Prediction of Waitlist Mortality in Adult Heart Transplant Candidates: The Candidate Risk Score
The cardiac allocation system in France is currently based on urgency and geography. Medical urgency is defined by therapies without considering objective patient mortality risk factors. This study aimed to develop a waitlist mortality risk score from commonly available candidate variables.
METHODS:The study included all patients, aged 16 years or older, registered on the national registry CRISTAL for first single-organ heart transplantation between January 2010 and December 2014. This population was randomly divided in a 2:1 ratio into derivation and validation cohorts. The association of variables at listing with 1-year waitlist death or delisting for worsening medical condition was assessed within the derivation cohort. The predictors were used to generate a candidate risk score (CRS). Validation of the CRS was performed in the validation cohort. Concordance probability estimation (CPE) was used to evaluate the discriminative capacity of the models.
RESULTS:During the study period, 2333 patients were newly listed. The derivation (n =1 555) and the validation cohorts (n = 778) were similar. Short-term mechanical circulatory support, natriuretic peptide decile, glomerular filtration rate, and total bilirubin level were included in a simplified model and incorporated into the score. The Concordance probability estimation of the CRS was 0.73 in the derivation cohort and 0.71 in the validation cohort. The correlation between observed and expected 1-year waitlist mortality in the validation cohort was 0.87.
CONCLUSIONS:The candidate risk score provides an accurate objective prediction of waitlist mortality. It is currently being used to develop a modified cardiac allocation system in France.
CET Conclusion
| Reviewer: | Centre for Evidence in Transplantation |
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| Conclusion: | This cohort analysis using the French registry database CRISTAL aimed to develop a heart transplant candidate risk score to predict 1-year waitlist mortality or delisting due to worsening medical condition. The population of 2333 adult, first, single-organ heart transplantation candidates was randomly divided in a derivation (67%) and validation cohort (33%). Thirteen percent of patients died or were delisted and 1-year survival on the waiting list was 79%. In the univariate model 22 candidate characteristics were associated with the 1-year mortality or delisting of which 7 remained significant in the multivariate model. A simplified model of four commonly reported characteristics was built and this was used to produce the candidate risk score. The study found a strong correlation between the observed and predicted 1-year waitlist mortality. |
Expert Review
| Reviewer: | Professor Maryl R. Johnson, Heart Failure and Transplant Cardiology, University of Wisconsin School of Medicine and Public Health, Madison, USA. |
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| Conflicts of Interest: | No |
| Clinical Impact Rating | 3 |
| Review: | This manuscript reports an analysis of the French CRISTAL registry of heart transplant candidates with the goal of defining objective predictors of waitlist mortality or delisting for worsening medical condition at 1 year. The defined model will be used to modify the cardiac allocation system in France. The authors defined a candidate risk score including four variables (short-term mechanical circulatory support, natriuretic peptide decile, glomerular filtration rate and total bilirubin) that correlated with observed 1-year outcomes. Although the goal had been to define predictive variables independent of treatment modalities, as the use of short-term mechanical circulatory support was at the discretion of clinicians, this goal was not entirely met (hemodynamics justifying the need for short-term mechanical circulatory support, if available, would have been more objective). In addition, one of the groups currently prioritized on the French allocation system, patients on long-term mechanical circulatory support with complications, was not specifically included in the analysis. The fact that the variables will change over time while on the list will also need to be taken into consideration in the development of a new allocation system. |
Study Details
| Aims: | To generate and validate a risk score in heart transplant candidates that predicts 1-year waitlist mortality or delisting for worsening medical condition based on candidate variables. |
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| Interventions: | Participants were randomly divided into a derivation and validation cohort and variables associated with the outcomes on the waiting list were analysed to generate a candidate risk score. |
| Participants: | 2333 adult patients aged ≥ 16 years of age on the French national waiting list for first, single-organ heart transplantation. |
| Outcomes: | The primary outcome measured was 1-year waitlist mortality or delisting for worsening medical condition. Other outcomes measured included candidate demographics, primary diagnosis, clinical status, device therapy, and, laboratory parameters at listing. |
| Follow Up: | 1 year |
Metadata
| Publication type: | Randomised Controlled Trial |
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| Organ: | Heart |
| Language: | English |
| MeSH terms: | Adolescent; Adult; Age Factors; Aged; Bilirubin; Biomarkers; Decision Support Techniques; Discriminant Analysis; Female; France; Glomerular Filtration Rate; Heart Failure; Heart Transplantation; Heart-Assist Devices; Humans; Male; Middle Aged; Natriuretic Peptides; Predictive Value of Tests; Registries; Reproducibility of Results; Risk Assessment; Risk Factors; Waiting Lists; Young Adult; 0 (Biomarkers); 0 (Natriuretic Peptides); RFM9X3LJ49 (Bilirubin) |