Elevated factor VIII activity and venous thromboembolism in patients referred to the Iranian Blood Transfusion Organization: A case control study

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Praca oryginalna/Original research article

Elevated factor VIII activity and venous

thromboembolism in patients referred to the Iranian Blood Transfusion Organization: A case control study

Seyed Mohammad Reza Tabatabaei

¹

, Seyed Mehdi Sajjadi

²

, Minoo Ahmadi Nejad

¹

, Farzaneh Tavasoli

¹

, Azita Azarkeivan

^1,

*

1IranianBloodTransfusionOrganizationResearchCenter,Tehran,Iran

2DepartmentofMedicalLaboratorySciences,SchoolofAlliedMedicalSciences,BirjandUniversityofMedicalSciences, Birjand,Iran

acta haematologica polonica 47 (2016)15–18

article info

Articlehistory:

Received:16.07.2015 Accepted:22.01.2016 Availableonline:02.02.2016

Keywords:

ElevatedfactorVIII

Venousthromboembolism

Iranianpopulation

abstract

Objective:A highplasmalevel offactoreight(FVIII) isa riskfactorfor venousthromboembolism(VTE).Since,therewasnoreportabouttheassociationofelevatedFVIIIand VTEinIranianpopulation,theincidenceofelevatedFVIIIanditsassociationtoVTEwas evaluated.Materials and methods: 152consecutive idiopathic VTEpatients referredto the Iranian Blood Transfusion Organization (IBTO) and 130 healthy matched blood donorswerestudied. Atleast oneconﬁrmed idiopathicdeep veinthrombosis(DVT) or pulmonaryembolism(PE)wasfoundamongallcases.Thebloodsampleswerecollected atleast3monthsafterDVT/PEdiagnosis.Thenormalreferencerangewasdetermined byusingtheControlsamplesofthedonors.FVIIIlevelsweremeasuredusingPTTbased one-stagedassay. Results: The FVIII levels inthe casesand controlswere157.353.4 and111.829.7,respectively.In cases,thelowestandthe highestlevelsof FVIIIwere 66IU/dland364IU/dl,whiletheywere42IU/dland195IU/dlforthecontrols.

Therewasnorelationbetweengender,ageandFVIIIlevelineithergroup.Thenormal referencerangeforthecontrolswas52–171IU/dl.Consideringthecut-offpointas180IU/

dl,theelevatedvalueswereseenin28.9%ofthecasegroupvs.3.1%ofthecontrolgroup.

Conclusion:Elevated factorVIII is likelyto be a risk factor for VTE. Moreover,a new normalreferencerangefortheIranianpopulationwasdeﬁned.

*Correspondingauthorat:IranianBloodTransfusionOrganizationResearchCenter,Tehran,IRAN(ISLAMICREPUBLICOF).

Tel.:+989121490645;fax:+982188060717.

E-mailaddress:azitaazarkeivan@yahoo.com(A.Azarkeivan).

ContentslistsavailableatScienceDirect

Acta Haematologica Polonica

journalhomepage:www.elsevier.com/locate/achaem

http://dx.doi.org/10.1016/j.achaem.2016.01.001

zo.o.Allrightsreserved.

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Introduction

Today,thrombosisinconjunctionwithcomplicatingembolic events is considered to be the most important cause of diseases and mortality in developed countries [1]. A wide varietyofacquiredandinheritedfactorsmayleadtothrom- bosis[2].ElevatedfactorVIII(FVIII)levelsisconsideredamain riskfactorforarterialdisease andvenousthromboembolism (VTE) [2–13]. Inthegeneral population,persistently elevated levels of coagulation FVIII above 150U/dL are a recognized riskfactorforVTEevents[14],whichisprobablydueto(1)the increased rateof thrombin generationinthe externalpath- wayofcoagulationand(2)enhancedplateletaggregationseen inthepresenceofelevatedlevelsofFVIII[15–17].

Theevaluationof bleedingriskasaresultof hereditary or acquired FVIII deﬁciency is the major reason for FVIII levelsmeasurement.Moreover,determinationofFVIIIlevels wouldhelpphysicianstomakebetterdecisionsforpatients’ ﬁrst-degree relatives [12]. To the best of our knowledge, therehasbeennostudyontheassociationofelevatedFVIII and VTE in the Iranian population along with a normal reference range. Thus, in this study, the prevalence of elevatedFVIIIlevelsanditsassociationwithvenousthrom- bosis in thrombotic patients referred to the coagulation laboratory of the Iranian Blood Transfusion Organization (IBTO)wereinvestigated.

Materials and methods

In this case–control study, 152 consecutive idiopathic VTE patientsand 130age-, sex-,andethnicity-matched healthy blooddonorswereenrolled.

AllcasesshowedatleastoneconﬁrmedidiopathicDVTor pulmonaryembolism(PE),usingdiagnosticmethodssuchas venography and spiral CT scan. For cases, blood samples weredrawnatleast threemonthsafterdiagnosisofDVT or PE,whichappearstobealongenoughperiodtoavoidacute- phase response caused by the thrombotic phenomenon.

Plasmafromhealthyblooddonorswasappliedtodetermine the normal reference range. All individuals were informed about thestudy and the samples were collected with their agreement. Since one-stage assays are the most common methodsusedtoanalyzeclinicalplasmasamples[18],factor VIII levelswere measuredby usingaone-stage assay– the PTT-basedDiagonisticaStagoontheSTAcompactautomated coagulation factor analyser. Blood samples taken from the antecubitalveinwerecollectedintotubescontaining0.129M trisodium citrate as an anticoagulant. In order to prepare plateletpoor plasma, within30min of blood collection, the sampleswere centrifugedat 48C, 2500g for20min.Then theplasmawasstoredat 708C.Theywerethawedfor5min ina378Cwaterbathtoperformassays.

So as tocompare the proportion of subjects above and belowtheuppercut-offvalueof180IU/dl,Fisher'sexacttest was used. The mean FVIII levels in the two groups were compared by the use of a Student's t-test. All statistical analysis was performed by SPSS software version 20 and p<0.05wasconsideredasstatisticallysigniﬁcant.

Results

Westudied152patientswithidiopathicVTEand130healthy blood donors as the control group. Cases consisted of 84 (55.3%)malesand68(44.7%)females,whilethecontrolgroup consistedof75(57.7%)malesand55(42.3%)females.Themean ageinthecasesandthecontrolswere40.713.6 yearsand 39.611.1years,respectively.Afamilyhistorywasascertained in33(21.7%)ofthe152patients.FVIIIlevelswere157.353.4 and 111.829.7 for cases and controls, respectively. In the case group, the lowest andhighest levels were 66IU/dland 364IU/dl,whiletheywere42IU/dland195IU/dlforcontrols.

AChi-square testshowedsigniﬁcant differencebetween the elevated levels of FVIII in the two groups (p0.001).

There werenorelationships betweengender,age andFVIII levels in the study population. In the age group over 60 years, the incidence of thrombosis was higher than the otheragegroups;however,theincreasewasnotstatistically signiﬁcant. Fig. 1 shows the comparison of the case and control groups by age. Accordingly, the normal reference rangeforhealthysubjectswas52–171IU/dl.

Considering180IU/dlasacut-offpoint,FVIIIlevelswere notably greater inthecases than the controlsubjectswith an ORof 9.41 (95%CI: 3.47,25.48).That is, elevated values were seen in 28.9% of the cases and in just 3.1% of the controls(TableI).

Discussion

ThereareseveralreportsreferringtoelevatedFVIIIlevelsas athromboembolismriskfactor[2–5,7–12,19,20].Theupside

4

27

43

35

17

4 13

28

38

31

24

18

0 5 10 15 20 25 30 35 40 45 50

<20 21-30 31-40 41-50 51-60 >60

n

Age group (year)

control case

Fig.1–Comparisonofageinthestudyandcontrolgroups

TableI–NormalandelevatedFVIIIlevelsinthestudyand controlgroupsbasedon180IU/dlasthecut-offpoint Factorlevel NormalFVIII ElevatedFVIII Total

Case 108(71.1%) 44(28.9%) 152(100%)

Control 126(96.9%) 4(3.1%) 130(100%)

Total 234 48 282

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of this study, as with someother research [12, 21], is the consecutiveidiopathicpatientsbeinginvestigated.Thehigh incidenceofelevatedFVIIIisseeninpatientswithﬁrst-time DVT (25%). In addition, 11% of healthy subjects in the controlgroupwereobservedwithFVIIIlevels ofmorethan 150IU/dl[22].

As the blood samples werecollected at least3 months after any VTE event in the cases, the effect of many transient risk factors for temporarily increased FVIII levels hadalreadybeeneliminated.Anewnormalrangehasbeen introducedfortheIranianpopulationinthisstudy.Further- more,newlower andupper limitsweredetermined inour patients(66–364IU/dl)andhealthysubjects(42–195IU/dl).

There are signiﬁcant differences in the cut-off values betweenthisstudy(180IU/dl)and thatof Wells’2005study (270IU/dl) [12]. However, the incidence rates of elevated FVIII levels in both studies are not signiﬁcantly different (20%vs.28%respectively).

In the present study, elevated FVIII levels were deter- mined for 23.8% of males and 35.3% of females, however, the difference was not statistically significant, so it could not be concluded that females are at a higher risk of thrombotic events than males. Finally, advancing age was consideredasa riskfactorfor thrombosis.Aswithgender, however,it wasnotstatisticallysignificant.Nonetheless,in order to increasethe chanceof identifyingmore high-risk cases,itwouldbeusefultodefineaspecificcut-offvaluefor patientsagedover60.

Itis clear that more clinical and laboratory studies are neededtoevaluatetheeffectsof FVIIIlevelson thrombotic tendencyandanyfactorsthatmayinﬂuencethistrend.

Authors’ contributions/Wkład autorów

SMRT–studydesign,literaturesearch,manuscriptprepara- tion.FT– datacollection.MAN–statisticalanalysis.SMS– manuscript preparation, literature search. AA – study design,datainterpretation,fundscollection.

Conﬂict of interest/Konﬂikt interesu

Nonedeclared.

Financial support/Finansowanie

We express our thanks to the Research Center of Blood Transfusion, High Institute for Education and Researchon Transfusion Medicine inIran for giving usthe opportunity tocollectsamplesandalsofortheirﬁnancialsupport.

Ethics/Etyka

The work described in this article has been carried out in accordance with The Code of Ethics of the World Medical Association(DeclarationofHelsinki)forexperimentsinvolving humans; EU Directive 2010/63/EU for animal experiments;

UniformRequirementsformanuscriptssubmittedtoBiomedi- caljournals.

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