IMPact of the COVID-19 epidemic on the moRTAlity of kidney transplant recipients and candidates in a French Nationwide registry sTudy (IMPORTANT)

Abstract

End stage kidney disease increase the risk of COVID-19 related death but how the kidney replacement strategy should be adapted during the pandemic is unknown. Chronic hemodialysis makes social distancing difficult to achieve. Alternatively, kidney transplantation could increase the severity of COVID-19 due to therapeutic immunosuppression and contribute to saturation of intensive care units. For these reasons, kidney transplantation was suspended in France during the first epidemic wave. Here, we retrospectively evaluated this strategy by comparing the overall and COVID-19 related mortality in kidney transplant recipients and candidates over the last three years. Cross-interrogation of two national registries for the period 1 March and 1 June 2020, identified 275 deaths among the 42812 kidney transplant recipients and 144 deaths among the 16210 candidates. This represents an excess of deaths for both populations, as compared with the same period the two previous years (mean of two previous years: 253 in recipients and 112 in candidates). This difference was integrally explained by COVID-19, which accounted for 44% (122) and 42% (60) of the deaths in recipients and candidates, respectively. Taking into account the size of the two populations and the geographical heterogeneity of virus circulation, we found that the excess of risk of death due to COVID-19 was similar for recipients and candidates in high viral risk area but four-fold higher for candidates in the low viral risk area. Thus, in case of a second epidemic wave, kidney transplantation should be suspended in high viral risk areas but maintained outside those areas, both to reduce the excess of deaths of candidates and avoid wasting precious resources.

Keywords: COVID-19; ESRD; SARS-CoV-2; mortality; renal transplantation.

Graphical abstract

Figure 1

Flowchart of the IMPact of the COVID-19 epidemic on the moRTAlity of kidney transplant recipients and candidates in a French Nationwide registry sTudy (IMPORTANT) study. COVID-19, coronavirus disease 2019; ESRD, end-stage renal disease.

Figure 2

Spatio-temporal characteristics of the epidemic of coronavirus disease 2019 (COVID-19) in France. (a) Cumulative incidence of the cases of COVID-19 diagnosed in France from February 1 to June 1, 2020 for renal transplant recipients (red curve) and candidates (blue curve). This study focuses on COVID-19–related mortality. Taking into account that (i) all cases were diagnosed between March 1 and April 1 and (ii) the 99% confidence interval for the delay between COVID-19 diagnosis and death is 30 days, the period of the study was set from March 1 to June 1, 2020. (b) Heat maps showing the geographic distribution of the cases of COVID-19 for renal transplant recipients (left panel) and candidates (right panel). The limit of the area in which the circulation of the virus was more intense is shown (high–viral risk area defined by the French government on May 11, 2020).

Figure 3

Comparison of the daily incidence of deaths over the past 3 years. (a,b) The moving average (10 days) method was used to plot the daily incidence of deaths observed from March 1 to June 1 over the past 3 years for, respectively, (a) renal transplant recipients and (b) candidates. (c,d) Stacked histograms showing, for each day of the period March 1 to June 1, 2020, the distribution between the number of deaths (moving average 10 days) due to coronavirus disease 2019 (COVID-19; black bar) versus cause (white bar) for, respectively, (c) renal transplant recipients and (d) candidates. (e) Heat maps showing the geographic distribution of the renal transplant candidates deceased due to COVID-19 during the first peak (left panel: March 1–April 15, 2020) and the second peak (right panel: April 16, June 1).

Figure 4

Comparison of the daily incidence of deaths during the epidemic between recipients and candidates. (a) The daily incidence of deaths (moving average 10 days), observed between March 1 and June 1, 2020 in renal transplant recipients (red curve) and candidates (blue curve), was normalized over the size of the population. (b–d) The daily incidence of deaths (moving average 10 days) observed between March 1 and June 1, 2020 was normalized over the mean number of deaths observed the same day for the 2 previous years. This mathematical transformation allows for direct comparison of the excess of risk of death due to the coronavirus disease 2019 epidemic for renal transplant recipients (red curve) and candidates (blue curve), despite the difference in size of the 2 populations. Comparisons were made at (a,b) the level of whole national territory, (c) inside the high–viral risk area, and (d) outside high–viral risk area.