We read with interest the study by Gwilym Webb and colleagues
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detailing outcomes of liver transplant recipients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection from two international registries. We congratulate them for this contribution to the evidence base, being an exemplar of the global collaboration required in response to COVID-19. However, we believe that the study has generated questions that need to be answered before we can reassure the liver transplant community.The authors developed a multiple logistic regression model for mortality among liver transplant recipients based on a limited number of variables. The liver transplant community is heterogeneous and practice varies between centres nationally and internationally (appendix). Compounding this variability are well documented differences in public health approaches to COVID-19 worldwide, which need to be considered in any analysis. We note that more than 50% of patients included within this study were from the UK or the USA.
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Although this is probably due to these being the host nations of the registries, it is possible that practices adopted by these nations might increase the risk of hospitalisation of liver transplant recipients with SARS-CoV-2 infection. Further interrogation and risk adjustment in a suitably powered cohort of liver transplant recipients are required to truly understand their risk of mortality from COVID-19.Comparing liver transplant recipients from multiple countries with patients admitted in Oxford (UK) is fraught with potential confounders. Although the authors have shown some similarities between both cohorts and have carried out a propensity-matched analysis for specific variables, we remain unconvinced that this cohort is a fair comparator. Mortality per population from COVID-19 was lower in Oxford than many areas where liver transplant centres are located in the UK.
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Adverse outcomes from COVID-19 have been frequently associated with non-White ethnic groups and low socioeconomic status.3
It is likely that there were differences between the Oxford cohort and non-liver transplant cohorts elsewhere in the world for these variables, but these data are unavailable. The development of an internationally representative comparator cohort of individuals who have not received a liver transplant is required for fair comparison.Rather than relying on clinician reporting, we believe that data acquired through primary and secondary care coding would better capture accurate information for cohorts of interest and for comparison. Although there are well described limitations to this method, it will ensure not only more robust data capture but also that the studies are adequately powered to truly understand the risk of mortality from COVID-19 in liver transplant recipients. Until then, we believe the jury is still out on this risk.
We declare no competing interests.
Supplementary Material
- Supplementary appendix
References
- 1.Outcomes following SARS-CoV-2 infection in liver transplant recipients: an international registry study.Lancet Gastroenterol Hepatol. 2020; 5: 1008-1016
- 2.Deaths involving COVID-19 by local area and socioeconomic deprivation: deaths occurring between 1 March and 30 June 2020.
- 3.Factors associated with COVID-19-related death using OpenSAFELY.Nature. 2020; 584: 430-436
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Published: October 30, 2020
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