Variations in transplant rates and post-transplant outcomes in liver transplantation based on season and climate regions in the United States
Shamaa MT, Kitajima T, Ivanics T, Elsabbagh A, Lu M, Delvecchio K, Mohamed A, Yeddula S, Rizzari M, Collins K, Yoshida A, Abouljoud M, and Nagai S. Variations in transplant rates and post-transplant outcomes in liver transplantation based on season and climate regions in the United States. Am J Transplant 2021; 21(SUPPL 1):35.
Am J Transplant
Introduction: Cold climate is known to affect the frequency and attributable mortality of various illnesses. Whether similar trends exist in LT donors and recipients remains unknown. This study aims to evaluate the effect of different seasons and regions on the rates and outcomes of liver transplant (LT).
Methods: We analyzed the data from United Network for Organ Sharing (UNOS) registry for 50,668 adult patients (≥18 years) who underwent single-organ LT between 2010 and 2019. Patients were categorized by seasons: Summer (n=15,614), Winter (n=18,252), and Spring/Fall (n=16,802). Secondary analysis was performed after stratifying states based on their mean winter temperature (Cold states, 0°-30° F; Intermediate states, 30°-40° F; Warm states, 40°-70° F; Figure 1). Post-LT outcomes were compared according to the season and states using Cox proportional hazard models.
Results: Deceased donors during winter were more likely to be older (>50 years, p<0.001), had higher BMI (>25, p<0.001), and died from cerebrovascular disease (p<0.001). Daily LT rates were significantly lower during winter (13.43 transplants/day, p<0.001) and even more pronounced in colder states (Figure 2). The adjusted risk of post-transplant graft loss (HR 1.116, p=0.001) and mortality (HR 1.172, p<0.001) was higher at 1-year in colder states compared to warmer states. Worse post-transplant outcomes in colder states were observed regardless of the season (Winter HR 1.151, p=0.025; spring/fall HR 1.160, p=0.023; Summer HR 1.217, p=0.004).
Conclusion: Our study showed significantly lower liver transplant activity during the winter. Colder states had worse post-LT outcomes regardless of the season.