Undoubtedly, kidney transplant recipients have a higher mortality due to COVID‐19 disease compared to the general population

Abstract

With interest, we read the article of Hugo et al, who described a mortality of 8.7% in 46 solid organ transplant recipients after COVID-19 infection [1. Because a misinterpretation may have detrimental implications for solid organ transplant recipients regarding COVID-19 vaccine prioritization, we think it is important to comment on the misleading title and the limitations of their conclusions due to an obvious selection bias in the control group. In the Berlin-Brandenburg region, we serve an area of 6.1 million people and approximately 2500 kidney transplant recipients. Here, 209.960 cases of COVID-19 (3.4% of the total population) and 6002 deaths due to COVID-19 (2.9% of registered COVID-19 cases) were documented up to March 7 [2. During the last year, we observed 114/2500 (4.6%) cases of COVID-19 in kidney transplant recipients and 10/114 (8.8%) deaths due to COVID-19. Hence, mortality was strikingly similar in our cohort compared to Hugo et al. [1 and lower as compared to previously described kidney transplant cohorts with mortality rates between 12% and 32% (see Table 1). In summary, mortality of kidney transplant recipients is at least three- to fourfold higher than in the general population, supporting the thorough analysis from the United Kingdom with a four-time higher hazard ratio of death for solid organ transplant recipients [3. Age > 60 RR > 20/min PCT LDH Dyspnea Cravedi et al. [5 Multicentric, TANGO Registry (US, Spain, Italy) March–May 2020 Older age Pneumonia Sanchez-Alvarez et al. [6 Multicentric, Registry of Spanish Society of Nephrology March - April 2020 Older age ARDS at admission Lung disease LDH Fava et al. [7 Multicentric, Spain March–April 2020 482 SOTR 318 KTR Age > 65 years Congestive heart failure Lung disease Obesity Diabetes Kates et al. [8 Multicentric, UW SOT COVID Registry March–May 2020 Akalin et al. [9 Monocentric, Montefiore Medical Center, New York, United States March–April 2020 Older Age Male Sex Jager et al. [10 Multicentric, ERA-EDTA Registry Feb–April 2020 De Meester et al. [11 Multicentric, Belgium March–May 2020 Older age Dyspnea Disease severity Allograft dysfunction Obesity CRP, IL-6, PCT Chest XR abnormality ICU/MV Kute et al. [12 Multicentric, India March–Sep 2020 In our view, a meaningful comparator should represent the general population, which was not the case in the recently published paper [1, where the control group exhibited a mortality of 17.5%, far exceeding the overall mortality from COVID-19 in Germany (70.800 deaths in 2.445 Mio infected people; 2.9%) [2, and suggesting a strong selection bias for controls. The control group was selected from the LEOSS registry of hospitalized COVID-19 cases, which are treated in large part at tertiary university hospitals [4. This can lead to selection bias for higher mortality, since these hospitals are referral centers for severe and complicated ICU cases. As a consequence, the control group had a substantial higher rate of complicated and critical cases (23.9% vs. 29.5% and 4.4% vs 8.6%, respectively). Unfortunately, the proportion of patients requiring an ICU stay was not reported in the study. Another major risk factor for mortality, namely age, appears highly unmatched, as the proportion of patients >65 years is almost twice as high in the control group (47.5% vs. 23.9%), which additionally distorts the conclusions. We acknowledge the authors’ ambition to gain insights about the risk attributable to immunosuppression and transplantation independent of the comorbidities of transplant recipients. However, because the control group does not reflect the general population, the conclusions in the article [1 are misleading and may have detrimental effects on the decision-making process regarding risk stratification and immunization, as all published data clearly demonstrate a much higher mortality from COVID-19 in solid organ transplant recipients. The authors declare no funding. The authors declare no conflicts of interest.

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