# Novel model to predict survival in DCD heart transplants: Development of a mortality risk score using UNOS data

## TL;DR

This study creates a new risk score to predict survival after heart transplants from circulatory death donors, using data from thousands of transplants.

## Contribution

The novel contribution is a mortality risk score specifically for DCD heart transplants, incorporating donor and recipient factors.

## Key findings

- One-, two-, and three-year survival rates for DCD heart transplants were 91.6%, 84.8%, and 80.3%, respectively.
- Recipient age >65, female sex, diabetes, and prior cardiac surgery were significant risk factors for increased mortality.
- Donor factors like male sex, age ≥45, and CMV mismatch also significantly influenced mortality.

## Abstract

While prior studies have compared outcomes between donation after brain death (DBD) and donation after circulatory death (DCD) heart transplants, this study focuses on donor and recipient characteristics influencing survival and develop a risk score exclusively in DCD heart transplants.

We analyzed adult DCD heart transplants in the UNOS database from January 2019 to June 2024. Mortality risk factors were assessed using multivariable Cox proportional hazards regression. The coefficients of the most significant factors were used to develop a mortality risk score.

Among 18,014 adult heart transplants, 1453 (8.1%) were DCD recipients. One-, two-, and three-year survival rates were 91.6%, 84.8%, and 80.3%, respectively. Statistically significant factors associated with increased mortality included recipient age >65 (HR=1.62, p=0.025), recipient female sex (HR=1.87, p=0.007), recipient diabetes (HR=1.64, p=0.009), prior cardiac surgery (HR=1.46, p=0.049), donor male sex (HR=1.96, p=0.034), longer ischemic time (HR=1.11 per hour, p=0.014) and CMV mismatch: donor-/recipient+ (HR=2.07, p=0.015); donor+/recipient- (HR=1.84, p=0.041). Though not statistically significant (p>0.05), donor age≥45, donor diabetes, donor cause of death, lung retrieval, recipients’ pretransplant dialysis, IV inotropes and mechanical ventilation were also added to the mortality risk score model due to its large effect sizes and clinical relevance.

We developed a mortality risk score for DCD heart transplants including 7 recipient factors: age >65, female sex, diabetes, prior cardiac surgery, pretransplant ventilator use, IV inotropes; 7 donor factors: age≥45, male sex, diabetes, ischemic time>4 h, cause of death, lung retrieval and CMV positive in either donors or recipients.