Impact of Market Competition on Allograft Acceptance and Utilization Practices in Heart Transplantation

S. Bakhtiyar¹, S. Sakowitz², S. Mallick³, P. Benharash^4
1University of Colorado, Aurora, Colorado ²UCLA David Geffen School of Medicine, Los Angeles, California ³UCLA, Los Angeles, California ⁴UCLA Division of Cardiac Surgery, Los Angeles, California

Purpose: In the absence of consensus guidelines dictating allograft acceptance, significant practice differences in organ utilization exist across heart transplant centers. However, the impact of surrounding market forces on such practices remains unknown. We evaluated the impact of hospital competition on organ acceptance and utilization, in the contemporary heart transplantation era.

Methods: All adult (≥18years) Donation after Brain Death or Donation after Circulatory Death(DCD) heart allograft donors from December 2019-April 2024 were identified within the Organ Procurement and Transplantation Network.

We quantified market competition using the broadly validated Herfindahl-Hirshman Index(HHI). This metric is calculated for each transplant program, and represents the sum of squared market shares, within a fixed 250-mile radius. In line with prior work, centers in the top HHI quartile were considered Most Competitive (all other institutions: Less Competitive)[1-5].

Allografts that were recovered, but not transplanted, were considered not utilized. Subsequently, the allograft non-use rate was computed as the delta between the total number of allografts recovered and accepted, divided by the total recovered. DCD allografts were identified as reported within the OPTN.

The primary study endpoint was the overall allograft acceptance rate. We secondarily considered the non-use rate. Finally, we additionally evaluated DCD transplantation practices at these institutions.

Results: Of 151 centers, 37 were Most Competitive. Most Competitive were of incrementally lower annual transplant volume, compared to Less Competitive (25 [17-36] vs 28 transplants/year [16-42], P< 0.001).

Considering all allografts, and compared to Less Competitive, Most Competitive demonstrated a greater organ acceptance rate (70.0%, 95% Confidence Interval[CI] 69.6-70.5%, vs 67.1%, CI 66.7-67.4%, P< 0.001). Following comprehensive adjustment, Most Competitive centers were 10% more likely to transplant an allograft, compared to Less Competitive programs (Adjusted Odds Ratio[AOR] 1.10, CI 1.03-1.17, FigureA-B).

Further, Most Competitive had an incrementally lower non-use rate, compared to others (29.9%, CI 29.5-30.4%, vs 32.9%, CI 32.6-33.3%). This similarly persisted following risk-adjustment for donor factors, such that Most Competitive demonstrated a ~4% reduction in allograft non-use, compared to other centers (β -3.8%, CI -4.4, -3.2%).

Considering DCD allografts, Most Competitive centers demonstrated a reduced DCD organ acceptance rate (63.1%, CI 60.0-66.3%, vs 77.8%, CI 76.5-78.9%, P< 0.001), and a higher non-use rate (36.9%, CI 33.7-40.0%, vs 22.3%, CI 21.1-23.5%, P< 0.001). These findings remained true following risk-adjustment, such that Most Competitive had an incrementally lower acceptance rate for DCD organs (β -7.1%, CI -9.7, -4.5%) and demonstrated lower odds of transplanting a DCD allograft (AOR 0.78, CI 0.62-0.99, FigureC-D).

Conclusion: While high-competition centers are more liberal in their acceptance of standard allografts, they are more risk-averse for DCD organs. These findings may reveal concerns regarding non-standard allograft utilization on overall center outcomes. Broader sharing of protocols at high-DCD allograft utilizing programs may contribute to improved organ acceptance and utilization practices.

Identify the source of the funding for this research project: None