Vascular Thrombosis in COVID-19: A Potential Association with Antiphospholipid Antibodies

TLDR: Analysis of pooled patients revealed that aPL were significantly more frequent in COVID-19 patients with stroke than stroke patients in the general population, and these antibodies may be a key mechanism of thrombosis in CO VID-19.

Abstract: Background Vascular thrombosis is common in patients with coronavirus disease 2019 (COVID-19). Etiologies underlying this complication are unclear. Purpose To determine the prevalence of antiphospholipid (aPL), including lupus anticoagulant, anti-cardiolipin and anti-β2-glycoprotein-1 antibodies, and its possible association with thrombotic manifestations of COVID-19. Data Sources We searched MEDLINE indexed journals on September 24, 2020 using the tool LitCovid and the pre-print server medRxIV. Study Selection Original investigations (cross-sectional studies, cohort studies, case series, and research letters) on COVID-19 and thrombosis were included. Data Extraction Data were independently extracted, and compiled into spreadsheets based on the PRISMA principles. Data Synthesis Hospitalized patients with COVID-19 showed a higher prevalence of lupus anticoagulant compared to non-COVID-19 patients. Temporally, lupus anticoagulant was generally positive early in the course of illness, whereas anti-cardiolipin and anti-β2-glycoprotein-1 antibodies appeared to emerge later in the disease. Some patients who were aPL-negative at an early time-point after disease onset became aPL-positive at a later time-point. Lupus anticoagulant was independently associated with thrombosis in 60 COVID-19 patients in New York had who had 32 thrombotic events (8 arterial and 24 venous). In 88 patients in Wuhan, who had more than 20 each of arterial and venous thrombotic events, medium/high positivity for multiple aPL was significantly associated with arterial thrombosis. However, the association of aPL with thrombosis was not evident in reports that had an overall lower number of or predominantly venous thrombotic events. Analysis of pooled patients revealed that aPL were significantly more frequent in COVID-19 patients with stroke than stroke patients in the general population. Furthermore, injection of IgG aPL fractions from COVID-19 patients into mice accelerated venous thrombosis. Limitation Limited data and paucity of prospective studies. Conclusion The aPL are prevalent in patients with COVID-19 and their presence is associated with thrombosis. Importantly, these antibodies may be a key mechanism of thrombosis in COVID-19. Follow-up studies are required to understand the relationship between aPL and the spectrum of vascular thrombosis during and after infection with SARS-CoV-2. Primary Funding Source None.

Figures

Table 2. Reports of antiphospholipid assays in patients with COVID-19 and thrombosis

Table 3. Cerebral infarction/stroke in patients with COVID-19

Full text

1
Vascular Thrombosis in COVID-19: A Potential Association with Antiphospholipid
Antibodies
A Rapid Systematic Review
Aneesh S Kallapur, MBBS
1
; Eric Y Yen, MD, MS
1
; Ram Raj Singh, MD
1,2,3,4
1
Department of Medicine, University of California at Los Angeles (UCLA) David Geffen
School of Medicine, Los Angeles, CA,
2
Jonsson Comprehensive Cancer Center, UCLA, Los
Angeles, CA,
3
Molecular Toxicology Interdepartmental Program, UCLA, Los Angeles, CA,
4
Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, CA.
Corresponding author: Ram Raj Singh, MD, Autoimmunity and Tolerance Laboratory,
Division of Rheumatology, UCLA, 1000 Veteran Avenue, Room 32-59, Los Angeles, CA
90095-1670 (rrsingh@mednet.ucla.edu).
Word count: 3,047 (Introduction to Conclusion)
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The copyright holder for thisthis version posted November 4, 2020. ; https://doi.org/10.1101/2020.11.02.20224642doi: medRxiv preprint
NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.

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
ABSTRACT
Background:Vascularthrombosisiscommoninpatientswithcoronavirusdisease
2019(COVID‐19).Etiologiesunderlyingthiscomplicationareunclear.
Purpose:Todeterminetheprevalenceofantiphospholipid(aPL),includinglupus
anticoagulant,anti‐cardiolipinandanti‐β2‐glycoprotein‐1antibodies,anditspossible
associationwiththromboticmanifestationsofCOVID‐19.
DataSources:WesearchedMEDLINEindexedjournalsonSeptember24,2020using
thetoolLitCovidandthepre‐printservermedRxIV.
StudySelection:Originalinvestigations(cross‐sectionalstudies,cohortstudies,case
series,andresearchletters)onCOVID‐19andthrombosiswereincluded.
DataExtraction:Datawereindependentlyextracted,andcompiledintospreadsheets
basedonthePRISMAprinciples.
DataSynthesis:HospitalizedpatientswithCOVID‐19showedahigherprevalenceof
lupusanticoagulantcomparedtonon‐COVID‐19patients.Temporally,lupus
anticoagulantwasgenerallypositiveearlyinthecourseofillness,whereasanti‐
cardiolipinandanti‐β2‐glycoprotein‐1antibodiesappearedtoemergelaterinthe
disease.SomepatientswhowereaPL‐negativeatanearlytime‐pointafterdiseaseonset
becameaPL‐positiveatalatertime‐point.Lupusanticoagulantwasindependently
associatedwiththrombosisin60COVID‐19patientsinNewYorkhadwhohad32
thromboticevents(8arterialand24venous).In88patientsinWuhan,whohadmore
than20eachofarterialandvenousthromboticevents,medium/highpositivityfor
multipleaPLwassignificantlyassociatedwitharterialthrombosis.However,the
associationofaPLwiththrombosiswasnotevidentinreportsthathadanoveralllower
numberoforpredominantlyvenousthromboticevents.Analysisofpooledpatients
revealedthataPLweresignificantlymorefrequentinCOVID‐19patientswithstroke
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preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in
The copyright holder for thisthis version posted November 4, 2020. ; https://doi.org/10.1101/2020.11.02.20224642doi: medRxiv preprint

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thanstrokepatientsinthegeneralpopulation.Furthermore,injectionofIgGaPL
fractionsfromCOVID‐19patientsintomiceacceleratedvenousthrombosis.
Limitation:Limiteddataandpaucityofprospectivestudies.
Conclusion:TheaPLareprevalentinpatientswithCOVID‐19andtheirpresenceis
associatedwiththrombosis.Importantly,theseantibodiesmaybeakeymechanismof
thrombosisinCOVID‐19.Follow‐upstudiesarerequiredtounderstandtherelationship
betweenaPLandthespectrumofvascularthrombosisduringandafterinfectionwith
SARS‐CoV‐2.
PrimaryFundingSource:None.


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perpetuity.
preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in
The copyright holder for thisthis version posted November 4, 2020. ; https://doi.org/10.1101/2020.11.02.20224642doi: medRxiv preprint

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INTRODUCTION
Thecoronavirusdisease2019(COVID‐19)pandemic,causedbythesevereacute
respiratorysyndromecoronavirus‐2(SARS‐CoV‐2)hasresultedintremendous
morbidityandmortality.ManypatientswithCOVID‐19exhibithypercoagulablestates,
withmanifestationsrangingfromdisseminatedintravascularcoagulationtovenous
thromboembolismandcerebrovasculardisease(1).Amongpatientswithacute
respiratorydistresssyndrome,morethromboticcomplicationswerediagnosedin
COVID‐19patientsthaninmatchedpatientswithoutCOVID‐19(oddsratio2.6[1.1–
6.1])(2).Anautopsystudydetectedvenousthromboembolisminmorethanhalfof
deceasedCOVID‐19patientsinwhomitwasnotsuspectedearlier(3).
Asthesethromboticmanifestationsbeganbeingreportedathighrates,attempts
arebeingmadetouncovertheunderlyingetiologies.AreportfromWuhan,China,in
April2020describedthreeCOVID‐19patientswhodevelopedthrombosisincluding
multiple‐vesselbraininfarctionandacro‐ischemia(4).Allthreepatientshadanti‐
cardiolipin(aCL)andanti‐β2glycoprotein‐1(aβ2GP1)antibodies,collectivelycalled
antiphospholipid(aPL)antibodies.
ThepresenceofaPLantibodiesandafunctionalassaycalledlupusanticoagulant
(LA)arethehallmarksofantiphospholipidsyndrome(APS)thatmanifestswithvenous
andarterialthrombosis(5).SomepatientswithAPShavenootherassociatedcondition
(primaryAPS),whileotherscanbeassociatedwithinfectionsandautoimmune
disorders.Variousinfections,notablyHepatitisCvirus(HCV)andHIV,havebeenshown
toinduceaPLantibodies,however,thesignificantthromboticriskwithaPLwasseen
onlyinHCVinfection(6,7).ItisunclearwhetherSARS‐CoV‐2elicitstheproductionof
aPLthatassociatewithincreasedthromboticrisk.
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preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in
The copyright holder for thisthis version posted November 4, 2020. ; https://doi.org/10.1101/2020.11.02.20224642doi: medRxiv preprint

5
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Inthissystematicreview,weidentifypatientswithCOVID‐19andthrombosis
whoweretestedforaPL,anddeterminetheprevalenceofaPLinthispopulation
comparedtothegeneralpopulationwithreferencetospecificthrombotic
manifestations.Wefurtherseekifanycausalrelationshipexistsbetweenthepresence
ofaPLinthesepatientsandthrombosis.

Methods
DataSourcesandSearches:WesearchedMEDLINEindexedjournalsusingthetool
LitCovid(8)onSeptember24,2020.Duetotherapidlychanginglandscapeofresearch
inCOVID‐19,wealsosearchedthepre‐printservermedRxIV,withtheacknowledgment
thatthosearticlesarenotpeer‐reviewed.

StudySelection:Weincludedalloriginalinvestigations(cross‐sectionalstudies,cohort
studies,caseseries,casereportsandresearchletters)relevanttoadultpatientsinthe
Englishlanguage.Weusedthefollowingsearchterms:“COVID‐19”,“Coronavirus”,
“ncov”,“2019‐ncov”and“Antiphospholipidantibodies”,“Antiphospholipidantibody
syndrome”,“Lupusanticoagulant”and“Stroke”,“Venousthromboembolism”,“Deep
veinthrombosis”(DVT),“Myocardialinfarction”and“Acutelimbischemia”.Articlesthat
didnotcontainanylaboratorydataandthosewhichdidnotcarryouttestingforaPL
wereexcluded.

DataExtractionandQualityAssessment:Datawereextractedbyonereviewer(A.K.),
andindependentlyreviewedbyothertwoauthors.Weassessedarticleforthequalityof
evidence(AppendixTable1).

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perpetuity.
preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in
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Frequently asked questions

Q1. What are the contributions in "Vascular thrombosis in covid-19: a potential association with antiphospholipid antibodies a rapid systematic review" ?

In this paper, the authors identify patients with COVID-19 and thrombosis who were tested for antiphospholipid ( aPL ) antibodies, and determine the prevalence of aPL in this population compared to the general population with reference to specific THrombotic manifestations. 

Q2. What have the authors stated for future works in "Vascular thrombosis in covid-19: a potential association with antiphospholipid antibodies a rapid systematic review" ?

Follow‐up testing is needed to identify whether these antibodies persist and pose a thrombosis risk in the future. Experimental transfer studies showing venous thrombosis in mice injected with human IgG from COVID‐19 patients with aPL suggest a potential pathogenicity of these antibodies ( 16 ), however, more studies are needed to establish a causal relation between aPL positivity and thrombosis in COVID‐19. 

Q3. What is the overall frequency of aPL in COVID19?

The overall aPL frequency in this analysis was estimated to be 13.5% for stroke, 11% for myocardial infarction, 9.5% for DVT, and 6% for pregnancy morbidity in the general population. 

Q4. How many pregnancies were lost in the US?

Of 458 pregnancies in hospitalized patients with COVID‐19 in the US, pregnancy loss occurred in 10 (2.2%) including four that occurred within 20 weeks of gestation (25). 

Q5. What is the common aPL in Chinese patients?

IgA aβ2GP1, IgA aCL, and IgG aβ2GP1 antibodies were the most prevalent aPL in Chinese patients, with many of them positive for multiple isotypes (12, 13). 

Q6. What is the cause of the COVID19 pandemic?

The coronavirus disease 2019 (COVID‐19) pandemic, caused by the severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) has resulted in tremendous morbidity and mortality. 

Q7. What is the common type of aPL in Chinese patients?

In 66 COVID‐19 patients from Wuhan, 38% developed arterial or venous thrombosis, and nearly half of all patients were positive for aPL antibodies (12). 

Q8. What was the common aCL in Chinese patients?

10 Chinese patients who were aPL negative at an early time point after disease onset became aPL positive later (12), and a French patient with isolated IgM aCL seroconverted to IgG aCL and aβ2GP1 antibodies (14). 

Q9. Why did the authors search the preprint server?

Due to the rapidly changing landscape of research in COVID‐19, the authors also searched the pre‐print server medRxIV, with the acknowledgment that those articles are not peer‐reviewed. 

Q10. What is the underlying cause of COVID19?

Many patients with COVID‐19 exhibit hypercoagulable states, with manifestations ranging from disseminated intravascular coagulation to venous thromboembolism and cerebrovascular disease (1). 

Q11. What are the main reasons for the lack of standardization in the aCL and a?

Antibody assays for aCL and aβ2GP1 antibodies also suffer from a lack of standardization and the presence of inter‐laboratory variation, which can influence the interpretation of tests with borderline results (36). 

Q12. What was the common aCL in the early report?

An early report described three COVID‐19 patients with multi‐vessel brain infarction, acro‐ischemia, and IgA/IgG aCL and aβ2GP1 antibodies (4). 

Q13. What is the significance of aPL in COVID19?

For one, testing of aPL could be recommended for critically ill patients if it is proven that aPL positivity is a harbinger of future thrombotic events. 

Q14. What is the association between aPL and asymptomatic COVID19?

Akin to reports in patients with APS, higher levels of aPL in COVID‐19 patients were associated with neutrophil hyperactivity including the release of neutrophil extracellular traps (NET), and IgG fractions isolated from patients with COVID‐19 promoted NET release from control neutrophils (16). 

Q15. How many patients were tested for aPL antibodies?

Of 438 COVID‐19 patients with ischemic stroke, 65 were tested for aPL antibodies, and 38 (58.4%) were found to be positive (Table 3). 

Q16. What is the common cause of aPL in COVID19?

injection of IgG fractions from COVID‐19 patients who have aPL antibodies into mice accelerated venous thrombosis (16).