CLD and cirrhosis
During the first wave of the pandemic, patients with CLD and cirrhosis were not found to be over-represented in large COVID-19 case series and population studies, suggesting that these conditions were unlikely to increase susceptibility to infection.
[42]- Williamson E.J.
- Walker A.J.
- Bhaskaran K.
- Bacon S.
- Bates C.
- Morton C.E.
- et al.
Factors associated with COVID-19-related death using OpenSAFELY.
,[43]- Richardson S.
- Hirsch J.S.
- Narasimhan M.
- Crawford J.M.
- McGinn T.
- Davidson K.W.
- et al.
Presenting characteristics, comorbidities, and outcomes among 5700 patients hospitalized with COVID-19 in the New York City Area.
One large North American study even found that patients with cirrhosis had lower risk of SARS-CoV-2 positivity than the general population.
[44]- Ioannou G.N.
- Liang P.S.
- Locke E.
- Green P.
- Berry K.
- O’Hare A.M.
- et al.
Cirrhosis and severe acute respiratory syndrome coronavirus 2 infection in US veterans: risk of infection, hospitalization, ventilation, and mortality.
This most likely reflects heightened vigilance and greater patient adherence to public health advice although interpretations are limited by retrospective design and lack of adjustment for certain relevant cofactors including socioeconomic status and occupational exposure. However, once patients with cirrhosis acquire SARS-CoV-2 infection it has become clear that they are at increased risk of adverse COVID-19 outcomes including death.
Overall mortality in patients with cirrhosis following SARS-CoV-2 infection was found to be 32% in a large registry cohort of 729 predominantly hospitalised patients with CLD across 29 countries, with case fatality rates incrementally increasing with each Child-Pugh (CP) class (CLD without cirrhosis; 8%, CP-A; 19%, CP-B; 35%, CP-C; 51%).
[45]- Marjot T.
- Moon A.M.
- Cook J.A.
- Abd-Elsalam S.
- Aloman C.
- Armstrong M.J.
- et al.
Outcomes following SARS-CoV-2 infection in patients with chronic liver disease: an international registry study.
Similar stepwise trends were observed in the rates of ICU admission, renal replacement therapy, and invasive mechanical ventilation. Furthermore, the risk of mortality in those with decompensated cirrhosis was significantly elevated compared to that in patients without CLD, after matching for age and comorbidity. Decompensated cirrhosis was also shown to be an independent risk factor for death based on outcome data from patients with CLD across 21 North American institutions.
[46]- Kim D.
- Adeniji N.
- Latt N.
- Kumar S.
- Bloom P.P.
- Aby E.S.
- et al.
Predictors of outcomes of COVID-19 in patients with chronic liver disease: US multi-center study.
High rates of COVID-19 mortality in cirrhosis, ranging between 20-30%, have also been replicated in an exclusively Asian registry
[47]- Sarin S.K.
- Choudhury A.
- Lau G.K.
- Zheng M.-H.
- Ji D.
- Abd-Elsalam S.
- et al.
Pre-existing liver disease is associated with poor outcome in patients with SARS CoV2 infection; the APCOLIS Study (APASL COVID-19 Liver Injury Spectrum Study).
and in several multicentre cohort studies across different geographical regions.
[46]- Kim D.
- Adeniji N.
- Latt N.
- Kumar S.
- Bloom P.P.
- Aby E.S.
- et al.
Predictors of outcomes of COVID-19 in patients with chronic liver disease: US multi-center study.
,[48]- Iavarone M.
- D’Ambrosio R.
- Soria A.
- Triolo M.
- Pugliese N.
- Del Poggio P.
- et al.
High rates of 30-day mortality in patients with cirrhosis and COVID-19.
,[49]- Bajaj J.S.
- Garcia-Tsao G.
- Biggins S.W.
- Kamath P.S.
- Wong F.
- McGeorge S.
- et al.
Comparison of mortality risk in patients with cirrhosis and COVID-19 compared with patients with cirrhosis alone and COVID-19 alone: multicentre matched cohort.
This risk of death following SARS-CoV-2 infection appears to be higher compared to other infective insults including spontaneous bacterial peritonitis.
[48]- Iavarone M.
- D’Ambrosio R.
- Soria A.
- Triolo M.
- Pugliese N.
- Del Poggio P.
- et al.
High rates of 30-day mortality in patients with cirrhosis and COVID-19.
An analysis of >220,000 patients with CLD in North America further emphasized the negative impact of advanced liver disease at a population level, with cirrhosis being associated with a 2.38-fold adjusted hazard of mortality 30 days after SARS-CoV-2 infection.
[50]- Ge J.
- Pletcher M.J.
- Lai J.C.
- Harper J.R.
- Chute C.G.
- Haendel M.A.
Outcomes of SARS-CoV-2 infection in patients with chronic liver disease and cirrhosis: a national COVID cohort collaborative study.
Similarly, a retrospective French cohort of >259,000 inpatients with COVID-19 including >15,000 with pre-existing CLD, demonstrated that patients with decompensated cirrhosis were at an increased adjusted risk for mortality.
[51]- Mallet V.
- Beeker N.
- Bouam S.
- Sogni P.
- Pol S.
Demosthenes research group
Prognosis of French COVID-19 patients with chronic liver disease: a national retrospective cohort study for 2020.
This is further corroborated by data derived from the electronic health records of >6 million UK adults which indicated an elevated adjusted hazard ratio for both hospitalisation and death related to COVID-19 in patients coded as having cirrhosis.
[52]- Clift A.K.
- Coupland C.A.C.
- Keogh R.H.
- Diaz-Ordaz K.
- Williamson E.
- Harrison E.M.
- et al.
Living risk prediction algorithm (QCOVID) for risk of hospital admission and mortality from coronavirus 19 in adults: national derivation and validation cohort study.
These findings contrast with those from a nationwide Swedish CLD cohort which did not demonstrate associations between cirrhosis and COVID-19-related mortality.
[53]- Simon T.G.
- Hagström H.
- Sharma R.
- Söderling J.
- Roelstraete B.
- Larsson E.
- et al.
Risk of severe COVID-19 and mortality in patients with established chronic liver disease: a nationwide matched cohort study.
However, this study was limited to patients with biopsy-proven CLD prior to 2017, and therefore more advanced liver disease may have been under-represented because these patients did not undergo biopsy or died before the onset of the pandemic. Lastly, meta-analysis of 63 outcome studies up until February 2021 revealed a pooled odds ratio for mortality of 2.48 (95% CI 2.02-3.04) in patients with cirrhosis and COVID-19.
[54]- Middleton P.
- Hsu C.
- Lythgoe M.P.
Clinical outcomes in COVID-19 and cirrhosis: a systematic review and meta-analysis of observational studies.
Of note, cirrhosis has also been found to be an independent risk factor of mortality and hospitalisation in patients with COVID-19 after vaccination.
[55]- Hippisley-Cox J.
- Coupland C.A.
- Mehta N.
- Keogh R.H.
- Diaz-Ordaz K.
- Khunti K.
- et al.
Risk prediction of covid-19 related death and hospital admission in adults after covid-19 vaccination: national prospective cohort study.
It is important to recognise that our understanding of the disease course of COVID-19 in patients with cirrhosis is nearly exclusively derived from data collected in the era preceding COVID-19 vaccination and the emergence of viral variants of concern (
e.g. omicron). However, in a retrospective analysis of US veterans with cirrhosis, receipt of even a single mRNA vaccine dose not only reduced rates of SARS-CoV-2 infection but markedly improved rates of hospitalisation and death in those developing breakthrough COVID-19.
[56]- John B.V.
- Deng Y.
- Scheinberg A.
- Mahmud N.
- Taddei T.H.
- Kaplan D.
- et al.
Association of BNT162b2 mRNA and mRNA-1273 vaccines with COVID-19 infection and hospitalization among patients with cirrhosis.
The impact of the highly prevalent omicron variant including all subvariants in patients with CLD, as well as the modifying effect of COVID-19 vaccination, needs to be further investigated.
There are several clinical hallmarks of COVID-19 in patients with cirrhosis. Firstly, new or worsening acute hepatic decompensation, predominantly with ascites and/or hepatic encephalopathy, is a common presenting feature in up to 46% of patients.
[45]- Marjot T.
- Moon A.M.
- Cook J.A.
- Abd-Elsalam S.
- Aloman C.
- Armstrong M.J.
- et al.
Outcomes following SARS-CoV-2 infection in patients with chronic liver disease: an international registry study.
In 20-58% of cases, this decompensation occurs in the absence of typical respiratory symptoms of COVID-19.
[45]- Marjot T.
- Moon A.M.
- Cook J.A.
- Abd-Elsalam S.
- Aloman C.
- Armstrong M.J.
- et al.
Outcomes following SARS-CoV-2 infection in patients with chronic liver disease: an international registry study.
,[48]- Iavarone M.
- D’Ambrosio R.
- Soria A.
- Triolo M.
- Pugliese N.
- Del Poggio P.
- et al.
High rates of 30-day mortality in patients with cirrhosis and COVID-19.
Presentation with gastrointestinal symptoms is more frequent in patients with cirrhosis than matched controls
[45]- Marjot T.
- Moon A.M.
- Cook J.A.
- Abd-Elsalam S.
- Aloman C.
- Armstrong M.J.
- et al.
Outcomes following SARS-CoV-2 infection in patients with chronic liver disease: an international registry study.
and is associated with a worse disease trajectory.
[46]- Kim D.
- Adeniji N.
- Latt N.
- Kumar S.
- Bloom P.P.
- Aby E.S.
- et al.
Predictors of outcomes of COVID-19 in patients with chronic liver disease: US multi-center study.
This is already a well-recognised phenomena within the general population
[57]- Mao R.
- Qiu Y.
- He J.-S.
- Tan J.-Y.
- Li X.-H.
- Liang J.
- et al.
Manifestations and prognosis of gastrointestinal and liver involvement in patients with COVID-19: a systematic review and meta-analysis.
and is thought to be secondary to greater gut permeability and systemic inflammation. Historic studies have shown a >30-fold increase in angiotensin-converting enzyme 2 (ACE2) receptor expression in cirrhotic
vs. healthy livers, suggesting that patients with cirrhosis may be uniquely susceptible to SARS-CoV-2-mediated hepatic dysfunction.
[58]- Paizis G.
- Tikellis C.
- Cooper M.E.
- Schembri J.M.
- Lew R.A.
- Smith A.I.
- et al.
Chronic liver injury in rats and humans upregulates the novel enzyme angiotensin converting enzyme 2.
In addition, Wanner
et al. have shown clear evidence of specific SARS-CoV-2 hepatotropism, further indicating that the virus could trigger decompensation in patients with pre-existing CLD.
[16]- Wanner N.
- Andrieux G.
- Badia-I-Mompel P.
- Edler C.
- Pfefferle S.
- Lindenmeyer M.T.
- et al.
Molecular consequences of SARS-CoV-2 liver tropism.
Acute-on-chronic liver failure (ACLF) following SARS-CoV-2 infection is also well recognised, being reported in up to 12%-50%
[45]- Marjot T.
- Moon A.M.
- Cook J.A.
- Abd-Elsalam S.
- Aloman C.
- Armstrong M.J.
- et al.
Outcomes following SARS-CoV-2 infection in patients with chronic liver disease: an international registry study.
,47- Sarin S.K.
- Choudhury A.
- Lau G.K.
- Zheng M.-H.
- Ji D.
- Abd-Elsalam S.
- et al.
Pre-existing liver disease is associated with poor outcome in patients with SARS CoV2 infection; the APCOLIS Study (APASL COVID-19 Liver Injury Spectrum Study).
, 48- Iavarone M.
- D’Ambrosio R.
- Soria A.
- Triolo M.
- Pugliese N.
- Del Poggio P.
- et al.
High rates of 30-day mortality in patients with cirrhosis and COVID-19.
, 49- Bajaj J.S.
- Garcia-Tsao G.
- Biggins S.W.
- Kamath P.S.
- Wong F.
- McGeorge S.
- et al.
Comparison of mortality risk in patients with cirrhosis and COVID-19 compared with patients with cirrhosis alone and COVID-19 alone: multicentre matched cohort.
of decompensating patients. In this context, several scoring models have been applied, with the CLIF-C (Chronic Liver Failure-Consortium) ACLF and organ failure scores appearing to outperform model for end-stage liver disease, NACSELD (North American Consortium for the Study of End-stage Liver Disease), and CP scores.
[45]- Marjot T.
- Moon A.M.
- Cook J.A.
- Abd-Elsalam S.
- Aloman C.
- Armstrong M.J.
- et al.
Outcomes following SARS-CoV-2 infection in patients with chronic liver disease: an international registry study.
,[59]- Mendizabal M.
- Ridruejo E.
- Piñero F.
- Anders M.
- Padilla M.
- Toro L.G.
- et al.
Comparison of different prognostic scores for patients with cirrhosis hospitalized with SARS-CoV-2 infection.
Despite SARS-CoV-2 triggering acute hepatic decompensation and ACLF, the predominant cause of death remains respiratory failure (71%) followed by liver-related complications (19%).
[45]- Marjot T.
- Moon A.M.
- Cook J.A.
- Abd-Elsalam S.
- Aloman C.
- Armstrong M.J.
- et al.
Outcomes following SARS-CoV-2 infection in patients with chronic liver disease: an international registry study.
The mechanistic links between hepatic dysfunction and subsequent lung injury are likely to be numerous and overlapping including cirrhosis-associated immune dysfunction, gut dysbiosis, altered pulmonary dynamics secondary to ascites and hepatic encephalopathy, and coagulopathy.
[15]- Marjot T.
- Webb G.J.
- Barritt A.S.
- Moon A.M.
- Stamataki Z.
- Wong V.W.
- et al.
COVID-19 and liver disease: mechanistic and clinical perspectives.
In a large nationwide cohort study in France, Mallet
et al. described an associated between pulmonary embolism and COVID-19 mortality, and reported a modest but significant increase in rates of pulmonary emboli in patients with
vs. without CLD.
[51]- Mallet V.
- Beeker N.
- Bouam S.
- Sogni P.
- Pol S.
Demosthenes research group
Prognosis of French COVID-19 patients with chronic liver disease: a national retrospective cohort study for 2020.
In addition, this study introduced the concept of limited ‘therapeutic effort’ for patients with cirrhosis and alcohol-related liver disease (ALD), both of whom had a lower chance of mechanical ventilation and a higher risk of death. This suggests that there were barriers to patients with cirrhosis receiving invasive ventilation. Indeed, this may reflect a perception that patients with cirrhosis represent an underserved population analogous to racial and socioeconomic minorities who also exhibit a higher risk of severe COVID-19.
[42]- Williamson E.J.
- Walker A.J.
- Bhaskaran K.
- Bacon S.
- Bates C.
- Morton C.E.
- et al.
Factors associated with COVID-19-related death using OpenSAFELY.
,[60]- Magesh S.
- John D.
- Li W.T.
- Li Y.
- Mattingly-App A.
- Jain S.
- et al.
Disparities in COVID-19 outcomes by race, ethnicity, and socioeconomic status: a systematic-review and meta-analysis.
Balancing the costs and benefits of ICU admission in severely unwell patients with cirrhosis has remained a consistent clinical challenge for decades,
[61]- Shawcross D.L.
- Austin M.J.
- Abeles R.D.
- McPhail M.J.W.
- Yeoman A.D.
- Taylor N.J.
- et al.
The impact of organ dysfunction in cirrhosis: survival at a cost?.
which may have become acutely unmasked during the COVID-19 pandemic.
EASL position- •
Patients with CLD with or without cirrhosis do not appear at increased risk of SARS-CoV-2 infection. However, those with cirrhosis are at high risk of COVID-19-related mortality.
- •
Liver disease severity is a strong predictor of developing severe COVID-19 and preventing liver disease progression may protect patients from the adverse effects of future SARS-CoV-2 infection.
- •
Limited data are available on the impact of viral variants and COVID-19 vaccination on the clinical course of SARS-CoV-2 infection in patients with CLD.
- •
SARS-CoV-2 infection can precipitate new or worsening acute hepatic decompensation and ACLF in patients with cirrhosis.
- •
Patients with cirrhosis and SARS-CoV-2 infection often present without typical respiratory symptoms but subsequently deteriorate with the predominant cause of death being COVID-19-related respiratory failure.
- •
Limitations of access to care, including invasive ventilation, may contribute to adverse outcomes in hospitalised patients with cirrhosis and COVID-19. Consequently, every effort must be made to facilitate access to intensive care units when appropriate.
Alcohol-related liver disease
The immunomodulating effects of alcohol are well recognised,
[62]Alcohol’s effect on host defense.
,[63]- Pasala S.
- Barr T.
- Messaoudi I.
Impact of alcohol abuse on the adaptive immune system.
with increased alcohol consumption known to predispose to a range of septic insults including community acquired bacterial and viral pneumonias.
[64]- Simou E.
- Britton J.
- Leonardi-Bee J.
Alcohol and the risk of pneumonia: a systematic review and meta-analysis.
A history of harmful alcohol use also appears to increase susceptibility to acute respiratory distress syndrome, a hallmark of severe COVID-19, in critically ill patients with sepsis.
[65]- Crews F.T.
- Bechara R.
- Brown L.A.
- Guidot D.M.
- Mandrekar P.
- Oak S.
- et al.
Cytokines and alcohol.
Both registry data and multicentre studies have identified ALD as being independently associated with COVID-19 mortality after controlling for important cofactors including baseline liver disease severity.
[45]- Marjot T.
- Moon A.M.
- Cook J.A.
- Abd-Elsalam S.
- Aloman C.
- Armstrong M.J.
- et al.
Outcomes following SARS-CoV-2 infection in patients with chronic liver disease: an international registry study.
,[46]- Kim D.
- Adeniji N.
- Latt N.
- Kumar S.
- Bloom P.P.
- Aby E.S.
- et al.
Predictors of outcomes of COVID-19 in patients with chronic liver disease: US multi-center study.
,[51]- Mallet V.
- Beeker N.
- Bouam S.
- Sogni P.
- Pol S.
Demosthenes research group
Prognosis of French COVID-19 patients with chronic liver disease: a national retrospective cohort study for 2020.
However, alcohol consumption in patients with CLD, categorised as either social drinking or current daily drinking, was not associated with all-cause mortality compared to abstinence in a multivariable model.
[46]- Kim D.
- Adeniji N.
- Latt N.
- Kumar S.
- Bloom P.P.
- Aby E.S.
- et al.
Predictors of outcomes of COVID-19 in patients with chronic liver disease: US multi-center study.
The precise mechanisms through which ALD negatively impacts on prognosis in COVID-19 remain to be established although this may plausibly be underpinned by poor nutritional status and functional immunosuppression. In addition, patients with ALD and severe COVID-19 were significantly less likely to receive mechanical ventilation in a large French cohort.
[51]- Mallet V.
- Beeker N.
- Bouam S.
- Sogni P.
- Pol S.
Demosthenes research group
Prognosis of French COVID-19 patients with chronic liver disease: a national retrospective cohort study for 2020.
The strength of this negative association exceeded that observed with any other individual comorbidity or category of Charlson comorbidity index, suggesting that mortality in hospitalised patients with ALD and COVID-19 may be partly explained by discrepancies in the allocation of healthcare resources. These findings are especially alarming given that the incidence of harmful drinking, ALD, and alcohol-related hospital admissions have dramatically increased since the onset of the pandemic (see below)
and collectively highlights the urgent need for concerted institutional and public health efforts to tackle the rise in alcohol-related harm.
NAFLD
The impact of NAFLD on COVID-19 outcomes has been closely scrutinised due to its association with well-established risk factors for severe COVID-19 including obesity, type 2 diabetes, cardiovascular disease, and hypertension.
[42]- Williamson E.J.
- Walker A.J.
- Bhaskaran K.
- Bacon S.
- Bates C.
- Morton C.E.
- et al.
Factors associated with COVID-19-related death using OpenSAFELY.
However, it has been challenging to accurately decipher an independent effect of NAFLD on COVID-19 disease course due to confounding factors and heterogeneity in diagnostic criteria and populations investigated. Several observational cohorts have demonstrated a significant increase in the risk of severe COVID-19 in patients with NAFLD,
67- Ji D.
- Qin E.
- Xu J.
- Zhang D.
- Cheng G.
- Wang Y.
- et al.
Non-alcoholic fatty liver diseases in patients with COVID-19: a retrospective study.
, 68- Mahamid M.
- Nseir W.
- Khoury T.
- Mahamid B.
- Nubania A.
- Sub-Laban K.
- et al.
Nonalcoholic fatty liver disease is associated with COVID-19 severity independently of metabolic syndrome: a retrospective case-control study.
, 69- Hashemi N.
- Viveiros K.
- Redd W.D.
- Zhou J.C.
- McCarty T.R.
- Bazarbashi A.N.
- et al.
Impact of chronic liver disease on outcomes of hospitalized patients with COVID-19: a multicentre United States experience.
which is corroborated by interval meta-analyses of epidemiological studies.
[70]- Singh A.
- Hussain S.
- Antony B.
Non-alcoholic fatty liver disease and clinical outcomes in patients with COVID-19: a comprehensive systematic review and meta-analysis.
,[71]- Hegyi P.J.
- Váncsa S.
- Ocskay K.
- Dembrovszky F.
- Kiss S.
- Farkas N.
- et al.
Metabolic associated fatty liver disease is associated with an increased risk of severe COVID-19: a systematic review with meta-analysis.
Mechanistically, this observation may be supported by gene expression datasets showing increased expression of key viral entry receptors (ACE2, FURIN, TMPRSS2) in patients with NAFLD and NASH.
[72]- Fondevila M.F.
- Mercado-Gómez M.
- Rodríguez A.
- Gonzalez-Rellan M.J.
- Iruzubieta P.
- Valentí V.
- et al.
Obese patients with NASH have increased hepatic expression of SARS-CoV-2 critical entry points.
In addition, ACE2 is upregulated in the liver, and in subcutaneous and visceral adipose tissue, in obese patients with NAFLD compared to obese controls without NAFLD.
[73]- Meijnikman A.S.
- Bruin S.
- Groen A.K.
- Nieuwdorp M.
- Herrema H.
Increased expression of key SARS-CoV-2 entry points in multiple tissues in individuals with NAFLD.
This increased receptor expression strongly correlated with degree of insulin resistance. Collectively this indicates that NAFLD in the context of the wider metabolic syndrome likely contributes to more severe and multisystem involvement of COVID-19. However, in contrast, some groups have failed to draw a link between NAFLD with severe COVID-19 or death after controlling for relevant comorbidities.
[74]- Mushtaq K.
- Khan M.U.
- Iqbal F.
- Alsoub D.H.
- Chaudhry H.S.
- Ata F.
- et al.
NAFLD is a predictor of liver injury in COVID-19 hospitalized patients but not of mortality, disease severity on the presentation or progression - the debate continues.
,[75]- Younossi Z.M.
- Stepanova M.
- Lam B.
- Cable R.
- Felix S.
- Jeffers T.
- et al.
Independent predictors of mortality among patients with NAFLD hospitalized with COVID-19 infection.
In addition, there appears to be a lack of association between gene variants associated with NAFLD (PNPLA3, TM6SF2, MBOAT7, GCKR) and severe COVID-19.
[76]- Valenti L.
- Jamialahmadi O.
- Romeo S.
Lack of genetic evidence that fatty liver disease predisposes to COVID-19.
,[77]- Innes H.
- Buch S.
- Barnes E.
- Hampe J.
- Marjot T.
- Stickel F.
The rs738409 G allele in PNPLA3 is associated with a reduced risk of COVID-19 mortality and hospitalization.
Indeed, a study from the UK biobank even reported a possible protective immunomodulatory effect of the
PNPLA3 rs738409 G allele,
[77]- Innes H.
- Buch S.
- Barnes E.
- Hampe J.
- Marjot T.
- Stickel F.
The rs738409 G allele in PNPLA3 is associated with a reduced risk of COVID-19 mortality and hospitalization.
although this was not replicated following targeted
PNPLA3 genotyping in 383 consecutive Sicilian patients with COVID-19.
[78]- Grimaudo S.
- Amodio E.
- Pipitone R.M.
- Maida C.M.
- Pizzo S.
- Prestileo T.
- et al.
PNPLA3 and TLL-1 polymorphisms as potential predictors of disease severity in patients with COVID-19.
Separate independent analyses using 2-step Mendelian randomisation techniques have also failed to identify a causal relationship between NAFLD and COVID-19 susceptibility and severity.
[79]- Liu D.
- Zhang Q.
- Bai P.
- Zhao J.
Assessing causal relationships between COVID-19 and non-alcoholic fatty liver disease.
,[80]- Li J.
- Tian A.
- Zhu H.
- Chen L.
- Wen J.
- Liu W.
- et al.
Mendelian randomization analysis reveals no causal relationship between nonalcoholic fatty liver disease and severe COVID-19.
This approach attempts to overcome confounding by using genetic variants as instrument variables to draw causal inferences between risk factors and health outcomes.
[79]- Liu D.
- Zhang Q.
- Bai P.
- Zhao J.
Assessing causal relationships between COVID-19 and non-alcoholic fatty liver disease.
In summary, from a purely epidemiological perspective it appears that patients with NAFLD are at increased risk of severe COVID-19. However, the extent to which this is driven by hepatic steatosis, or the presence of overlapping risk factors and comorbidities remains incompletely resolved.
Autoimmune liver disease
Understanding the clinical impact of pre-existing immunosuppression on COVID-19 risk and severity remains complex. Various concerns have been raised in specific disease groups,
e.g. regarding the use of maintenance corticosteroids and thiopurines in patients with rheumatoid conditions and inflammatory bowel disease, respectively.
[81]- Gianfrancesco M.
- Hyrich K.L.
- Al-Adely S.
- Carmona L.
- Danila M.I.
- Gossec L.
- et al.
Characteristics associated with hospitalisation for COVID-19 in people with rheumatic disease: data from the COVID-19 Global Rheumatology Alliance physician-reported registry.
,[82]- Ungaro R.C.
- Brenner E.J.
- Gearry R.B.
- Kaplan G.G.
- Kissous-Hunt M.
- Lewis J.D.
- et al.
Effect of IBD medications on COVID-19 outcomes: results from an international registry.
Conversely, the disease course in those on immunosuppression following solid organ transplantation appears comparable to non-immunosuppressed individuals.
[83]- Webb G.J.
- Marjot T.
- Cook J.A.
- Aloman C.
- Armstrong M.J.
- Brenner E.J.
- et al.
Outcomes following SARS-CoV-2 infection in liver transplant recipients: an international registry study.
,[84]- Kulkarni A.V.
- Tevethia H.V.
- Premkumar M.
- Arab J.P.
- Candia R.
- Kumar K.
- et al.
Impact of COVID-19 on liver transplant recipients-A systematic review and meta-analysis.
A large-scale European survey of 1,752 individuals with AIH performed between June and October 2020 indicated low rates of self-reported COVID-19, providing reassuring real-world data that these patients are unlikely to be at significantly increased risk of severe disease.
[85]- Zecher B.F.
- Buescher G.
- Willemse J.
- Walmsley M.
- Taylor A.
- Leburgue A.
- et al.
Prevalence of COVID-19 in patients with autoimmune liver disease in Europe: a patient-oriented online survey.
Subsequently, in an international cohort of 70 patients with AIH and COVID-19, of whom 86% were immunosuppressed, no differences were found in the rates of adverse outcomes including hospitalisation, ICU admission, and death compared to those with other causes of CLD.
[86]- Marjot T.
- Buescher G.
- Sebode M.
- Barnes E.
- Barritt A.S.
- Armstrong M.J.
- et al.
SARS-CoV-2 infection in patients with autoimmune hepatitis.
When compared to propensity score-matched patients without CLD, patients with AIH had no increased risk of ICU admission or death but did appear to have higher rates of hospitalisation which may have reflected heightened clinical concern. Age and baseline liver disease severity constituted independent risk factors for death in this analysis, but not the use of immunosuppressive medications. Similar findings were concurrently reported in a multicentre cohort of 110 patients with AIH who also had comparable outcomes to other liver disease types.
[87]- Efe C.
- Dhanasekaran R.
- Lammert C.
- Ebik B.
- Higuera-de la Tijera F.
- Aloman C.
- et al.
Outcome of COVID-19 in patients with autoimmune hepatitis: an international multicenter study.
However, a larger retrospective study from the same group including 254 patients with AIH and COVID-19 did indicate that baseline treatment with systemic glucocorticoids (median dose 5 mg/day) or azathioprine (median dose 75 mg/day) was associated with more severe COVID-19
[88]- Efe C.
- Lammert C.
- Taşçılar K.
- Dhanasekaran R.
- Ebik B.
- Higuera-de la Tijera F.
- et al.
Effects of immunosuppressive drugs on COVID-19 severity in patients with autoimmune hepatitis.
after adjusting for age, sex, comorbidities, and presence of cirrhosis. Data for patients with primary biliary cholangitis and primary sclerosing cholangitis are limited. One nationwide study in Spain did observe a higher cumulative incidence of hospitalisation and mortality in patients with primary biliary cholangitis compared with the general population although interpretations are limited by the lack of adjustment for comorbidities.
[89]- Ampuero J.
- Lucena A.
- Hernández-Guerra M.
- Moreno-Moraleda I.
- Arenas J.
- Conde I.
- et al.
Primary biliary cholangitis and SARS-CoV-2 infection: incidence, susceptibility and outcomes.
EASL position- •
Patients with AIH on immunosuppression do not appear to be at a higher risk of SARS-CoV-2 infection or COVID-19-related mortality.
- •
However, baseline use of glucocorticoids or azathioprine may be associated with more severe COVID-19; yet, discontinuing, or reducing the dose of these agents should only occur following careful assessment of all risks and benefits.
Chronic viral hepatitis
Several studies have investigated the clinical impact of co-existing chronic HBV or HCV infection with SARS-CoV-2. A large territory-wide retrospective cohort study in Hong Kong
[90]- Yip T.C.-F.
- Wong V.W.-S.
- Lui G.C.-Y.
- Chow V.C.-Y.
- Tse Y.-K.
- Hui V.W.-K.
- et al.
Current and past infections of HBV do not increase mortality in patients with COVID-19.
showed that COVID-19 outcomes were no different between 359 patients with previous exposure to HBV, 353 patients with HBV infection, and a comparator group of 4,927 individuals without HBV. In addition, the rates and pattern of acute liver biochemistry abnormalities during COVID-19 were the same across groups. Notably, 73 treatment-naïve patients with chronic HBV were started on HBV-targeted nucleoside analogues (NAs) during the course of COVID-19, either as a prophylactic measure against HBV reactivation due to the introduction of steroids (n = 48) or following marked elevations in ALT and HBV DNA levels (n = 16). Whilst patients who received NA treatment had a higher peak ALT than those who did not receive NAs, the ALT level at discharge was comparable between treated and untreated groups. A retrospective review of health insurance records in Korea also demonstrated that patients with chronic HBV did not have a significantly greater risk of severe COVID-19.
[91]- Kang S.H.
- Cho D.-H.
- Choi J.
- Baik S.K.
- Gwon J.G.
- Kim M.Y.
Association between chronic hepatitis B infection and COVID-19 outcomes: a Korean nationwide cohort study.
Furthermore, in those with COVID-19 the proportion of patients with chronic HBV was lower than the general population after adjusting for comorbidities and socioeconomic status, indicating that patients with HBV may be less susceptible to SARS-CoV-2 infection.
[91]- Kang S.H.
- Cho D.-H.
- Choi J.
- Baik S.K.
- Gwon J.G.
- Kim M.Y.
Association between chronic hepatitis B infection and COVID-19 outcomes: a Korean nationwide cohort study.
It has been suggested that this protective effect is mediated by the use of antiviral treatments, including tenofovir and entecavir, which have been shown to be associated with a reduced rate of SARS-CoV-2 positivity.
[91]- Kang S.H.
- Cho D.-H.
- Choi J.
- Baik S.K.
- Gwon J.G.
- Kim M.Y.
Association between chronic hepatitis B infection and COVID-19 outcomes: a Korean nationwide cohort study.
,[92]- Lens S.
- Miquel M.
- Mateos-Muñoz B.
- García-Samaniego J.
- Forns X.
SARS-CoV-2 in patients on antiviral HBV and HCV therapy in Spain.
Similar protective effects have also been reported in HIV-positive patients receiving tenofovir as part of antiretroviral combinations.
[93]- Del Amo J.
- Polo R.
- Moreno S.
- Díaz A.
- Martínez E.
- Arribas J.R.
- et al.
Incidence and severity of COVID-19 in HIV-positive persons receiving antiretroviral therapy : a cohort study.
NAs may have immunomodulatory effects and possibly specific antiviral properties against SARS-CoV-2, as postulated in pilot studies and preclinical models.
94- Parienti J.-J.
- Prazuck T.
- Peyro-Saint-Paul L.
- Fournier A.
- Valentin C.
- Brucato S.
- et al.
Effect of Tenofovir Disoproxil Fumarate and Emtricitabine on nasopharyngeal SARS-CoV-2 viral load burden amongst outpatients with COVID-19: a pilot, randomized, open-label phase 2 trial.
, 95- Chien M.
- Anderson T.K.
- Jockusch S.
- Tao C.
- Li X.
- Kumar S.
- et al.
Nucleotide analogues as inhibitors of SARS-CoV-2 polymerase, a key drug target for COVID-19.
, 96- Park S.-J.
- Yu K.-M.
- Kim Y.-I.
- Kim S.-M.
- Kim E.-H.
- Kim S.-G.
- et al.
Antiviral efficacies of FDA-approved drugs against SARS-CoV-2 infection in ferrets.
However, the use of these agents in patients with chronic HBV has not been consistently shown to attenuate the disease course of subsequent COVID-19.
[91]- Kang S.H.
- Cho D.-H.
- Choi J.
- Baik S.K.
- Gwon J.G.
- Kim M.Y.
Association between chronic hepatitis B infection and COVID-19 outcomes: a Korean nationwide cohort study.
Analysis from a large American Veterans dataset demonstrated that a greater proportion of HCV-positive patients (n = 975) with COVID-19 were hospitalised compared to propensity score-matched HCV-negative individuals, particularly among those with elevated non-invasive markers of advanced fibrosis. However, rates of ICU admission and mortality did not differ between those with and without HCV infection.
[97]- Butt A.A.
- Yan P.
- Chotani R.A.
- Shaikh O.S.
Mortality is not increased in SARS-CoV-2 infected persons with hepatitis C virus infection.
Two subsequent single-centre studies have indicated adverse outcomes in patients with co-existing HCV and SARS-CoV-2, including increased ICU admissions and mortality, particularly in those with elevated HCV RNA levels.
[98]- Ronderos D.
- Omar A.M.S.
- Abbas H.
- Makker J.
- Baiomi A.
- Sun H.
- et al.
Chronic hepatitis-C infection in COVID-19 patients is associated with in-hospital mortality.
,[99]- Cerbu B.
- Pantea S.
- Bratosin F.
- Vidican I.
- Turaiche M.
- Frent S.
- et al.
Liver impairment and hematological changes in patients with chronic hepatitis C and COVID-19: a retrospective study after one year of pandemic.
However, interpretations are limited by small sample sizes and the lack of adjustment for the presence of cirrhosis. The repurposing of direct-acting antivirals (DAAs) for the treatment of COVID-19 has been investigated but results remain contentious (discussed below).
100- Kumar P.
- Kulkarni A.
- Sharma M.
- Rao P.N.
Repurposing hepatitis C direct-acting antivirals against COVID-19.
, 101- Kow C.S.
- Javed A.
- Ramachandram D.
- Hasan S.S.
Clinical outcomes of sofosbuvir-based antivirals in patients with COVID-19: a systematic review and meta-analysis of randomized trials.
, 102- Hsu C.-K.
- Chen C.-Y.
- Chen W.-C.
- Lai C.-C.
- Hung S.-H.
- Lin W.-T.
The effect of sofosbuvir-based treatment on the clinical outcomes of patients with COVID-19: a systematic review and meta-analysis of randomized controlled trials.
Liver transplant recipients
Early in the pandemic, country-wide data from Spain and the UK suggested that diagnoses of SARS-CoV-2 infection were more frequent in LT recipients than in the general population.
[104]- Colmenero J.
- Rodríguez-Perálvarez M.
- Salcedo M.
- Arias-Milla A.
- Muñoz-Serrano A.
- Graus J.
- et al.
Epidemiological pattern, incidence, and outcomes of COVID-19 in liver transplant patients.
,[105]- Ravanan R.
- Callaghan C.J.
- Mumford L.
- Ushiro-Lumb I.
- Thorburn D.
- Casey J.
- et al.
SARS-CoV-2 infection and early mortality of waitlisted and solid organ transplant recipients in England: a national cohort study.
Given that LT recipients have been shown to have diminished responses to COVID-19 vaccination these patients should continue to be considered as being particularly susceptible to SARS-CoV-2 acquisition
[106]- Galmiche S.
- Luong Nguyen L.B.
- Tartour E.
- de Lamballerie X.
- Wittkop L.
- Loubet P.
- et al.
Immunological and clinical efficacy of COVID-19 vaccines in immunocompromised populations: a systematic review.
(discussed below). However, LT recipients who develop COVID-19 do not appear to have an increased risk of mortality compared to patients without LT after matching for relevant cofactors.
[83]- Webb G.J.
- Marjot T.
- Cook J.A.
- Aloman C.
- Armstrong M.J.
- Brenner E.J.
- et al.
Outcomes following SARS-CoV-2 infection in liver transplant recipients: an international registry study.
In line with the general population, the major risk factors for developing severe COVID-19 in LT recipients are advancing age and burden of comorbidity.
[107]- Becchetti C.
- Gschwend S.G.
- Dufour J.-F.
- Banz V.
COVID-19 in liver transplant recipients: a systematic review.
,[108]- Webb G.J.
- Moon A.M.
- Barnes E.
- Barritt A.S.
- Marjot T.
Age and comorbidity are central to the risk of death from COVID-19 in liver transplant recipients.
Concerns that immunosuppressive medications in LT recipients may increase susceptibility to SARS-CoV-2 infection must be balanced with their potential to positively influence the course of COVID-19 by suppressing inflammation in the later stages of the disease. Whilst antimetabolic drugs seem to have a negative effect,
[104]- Colmenero J.
- Rodríguez-Perálvarez M.
- Salcedo M.
- Arias-Milla A.
- Muñoz-Serrano A.
- Graus J.
- et al.
Epidemiological pattern, incidence, and outcomes of COVID-19 in liver transplant patients.
calcineurin inhibitors (
e.g. tacrolimus, cyclosporin) and mTOR inhibitors may have a favourable impact on disease course.
109- Gálvez-Romero J.L.
- Palmeros-Rojas O.
- Real-Ramírez F.A.
- Sánchez-Romero S.
- Tome-Maxil R.
- Ramírez-Sandoval M.P.
- et al.
Cyclosporine A plus low-dose steroid treatment in COVID-19 improves clinical outcomes in patients with moderate to severe disease: a pilot study.
, 110- Belli L.S.
- Perricone G.
- Adam R.
- Cortesi P.A.
- Strazzabosco M.
- Facchetti R.
- et al.
Impact of DAAs on liver transplantation: major effects on the evolution of indications and results. An ELITA study based on the ELTR registry.
, 111- Solanich X.
- Antolí A.
- Rocamora-Blanch G.
- Padullés N.
- Fanlo-Maresma M.
- Iriarte A.
- et al.
Methylprednisolone pulses plus tacrolimus in addition to standard of care vs. standard of care alone in patients with severe COVID-19. A randomized controlled trial.
, 112Cancer therapy with decreased SARS-CoV-2 infection rates in cancer patients.
Therefore, adjustments to the dose and type of immunosuppression during SARS-CoV-2 infection should be individually tailored based on COVID-19 severity, the specific regimen used, time post-transplant, and the risk of allograft rejection. Clinical features of COVID-19 among solid organ transplant (SOT) recipients are variable. However, gastrointestinal symptoms including diarrhoea appear more frequent, particularly in patients receiving mycophenolate mofetil (MMF)
[83]- Webb G.J.
- Marjot T.
- Cook J.A.
- Aloman C.
- Armstrong M.J.
- Brenner E.J.
- et al.
Outcomes following SARS-CoV-2 infection in liver transplant recipients: an international registry study.
,[107]- Becchetti C.
- Gschwend S.G.
- Dufour J.-F.
- Banz V.
COVID-19 in liver transplant recipients: a systematic review.
,[113]- Belli L.S.
- Fondevila C.
- Cortesi P.A.
- Conti S.
- Karam V.
- Adam R.
- et al.
Protective role of tacrolimus, deleterious role of age and comorbidities in liver transplant recipients with Covid-19: results from the ELITA/ELTR multi-center European study.
EASL position- •
At present, there is no convincing evidence that liver transplantation by itself is an independent risk factor for COVID-19-related mortality. However, liver transplant recipients should be considered at high-risk of SARS-CoV-2 infection because of their comorbidities, non- or hypo-responsiveness to COVID-19 vaccination and immunosuppression.
- •
In liver transplant recipients with COVID-19, a dose reduction or temporary discontinuation of anti-metabolites (e.g. azathioprine or MMF) may be considered.