The Prevalence of Antiphospholipid Antibodies in Women With Recurrent Spontaneous Abortion Women With Successful Pregnancies and Women Who Have Never Been Pregnant.

1231
THE PREVALENCE OF ANTIPHOSPHOLIPID
ANTIBODIES IN WOMEN WITH RECURRENT
SPONTANEOUS ABORTION, WOMEN WITH
SUCCESSFUL PREGNANCIES, AND WOMEN WHO
HAVE NEVER BEEN PREGNANT
ANN L. PARKE, DANIEL WILSON, and DONALD MAIER
Antibodies to negatively charged phospholipids
are associated with a predisposition to both arterial and
venous thrombosis, recurrent fetal wastage, and thrombocytopenia. These associations have been reported in
patients who do not fulfill criteria for connective tissue
diseases. In this study, we determined the prevalence of
antiphospholipid antibodies in 81 women who had had
recurrent spontaneous abortion (3 or more fetal losses),
in 88 women whose pregnancies were successful, and in
64 women who had never been pregnant. Antiphospholipid antibodies were found in 16% of women
with recurrent spontaneous abortion, and at a statistically greater prevalence than in women who had successful pregnancies (7 %) as well as those who had never
been pregnant (3%). A false-positive VDRL and IgG
anticardiolipin antibodies were more specific for fetal
wastage than was either the lupus anticoagulant or IgM
anticardiolipin antibodies.
Antibodies to negatively charged phospholipids, measured as the biologically false-positive test
From the Division of Rheumatic Diseases, Department of
Medicine, and Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of
Connecticut School of Medicine, Farmington.
Supported by NIH Multipurpose Arthritis Center grant
AR-20621.
Ann L. Parke, MBBS (FRCP): Associate Professor, Division of Rheumatic Diseases, Department of Medicine; Daniel Wilson, BA Biol: Research Assistant, Division of Rheumatic Diseases,
Department of Medicine; Donald Maier, MD: Associate Professor,
Division of Reproductive Endocrinology and Infertility, Department
of Obstetrics and Gynecology.
Address reprint requests to Ann L. Parke, MBBS (FRCP),
University of Connecticut Health Center, 263 Farmington Avenue,
Farmington, CT 06030.
Submitted for publication December 26, 1990; accepted in
revised form May 17, 1991.
Arthritis and Rheumatism, Vol. 34, No. 10 (October 1991)
for syphilis (VDRL), lupus anticoagulant (LAC), and
anticardiolipin antibodies (aCL), are associated with a
clinical syndrome having the predominant features of
arterial and venous thrombosis, thrombocytopenia,
and recurrent fetal wastage (1-5). The mechanisms for
these associations are unknown, but it has been suggested that recurrent fetal wastage is a result of
placental infarction (6). Anticardiolipin antibodies
have been shown to be a predictor of fetal death in
patients with systemic lupus erythematosus (SLE) (7).
Some patients with antiphospholipid antibodies do not
fulfill criteria for any well-defined connective tissue
disease (8), and the significance of the presence of
these antibodies in such patients is less certain (9).
Previous studies addressing the prevalence of
antiphospholipid antibodies in women who experience
recurrent spontaneous abortion (RSA) have often
lacked a control group and have involved only small
numbers of patients (10-12). We designed this prospective study to determine the true prevalence of
antiphospholipid antibodies in patients with RSA (3 or
more fetal losses) compared with women who had
successful pregnancies and with women who have
never been pregnant. The latter group was added in an
attempt to control for the possibility that pregnancy
may induce the production of antiphospholipid antibodies.
PATIENTS AND METHODS
Two hundred thirty-three women were enrolled into
the study: 81 with RSA, 88 with successful pregnancies, and
64 who had never been pregnant. Women with RSA had
experienced a t least 3 fetal losses, and the total number of
pregnancies for this group was approximately double that for
PARKE ET AL
1232
the normal pregnancy group. Women with RSA were recruited from the infertility clinic at the University of Connecticut Health Center and from infertility clinics in the
surrounding Hartford area. All consecutive women with
RSA were studied, regardless of the results of their gynecologic evaluation. Control subjects were recruited from respondents to advertisements in the local press.
Subjects taking any medication known to be associated with the induction of the lupus anticoagulant phenomenon and those taking oral contraceptives were excluded.
Each subject completed a questionnaire detailing her full
obstetric history, medical history, and current medical
symptoms. Subjects with any features suggestive of a connective tissue disease were excluded, regardless of their
study group.
Blood (15 cc) was drawn from each patient and tested
for LAC, VDRL reactivity, and aCL. The presence of a
lupus anticoagulant was evaluated by a dilute tissue thromboplastin time using Organon Teknika (West Chester, PA)
Simplastin Excel at 3 dilutions. Any ratio greater than 1.3
was taken as a positive result. Each patient also had the
prothrombin time and partial thromboplastin time (PTT)
measured. Patients found to have a prolonged PTT had a
platelet neutralization procedure (13) as a check for the
presence of LAC.
A VDRL test was performed using antigen provided
by the Connecticut state laboratory. A fluorescent treponema1 antibody (FTA) test was performed on all who had
positive VDRL results to determine if the VDRL was truly
or falsely positive. Anticardiolipin antibodies were detected
using an enzyme-linked immunosorbent assay with cardiolipin antigen provided by Sigma (St. Louis, MO). Serum
samples were diluted 1:100, run in triplicate, and run against
blank control wells. This assay has been standardized using
sera provided by St. Thomas’ Hospital (London, UK) and
has been part of the Kingston Anti-Phospholipid Antibody
Study (14).
RESULTS
Antiphospholipid antibodies were found in 16%
of subjects with RSA, 7% of those with successful
pregnancies, and 3% of those who had never been
pregnant. These results confirm the findings of our
previous small preliminary study, which showed that
at least 10% of all subjects with RSA had antiphospholipid antibodies, and that some, especially those in
whom no gynecologic cause of their recurrent fetal
wastage could be found, had antiphospholipid antibodies and multiple laboratory abnormalities suggestive of
subclinical autoimmune disease (15).
Using Fisher’s exact test to determine the significance of the individual tests for antiphospholipid
antibodies, it was determined that only the VDRL test
result reached statistical significance when comparing
RSA subjects with the 2 control groups: P = 0.02
versus normal pregnancy controls and P = 0.01 versus
never-pregnant controls (Table 1). The prevalence of
Table 1. Antiphospholipid antibodies in women with RSA, women
with successful pregnancies, and women who have never been
pregnant*
Antibody
test
RSA
group
(n = 81)
Successful
pregnancy
group
(n = 88)
Neverpregnant
group
(n = 64)
LAC
VDRL
IgG aCL
IgM aCL
4
7-F
6$
4
4
1
0
2
0
1
0
1
* Values are the number positive. RSA = recurrent spontaneous
abortion (3 or more fetal losses); LAC = lupus anticoagulant; aCL
= anticardiolipin antibodies (IgG aCL normal <20 units; IgM aCL
normal <7 units).
t P = 0.02 versus successful pregnancy group and P = 0.01 versus
never-pregnant group.
$ P = 0.01 versus successful pregnancy group.
IgG anticardiolipin was statistically significantly different only when comparing the 2 pregnancy groups (P
= 0.01). The differences in results of the LAC test and
the IgM aCL test failed to reach statistical significance. These findings suggest that of the current tests
for antiphospholipid antibodies, the VDRL and IgG
aCL tests appear to be more specific for fetal wastage.
It is also important to note that only subjects in the
RSA group had positive results on more than one test.
Of the 13 RSA group subjects found to have antiphospholipid antibodies, 2 had 3 positive results and 4 had
2 positive results; thus, 46% of the patients with
antiphospholipid antibodies had 2 or more positive
results. Some of these patients with more than one
positive result had the highest aCL levels found in the
Table 2. Positive antiphospholipid antibody test results in women
with recurrent spontaneous abortion*
Patient
no.
84
86
79
59
6
15
I&60
65
52
17
55
29
* LAC
LAC
VDRL
IgG aCL
IgM aCL
Pos.
Pos.
Pos.
Pos.
-
Pos.
Pos.
Pos.
Pos .
Pos .
Pos.
Pos.
-
91
109
56
-
-
11
23
-
44
38
60
30
16
-
-
= lupus anticoagulant; aCL = anticardiolipin antibodies
(IgG aCL normal <20 units; IgM aCL normal <7 units).
PREVALENCE OF ANTIPHOSPHOLIPID ANTIBODIES
1233
DISCUSSION
- - -&_
__
1:
L
I ':,rI;
,
,, f
I'i!
N 1I ,
,>,a,
RSA
(81)
NORMAL
PREGNANCY
(88)
NEVER
PREGNANT
1641
Figure 1. Anticardiolipin antibodies in women with systemic lupus
erythematosus (SLE), women with recurrent spontaneous abortion
(RSA) (3 or more fetal losses), women with successful pregnancies,
and women who have never been pregnant (n values shown in
parentheses). Values are given in IgG phospholipid (GPL) units.
Bars show the mean ? 2 SD; broken line marks cutoff point for
normal results (5 SD from the normal mean).
RSA group (Table 2), and repeated testing showed that
these positive results were quite constant. The presence of both a positive VDRL and an IgG aCL
conferred a relative risk of 4.29 for recurrent spontaneous abortion.
Figure 1 compares IgG aCL levels in the 3
groups of study subjects with those in a group of
female SLE patients. The data from the SLE patients
were collected as part of a previous study and are
included to show the similarity in the titers of IgG aCL
found in subjects with RSA and in patients with SLE.
Only SLE patients and RSA subjects had significantly
elevated levels of IgG aCL. The lupus patients were 69
consecutive nonselected female patients who attend
the lupus clinic at the University of Connecticut
Health Center. All of these patients fulfilled the American College of Rheumatology (formerly, the American
Rheumatism Association [ARA]) criteria for SLE (16).
The prevalence of antiphospholipid antibodies
in women who experience recurrent spontaneous
abortion has been studied previously, but many of
those studies described small numbers of individuals,
and some did not include control groups (9-11,17,18).
These studies have produced discrepant results
(17,18). In the present study, we have shown that
antiphospholipid antibodies are more prevalent in
women with RSA than in those who have successful
pregnancies or in those who have never been pregnant.
It was somewhat surprising that the LAC was
not significantly more prevalent in the RSA group than
in the 2 control groups, although it has been suggested
that lupus anticoagulant is not as sensitive as anticardiolipin antibodies for predicting fetal wastage (7,19).
Our test for the lupus anticoagulant (the dilute tissue
thromboplastin time) is not one of the most sensitive
tests for detecting lupus anticoagulants. Previous studies using kaolin clotting time showed that 8% of
normal individuals have a lupus anticoagulant (20),
whereas in our study, the test result was positive in
only 3.3% of controls (5 of 152).
It has been suggested that a biologically falsepositive VDRL result alone is insufficient laboratory
evidence for the diagnosis of primary antiphospholipid
antibody syndrome (21). A biologically false-positive
test for syphilis is one criterion of the ARA revised
criteria for the classification of SLE (16). However,
patients who eventually develop SLE may have a
biologically false-positive VDRL for years before any
other markers of connective tissue disease develop
(22). Our study shows that a biologically false-positive
test for syphilis is a more specific marker for predicting
fetal wastage than is the test for lupus anticoagulant.
Indeed, we have a young patient whose only laboratory abnormality was a biologically false-positive
VDRL. This patient was enrolled into the study because of a history of 3 fetal losses. She subsequently
developed a right middle cerebral artery thrombosis at
the age of 29, a classic clinical feature of the antiphospholipid antibody syndrome. It is therefore evident
that in some cases, a biologically false-positive VDRL
may be the only laboratory marker for the antiphospholipid antibody syndrome.
Previous studies have suggested that the prevalence of a biologically false-positive test for syphilis
(using the rapid plasma reagin [RPR] test) is no different in women experiencing fetal wastage than in
women successfully completing pregnancy (21). Other
PARKE ET AL
1234
studies are not consistent with these findings (23) but
are consistent with the findings of our study, that a
biologically false-positive test for syphilis confers significant risk for fetal wastage, especially if IgG aCL
are present.
There are many reasons for recurrent spontaneous abortion. Some gynecologic causes are easily
corrected, but frequently, patients are not fully evaluated for fetal wastage until after they have experienced 3 fetal losses. This study evaluated all women
with 3 fetal losses, regardless of their gynecologic
findings. Even in these nonselected RSA subjects,
there was a statistically significant difference in the
prevalence of antiphospholipid antibodies compared
with the 2 control groups.
Our previous studies support the findings of
other investigators and suggest that some women with
unexplained RSA, i.e., women in whom no gynecologic cause for fetal wastage can be determined, have
antiphospholipid antibodies and that these antibodies
may be associated with numerous other laboratory
markers suggestive of subclinical autoimmune disease
(15,24). It is possible, therefore, that recurrent spontaneous abortion may be an early manifestation of
autoimmune disease in some patients. Long-term followup of these women with antiphospholipid antibodies whose primary complaint is fetal wastage is necessary to determine if they remain clinically stable or
progress to develop overt connective tissue disease, as
has been demonstrated by studies of women with
antibodies to various components of the extractable
nuclear antigen (25). The relationship between SLE
and the primary antiphospholipid antibody syndrome
is not clear; however, some patients with the primary
antiphospholipid antibody syndrome have close family
members who do meet the ARA criteria for SLE
(8,261.
Several reports have suggested that fetal wastage can be reduced from more than 90% to approximately 30% in women with antiphospholipid antibodies, by using therapies aimed at inhibiting thrombosis
and lowering the levels of these antiphospholipid antibodies (3,4). Such claims need to be substantiated by
well-controlled, randomized studies. The fact that
such studies have not been done are testament to the
confusion that surrounds this syndrome. Whether
these antibodies are an epiphenomenon associated
with an underlying thrombotic diathesis or an early
marker of a developing connective tissue disease remains to be determined. The significance of a recently
described serum cofactor that appears to be necessary
for the binding of antiphospholipid antibodies to phospholipids (27,28) also needs to be determined.
Antiphospholipid antibodies are more prevalent
in women with RSA than in women with successful
pregnancies or women who have never been pregnant.
Our studies lead us to conclude that patients with
recurrent fetal wastage should be evaluated for the
presence of antiphospholipid antibodies, especially if
no gynecologic cause for the fetal wastage has been
found. Long-term studies are needed to determine if
those with RSA and antiphospholipid antibodies progress to develop other clinical features typical of
autoimmune disease.
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