Regional differences in recipient waitlist time and pre- and post-transplant mortality after the 2006 United Network for Organ Sharing policy changes in the donor heart allocation algorithm

Abstract

Objectives: This study examined the impact of the United Network for Organ Sharing (UNOS) policy changes for regional differences in waitlist time and mortality before and after heart transplantation.

Background: The 2006 UNOS thoracic organ allocation policy change was implemented to allow for greater regional sharing of organs for heart transplantation.

Methods: We analyzed 36,789 patients who were listed for heart transplantation from January 1999 through April 2012. These patients were separated into 2 eras centered on the July 12, 2006 UNOS policy change. Pre- and post-transplantation characteristics were compared by UNOS regions.

Results: Waitlist mortality decreased nationally (up to 180 days: 13.3% vs. 7.9% after the UNOS policy change, p < 0.001) and within each region. Similarly, 2-year post-transplant mortality decreased nationally (2-year mortality: 17.3% vs. 14.6%; p < 0.001) as well as regionally. Waitlist time for UNOS status 1A and 1B candidates increased nationally 17.8 days on average (p < 0.001) with variability between the regions. The greatest increases were in Region 9 (59.2-day increase, p < 0.001) and Region 4 (41.2-day increase, p < 0.001). Although the use of mechanical circulatory support increased nearly 2.3-fold nationally in Era 2, significant differences were present on a regional basis. In Regions 6, 7, and 10, nearly 40% of those transplanted required left ventricular assist device bridging, whereas only 19.6%, 22.3%, and 15.5% required a left ventricular assist device in regions 3, 4, and 5, respectively.

Conclusions: The 2006 UNOS policy change has resulted in significant regional heterogeneity with respect to waitlist time and reliance on mechanical circulatory support as a bridge to transplantation, although overall both waitlist mortality and post-transplant survival are improved.

Keywords: United Network of Organ Sharing; heart transplantation; ventricular assist device.

Figure 1. Comparison of 180-Day Waitlist Prognosis

(A) Comparison of the cumulative event rate including death and delisting (15.3% vs. 11.6%, p < 0.001) between the 2 eras. (B) Mortality while being listed (13.3% vs. 7.9%, p < 0.001) in the 2 eras. Blue = Era 1 (January 20, 1999 to July 11, 2006); green = Era 2 (July 12, 2006 to April 30, 2012).

Figure 2. Regional Differences in Waitlist Prognosis: Death and Delisting

The comparison of regional differences chows a uniform trend toward better prognosis of patients listed for heart transplantation. Blue = Era 1 (January 20, 1999 to July 11, 2006); green = Era 2 (July 12, 2006 to April 30, 2012).

Figure 3. Percentage of Cumulative Waiting Time in Each UNOS Category

The analysis revealed a uniform trend toward an increased time listed as United Network for Organ Sharing (UNOS) status 1A and 1B during the time waiting for heart transplantation. Total waiting time equals 100%. Left bar = Era 1 (January 20, 1999 to July 11, 2006); right bar = Era 2 (July 12, 2006 to April 30, 2012).

Figure 4. UNOS Listing Status at Time of Transplantation

The analysis revealed a uniform trend toward a lower percent of United Network for Organ Sharing (UNOS) status 2 patients and increased proportion of patients at UNOS status 1A and 1B at the time of heart transplantation. Left bar = Era 1 (January 20, 1999 to July 11, 2006); right bar = Era 2 (July 12, 2006 to April 30, 2012).

Figure 5. Comparison of Post-Transplant Mortality

Analysis of outcomes after heart transplantation up to 2 years between the 2 eras. Blue = Era 1 (January 20, 1999 to July 11, 2006); green = Era 2 (July 12, 2006 to April 30, 2012).

Figure 6. Comparison of Post-Transplant Mortality

Survival after heart transplantation was analyzed after stratifying for United Network for Organ Sharing (UNOS) regions and compared between the 2 eras. Blue = Era 1 (January 20, 1999 to July 11, 2006); green = Era 2 (July 12, 2006 to April 30, 2012).

Figure 7. Comparison of Annualized Waiting Time to HTx, Waitlist Prognosis, and Transplant Rate

Annualized event rates were analyzed for the entire population of patients undergoing heart transplantation (HTx) showing a temporary response after the 2006 change in the United Network for Organ Sharing allocation rules that was not detectable in the current era. Event rates increased in the most recent era stepwise.