www.thelancet.com Published online September 6, 2010 DOI:S0140-6736(10)60709-X 1
September 6, 2010
Service of Internal Medicine,
Hospital de Cruces-University
of the Basque Country, Bizkaia,
Spain (Prof G Ruiz-Irastorza MD);
St Joseph Hospital and
Hamilton, ON, Canada
(Prof M Crowther FRCPC);
University of Utah Health
Sciences Center, Department of
Obstetrics and Gynecology,
and Intermountain Healthcare,
Salt Lake City, UT, USA
(Prof W Branch MD); and Lupus
Research Unit, Rayne Institute,
St Thomas Hospital, King’s
College, London, UK
(M A Khamashta FRCP)
Dr Guillermo Ruiz-Irastorza,
Servicio de Medicina Interna,
Hospital de Cruces, 48903
Guillermo Ruiz-Irastorza, Mark Crowther, Ware Branch, Munther A Khamashta
The antiphospholipid syndrome causes venous, arterial, and small-vessel thrombosis; pregnancy loss; and preterm
delivery for patients with severe pre-eclampsia or placental insuffi ciency. Other clinical manifestations are cardiac
valvular disease, renal thrombotic microangiopathy, thrombocytopenia, haemolytic anaemia, and cognitive
impairment. Antiphospholipid antibodies promote activation of endothelial cells, monocytes, and platelets; and
overproduction of tissue factor and thromboxane A2. Complement activation might have a central pathogenetic role.
Of the diff erent antiphospholipid antibodies, lupus anticoagulant is the strongest predictor of features related to
antiphospholipid syndrome. Therapy of thrombosis is based on long-term oral anticoagulation and patients with
arterial events should be treated aggressively. Primary thromboprophylaxis is recommended in patients with systemic
lupus erythematosus and probably in purely obstetric antiphospholipid syndrome. Obstetric care is based on
combined medical-obstetric high-risk management and treatment with aspirin and heparin. Hydroxychloroquine is a
potential additional treatment for this syndrome. Possible future therapies for non-pregnant patients with
antiphospholipid syndrome are statins, rituximab, and new anticoagulant drugs.
The term antiphospholipid syndrome was coined in the
early 1980s to describe a unique form of autoantibody-
induced thrombophilia, whose hallmarks are recurrent
thrombosis and pregnancy complications.1 The clinical
spectrum of this syndrome has widened,2,3 with important
advances in the knowledge of its pathogenesis and clinical
management made during the past several years.
Research shows the central role of endothelial cells,
monocytes, platelets, and complement in induction of
thrombosis and fetal death in antiphospholipid syndrome.
Endothelial cells and monocytes can be activated by
antiphospholipid antibodies with anti-β2-glycoprotein-1
activity. In turn, endothelial cells express adhesion
molecules such as intercellular cell adhesion molecule-1,
vascular cell adhesion molecule-1, E-selectin, and both
endothelial cells and monocytes upregulate the production
of tissue factor.4 Activated platelets increase expression of
glycoprotein 2b-3a and synthesis of thromboxane A2.
Nuclear factor κB (NFκB) and p38 mitogen-activated
protein kinase (p38 MAPK) are important mediators of
these three processes.4–7 Despite the historical view that
infl ammation was unimportant in the pathogenesis of
antiphospholipid syndrome, results from studies in mice
show a pivotal role for complement activation in thrombosis
and fetal loss induced by antiphospholipid antibodies.8,9
Moreover, C4d and C3b fragments are deposited in the
placentas of patients with antiphospholipid syndrome.10
Pierangeli and colleagues11 have proposed that, after
activation of endothelial cells, monocytes, and platelets
by antiphospholipid antibodies, a procoagulant state is
induced, which is mainly mediated by the increased
synthesis of tissue factor and thromboxane A2. Activation
of the complement cascade might close the loop7 and
provoke thrombosis, often in the presence of a second
hit12 (fi gure 1). Traditional cardio vascular risk factors such
as tobacco, infl ammation, or oestrogens might have an
important role at this point, and such risk factors are
present in more than 50% of patients with
epidemiological study showed that the risk of myocardial
infarction or stroke in young women with lupus
anticoagulant is increased in those who smoke or take
oral oestrogenic therapy.13
Furthermore, interaction of antiphospholipid anti-
bodies with proteins implicated in clotting regulation,
such as prothrombin, factor X, protein C, and plasmin,
might hinder inactivation of procoagulant factors and
impede fi brinolysis.4,12 Interference with annexin A5, a
natural anticoagulant, might favour placental thrombosis
and fetal loss.4 Abnormalities in placentation have also
been described in pregnancy loss related to anti-
phospholipid antibodies.14 β2-glycoprotein 1 directly
binds to cultured cytotrophoblast cells and is subsequently
recognised by antibodies to β2-glycoprotein 1.15
Antiphospholipid antibody binding reduces the secretion
of human chorionic gonadotropin (hCG). Moreover,
Findings from an
might trigger an
Search strategy and selection criteria
In this Seminar we aimed to off er an up-to-date view of the
main pathophysiological, clinical, diagnostic and therapeutic
advances in the discipline of the antiphospholipid syndrome.
The literature search was done from January, 2005, to
January, 2010. The PubMed database was used with the
medical subject heading terms “antiphospholipid syndrome”
OR “antibodies, antiphospholipid “ OR “lupus coagulation
inhibitor”. Embase search included the terms
“antiphospholipid syndrome”, “lupus anticoagulant”, and
“cardiolipin antibody”. The Cochrane database of systematic
reviews was searched, with the key word “antiphospholipid”.
We obtained additional articles from reference sections of the
selected manuscripts as well as from personal databases of
the authors. We paid special attention to systematic reviews,
randomised clinical trials, consensus documents and review
articles focused on the pathogenesis of antiphospholipid
syndrome. Older articles were also included to draw attention
to pathogenetic, clinical, and epidemiological issues.
www.thelancet.com Published online September 6, 2010 DOI:S0140-6736(10)60709-X
infl ammatory response mediated by the TLR4/MyD88
pathway resulting in trophoblast damage.16
The likelihood that an antiphospholipid antibody
contributes to the pathogenesis of thrombosis or
pregnancy complications, or both, varies between clinical
settings. About 40% of patients with systemic lupus
erythematosus have antiphospholipid antibodies,17 but
less than 40% of them will eventually have thrombotic
events.18,19 However, thrombotic
syndrome is regarded as a major adverse prognostic
factor in patients with lupus.18 In the general population,
antiphospholipid antibodies can be detected in about
one in fi ve patients who have had a stroke at less than
50 years of age.20 The clinical presentation modifi es the
pretest probability, with higher likelihood of positivity
for antiphospholipid antibodies in young patients
presenting with other features of antiphospholipid
syndrome, such as miscarriage. However, patients older
than 70 years with several vascular risk factors have a
much lower probability of having antiphospholipid
antibodies in the presence of a cerebrovascular accident
than do younger patients.20 24% of 4494 patients with
venous thromboembolism in whom a thrombophilia
test was done had antiphospholipid antibodies,21
although this frequency might depend on the type of
testing done and the defi nition of a positive test. This
frequency was close to that of factor V Leiden, and was
not substantially modifi ed by age of patients or by
presence of recurrent events.
Recurrent miscarriage occurs in about 1% of the
general population attempting to have children.22 About
10–15% of women with recurrent miscarriage are
diagnosed with antiphospholipid syndrome.23,24 Fetal
death in the second or third trimesters of pregnancy
occurs in up to 5% of unselected pregnancies,25
dependent on the span of gestational age studied, but is
less likely as pregnancy advances.26 Although fetal death
is linked to antiphospholipid syndrome,27 the overall
contribution of this syndrome is uncertain, partly
because of the eff ect of other possible contributing
factors such as underlying hypertension or pre-existing
comorbidities such as systemic lupus erythematosus or
renal disease. Pending results from a population-based
study of fetal deaths at more than 20 weeks’ gestation
(the Stillbirth Collaborative Research Network sponsored
by National Institutes of Health) should prove relevant
to better understanding of the frequency of
antiphospholipid syndrome as a cause of fetal death.
About 5–10% of all pregnancies are complicated by pre-
eclampsia or placental insuffi ciency (as manifested by
fetal growth restriction), or both, and severe
manifestations of these disorders account for about 75%
of indicated preterm deliveries.28 Pregnant women with
a previous diagnosis of antiphospholipid syndrome are
at increased risk for developing pre-eclampsia or
placental insuffi ciency, but the association between
antiphospholipid antibodies and these disorders in the
absence of antiphospholipid syndrome is uncertain.29
Results of case-control
antiphospholipid antibodies are detected in 11–29% of
women with pre-eclampsia, compared with 7% or less
in controls. Findings from one study showed that 25%
of women delivering growth restricted fetuses had
antiphospholipid antibodies, but results from others do
not show an association.29 Results from prospective
cohort studies indicate that of pregnant women with
high concentrations of antiphospholipid antibodies,
10–50% develop pre-eclampsia, and more than 10% of
these women deliver infants who are small for
studies show that
Panel 1 shows the main clinical manifestations of
antiphospholipid syndrome. Thromboses are one of the
hallmarks of this syndrome, and venous thrombosis, or
embolism, is the most frequent manifestation.2 However,
by contrast with thromboses associated with congenital
thrombophilias, those associated with antiphospholipid
syndrome might also occur in any vascular bed.2 In the
arterial bed, the CNS is most generally aff ected,2 usually
in the form of stroke or transient ischaemic attacks.
Antiphospholipid antibodies have also been associated
with venous sinus thrombosis, myelopathy, chorea,
Figure 1: Pathogenesis of thrombosis in antiphospholipid syndrome
Monocyte Platelets Endothelial cell
tissue factor production
Expression of glycoprotein
Other procoagulant conditions
(inflammation, oestrogens, etc.)
Upregulation of thromboxane
Expression of adhesion
Interaction with coagulation-regulatory
proteins (protein C, prothrombin, plasmin)
Upregulation of tissue factor
www.thelancet.com Published online September 6, 2010 DOI:S0140-6736(10)60709-X 3
migraine, and epilepsy.30 The presence of anticardiolipin
antibodies has been linked with cognitive impairment in
patients with systemic lupus erythematosus.31,32 Similarly,
mild cognitive dysfunction has been recorded in more
than 40% of patients with antiphospholipid syndrome,
with a strong association with cerebral white matter
lesions.33 Multiple sclerosis-like CNS lesions and
compatible clinical presentations have been noted in a
subset of patients with antiphospholipid syndrome.34
Antiphospholipid antibodies are associated with cardiac
valvular disease, with the mitral valve most frequently
aff ected, followed by the aortic valve.35 Regurgitation is
more common than is stenosis and many patients remain
asymptomatic for years.35 Acute coronary syndromes are
much less prevalent than cerebrovascular disease.2
Renal involvement in antiphospholipid syndrome was
fi rst described in 1992.36 Thrombotic microangiopathy is
the most characteristic fi nding in this syndrome
nephropathy; however, fi brous intimal hyperplasia, focal
cortical atrophy, and arterial occlusions have also been
(often subnephrotic) and renal insuffi ciency are
typical presentations of antiphospholipid syndrome
nephropathy.36,37 Renal artery stenosis can also present as
Other clinical features associated with antiphospholipid
antibodies are, in order of frequency, thrombocytopenia,
haemolytic anaemia, skin ulcers, avascular bone necrosis,
and adrenal insuffi ciency.2 Livedo reticularis (fi gure 2) is
present in about a quarter of patients with anti-
phospholipid syndrome, constituting a physical sign that
should make the clinician suspect the diagnosis of this
syndrome in the appropriate clinical context. Moreover,
livedo reticularis can be a marker of patients at a high
risk for arterial thrombosis.39
The most severe and fortunately infrequent form of
phospholipid syndrome. This form is characterised by
widespread small-vessel thrombosis with multiorgan
failure and more than 50% mortality.40
Obstetric complications are the other hallmark of
antiphospholipid syndrome. The most common
obstetric manifestation of this syndrome is recurrent
miscarriage, which is usually defi ned as three or more
consecutive miscarriages before the mid-second
trimester, with most losses occurring before the 10th
week of gestation. Other obstetric features of
antiphospholipid syndrome are one or more fetal
deaths occurring at or beyond the 10th week of
gestation, severe pre-eclampsia,
insuffi ciency prompting delivery at more than 34 weeks’
gestation.2,41,42 In a population-based analysis of
141 286 deliveries in Florida, USA, positivity for anti-
phospholipid antibodies increased the risk for both
pre-eclampsia and placental insuffi ciency (adjusted
odds ratio 2·93 (95% CI 1·51–5·61) and 4·58 (95% CI
2·00–10·51), respectively.43 In a retrospective study,
women with obstetric antiphospholipid syndrome were
at high risk of subsequent thrombotic complications.44
is catastrophic anti-
Classifi cation criteria and risk stratifi cation
In 1998, the preliminary classifi cation criteria for
antiphospholipid syndrome were proposed at Sapporo,
Panel 1: Clinical manifestations of antiphospholipid
Frequent (>20% of cases)
• Venous thromboembolism
• Miscarriage or fetal loss
• Stroke or transient ischaemic attack
• Livedo reticularis
Less common (10–20% of cases)
• Heart valve disease
• Pre-eclampsia or eclampsia
• Premature birth
• Haemolytic anaemia
• Coronary artery disease
Unusual (<10% of cases)
• Vascular dementia
• Retinal artery or vein thrombosis
• Amaurosis fugax
• Pulmonary hypertension
• Leg ulcers
• Digital gangrene
• Antiphospholipid syndrome nephropathy
• Mesenteric ischaemia
Rare (<1% of cases)
• Adrenal haemorrhage
• Transverse myelitis
• Budd-Chiari syndrome
Figure 2: Livedo reticularis in a woman with antiphospholipid syndrome
www.thelancet.com Published online September 6, 2010 DOI:S0140-6736(10)60709-X
Japan.45 Classifi cation for this syndrome needed at least
one clinical manifestation together with positive tests for
circulating antiphospholipid antibodies, including lupus
anticoagulant or anticardiolipin, or both, at medium-high
values, detected at least twice in 6 weeks.
In 2006, classifi cation criteria were updated (panel 2).46
Essentially, the clinical criteria remained unchanged;
however, two important modifi cations were made: the
time elapsed between two positive determinations was
extended to 12 weeks to assure the detection of persistent
antibodies only; and anti-β2-glycoprotein 1, both IgG
and IgM, were added to the laboratory criteria. Medium
titres of anticardiolipin, or anti-β2-glycoprotein 1, were
defi ned as more than 40 GPL or MPL or higher than the
99th percentile. Notably, IgA isotypes, antiprothrombin
antibodies, and antibodies
phosphatidylserine-prothrombin complex remained
excluded from the criteria.
These modifi cations have been criticised,47 and the
debate about the clinical implications of diff erent
antiphospholipid antibodies is still open. Lupus
anticoagulant is consistently the most powerful predictor
of thrombosis.19,48,49 In a Dutch case-control study in
women younger than 50 years, lupus anticoagulant
increased the odds of stroke more than 40-fold and of
myocardial infarction more than fi ve-fold.13 Similarly,
lupus anticoagulant has been strongly associated with
recurrent miscarriage before the 24th week of gestation.50
Furthermore, lupus patients negative for lupus
anticoagulant with persistently positive anticardiolipin
(defi ned as at least two of three positive tests) had
thrombosis more frequently than did patients negative
for both lupus anticoagulant and anticardiolipin,
although intermittent anticardiolipin positivity did not
increase the frequency of thrombosis.19,49 Both IgG and
IgM anticardiolipins are associated with an increased
risk of miscarriage, albeit to a lesser degree than
Anti-β2-glycoprotein-1 antibodies were not associated
with either thrombosis or recurrent early miscarriage in
any of three systematic reviews.48,50,51 In the Dutch case-
control study, anti-β2-glycoprotein 1 only doubled the
risk of stroke but not of myocardial infarction.13 However,
work by Galli and colleagues52 lends support to the
association between anti-β2-glycoprotein
thrombosis in patients with a concomitant lupus
anticoagulant. Others have noted that the presence of
more than one class of antiphospholipid antibodies
increased thrombotic risk.53 Pengo and colleagues’54
fi ndings have shown that patients with triple positivity
for lupus anticoagulant, anticardiolipin, and anti-β2-
glycoprotein 1 are at the highest risk for venous and
arterial thrombosis and for obstetric complications.54,55
Moreover, results from a follow-up study showed a 30%
rate of thrombotic recurrence in this subgroup of triple
positivity even while on anticoagulant therapy.56 Patients
with triple positivity tend to have higher values of anti-
β2-glycoprotein 1 compared with patients with less than
three positive antibodies54 and are more likely to have
stable concentrations of antiphospholipid antibodies
Specifi c ELISA for antibodies directed against the
domain 1 of β2-glycoprotein is one of the new expected
tests that will need assessment.57 These antibodies, with
lupus anticoagulant activity, are strongly associated with
Panel 2: Revised classifi cation criteria for antiphospholipid
• One or more clinical episodes of arterial, venous, or small
vessel thrombosis, in any tissue or organ.
• Thrombosis should be supported by objective validated
criteria—ie, unequivocal fi ndings of appropriate imaging
studies or histopathology. For histopathological support,
thrombosis should be present without substantial
evidence of infl ammation in the vessel wall.
Pregnancy morbidity, defi ned by one of the following criteria:
• One or more unexplained deaths of a morphologically
healthy fetus at or beyond the 10th week of gestation,
with healthy fetal morphology documented by
ultrasound or by direct examination of the fetus.
• One or more premature births of a morphologically
healthy newborn baby before the 34th week of gestation
because of: eclampsia or severe pre-eclampsia defi ned
according to standard defi nitions or recognised features
of placental failure.
• Three or more unexplained consecutive spontaneous
abortions before the 10th week of gestation, with
maternal anatomical or hormonal abnormalities and
paternal and maternal chromosomal causes excluded.
In studies of populations of patients who have more than one
type of pregnancy morbidity, investigators are strongly
encouraged to stratify groups of patients according to one of
the three criteria.
• Lupus anticoagulant present in plasma, on two or more
occasions at least 12 weeks apart, detected according to
the guidelines of the International Society on Thrombosis
and Hemostasis (Scientifi c Subcommittee on lupus
• Anticardiolipin antibody of IgG or IgM isotype, or both, in
serum or plasma, present in medium or high titres (ie,
>40 GPL or MPL, or greater than the 99th percentile) on
two or more occasions, at least 12 weeks apart, measured
by a standardised ELISA.
• Anti-β2-gycoprotein 1 antibody of IgG or IgM isotype, or
both, in serum or plasma (in titres greater than the 99th
percentile), present on two or more occasions, at least
12 weeks apart, measured by a standardised ELISA,
according to recommended procedures.
www.thelancet.com Published online September 6, 2010 DOI:S0140-6736(10)60709-X 5
thrombosis.58 Moreover, results from a multicentre
study including patients with repeatedly positive anti-
β2-glycoprotein-1 antibodies showed an increased risk
for obstetric complications and thrombosis in patients
with IgG antibodies with specifi city against domain 1 of
β2-glycoprotein.59 Furthermore, resistance to the
anticoagulant eff ects of annexin A5 seems to be
associated with the occurrence of both pregnancy losses
Management of thrombosis
Prevention of thrombosis is a major goal of therapy in
patients with antiphospholipid antibodies. There are two
diff erent clinical settings: patients with antiphospholipid
syndrome who have already had a thrombotic event
(secondary thromboprophylaxis); and antiphospholipid
antibody carriers without previous thrombosis, which
can be either purely asymptomatic individuals, patients
with systemic lupus erythematosus, or women with
obstetric antiphospholipid syndrome (primary thrombo-
With regard to secondary thromboprophylaxis, the
main treatment for antiphospholipid syndrome patients
with thrombosis is antithrombotic treatment, rather than
immunosuppression (fi gure 3).61 The two key issues are
whether patients with antiphospholipid syndrome should
receive the same treatment as the general population
with similar manifestations, and whether arterial and
venous events should be treated diff erently. The answers
are not straightforward, and two systematic reviews give
contradictory views of this issue.62,63
Lim and colleagues62 recommended indefi nite oral
anticoagulation to a target international normalised ratio
(INR) of 2·0–3·0 for patients with venous and arterial
non-cerebral events, and either low-dose aspirin or oral
anticoagulation to a target INR of 1·4–2·8 for those with
stroke. Since these recommendations were based on the
results of randomised clinical trials, only three studies
met the eligibility criteria. Two, comparing high (target
INR 3·0–4·0) with standard (target INR 2·0–3·0)
intensity of anticoagulation, recruited a high proportion
of defi nite antiphospholipid syndrome patients with
venous events;64,65 those with recent stroke64 and those
with recurrent events on anticoagulant treatment were
excluded.64,65 Anticoagulation in patients in the high-
intensity groups was often lower than the prespecifi ed
therapeutic range;64,65 and most recurrent thrombotic
events in both treatment groups took place while the INR
was lower than 3·0.64
The only selected study focusing on patients with
stroke, the Antiphospholipid Antibodies and Stroke
Study (APASS),66 was actually a subgroup analysis of a
previous trial.67 A nested design was used, thus one
measure of antiphospholipid antibodies was done in
samples stored at the time of enrolment.66 Most patients
positive for antiphospholipid antibodies had low
concentrations of anticardiolipin (IgA anticardiolipin
included) and did not have double positivity for both
anticardiolipin and lupus anticoagulant. No patients
included in APASS met accepted classifi cation criteria
for antiphospholipid syndrome since repeat testing was
not done.45,46 Therefore, patients with this syndrome and
stroke are not well represented in Lim and colleagues’
With a diff erent approach, the systematic review by Ruiz-
Irastorza and colleagues63 included observational studies
that raised the number of reports to 16 and of patients to
1740.63 Several subgroups could be identifi ed according to
the risk of recurrent thrombosis. Patients not fulfi lling
laboratory criteria for defi nite anti phospholipid syndrome
were at a risk of recurrences similar to that for the general
population, irrespective of whether presenting with venous
or arterial events. Patients with defi nite antiphospholipid
syndrome presenting with a fi rst venous event were well
protected from recurrences with oral anticoagulation to a
target INR of 2·0–3·0. However, patients with defi nite
syndrome having arterial or recurrent events, or both,
were at an increased risk for recurrences, even when
treated with oral anticoagulation to a target INR of 2·0–3·0.
Overall, recurrences were very infrequent in patients
eff ectively receiving oral anticoagulation to an INR of
3·0–4·0. 18 patients died as a result of recurrent
thromboses, mostly arterial, versus only one dying of
bleeding. The investigators could not address the eff ect of
concomitant cardiovascular risk factors on the outcome of
Tissue factor+factor VIIa
Anticoagulant inactivating adjacent enzyme
Figure 3: Coagulation cascade and sites of action of antithrombotic drugs
www.thelancet.com Published online September 6, 2010 DOI:S0140-6736(10)60709-X
With the present state of knowledge, which is largely
based on retrospective studies with inherent weaknesses,
we recommend indefi nite anticoagulation at an INR of
2·0–3·0 for patients with antiphospholipid syndrome
presenting with fi rst venous events.62,63 However, debate
persists about treatment for patients with arterial
thromboses.61–63,68 We believe that antiphospholipid
patients with arterial disease or recurrent events, or both,
need a more aggressive treatment, which might include
warfarin with a target INR of more than 3·0 or combined
antithrombotic therapy. However, new recommendations,
taking into account both the clinical and immunological
profi le of patients with antiphospholipid syndrome, are
likely to be agreed after the recent International Congress
on Antiphospholipid Antibodies, held in Texas, USA, in
April, 2010. Patients with single positivity for
antiphospholipid antibodies (anticardiolipin or anti-β2-
glycoprotein 1) and non-life threatening thrombosis will
probably be recommended to receive less intense or
extended antithrombotic regimens, especially in the
setting of reversible triggers. Concomitant vascular risk
factors, which increase the likelihood of thrombosis in
patients with antiphospholipid antibodies,13,69–71 have to be
addressed and treated. Patients with thrombosis and
antiphospholipid antibodies not meeting laboratory
criteria for antiphospholipid syndrome should be
managed in the same way as the general population.63
Table 1 shows a summary of recommendations for
With regard to primary thromboprophylaxis, retrospect-
ive studies suggest that patients with lupus and
antiphospholipid antibodies will develop thrombosis at a
yearly rate of about 3–4%.72,73 Between 3% and 7% of women
with purely obstetric antiphospholipid syndrome might
also have subsequent thromboses per year,44,73 although
other series have recorded yearly incidences of less than
1%.74 However, the actual risk in healthy asymptomatic
carriers of antiphospholipid antibodies is probably low.75
Results from a randomised trial showed no diff erence
between asymptomatic antiphospholipid
carriers given low-dose aspirin and those given placebo.76
However, the rate of thrombosis in patients given placebo
was zero, and the study was underpowered to detect a
benefi cial eff ect of aspirin. Such a low risk of events could
be attributable to short follow-up, good control of vascular
risk factors, and patients’ immunological profi le, which
included IgA anticardiolipin. The number of patients
with lupus anticoagulant or with obstetric anti-
phospholipid syndrome was not clear. By contrast, results
from observational studies have consistently shown a
protective eff ect of aspirin in asymptomatic anti-
phospholipid antibody carriers with systemic lupus
erythematosus13,71,77–79 and in women with obstetric
In view of its low potential for toxic eff ects, many
experts understandably recommend low-dose aspirin
(combined with hydroxychloroquine) to be considered as
primary thromboprophylaxis in patients with systemic
lupus erythematosus having lupus anticoagulant or
persistently positive anticardiolipin, or both. Women
with obstetric antiphospholipid syndrome are also
candidates for long-term treatment with aspirin,
dependent on the characteristics of their profi le of
antiphospholipid antibodies. Data from higher-quality
studies would be useful. Therapy for healthy carriers of
antiphospholipid antibodies should be individualised,
Patients with defi nite antiphospholipid syndrome and fi rst venous event*
Patients with defi nite antiphospholipid syndrome and arterial event*
Indefi nite anticoagulation to a target INR 2·0–3·0
Indefi nite anticoagulation to a target INR 3·0–4·0 or combined antithrombotic
Indefi nite anticoagulation to a target INR 3·0–4·0 or alternative therapies such
as extended therapeutic dose low-molecular-weight heparin
As per usual recommendations for deep vein thrombosis treatment
Patients with defi nite antiphospholipid syndrome and recurrent events
despite warfarin with a target intensity of 2·0–3·0
Patients with venous thromboembolism with single positive or low-titre
Patients with arterial thrombosis with single positive or low-titre
As per usual recommendations for arterial thrombosis
INR=international normalised ratio. *Less aggressive or long-lasting antithrombotic treatments might be appropriate in low-risk patients.
Table 1: Recommendations for secondary prophylaxis in patients with antiphospholipid antibodies and thrombosis
Patients with systemic lupus erythematosus and lupus anticoagulant and/or
persistently positive anticardiolipin
Patients with obstetric antiphospholipid syndrome
Asymptomatic carriers of antiphospholipid antibodies
All patients with antiphospholipid antibodies
High-risk situations (surgery, post partum, long-lasting immobilisation)
Hydroxychloroquine and consider low-dose aspirin
Low-dose aspirin or no therapy
No therapy or low-dose aspirin
Strict control of vascular risk factors
Table 2: Primary thromboprophylaxis in patients with antiphospholipid antibodies
www.thelancet.com Published online September 6, 2010 DOI:S0140-6736(10)60709-X 7
and treatment of patients with persistent positivity of
several antiphospholipid antibodies, including lupus
anticoagulant, should be considered. Other vascular risk
factors should be aggressively sought and managed in all
patients with antiphospholipid antibodies (table 2).
On the basis of experience of the CAPS registry, less
severe cases of CAPS can be managed with anticoagulation
and high-dose steroids. For life-threatening manifest-
ations, either intravenous immunoglobulins or plasma
exchange should be added.80 With this regimen, more
than 65% of patients with severe disease survive.80
With proper management, more than 70% of pregnant
women with antiphospholipid syndrome will deliver a
viable live infant.81 Ideally, preconception counselling
gives the physician the opportunity to understand the
specifi c context of each patient with the syndrome and to
outline the risks of pregnancy and treatment. Pregnancy
should be discouraged in all women with important
pulmonary hypertension because of the high risk of
maternal death,82 and should be postponed in the setting
of uncontrolled hypertension or recent thrombotic
events, especially stroke.82
A complete profi le of antiphospholipid antibodies,
including repeated anticardiolipin
anticoagulant, should be available before planning of
pregnancy. However, these tests do not need to be
repeated during pregnancy, since subsequent negative
results (after diagnostic, repeatedly positive tests) do
not eliminate the risk of complications.82 We recommend
frequent prenatal visits, at least every 2–4 weeks before
mid-gestation and every 1–2 weeks thereafter. The
objectives of prenatal care in the second and third
trimesters are close observation
hypertension, proteinuria and other features of pre-
eclampsia, frequent patient assessment, obstetric
ultrasound to assess fetal growth and amniotic fl uid
volume, and appropriate fetal surveillance testing.
Surveillance testing should begin at 32 weeks’ gestation,
or earlier if the clinical situation for placental
insuffi ciency is suspected, and should continue at least
every week until delivery. Uterine and umbilical artery
Doppler assessments are widely used in Europe to
assess the risk for pre-eclampsia, placental insuffi ciency,
and fetal growth restriction after the 20th week of
gestation, and normal examinations have high negative
predictive values.83 Regular and coordinated medical
consultation every 2–4 weeks, especially in women with
systemic lupus erythematosus, is recommended.
The goals of treatment in pregnant women with
antiphospholipid syndrome are to improve maternal
and fetal-neonatal outcomes by keeping to a minimum
the risks of the recognised complications of the disorder,
including maternal thrombosis, fetal loss, pre-
eclampsia, placental insuffi ciency, and fetal growth
restriction, and the need for iatrogenic preterm birth.41
Heparin and low-dose aspirin are the treatments of
choice for antiphospholipid syndrome in pregnancy.
Heparin is usually started in the early fi rst trimester
after presence of a live embryo is shown by
ultrasonography. Most investigators
preconceptional aspirin because of its possible benefi cial
eff ect on early stages of implantation.84 Early enthusiasm
for glucocorticoids to treat pregnant women with
antiphospholipid syndrome waned in the early 1990s
when two small randomised trials recorded no
benefi t.85,86 Moreover, results from randomised trials
showed no benefi t from use of intravenous immuno-
globulins either when added to heparin or used alone.87–89
A subsequent Cochrane analysis concluded that
intravenous immunoglobulins were associated with an
increased risk of pregnancy loss or premature birth,
compared with heparin and low-dose aspirin.90
Pregnant patients with antiphospholipid syndrome
without having had a previous thrombotic event might
be classifi ed into one of two groups for the benefi t of
treatment: (1) patients with recurrent early (pre-
embryonic or embryonic) miscarriage and no other
features of antiphospholipid syndrome, or (2) those with
one or more previous fetal deaths (at more than 10 weeks’
gestation) or previous early delivery (at less than 34 weeks’
gestation) because of severe pre-eclampsia or placental
insuffi ciency. A third group of patients consists of those
with a history of thrombosis, irrespective of pregnancy
history. Table 3 summarises recommended treatments
for the three groups.
Three randomised trials92–94 and one trial with
consecutive treatment assignment95 have addressed
pregnancy in patients with antiphospholipid syndrome
who have predominantly recurrent early miscarriage. In
two trials,92,95 the proportion of successful pregnancies
unfractionated heparin to low-dose aspirin. Two other
randomised trials,93,94 both using low-molecular-weight
heparin, proved negative. Of note is that the heterogeneity
in the results is attributable to outcomes in women
receiving aspirin only. Additionally, two studies recorded
no diff erences in pregnancy outcomes when comparing
unfractionated heparin with low-molecular-weight
heparin, both combined with aspirin.96,97 Finally, several
observational studies have reported pregnancy success
rates of 79–100% with low-dose aspirin alone.84,85,98–102
Moreover, data from meta-analysis103 have shown a
signifi cant reduction of pregnancy complications in
women at high risk for pre-eclampsia who were given
antiplatelet agents (mostly aspirin). In all clinical trials,
maternal and fetal-neonatal outcomes in pregnancies
progressing beyond 20 weeks’ gestation were benign,
with the frequencies of fetal death, pre-eclampsia, severe
placental insuffi ciency, and iatrogenic preterm birth
close to those of the general obstetric population.
Despite the obvious controversies raised by these trials,
a 2005 Cochrane systematic review concluded that
with the addition of
www.thelancet.com Published online September 6, 2010 DOI:S0140-6736(10)60709-X
women with recurrent miscarriage and antiphospholipid
syndrome should be given a combination of heparin
5000 IU subcutaneously twice daily and low-dose
aspirin.90 Expert guidelines recommend the combination
of aspirin with either low-dose heparin or low-molecular-
weight heparin.91 However, we believe that the option of
monotherapy with aspirin cannot be ruled out in this
subgroup of women.
Results from randomised trials do not defi ne optimum
treatment for women with fetal death (>10 weeks’
gestation) or previous early delivery (<34 weeks’
gestation) due to severe pre-eclampsia or placental
insuffi ciency. Most experts recommend low-dose aspirin
and either prophylactic or intermediate-dose heparin
(table 3).41,90,91 The preponder ance of data show that good
pregnancy outcomes are achieved with heparin started
in the early fi rst trimester when a live embryo is
detectable by ultrasound.
For pregnant women with antiphospholipid syndrome
who have had a previous thrombotic event, low-dose
aspirin and therapeutic dose heparin or low-molecular-
weight heparin anticoagulation are recommended
(table 3).91 Vitamin K antagonists are teratogenic and
should be avoided between 6 and 12 weeks’ of gestation.
Because of the risk of fetal bleeding thereafter,91,104
warfarin after 12 weeks’ gestation should be given only in
Antithrombotic coverage of the post-partum period is
recommended in all women with antiphospholipid
syndrome, with or without previous thrombosis.91
Generally, women with previous thrombosis will need
long-term anticoagulation, and we prefer switching the
treatment to warfarin, as soon as the patient is clinically
stable after delivery. In patients with no previous
thrombosis, the recommendation is prophylactic dose
heparin or low-molecular-weight heparin therapy for
4–6 weeks after delivery,91 although warfarin is an
option. Both heparin and warfarin are safe for
Several potential new therapeutic approaches for
antiphospholipid syndrome are emerging (panel 3).
Antiplatelet drugs other than aspirin have been used only
rarely in patients with this disorder.105 However,
combination treatment with aspirin plus dipyridamole
and aspirin plus clopidogrel have shown higher effi cacy
than has aspirin alone in patients with stroke106 or atrial
fi brillation,107 respectively. Such combinations might be
considered in selected patients with antiphospholipid
syndrome in whom warfarin is not eff ective or safe.
Likewise, studies of new oral antifactor Xa and anti-
factor IIa drugs have not been done in patients with
dabigatran have been licensed for primary thrombo-
prophylaxis after orthopaedic surgery in many settings.
The results of the RE-LY trial, done in 18 113 patients with
atrial fi brillation at high risk for arterial thromboembolism,
showed that dabigatran, at a dose of 110 mg twice daily is
as eff ective but safer than warfarin, whereas doses of
Panel 3: Potential future therapies for antiphospholipid
• Combination antiaggregant therapy (low-dose aspirin
plus clopidogrel or dipyridamole)
• Oral antifactor Xa drugs (rivaroxaban, apixaban)
• Direct thrombin inhibitors (dabigatran)
• Statins (fl uvastatin, rosuvastatin)
• B-cell depletion (rituximab)
Antiphospholipid syndrome without previous thrombosis and
recurrent early (pre-embryonic or embryonic) miscarriage
Antiphospholipid syndrome without previous thrombosis and
fetal death (more than 10 weeks’ gestation) or previous early
delivery (<34 weeks gestation) due to severe pre-eclampsia or
placental insuffi ciency
Low-dose aspirin alone or together with either unfractionated heparin (5000–7500 IU
subcutaneously every 12 h) or LMWH (usual prophylactic doses)
Low-dose aspirin plus:
• Unfractionated heparin (7500–10 000 IU subcutaneoulsy every 12 h in the fi rst trimester;
10 000 U subcutaneously every 12 h in the second and third trimesters, or every 8–12 h
adjusted to maintain the mid-interval aPTT* 1·5 times the control mean)
• LMWH (usual prophylactic doses)
Low-dose aspirin plus:
• Unfractionated heparin (subcutaneously every 8–12 h adjusted to maintain the mid-
interval aPTT* or heparin concentration (anti-Xa activity)* in the therapeutic range)
• LMWH (usual therapeutic dose—eg, enoxaparin 1 mg/kg subcutaneously, or dalteparin
100 U/kg subcutaneously every 12 h, or enoxaparin 1·5 mg/kg/day subcutanously, or
dalteparin 200 U/kg/day subcutaneously)†
Antiphospholipid syndrome with thrombosis
aPTT= activated partial thromboplastin time. LMWH=low-molecular-weight heparin. *Women without a lupus anticoagulant in whom the aPTT is normal can be monitored
with the aPTT. Women with lupus anticoagulant should be monitored with antifactor Xa activity. †Need for dose adjustments over the course of pregnancy remains
controversial.91 Some experts argue that in the absence of better evidence, it is prudent to monitor anti-factor Xa LMWH concentrations 4–6 h after injection with dose
adjustment to maintain a therapeutic antifactor Xa concentration (0·6 to 1·0 U/mL if a twice-daily regimen is used; slightly higher if a once-daily regimen is chosen).
Table 3: Suggested regimens for the treatment of antiphospholipid syndrome in pregnancy
www.thelancet.com Published online September 6, 2010 DOI:S0140-6736(10)60709-X 9
150 mg twice daily are more eff ective and equally safe.109
Data of the RE-COVER study,110 comparing dabigatran
150 mg twice daily with warfarin in the treatment of acute
venous thrombo embolism after heparin treatment,
showed an equivalence of both therapies in relation to
effi cacy and toxic eff ects.110 One of the major advantages
of dabigatran and rivaroxaban is that regular blood tests
are not needed to monitor the anticoagulant eff ect.
However, both are limited by the inability to reverse their
anticoagulant eff ect.
B-cell depletion therapy with the chimeric monoclonal
antibody rituximab has been tested in patients with
severe forms of antiphospholipid syndrome. Experience
is limited to case reports; however, a high response
rate—more than 90%—has been recorded.111
Of non-antithrombotic drugs, statins and hydroxy-
chloroquine deserve particular attention. Statins inhibit
NFκB and, in addition to their known cholesterol-
lowering eff ects, could have antithrombotic properties in
patients with antiphospholipid syndrome.112 Fluvastatin
inhibits tissue factor production induced by anti-
phospholipid antibodies both in mice models113 and in
cultured human endothelial cells.114 Statins also prevent
the increased adhesiveness of endothelial cells induced
by anti-β2-glycoprotein 1.115 In a pilot trial with fl uvastatin
in nine patients with antiphospholipid syndrome,
fl uvastatin at 40 mg per day decreased the concentrations
of infl ammatory and thrombogenic mediators after
30 days of treatment.116 For patients without anti-
treatment with statins is recommended in patients with
stroke or transient ischaemic attack.117 Moreover, data
from the JUPITER trial showed a decreased risk of
venous thromboembolism in healthy people with normal
cholesterol concentrations given rosuvastatin.118 Thus,
statins will probably be widely prescribed to patients with
antiphospholipid syndrome, including those with normal
cholesterol values, once clinical studies are available for
this group of patients. Clinicians should be aware,
though, that statins are qualifi ed as category X by US
Food and Drug Administration and are therefore
contraindicated in pregnancy.
Hydroxychloroquine is a cornerstone drug for
systemic lupus erythematosus because of its benefi cial
eff ects on lupus activity and damage, resulting in an
improvement of survival.119 A reduction of thrombosis
and cardiovascular deaths has been recorded in lupus
patients taking antimalarial drugs.119 Observational
studies have suggested an antithrombotic eff ect of
hydroxychloroquine in patients with antiphospholipid
antibodies, most of whom have systemic lupus
erythematosus.19,71,120 Furthermore, results from basic
studies have shown a dose-dependent reduction by
hydroxychloroquine of platelet activation and clotting
induced by antiphospholipid antibodies.121,122 Hydroxy-
chloroquine directly inhibits the binding of anti-
phospholipid antibody-β2-glycoprotein-1 complexes
to phospholipid surfaces.123 An additional and previously
unrecognised role of hydroxychloroquine in prevention
of pregnancy loss is suggested by the description of its
protective eff ect of the annexin A5 shield formed over
phospholipid bilayers from damage induced by
In view of the excellent safety profi le, including the
absence of any adverse eff ects on the fetus-neonate,119
and the absence of associated bleeding, hydroxy-
chloroquine should be considered for an adjuvant
antithrombotic role in patients with systemic lupus
erythematosus who are positive for antiphospholipid
antibodies. Patients with primary antiphospholipid
syndrome and recurrent thrombosis despite adequate
anticoagulation, who have diffi culty maintaining
adequate anticoagulation intensity, or have a high-risk
profi le for major haemorrhage, might also benefi t from
All authors contributed equally to writing the manuscript.
Confl icts of interest
We declare that we have no confl icts of interests.
GR-I is supported by the Department of Education, Universities and
Research of the Basque Government. MC holds a Career Investigator
Award from the Heart and Stroke Foundation of Canada. WB is
supported by the HA and Edna Benning Foundation at the University
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