[Covid-19 in kidney transplantation: Lessons from the French Registry]

The Covid-19 pandemic hits the French transplant population on March 3, 2020. Very quickly, a French registry was set up on behalf of the French Society of Transplantation allowing the collection of confirmed cases of Covid-19 occurring in kidney transplant recipients in almost all French centers. The analysis of this registry in conjunction with the data from the Agence de la Biomédecine (Cristal) has enabled us to obtain instructive results. We first showed that the incidence of severe forms among transplant patients hospitalized for Covid-19 was 46% and that their mortality was 22.8%. The risk factors for severe forms and mortality are described. Then we showed, by comparing transplant patients with immunocompetent patients matched for the main severity factors of the disease, that mortality among transplant patients was higher (17.9% vs 11.4%; P<0.001). In multivariate analysis, a creatinine level at admission above 115 μmol/L was associated with death, whereas being transplanted was not. Finally, comparing the transplant cohort with patients on the kidney transplant waiting list during the period from February to June 2020, we found that patients on the waiting list had a higher Covid-19-related excess mortality than transplant patients, mainly in areas of low viral circulation. In conclusion, the French Registry of transplant patients with Covid-19, which was rapidly set up at the beginning of the epidemic, has already enabled us to draw several lessons about this initially unknown infection, particularly in kidney transplant patients, a population which appeared to be particularly at risk.