EVIDENCE BASED MANAGEMENT OF PEDIATRIC Professor Azza Abdel Gawad Tantawy, MD Professor of Pediatrics Pediatric /Oncology Unit Ain Shams University, Cairo , Egypt • TO DEFINE THROMBOPHILIA • TO IDENTIFY CAUSES OF THROMBOPHILIA • TO PRESENT EVIDENCE BASED UPDATES IN PEDIATRIC THROMBOPHILIA: WHO TO TEST , WHY TO TEST AND CLINICAL IMPACT OF THROMBOPHILIA TESTING Thrombophilia

Thrombophilia is defined as both an acquired or congenital abnormality of hemostasis predisposing to venous and/or arterial

Acquired Inherited Mixed/unknown Immobilization Antithrombin deficiency High levels of factor VIII Plaster cast High levels of factor IX Trauma High levels of factor XI Major surgery (FVL) High levels of fibrinogen Orthopedic surgery Prothrombin 20210A High levels of TAFI Malignancy Low levels of TFPI Factor XIII 34val APC-resistance in the absence of FVL

Fibrinogen (G) 10034T Antiphospholipid syndrome Non-O blood group Hyperhomocysteinemia Myeloproliferative disorders High levels of PCI (PAI-3) Polycythemia vera Central venous catheters Age Obesity

F. R. ROSENDAAL and P. H. REITSMA ; JHT 2009 TAFI, thrombin-activatable fibrinolysis inhibitor; TFPI, tissue factor pathway inhibitor; PCI, protein C inhibitor; PAI-3, plasminogen-activator inhibitor-3.

Age-distribution at the first thrombotic onset in pediatric patients with spontaneous venous thrombosis [not associated with secondary causes of thrombosis]

Ulrike Nowak-Göttl et al ; Blood 2001 Genetic risk factors for venous thrombosis

Strong risk factors deficiencies of antithrombin, protein C and protein S Moderately strong factor V Leiden, prothrombin 20210A, non-O blood group & fibrinogen 10034T Many weak genetic risk factors including variants of fibrinogen, factor XIII and factor XI

F. R. ROSENDAAL and P. H. REITSMA ; JTH 2009

Strong risk factors Deficiencies of natural inhibitors ● Deficiencies of antithrombin, protein C, and its cofactor protein S found in less than 1% of the population (antithrombin deficiency in only 1 per 5000)

● Hundreds of mutations responsible for defective genes

● Deficiencies can lead to a highly penetrant phenotype with over tenfold increased risks for heterozygous carriers

● Prevalence in Caucasians 0.2–0.5% ● Less common than factor V Leiden or mutation ● Associated with familial venous thrombosis ● Autosomal dominant ; gene on chromosome 2 (2q13–14)

Homozygotes can develop severe thrombotic tendency in infancy characterized as fulminans

Heterozygotes for protein C deficiency have an increased risk of developing warfarin-induced skin necrosis

Protein C deficiency has been implicated in adverse pregnancy outcomes such as DVT, preeclampsia, intrauterine growth restriction and recurrent pregnancy loss Classical clinical presentation of homozygous PC /PS deficiency : ● Cerebral or ophthalmic damage (or both) that occur in utero ● within hours or days of birth ● Rarely large-vessel thrombosis

● Purpura fulminans : acute, lethal syndrome of DIC characterized by rapidly progressive hemorrhagic necrosis of skin due to dermal vascular thrombosis ● Skin lesions start as small, ecchymotic sites , increase in radial fashion, become purplish black with bullae, then turn necrotic and gangrenous ● Lesions occur mainly on extremities but can occur on buttocks, abdomen, scrotum, and scalp, at pressure points, at sites of previous punctures, and at previously affected sites Purpura Fulminans Diagnosis

Diagnosis : •Protein C/protein S level usually undetectable The presence of very low levels of •Heterozygous state in parents protein C/protein S in the • Identification of the molecular defect absence of clinical manifestations and of a family history cannot be considered diagnostic because physiologic plasma levels can be as low as 0.12 U/mL in neonate Antithrombotic Therapy in Neonates and Children : American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (9th Edition)

● For neonates with homozygous protein C Replacement therapy should be continued deficiency, we recommend administration of until all of the clinical lesions resolve, either 10 to 20 mL/kg of FFP q12h or protein C which is usually at 6 to 8 weeks concentrate, when available, at 20 to 60 U/kg until the clinical lesions resolve (Grade 1B)

● We suggest long-term treatment with VKAs (Grade 2C), LMWH (Grade 2C), protein C In addition to the clinical course, replacement (Grade 1B), or liver transplantation plasma d-dimer concentrations (Grade 2C) may be useful for monitoring the effectiveness of therapy

Monagle P, e tal . Chest. 2012 Feb;141(2 Suppl):e737S-e801S. doi: 10.1378/chest.11-2308. 2018 ASH GUIDELINES IN HOMOZYGOUS PROTEIN C DEFICIENCY AND PURPURA FULMINANS

IN ACUTE SETTING Anticoagulation plus protein C replacement, rather than anticoagulation alone

AFTER ACUTE ATTACK ▪ ASH suggests protein C replacement, rather than anticoagulation ▪ But if cannot supply full dose of protein C , ASH suggests combined anticoagulation and protein C The ASH guideline panel suggests using either liver transplantation or no liver transplantation (anticoagulation or protein C replacement) in pediatric patients with congenital purpura fulminans due to homozygous protein C deficiency

Monagle P et al , Blood Adv. 2018 Nov 27; 2(22): 3292– 3316 Genetic risk factors for venous thrombosis

Strong risk factors deficiencies of antithrombin, protein C and protein S

Moderately strong factor V Leiden, prothrombin 20210A, non-O blood group & fibrinogen 10034T

Many weak genetic risk factors including C>T variant at position 677 in MTHFR , variants of fibrinogen, factor XIII and factor XI

F. R. ROSENDAAL and P. H. REITSMA ; JTH 2009 Moderately Strong genetic risk factors Factor V Leiden

1st described in in 1994 by Bertina et al

A transition (guanine to adenine) at nucleotide 1691 results in replacement of arginine by glutamine. This gene product: factor V Leiden (after Netherlands city it was first identified) , also called factor V Q506

F.V Leiden is not susceptible to cleavage by APC →hypercoagulable state as more factor Va is available increasing generation of thrombin FV Leiden decreases the anticoagulant activity of activated protein C

● Found in 20% of patients with venous thrombosis ● Found in 50% of patients with familial thrombophilia ● Thrombosis risk is 5-fold increased in heterozygotes, & 50 fold in homozygotes Moderately Strong genetic risk factors Prothrombin 20210A

Described in 1996 by Poort et al

A mutation in the 3'-untranslated part of the prothrombin gene (prothrombin 20210A) leads to increased prothrombin levels, which are associated with an increased risk of venous thrombosis

Almost exclusively found in Caucasians ● Carriers have a 2- to 3-fold increased risk of venous thrombosis ● Found in approximately 6% of patients with venous thrombosis ● As factor V Leiden and prothrombin 20210A both are common, compound heterozygotes are not exceedingly rare, have 20-fold increased risk of thrombosis compared to individuals with neither mutation

Khan &Dickermann;J.Thrombosis,2006 Weak genetic risk factors

Several genetic factors have a weak effect on thrombosis, i.e. with relative risks between 1.0 and 1.5

The C>T variant at position 677 in MTHFR renders the enzyme thermolabile, resulting in slightly elevated homocysteine levels

The variant is common (10% of the general population are carriers), but effect on homocysteine levels is small, which may explain conflicting results about effect of carriership on risk of thrombosis

A meta-analysis suggested weak effect (relative risk 1.20), but large single study (the MEGA study) showed no association at all

N.A.Goldenberg , Hematology 2008;F. R. Rosendaal and P. H. Reitsma ; JTH 2009 Prevalence of inherited thrombophilia and relative risk estimates for various clinical manifestations

Antithrombin Protein C Protein S F2 G20210A Anticardiolipin Factor V Leiden deficiency deficiency deficiency mutation anticoagulant antibodies Prevalence in the general 0·02% 0·2% 0·03–0·13% 3-7% 0·7–4% 1–8% 5% population Relative risk for a first venous 5–10 4–6·5 1–10 20% 2–3 3–10 0·7 thrombosis Relative risk for recurrent 1·9–2·6 1·4–1·8 1·0–1·4 1.4 1·4 2–6 1–6 venous thrombosis Relative risk ???No No No consistent for arterial consistent 1.3 0·9 10 1·5–10 association association thrombosis association

S. Middeldorp ,ASH Education Book 2016 Prevalence of genetic defects among Caucasians

Incident VTE (%) recurrent VTE (%) Normal population

Activated Protein C resistance (Factor V 20 40–50 3–7 Leiden)

Prothrombin G20210A mutation 3–8 15–20 1–3

Antithrombin deficiency 1–2 2–5 0.02–0.04

Protein C deficiency 2–5 5–10 0.2–0.5

Protein S deficiency 1–3 5–10 0.1–1

Khan and Dickerman ;Thrombosis Journal 2006 HYPERHOMOCYSTEINEMIA

INHERITED ● Homozygous cystathionine synthetase deficiency (severe)---premature atherosclerosis , arterial and venous thrombosis ● Heterozygous ● Others : remethylation pathways defects ACQUIRED ● Nutritional deficiencies : B12 ,folic acid, pyridoxine ( cofactors of homocysteine metabolism) ● Relative deficiency in chronic hemolytic anemias ● Drugs that interfere with metabolism of these factors The antiphospholipid syndrome (APS)

● APS is autoimmune condition characterized by the persistent presence of antiphospholipid antibodies (aPL), in association with thrombosis (which can be arterial, microvascular or venous) and/ or pregnancy morbidity

● APS can occur alone when it is known as primary APS or associated with another auto-immune disease, most commonly systemic lupus erythematosus, when it is known as secondary APS

Kamat et al,Haematologica 2006 International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome Revised classification criteria for the antiphospholipid syndrome

Antiphospholipid antibody syndrome (APS) is present if at least one of the clinical criteria and one of the laboratory criteria that follow are met

Miyakis S, et al. J Thromb Haemost. 2006 J.A. Gómez-Puerta, R. Cervera / Journal of Autoimmunity 48-49 (2014) 20e25 Revised classification criteria for the antiphospholipid syndrome Clinical criteria

1. Vascular thrombosis

One or more clinical episodes of arterial, venous, or small vessel thrombosis, in any tissue or organ.

2. Pregnancy morbidity

(a) One or more unexplained deaths of a morphologically normal fetus at or beyond the 10th week of gestation, with normal fetal morphology documented by ultrasound or by direct examination of the fetus, or (b) One or more premature births of a morphologically normal neonate before the 34th week of gestation because of: (i) eclampsia or severe pre-eclampsia defined according to standard definitions or (ii) recognized features of placental insufficiency, or (c) Three or more unexplained consecutive spontaneous abortions before the 10th week of gestation, excluding maternal anatomic or hormonal abnormalities and paternal and maternal chromosomal causes Miyakis S, et al. J Thromb Haemost. 2006 J.A. Gómez-Puerta, R. Cervera / Journal of Autoimmunity 48-49 (2014) 20e25 Revised classification criteria for the antiphospholipid syndrome Laboratory criteria

1. Lupus anticoagulant (LA) present in plasma, on two or more occasions at least 12 weeks apart

2. Anticardiolipin (aCL) antibody of IgG and/or IgM isotype in serum or plasma, present in medium or high titer (i.e. >40 GPL or MPL, or >the 99th percentile), on two or more occasions, at least 12 weeks apart, measured by a standardized ELISA

3. Anti-β2 glycoprotein-I antibody of IgG and/or IgM isotype in serum or plasma (in titer >the 99th percentile), present on two or more occasions, at least 12 weeks apart, measured by a standardized ELISA

Miyakis S, et al. J Thromb Haemost. 2006 J.A. Gómez-Puerta, R. Cervera / Journal of Autoimmunity 48-49 (2014) 20e25 European Ped-APS Registry Characteristics of Patients With Pediatric APS

Study cohort 121 (100%) Primary APS 60 (49.5) APS associated with 60 (49.5) SLE 46 (38.0) Lupus-like disease 4 (3.0) Autoimmune thyroiditis 4 (3.0) Rheumatic fever 2 (2.0) ITP 1 (1.0) Hemolytic-uremic syndrome 1 (1.0) Pauci-immune glomerulonephritis 1 (1.0) Behçet disease 1 (1.0) APS associated with malignant disease 1 (1.0)

Avcin T, et al., Pediatrics,2008 European Ped-APS Registry Thrombotic Events at the Onset of Pediatric APS Venous thrombosis 72 (60%) DVT in the lower extremities 49 (40) Cerebral sinus vein thrombosis 8 (7) Portal vein thrombosis 4 (3) DVT in the upper extremities 3 (2) Superficial vein thrombosis 2 (2) Thrombosis in the left atrium 2 (2) Jugular vein thrombosis 1 (1) Inferior vena cava thrombosis 1 (1) 1 (1) Retinal vein thrombosis 1 (1) Arterial thrombosis 39 (32%) Ischemic stroke 31 (26) Peripheral arterial thrombosis 3 (2) Retinal artery thrombosis 2 (2) Myocardial infarction 1 (1) Renal artery thrombosis 1 (1) Splenic infarction 1 (1) Small-vessel thrombosis 7 (6%) Digital ischemia 4 (3) Renal thrombotic microangiopathy 3 (2) Mixed arterial and venous thrombosis 3 (2%)

Avcin T, et al., Pediatrics,2008 Nonthrombotic manifestations of APS Dermatological manifestations

● splinter haemorrhages (red or black streaks found on nails) ● leg ulcers ● superficial thrombophlebitis ● blue toe syndrome ● Vasculitis ● Livedo reticularis refers to a condition in which dilation of capillary blood vessels and stagnation of blood within these vessels causes mottled discolouration of the skin

Nonthrombotic manifestations of APS Neurological manifestations

Migraines (7%), chorea (4%) and epilepsy (3%) were the most common non-thrombotic neurologic manifestations in the Pediatric APS registry

Muscal E, et al, Lupus. 2010 Nonthrombotic manifestations of APS Hematological manifestations

● as a manifestation of 1ry(APS) has a prevalence of 30% - 46%.

●Thrombocytopenia is is usually moderate and requires no intervention.

●Possible mechanisms of role of (aPL) in thrombocytopenia: direct binding of aPL to phospholipids, immune mediated, and platelet activation and/or damage

● Autoimmune hemolytic anemia (AIHA) and Evans syndrome have a frequency of 4% and 10%

Uthman I, et al, Blood Rev. 2008 ; Comellas-Kirkerup L, et al, Blood,2010 Catastrophic antiphospholipid syndrome in children

● Catastrophic APS is a rare, potentially life-threatening variant of APS defined as an accelerated form of thrombosis resulting in multiorgan failure despite treatment

● It is estimated that catastrophic APS represents less than 1% of adult patients with APS

● Catastrophic APS has also been reported in pediatric patients, mostly associated with preceding infections as a precipitating event

● Although large-vessel occlusions do occur in catastrophic APS, the clinical picture is usually dominated by aggressive microvascular occlusive disease affecting kidney, liver,CNS, heart, lung and skin

Tadej Avcin , Current Opinion in Rheumatology 2008 MULTIPLE PROTHROMBOTIC RISK FACTORS AND RECURRENT VTE DISEASE

● Cumulative recurrent-free survival in pediatric patients with combined prothrombotic risk factors compared with subjects carrying one single prothrombotic risk factor and no prothrombotic defect. Dotted line indicates combined defects (30/62); solid line, single defects (31/176); and dashed line, with out defects (3/63).

Ulrike Nowak-Göttl et al ; Blood 2001

CLINICAL SIGNIFICANCE Thrombophilia in Children: Who to Test, How, When, and Why? TESTING CHILDREN FOR INHERITED THROMBOPHILIA: MORE QUESTIONS THAN ANSWERS

Most young children who develop thrombosis have multiple coexisting risk factors

The reported prevalence of thrombophilia in children with venous and arterial thrombotic events varies greatly, from as low as 13% to as high as 79%

L. Raffini and C Thornburg , BJH 2009 Evolution of inherited thrombophilia testing over time

The left pyramid indicates the evolution from testing in rare populations to testing in consecutive patients and for broader indications

The right inverted pyramid shows how the perceived prevalence and benefits of inherited thrombophilia and its associated risk evolved from very high to low, discouraging testing in most situations

S. Middeldorp ,ASH Education Book 2016 Common & diagnostic laboratory studies

Thrombophilia Laboratory Tests Level I Testing Factor V Leiden PCR or screening with clotting assay

Prothrombin 20210 PCR

Antithrombin deficiency Chromogenic or clotting assay

Protein C deficiency Chromogenic or clotting assay

Protein S deficiency Clotting assay or immunologic assay of free and total protein S antigen Hyperhomocystenemia Fasting homocysteine

Elevated lipoprotein (a) ELISA

Antiphospholipid antibodies (PTT, LA) ,ELISA for IgG and IgM antibodies against cardiolipin and β2 glycoprotein Elevated factor VIII clotting assay, chromogenic assay

Level II Testing* Dysfibrinogenemia Clotting assay ,immunologic assay, thrombin time

Elevated factor IX, XI One-stage clotting assay

*if thrombophilic defect strongly suspected and level I testing is normal L. Raffini , Hematology 2008 CLINICAL CONDITIONS ASSOCIATED WITH ACQUIRED THROMBOPHILIC LABORATORY ABNORMALITIES

● Acute thrombosis ● Complex congenital heart disease (single ventricle) Low protein S Low protein S Low protein C Low protein C Low antithrombin Low antithrombin ● Infection ● Asparaginase (ALL) Antiphospholipid antibodies Low antithrombin ● Inflammation ● Liver disease Elevated factor VIII Low protein S Low free protein S Low protein C Elevated Lp(a) Low antithrombin ● Nephrotic syndrome ● Warfarin therapy Low protein C Low protein S Low protein S Low protein C Elevated Lp(a) ● Heparin therapy ● Nutritional deficiency Low antithrombin Elevated homocysteine

L. Raffini , Hematology 2008 WHO SHOULD BE TESTED FOR THROMBOPHILIA AND WHY PERFORMING THE TESTS

Acute thrombosis management Duration of therapy Pathogenesis Thromboprophylaxis in high-risk situations Risk of recurrence Identification of other family members WHY TEST THE CHILD FOR THROMBOPHILIA

•Acute thrombosis management •Duration of therapy •Pathogenesis •Risk of recurrence •Thromboprophylaxis in high-risk situations •Identification of other family members Why Thrombophilia Test in Child with an Acute Thrombosis?

Acute management

Identification of a thrombophilic marker will almost never influence acute management of patient with venous thrombosis, mainstay of therapy is therapeutic anticoagulation

The exception would be a neonate or older child with severe (homozygous or compound heterozygous) deficiency of protein C or S or antithrombin deficiency who presents with purpura fulminans, extensive large vessel thrombosis or DIC, all are life-threatening

Early identification of one of these rare conditions is likely to influence treatment because replacement therapy with plasma-derived concentrate (protein C or antithrombin) or FFP is effective management Monagle P et al , Antithrombotic therapy in neonates and children , CHEST ,2012 Why Test the Child with an Acute Thrombosis? Acute management

Initiation and intensity of anticoagulant therapy following a diagnosis of acute venous thrombosis should be the same in patients with and without heritable thrombophilia (1B).

Neonates and children with purpura fulminans should be tested urgently for protein C and S deficiency (1B). A variety of functional methods may be required to identify specific severe type 2 functional defects when levels of protein C or S are not <5% (1B).

Baglin T, et al ; British Committee for Standards in Haematology. Clinical guidelines for testing for heritable thrombophilia. Br J Haematol. 2010 Apr;149(2):209-20.

Why Test the Child with Acute Thrombosis? DURATION OF THERAPY

Why Test the Child with Acute Thrombosis? Duration of therapy

Patients with VTE heterozygous for the factor V Leiden or prothrombin gene have modestly increased risk of recurrent VTE, odds ratios of 1.41 and 1.72; recurrence risk does not exceed hemorrhagic risk of long-term anticoagulation

Patients with high-risk" defect, such as AT deficiency, homozygous factor V Leiden, or more than one congenital risk factor, may benefit from long-term anticoagulation

Patients with criteria for APL syndrome need long-term anticoagulation Many pediatric patients with thrombosis have transient↑of these antibodies Contribution of these transient antibodies to thrombosis not known

S. Middeldorp & A.vH.Vlieg, BJH 2008; L. Raffini , Hematology 2008 Provoked DVT or PE Using anticoagulation for ≤3 months Unprovoked DVT or PE rather than anticoagulation for >3 using anticoagulation for 6 to 12 months months in pediatric patients with provoked rather than anticoagulation for >6 to 12 DVT or PE (conditional recommendation) months in pediatric patients with Remarks: unprovoked DVT or PE (conditional However, for patients who have recommendation ) persistence of the causative risk factor for Remarks: There were little pediatric data. provoked DVT/PE, longer anticoagulation Extrapolation of adult data might favor could be considered. prolonged treatment periods in terms of VTE recurrence.

Monagle P, et al.. Blood Adv. 2018;2(22):3292–3316. Why Test the Child with Acute Thrombosis? Duration of therapy

For children with VTE, independent of the presence or absence of inherited thrombophilic risk factors, we suggest that the duration and intensity of anticoagulant therapy as per Recommendation Monagle P et al , CHEST ,2012 Why Test the Child with Acute Thrombosis? Duration of therapy

British Committee for Standards in Haematology. Clinical guidelines for testing for heritable thrombophilia 2010

Decisions regarding duration of anticoagulation in unselected patients should be made with reference to whether or not a first episode of venous thrombosis was provoked or not, other risk factors, and risk of anticoagulant therapy-related , regardless of whether a heritable thrombophilia is known (1B).

Testing for heritable thrombophilia in selected patients, such as those with a strong family history of unprovoked recurrent thrombosis, may influence decisions regarding duration of anticoagulation (C). It is not possible to give a validated recommendation as to how such patients should be selected.

Baglin T, et al ;. Br J Haematol. 2010 Apr;149(2):209-20.

Thromboprophylaxis in high-risk situations Identification of an inherited thrombophilia in a child with VTE may lead to the increased use of thromboprophylaxis in future high-risk situations, Though many would argue that the history of VTE alone is enough to warrant early thromboprophylaxis

L. Raffini , ASH 2008 WORK UP FOR INHERITED THROMBOPHILIA IS NOT INDICATED TO PREVENT RECURRENCE OF VTE.

In unselected patients who have had a first episode of VTE, testing for heritable thrombophilia does not allow prediction of recurrent VTE in the first 2 years after anticoagulant therapy is stopped. However, assessment of clinical risk factors associated with the first episode of VTE does predict risk of recurrence.

▪ Thrombophilia testing in patients with first VTE does not reduce the incidence of recurrence in clinical practice

▪ Recurrence risk is the same in patients with and without inherited thrombophilia

Christiansen SC, et al.. JAMA. 2005 May 18;293(19):2352-61. Ashraf N et al .Blood Coagulation and Fibrinolysis 2019, 30:249–252

Why Test the Child with Acute Thrombosis? Identification of other family members

● Discovery of an inherited thrombophilia in an individual with VTE may lead to identification of other family members who can be counseled regarding risk

● These asymptomatic individuals may be more likely to receive primary prophylaxis in the presence of transient risk factors

● It is also possible that knowledge of an inherited thrombophilia may lead to healthy lifestyle choices

F. A. Spencer &R. J. Goldenberg ; JHT 2005 ; Middeldorp, ASH 2011 Case finding of asymptomatic relatives with high risk thrombophilia, such as deficiency of antithrombin, protein C or protein S, should only be considered in selected thrombosis- prone families (1B) Baglin T, et al ; .Br J Haematol. 2010.

Primary prevention in relatives of VTE patients •Should family members of patients with VTE or hereditary thrombophilia undergo thrombophilia testing?

Guidance Statement Do not test for thrombophilia in asymptomatic family members of patients with VTE or hereditary thrombophilia.

Remark As a family history of VTE confers an excess risk of thrombosis, relatives should be counseled regarding use of prophylaxis in high risk situations.

Stevens SM, et al . J Thromb Thrombolysis. 2016 Jan;41(1):154-64 WHO SHOULD BE TESTED FOR THROMBOPHILIA Thrombophilia testing in children WHO SHOULD BE TESTED FOR THROMBOPHILIA

Neonates and children with purpura fulminans should be tested urgently for protein C and S deficiency (1B). A variety of functional methods may be required to identify specific severe type 2 functional defects when levels of protein C or S are not <5% (1B).

Who Recommendation Why Comments

Identify combined defects Counsel regarding risk of This group has the highest Adolescents with Testing should be recurrence prevalence of inherited spontaneous thrombosis strongly considered Counsel/test other family thrombophilia members

L. Raffini , ASH Education book 2008 Thrombophilia testing in children WHO SHOULD BE TESTED FOR THROMBOPHILIA

Patients presenting with VTE at a young age (under the age of 50 years), with Finding a strong ▪ **History of recurrent thromboembolism hypercoagulable state has ▪ Thrombosis occurring in unusual sites including cerebral, clinical implications for portal, mesenteric and hepatic veins recommendations regarding ▪ **History of thrombosis within first degree relatives ▪ preventive strategies ▪ Warfarin-induced skin necrosis ▪ long term anticoagulation for secondary VTE prophylaxis ▪ Thrombosis following use of estrogen-containing ▪ discussion with the patient contraception or hormone replacement therapy (HRT) and family members against hormonal contraception. are likely to benefit from screening for inherited or acquired thrombophilia .

Ashraf N et al .Blood Coagulation and Fibrinolysis 2019, 30:249–252 Kujovich JL. Factor V Leiden thrombophilia. Genet Med 2011; 13:1–16. CHILD WITH RECURRENT VTE DISEASE

In children with recurrent idiopathic VTE, we recommend indefinite treatment with VKAs (Grade 1A)

Monagle P et al , CHEST ,2012 INHERITED THROMBOPHILIA WORKUP

NOT NECESSARY FOR PATIENTS WITH VTE FOLLOWING A MAJOR PROVOCATION

Extended duration of anticoagulation is not indicated for patients with VTE provoked by a major transient risk factor including surgery, immobility and trauma (adopting ‘Choosing Wisely’ guidelines published by the American Society of Hematology (ASH), which recommend against testing)

NOT NEEDED FOR PATIENTS WITH UNPROVOKED VTE

▪ Patients in this group need long-term anticoagulation therapy (6-12 MONTHS), regardless of screening results, provided there is no significant bleeding risk

▪ A negative thrombophilia screening is not sufficient to stop anticoagulation after a limited time interval following an episode of unprovoked VTE, in a patient with low-bleeding risk and willingness to continue therapy

Ashraf N et al .Blood Coagulation and Fibrinolysis 2019, 30:249–252 Middeldorp S. ASH Educ Program 2016; 2016:1–9 Stevens. SM, et al. J Thromb Thrombolysis. 2016 Jan;41(1):154-64 THROMBOPHILIA TESTING IN SPECIAL THROMBOSIS SITES Testing for heritable thrombophilia is not indicated in patients with adults with arterial thrombosis (1B).

It is suggested that testing for heritable thrombophilia is not indicated in children with arterial ischemic stroke AIS (2C).

Baglin T, et al; British Committee for Standards in Haematology. Clinical guidelines for testing for heritable thrombophilia. Br J Haematol. 2010 Apr;149(2):209-20. THROMBOPHILIA SCREENING IS NOT INDICATED FOR RECURRENT ARTERIAL THROMBOEMBOLIC EPISODES WITHOUT VTE.

Rao AK, Sheth S, Kaplan R. Inherited hypercoagulable states. Vasc Med 1997; 2:313–320 Curtis C et al , BLOOD, 18 MAY 2017 x VOLUME 1292794-2800 DeVeber et al

CANADA, GERMANY, UK 894 CHILDREN AGED 1-18 YEARS DIAGNOSED ARTERIAL ISCHEMIC STROKE (AIS) 160 (17.9%) HAD RECURRENCE UP TO 130Ms 288 PATIENTS HAD VASCULOPATHY

288 children had vasculopathy recurrence was significantly more common [hazard ratio (HR) 2.5, 95% confidence interval (95% CI) 1.92-3.5] compared to the rate in children without vasculopathy. CANADA, GERMANY, UK 894 CHILDREN AGED 1-18 YEARS 160 (17.9%) HAD RECURRENCE UP TO 130Ms

Adjusting for vasculopathy, isolated antithrombin deficiency , isolated elevated lipoprotein (a) ,and the presence of more than one prothrombotic risk factor were independently associated with an increased risk of recurrence.

Recurrence rates calculated per 100 person-years were ▪ 10 (95% CI: 3-24) for antithrombin deficiency ▪ 6 (95% CI: 4-9) for elevated lipoprotein (a), ▪ 13 (95% CI: 7-20) for the presence of more than one prothrombotic risk factor. CANADA, GERMANY, UK 894 CHILDREN AGED 1-18 YEARS 169 (17.9%) HAD RECURRENCE UP TO 130Ms

Adjusting for vasculopathy, isolated antithrombin deficiency , isolated elevated lipoprotein (a) ,and the presence of Identifyingmore than one children prothrombotic measuresat increased risk factor aimed were risk ofat apreventing second stroke such isrecurrences. important in order to intensify independently associated with an increased risk of recurrence.

Recurrence rates calculated per 100 person-years were 10 (95% CI: 3-24) for antithrombin deficiency, 6 (95% CI: 4-9) for elevated lipoprotein (a), and 13 (95% CI: 7-20) for the presence of more than one prothrombotic risk factor. 68 eligible studies, which collectively enrolled 11 916 stroke patients and 96 057 controls. Compared with controls, patients with arterial ischemic stroke were significantly more likely to have the following inherited thrombophilias: factor V Leiden (OR, 1.25; 95% CI, 1.08–1.44; I2=0%), prothrombin G20210A mutation (OR, 1.48; 95% CI, 1.22–1.80; I2=0%), protein C deficiency (OR, 2.13; 95% CI, 1.16–3.90; I2=0%), and protein S deficiency (OR, 2.26; 95% CI, 1.34–3.80; I2=8.8%). Statistical significance was not reached for antithrombin deficiency (OR, 1.25; 95% CI, 0.58–2.67; I2=8.8%). Conclusions Inherited thrombophilias (factor V Leiden, prothrombin G20210A mutation, protein C deficiency, and protein S deficiency) are associated with an increased risk of arterial ischemic stroke in adults. The implications of these findings with respect to clinical management of patients with ischemic stroke require further investigation. When Should Testing be Performed?

Thrombophilia testing in the acute setting may result in an incorrect diagnosis of inherited conditions ● Levels of antithrombin, protein C and protein S may transiently decrease during acute thrombosis ● Factor VIII and lipoprotein(a) can be elevated in inflammatory conditions ● Levels of antithrombin may be decreased in patients who are on heparin ● vitamin K antagonists result in low levels of protein C and protein S

Any test that is abnormal during the acute setting should be repeated later, ideally off anticoagulation , and testing both parents should also be considered before committing to a diagnosis of an inherited deficiency

The diagnostic accuracy of molecular mutation testing is not affected, and can be sent even during an acute episode

Stevens SM, et al. J Thromb Thrombolysis. 2016 Jan;41(1):154-64 Authors conducted a retrospective audit of all consecutive patients diagnosed with a venous or arterial TEE during a 1-year period (January to December 2015). In Children’s Medical Center, Dallas, is a quaternary care children’s hospital

Gavva C et al .Blood Advances 2017 CONCLUSIONS ● As pediatric thrombophilia is rare event , evidence based guidelines in pediatric thrombophilia are not solid enough as most are extrapolated from adult guidelines ● Thrombophilia testing is performed far more frequently than can be clinically justified based on available evidence; the majority of such testing is not of benefit to the patient and may represent a health status and economic burden ● However, in selected children with thrombotic events, mainly based on clinical risk criteria , thrombophilia screening could be of additive value in long term patient management