Spain and the US in the increased number of donors was in the 45-year-old group, representing 30.3% of donors in Spain in 1999 (44 donors pmp). If the US increased its older donor rates to match Spain's, an incremental 1235 donors per year would be realized. The high Spanish organ donation rates are largely attributable to increased use of older donors. Utilizing similar proportions of older donors in the US would increase the donor pool by almost 40%.

Introduction

In the United States, organ transplantation has been limited by the shortage of available donor organs, resulting in a significant imbalance between organ availability and the need for organ transplantation services. The gap between supply and demand has been growing at an especially alarming rate for the past 10 years. In 1999 there were more than 72 000 registrations on the OPTN transplant waitlists, which represented a 230% increase since 1990. During 1999 more than 6000 patients were removed from the list because of death while awaiting transplantation. Furthermore, many potential candidates for transplantation die before they are placed on the waiting list. Unfortunately, the number of cadaveric organ donors in the US increased only 30% between 1990 and 1999 (1).

Similar trends have been observed by European organ donor networks, although Spain appears to be a notable exception. Since 1989, when the Organizacion Nacional de Trasplantes (ONT) was created in Spain, the number of cadaveric donors in Spain has increased at a rate far higher than that seen in other European countries and the US (2). This effort has been so successful that it has led to a completely unique finding – a 28% decrease in size of the waiting list for kidney transplantation in Spain between 1991 and 1997 (3). During this same time period, the US kidney waiting list nearly doubled in size (1).

The so-called ‘Spanish Model’ has been outlined as a structure of national, regional, and local or in-hospital efforts to increase organ donation. The management structure consists of a front-line in-hospital transplant coordinator who is fully involved and accountable for the donor recruitment effort. Furthermore, transplant donor coordination has been ‘professionalized’ and most coordinators are qualified doctors, mainly intensive care specialists and nephrologists, who have dedicated time allocated to transplant coordination (4). Moreover, the Spanish system adheres to the principles of decentralization of the donor coordination effort through the use of regional coordinators and the establishment of organ procurement as the main priority for national, regional, and hospital coordinators.

There has been great interest in implementing a ‘Spanish Model’ for organ donation in the US and other countries. Calls for funding similar types of organizational structures have been made on the grounds that this change will result in an increase in organ availability.

Although the change in the number of donors in Spain may be a result of this paradigm shift in organ procurement structure, it may also be attributable to increased organ utilization from donors previously thought to be too old. The higher utilization rate may be responsible for the increase in the number of transplants performed in Spain. We hypothesized that an increase in the number of older donors providing organs is responsible for much of Spain's high rate of cadaveric organ donation.

Methods

Spain

The ONT database was evaluated for all Spanish organ donors for the years 1989 through 1999. Donor characteristics that were examined included age, type of donor (living, cadaveric), organ type, and regional distribution. For the present analysis the focus was on cadaveric donors of any organ type. Population data was extracted from analysis of Spain's Instituto Nacional de Estadistica (INE) database. Population data were stratified by age and examination of death rates by cause was performed.

US

Data from the US SRTR as reported to the Organ Procurement and Transplantation Network (OPTN) were evaluated for all organ donors in the US for the years 1989 through 1999. Donor characteristics were examined and analyzed as described earlier for Spain. Population data were extracted from the US Census Bureau (USCB) and the US Center for Disease Control (CDC) National Center for Health Care Statistics (NCHS) databases.

World wide web

Data were gathered from world wide web sites of the respective organizations including the ONT (http://www.msc.es/ont), INE (http://www.ine.es), OPTN (http://www.optn.org), USCB (http://www.census.gov), and the CDC (http://www.cdc.gov/nchs). Additional data were obtained by query request to the specific organizations.

Analysis and statistics

Annual cadaveric organ donation rates were determined for the following donor age groups: <15 years, 15–30 years, 30–45 years, 45–60 years, and >60 years. Because the total population of the US is almost 7-fold the total population of Spain, annual organ donors were normalized to the number of donors per million population. Multiple regression analyses were performed to determine the difference in the slope of change in organ donation rates with 95% confidence intervals. Estimates of the potential donor rates in the US were made based on application of Spain's reported donor rates per million population.

As cerebrovascular diseases are leading causes of death among older patients and could influence organ donation rates, death statistics in the US and Spain were compared. Moreover, as not all donated organs are suitable for transplantation the organ discard rates in Spain and the US were examined.

Results

Spain

In 1989 the ONT registered a total of 550 cadaveric organ donors and the INE reported the total population of Spain as 38.8 million (14.3 donors per million). In 1999 ONT registered 1334 organ donors while the total population was little changed at 39.2 million (33.7 donors per million). This represents a 136% increase in cadaveric donation per million population over a 10-year period (Figure 1).

Figure 1.

Number of cadaveric organ donors per million population by year in Spain and the US. In the 10 years since 1989, there has been a 136% increase in Spain and only a 32% increase in the US.

US

In 1989 the OPTN/SRTR registered a total of 4011 cadaveric organ donors and the USCB reported the total population of the US as 247 million (16.2 donors per million). In 1999 there were a total of 5843 organ donors and an increase in the total population to 273 million (21.4 donors per million). This represents a 46% increase in the total number of donors but only a 32% increase in the number of cadaveric donors per million during this 10-year period (Figure 1).

Change in donor distribution by age

The total numbers of Spanish and US donors between 1992 and 1999 in each age category are shown in Figure 2. In 1999 the two oldest age categories accounted for approximately 57% of the total donor pool in Spain. In fact donors >60 years old comprise the single largest age category in Spain, and now represent more than 30% of the total donor pool, compared with only 13.3% in the US.

Figure 2.

Figure 2.

Total number of cadaveric organ donors by year in each age group: Spain (A) and the US (B).

Figure 2.

Figure 2.

Total number of cadaveric organ donors by year in each age group: Spain (A) and the US (B).

Using a multiple regression model, the differences in the slopes of the change in donors per million at each age group was calculated and 95% confidence intervals determined. These differences are shown in Figure 3. There was no significant difference between Spain and the US in the age groups <45 years. However, there were significant differences in the rate of change in donation for the 45–60-year-old group (1.21 ± 0.87) and the >60-year-old group (3.55 ± 0.28). This analysis demonstrates that the primary increase in the Spanish system was the use of older donors as compared with the US.

Figure 3.

Comparison of the rate of change in the number of cadaveric donors over time. The difference in the slopes of the change in the number of cadaveric donors per million for each age group with 95% confidence intervals are shown for Spain and the US. No significant differences are seen for age groups <45 years. The greatest difference is seen for the >60-year-old group.

Organ utilization rates

Organ discard rates have been on the rise in Spain and are shown for kidneys and livers in Figure 4(A). Similarly rates in the US are shown in Figure 4(B). The number of kidneys per million donors that were recovered but not used or consented but not recovered slowly increased over the past 10 years in the US. However the number per million population for livers has actually decreased during this same period. This is in contrast to the trends in Spain that have shown a rise in discard rates for both organs. With the higher rates of organ procurement from older donors, the percentage of discarded organs is higher in Spain than in the US. In 1999 the percentage of discarded kidneys and livers were 21% and 18% for Spain and 11% and 5.5% for the US, respectively.

Figure 4.

Percentage of cadaveric donor organs discarded. The annual discard rates for kidneys and livers in Spain (A) and the US (B) are shown.

Cerebrovascular death rates

In 1998 there were a total of 36 478 cerebrovascular deaths among persons aged 60 years and older in Spain (4042 per million) compared with 144 734 cerebrovascular deaths among such persons in the US (3242 per million). While the death rate from cerebrovascular causes is high in the older Spanish population, and could be an explanation for the higher rate of recovery of organs from this population, the 25% higher incidence of cerebrovascular death in Spain is much smaller than the 150% higher Spanish donation rate from individuals aged older than 60 years (36.6 donors per million) compared with the US (14.7 donors per million).

Discussion

Since the creation of Spain's National Transplant Organization (ONT) in 1989, the number of cadaveric donors in Spain has steadily increased (2). Although this change may reflect a paradigm shift in societal and cultural attitudes towards organ donation, it may also be attributable to other effects related to organ utilization. Our data demonstrates that the increase in the availability of organs in Spain is primarily through the use of older donors, which may result either from increased organ recovery from potential donors in this age group or greater utilization of these donors in Spain as compared with the US. If a similar proportion of older donors were recovered and utilized in the US, the impact would be to increase the donor pool by almost 40%. In comparison to Spain, the US has also experienced increases in the number of donors in the older age groups, however, this effect has been much smaller than in Spain. By 1999 donors >60 year olds comprised only 13.3% of the total US donor pool, representing a near doubling of the percentage of donors >60 years providing organs in 1992. This suggests that the transplant centers seem to be able to accept the use of the older donor organ but the rates of acceptance among centers in the US have lagged behind those in Spain. During this same time, the percentage of donors >60 years old in Spain's donor pool tripled from 10% to 30.3%.

Our data does not allow for differentiation between changes in organ donation or utilization as affecting increases in organ donation and transplantation in Spain. This distinction is important as the allocation of resources to increase organ donation needs to be focused and the results from Spain make the Spanish Model a tempting target for resource allocation. If the implementation of this model is dependent upon the increased utilization of the older donor organs in a system where these organs are unlikely to be used, the model will fail.

Increased utilization of older donors will not result in accrual of all of these donors' kidneys to the pool of transplantable organs. For example, 538 kidneys were discarded in Spain in 1999. During this time a total of 1334 donors were procured. Assuming that two kidneys were available from each donor, this means that greater than 20% of all procured kidneys were not utilized. This compares with 132 or 9.7% in 1990 (5). Thus along with the rise in the total number of donors in Spain over the past decade, the number of unutilized kidneys as a percentage of the total number of donors has disproportionately increased. Similar figures exist for livers as well. The overall rates are lower for the US where a total kidney discard rate of 11% was noted in 1999 with a range of 4.2% for the <15-year-old age group to 42% for the >60-year-old age group (1). There may also be marginal donor criteria other than age that have an impact on total procurement and utilization rates. Taken together this suggests that the increased procurement of marginal donors would lead to a smaller increase in the actual number of organs available for transplantation. Nonetheless the net effect in Spain has been to increase the number of organs available for transplantation as evidenced by the number of patients transplanted resulting in the decrease in the number of patients on the waiting list.

One potential criticism to this approach is that the use of older donors in organ transplantation might be accompanied by a decrease in graft survival for kidney, liver and heart transplants (6,7); although the effect may be much less pronounced for livers (8). If the number of organ transplantations is increased by the use of these older donors, this could result in poorer survival and an increased cost of transplantation. It is possible that the overall survival of the patients awaiting transplantation can be increased if these organs from older donors are used in patients who are likely to die while awaiting transplantation. The older donor organs, which might have otherwise been discarded, might be usable in these older recipients. There is additional rationale for this approach, as a lower incidence of acute rejection and immunologic reactivity when kidneys from older donors are transplanted into older recipients has been observed (9,10). Moreover it has recently been shown that the life expectancy in recipients of marginal cadaveric donor kidneys, including older donor kidneys, is increased when compared with chronic renal replacement therapy (11).

The increased utilization of older donors may not be a panacea for the problem of organ shortage. However, if there are advantages to transplantation of these older donor organs in terms of survival, barriers that prevent the utilization should be removed. This would include a change in the payment structure for organ transplantation to compensate for the increased cost of care of the recipients of these organs after transplantation. This could include a modifier of the DRG code that would be employed when an older donor or other marginal kidney was used. The increased use of older donors is unlikely to be the only reason that Spain has been so successful with its organ donation efforts. However it is the most tangible and adoptable aspect of their system. Efforts to increase organ donation in the US should incorporate a change in recipient wait-listing strategies to take into account recipient characteristics that may facilitate the appropriate utilization of the older donor. The recent institution of the expanded donor concept in kidney transplantation in the US is a step in the right direction.

Acknowledgments

The authors would like to express great appreciation to Natividad Cuende, MD, PhD, of Spain's Organizacion Nacional de Trasplantes for her terrific assistance with the Spanish data, to Robert Merion, MD, Department of Surgery, University of Michigan, for his editorial input, and to Peter Bacchetti, PhD, without whose expert assistance with the statistical analyses this effort would not have been possible. The authors also recognize the funding support of the American Society of Transplant Surgeons and the Association of Organ Procurement Organizations.

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