Survival outcomes following urgent lung transplantation in France and the USA.

INTRODUCTION: Lung graft allocation can be based on a score (Lung Allocation Score) as in the USA or sequential proposals combined with a discrete priority model as in France. We aimed to analyse the impact of allocation policy on the outcome of urgent lung transplantation (LT). METHODS: US United Network for Organ Sharing (UNOS) and French Cristal databases were retrospectively reviewed to analyse LT performed between 2007 and 2017. We analysed the mortality risk of urgent LT by fitting Cox models and adjusted Restricted Mean Survival Time. We then compared the outcome after urgent LT in the UNOS and Cristal groups using a propensity score matching. RESULTS: After exclusion of patients with chronic obstructive pulmonary disease/emphysema and redo LT, 3775 and 12 561 patients underwent urgent LT and non-urgent LT in the USA while 600 and 2071 patients underwent urgent LT and non-urgent LT in France. In univariate analysis, urgent LT was associated with an HR for death of 1.24 (95% CI 1.05 to 1.48) in the Cristal group and 1.12 (95% CI 1.05 to 1.19) in the UNOS group. In multivariate analysis, the effect of urgent LT was attenuated and no longer statistically significant in the Cristal database (HR 1.1 (95% CI 0.91 to 1.33)) while it remained constant and statistically significant in the UNOS database (HR 1.12 (95% CI 1.05 to 1.2)). Survival comparison of urgent LT patients between the two countries was significantly different in favour of the UNOS group (1-year survival rates 84.1% (80.9%-87.3%) vs 75.4% (71.8%-79.1%) and 3-year survival rates 66.3% (61.9%-71.1%) vs 62.7% (58.5%-67.1%), respectively). CONCLUSION: Urgent LT is associated with adverse outcome in the USA and in France with a better prognosis in the US score-based system taking post-transplant survival into account. This difference between two healthcare systems is multifactorial.

Waitlist Outcomes in Candidates With Rare Causes of Heart Failure After Implementation of the 2018 French Heart Allocation Scheme.

BACKGROUND: In 2018, an algorithm-based allocation system for heart transplantation (HT) was implemented in France. Its effect on access to HT of patients with rare causes of heart failure (HF) has not been assessed. METHODS: In this national study, including adults listed for HT between 2018 and 2020, we analyzed waitlist and posttransplant outcomes of candidates with rare causes of HF (restrictive cardiomyopathy [RCM], hypertrophic cardiomyopathy, and congenital heart disease). The primary end point was death on the waitlist or delisting for clinical deterioration. Secondary end points included access to HT and posttransplant mortality. The cumulative incidence of waitlist mortality estimated with competing risk analysis and incidence of transplantation were compared between diagnosis groups. The association of HF cause with outcomes was determined by Fine-Gray or Cox models. RESULTS: Overall, 1604 candidates were listed for HT. At 1 year postlisting, 175 patients met the primary end point and 1040 underwent HT. Candidates listed for rare causes of HF significantly differed in baseline characteristics and had more frequent score exceptions compared with other cardiomyopathies (31.3%, 32.0%, 36.4%, and 16.7% for patients with hypertrophic cardiomyopathy, RCM, congenital heart disease, and other cardiomyopathies). The cumulative incidence of death on the waitlist and probability of HT were similar between diagnosis groups (P=0.17 and 0.40, respectively). The adjusted risk of death or delisting for clinical deterioration did not significantly differ between candidates with rare and common causes of HF (subdistribution hazard ratio (HR): hypertrophic cardiomyopathy, 0.51 [95% CI, 0.19-1.38]; P=0.18; RCM, 1.04 [95% CI, 0.42-2.58]; P=0.94; congenital heart disease, 1.82 [95% CI, 0.78-4.26]; P=0.17). Similarly, the access to HT did not significantly differ between causes of HF (hypertrophic cardiomyopathy: HR, 1.18 [95% CI, 0.92-1.51]; P=0.19; RCM: HR, 1.19 [95% CI, 0.90-1.58]; P=0.23; congenital heart disease: HR, 0.76 [95% CI, 0.53-1.09]; P=0.14). RCM was an independent risk factor for 1-year posttransplant mortality (HR, 2.12 [95% CI, 1.06-4.24]; P=0.03). CONCLUSIONS: Our study shows equitable waitlist outcomes among HT candidates whatever the indication for transplantation with the new French allocation scheme.

Development and Validation of a Risk Score Predicting Death Without Transplant in Adult Heart Transplant Candidates.

Importance: The US heart allocation system prioritizes medically urgent candidates with a high risk of dying without transplant. The current therapy-based 6-status system is susceptible to manipulation and has limited rank ordering ability. Objective: To develop and validate a candidate risk score that incorporates current clinical, laboratory, and hemodynamic data. Design, Setting, and Participants: A registry-based observational study of adult heart transplant candidates (aged ≥18 years) from the US heart allocation system listed between January 1, 2019, and December 31, 2022, split by center into training (70%) and test (30%) datasets. Adult candidates were listed between January 1, 2019, and December 31, 2022. Main Outcomes and Measures: A US candidate risk score (US-CRS) model was developed by adding a predefined set of predictors to the current French Candidate Risk Score (French-CRS) model. Sensitivity analyses were performed, which included intra-aortic balloon pumps (IABP) and percutaneous ventricular assist devices (VAD) in the definition of short-term mechanical circulatory support (MCS) for the US-CRS. Performance of the US-CRS model, French-CRS model, and 6-status model in the test dataset was evaluated by time-dependent area under the receiver operating characteristic curve (AUC) for death without transplant within 6 weeks and overall survival concordance (c-index) with integrated AUC. Results: A total of 16 905 adult heart transplant candidates were listed (mean [SD] age, 53 [13] years; 73% male; 58% White); 796 patients (4.7%) died without a transplant. The final US-CRS contained time-varying short-term MCS (ventricular assist-extracorporeal membrane oxygenation or temporary surgical VAD), the log of bilirubin, estimated glomerular filtration rate, the log of B-type natriuretic peptide, albumin, sodium, and durable left ventricular assist device. In the test dataset, the AUC for death within 6 weeks of listing for the US-CRS model was 0.79 (95% CI, 0.75-0.83), for the French-CRS model was 0.72 (95% CI, 0.67-0.76), and 6-status model was 0.68 (95% CI, 0.62-0.73). Overall c-index for the US-CRS model was 0.76 (95% CI, 0.73-0.80), for the French-CRS model was 0.69 (95% CI, 0.65-0.73), and 6-status model was 0.67 (95% CI, 0.63-0.71). Classifying IABP and percutaneous VAD as short-term MCS reduced the effect size by 54%. Conclusions and Relevance: In this registry-based study of US heart transplant candidates, a continuous multivariable allocation score outperformed the 6-status system in rank ordering heart transplant candidates by medical urgency and may be useful for the medical urgency component of heart allocation.