Randomized study of subcutaneous low molecular weight heparin plus aspirin versus intravenous immunoglobulin in the treatment of recurrent fetal loss associated with antiphospholipid antibodies
To compare the 2 most efficacious therapeutic regimens, intravenous immunoglobulin (IVIG) and anticoagulation with low molecular weight (LMW) heparin plus low-dose aspirin, in women with recurrent pregnancy loss associated with antiphospholipid antibodies (aPL).
We examined 40 women with recurrent abortion (at least 3 occurrences) and repeatedly positive test results for anticardiolipin or lupus anticoagulant. The subjects were randomly assigned to treatment with IVIG or LMW heparin plus low-dose aspirin. Both therapies were started when the women were pregnant as documented by a positive urine test. IVIG was stopped at the thirty-first week of gestation, aspirin at the thirty-fourth week, and heparin at the thirty-seventh week. The primary outcome of interest was the rate of live births with the 2 treatments.
The characteristics of the 2 groups were similar at the time of randomization. The women treated with LMW heparin plus low-dose aspirin had a higher rate of live births (84%) than those treated with IVIG (57%).
Treatment with LMW heparin plus low-dose aspirin should be considered as the standard therapy for recurrent pregnancy loss due to aPL.
Recurrent fetal loss is associated with many causes that include anatomic, genetic, and hormonal disorders. Miscarriages are a manifestation of several autoimmune disorders, but remain unexplained in many cases.
Lupus anticoagulant (LAC), antiphospholipid antibodies (aPL), and antibodies against molecules involved in the coagulation process have been known to be associated with recurrent miscarriage (3 or more consecutive spontaneous abortions) (1, 2). Women with this condition have a rate of fetal loss of 90% in the absence of treatment and are diagnosed as having antiphospholipid syndrome (APS). Treatments have included moderate-to-high doses of prednisone, aspirin, intravenous immunoglobulin (IVIG), and heparin, as single agents or in combination (3–5).
Although several reports have been published on this topic, available data are limited. Studies frequently include both women with early and those with late pregnancy loss or with systemic lupus erythematosus (SLE). Only a small number of patients have been included in most individual studies, and only a few randomized controlled trials have been conducted (6). In a recent study, Laskin et al (3) demonstrated that prednisone was not effective in preventing fetal loss in women with aPL. The beneficial effect of IVIG has been proved only in uncontrolled studies (5). To date, the combined use of low-dose aspirin and heparin is considered the standard therapy for this condition (7).
The aim of the present randomized controlled study was to compare the 2 most effective therapies, IVIG and an anticoagulation regimen (low-dose aspirin and heparin), in aPL-positive women with recurrent pregnancy loss. Long-term treatment with unfractionated (UF) heparin requires monitoring, causes osteoporosis, and can lead to the development of heparin-induced thrombocytopenia. Low molecular weight (LMW) heparins, which have been recently introduced into clinical practice, have been demonstrated to be safe and effective for prevention and treatment of acute deep vein thrombosis (6). These agents do not require monitoring, and preliminary results suggest that they may cause less osteopenia; they also appear to be safe for the fetus. Although LMW heparin has been extensively used in Europe, limited data are available on its use as antithrombotic therapy in pregnant women with APS (8). In this trial, LMW heparin was substituted for UF heparin.
The primary outcome of interest was pregnancy loss. The secondary end points included maternal side effects during pregnancy and after the delivery (hemorrhages, pregnancy-associated hypertension, fractures during pregnancy or up 2 months post partum, reduced maternal bone mineral density, death). For the infants, the end points included preterm delivery (before the thirty-seventh week of gestation), neonatal intensive care unit admission, low birth weight, and neonatal bleeding or bruising.
PATIENTS AND METHODS
We evaluated 383 women who had been referred to our institution for unexplained fetal loss between January 1995 and December 2000. All had lost at least 3 fetuses. One hundred twenty-two of the women were positive for at least 1 serum autoantibody (antinuclear, anti–thyroid peroxidase, antithyroglobulin, anti–gastric parietal cell, and/or anticardiolipin [aCL]). Among them, 42 women had repeatedly positive test results for aCL in the absence of other detectable autoantibodies; lupus anticoagulant (LAC) was present in 27 of these women. No other clinical manifestations were present, and other causes of fetal loss were excluded. All 42 women agreed that they would participate in the study when they became pregnant.
Criteria for inclusion were age 18–39 years, ≥3 consecutive fetal losses before 10 weeks' gestation, and ≥2 positive results for aCL (with testing performed at intervals of ≥3 months), with levels of IgG phospholipid units (GPL) >40. Exclusion criteria were a chromosomal or anatomic abnormality or a luteal phase defect, confirmed peptic ulcer, SLE, diabetes mellitus or abnormal results of an oral glucose tolerance test, previous thromboembolism, sensitivity to aspirin, hypertension or current treatment with antihypertensive drugs, previous prednisone therapy, an abnormal chest radiographic result, or a positive result of a tuberculin skin test. Women considered eligible for the study were asked to provide informed consent. The study was approved by the Human Experimentation Committee of the University of Palermo.
Serum samples were stored at −20°C and assayed simultaneously in duplicate. A commercially available β2-glycoprotein I–dependent aCL antibody test was used (IPR, Catania, Italy). The test was standardized with serum samples of known IgG aCL. The cutoff in this assay was 12.5 GPL. The occurrence of LAC was also investigated in all subjects, LAC was considered to be present if any of the following were prolonged: partial thromboplastin time, Russell's viper venom time, or kaolin-cephalin clotting time. The presence of LAC was documented by mixing and confirmatory tests (9).
The subjects were randomly assigned to receive treatment with IVIG or with LMW heparin plus low-dose aspirin. Randomization was performed at a central location, with a computer-generated sequence of random numbers. Women in the IVIG group started IVIG as soon as they had a positive result on a pregnancy test. The dosage of IVIG (IgVENA N; Sclavo, Siena, Italy) was 400 mg/kg/day given for 2 consecutive days followed by a single dose each month. Treatment was stopped at 31 weeks' gestation or at the time of miscarriage. Women in the LMW heparin plus low-dose aspirin group started taking low-dose aspirin (75 mg daily) and heparin (self-administered injection; 5,700 IU/day) (Seleparina; ItalFarmaco, Milan, Italy) as soon as they had a positive result on a pregnancy test; aspirin was discontinued at 34 weeks' gestation or at the time of miscarriage, and heparin at 37 weeks' gestation or at the time of miscarriage. Gestational age at delivery was determined by menstrual dates, confirmed by ultrasound examination. From 24 weeks' gestation, pregnancies were monitored by serial ultrasonography and Doppler studies of the umbilical artery circulation.
Student's t-test and Fisher's exact test were used to compare outcomes in the 2 treatment groups.
The characteristics of the 2 groups were similar at the time of randomization (Table 1). Mean ± SD aCL levels were 52.6 ± 11.1 GPL in the IVIG group and 53.9 ± 10.6 GPL in the LMW heparin plus low-dose aspirin group. LAC was found to be present in 13 women in the IVIG group and 14 in the heparin plus aspirin group. No subject had LAC without aCL. None of the women in the IVIG group withdrew from the trial. Two women in the heparin plus aspirin group withdrew during the first trimester because of poor compliance with the heparin therapy. Thus, a total of 21 women in the IVIG group and 19 women in the heparin plus aspirin group completed the trial.
Table 1. Baseline characteristics of the women in the study groups*
|Age at randomization, mean ± SD years||32.1 ± 3||30.3 ± 5|
|No. of previous fetal losses, mean ± SD||3.7 ± 1.3||3.6 ± 0.9|
|Cumulative no. of previous pregnancies||87||84|
|Cumulative previous fetal losses, no. (%)||85 (97.7)||81 (96.4)|
|aCL positive, no. (%)||21 (100)||19 (100)|
|LAC positive, no. (%)||13 (62)||14 (74)|
|Current smokers, no.||2||3|
The outcomes of 40 pregnancies are shown in Table 2. The women treated with LMW heparin plus low-dose aspirin had a higher rate of live births (84%) than those treated with IVIG (57%) (odds ratio 0.25 [95% confidence interval 0.05–1.13]). The mean ± SD duration of pregnancy was 38.3 ± 2.1 weeks in the IVIG group and 38.7 ± 2.4 weeks in the heparin plus aspirin group. In 1 woman in the IVIG group, preeclampsia was diagnosed at 37 weeks' gestation, resulting in a preterm cesarean delivery and live birth.
Table 2. Major outcomes of pregnancy in the study groups*
|No. of pregnancies||21||19|| |
|Live births, no. (%)||12 (57)||16 (84)||0.06†|
|Duration of pregnancy, mean ± SD weeks||38.3 ± 2.1||38.7 ± 2.4||0.67‡|
|Birth weight, mean ± SD gm||3,246 ± 218||3,298 ± 236||0.46‡|
|Preterm deliveries, no.||1||0|
|Infants admitted to NICU, no.||1||0|
|Congenital anomalies, no.||0||0|
|Cesarean deliveries, no.||1||0|
|First-trimester fetal loss, no. (%)||6 (29)||2 (11)|
|Fetal loss after 13 weeks, no.||2||0|
|Intrauterine death, no.||1||1|
Among the women receiving IVIG, spontaneous abortions occurred during the first trimester in 6 cases and during the second trimester (14 and 17 weeks' gestation, respectively) in 2 cases. In 1 case, intrauterine death was diagnosed. Among those receiving LMW heparin plus low-dose aspirin, spontaneous abortion occurred during the first trimester in 2 cases, and a preterm delivery occurred at 28 weeks' gestation after premature rupture of the membranes in 1 case. No other complications were observed, except for mild thrombocytopenia in 2 women in the LMW heparin plus aspirin group. No women developed thromboembolic complications during pregnancy or post partum. No decrease in lumbar spine bone density was observed in the 12 women in the heparin plus aspirin group in whom dual x-ray absorptiometry bone densitometry was performed at 14 weeks' gestation and postnatally. Babies of the mothers in both groups were examined by a pediatrician after delivery, and no abnormalities were observed.
Women with antiphospholipid antibodies have a high frequency of pregnancy loss. Pregnancies can also be complicated by premature delivery and uteroplacental insufficiency. Adverse pregnancy outcomes in these conditions may reflect poor placental perfusion caused by local thrombosis.
Treatment with steroids, low-dose aspirin, heparin, and IVIG in various combinations improves live birth rates (7). Both minor and serious adverse events have been reported with these therapeutic interventions (7). A number of relatively small randomized controlled trials have been performed. Recently, a prospective trial showed that heparin plus aspirin was more effective than aspirin alone (4). IVIG has been used to treat some autoimmune conditions in pregnancy, but a randomized controlled study demonstrated no benefit of IVIG as compared with heparin and aspirin (7).
The beneficial role of IVIG has been attributed to its capacity to inhibit aCL and LAC, resulting in an increase in antibody clearance but also to antiidiotype antibody–mediated decreases in aCL production by interaction with B cell antigen receptors (10). Aspirin and heparin may improve pregnancy outcome by blocking platelet cyclooxygenase and thromboxane synthesis (11) and by promoting implantation in early pregnancy and anticoagulation (12), respectively. Low-dose aspirin also acts as a potent stimulator of interleukin-3, which has been found to be deficient during APS-associated miscarriage (13).
The present trial was designed to evaluate the effect of LMW heparin plus aspirin and of IVIG in the treatment of pregnancy loss due to aPL. The live birth rate was 84% for the pregnancies in which the women were treated with LMW heparin plus low-dose aspirin, but 57% for those treated with IVIG. Most miscarriages occurred in the first trimester of pregnancy. The difference between the 2 treatment groups with respect to fetal outcome was more evident during this period. There was not a difference between treatments after 13 weeks' gestation. In this regard, one could hypothesize that heparin contributes to reduction of fetal loss, especially in the first trimester, by binding to aPL and protecting trophoblast phospholipids from attack, and producing successful implantation in early pregnancy (14).
Only minor adverse events were observed in both groups, with the exception of a case of preeclampsia in an IVIG-treated woman and a case of premature membrane rupture in an LMW heparin plus aspirin–treated woman. This low rate of adverse events may seem surprising. However, it should be noted that the eligibility criteria excluded women with SLE or SLE-like disorders, and there is no doubt that the type and severity of the APS may affect fetal survival and maternal morbidity. Emotional support and continuity of care by the same health care personnel were also provided during the study, including admission for clinical and/or laboratory evaluation upon patient request. Similar success rates with increased supportive care have previously been observed in women with unexplained recurrent miscarriages (15) and more recently by our group in a study of short-term IVIG therapy for recurrent spontaneous abortion (16).
LMW heparin, a fraction with high bioavailability and a relatively long half-life (only once-daily injection), has been used extensively in Europe in the last decade and has been shown to be at least as effective as the traditional UF heparin in preventing thromboembolic events, with fewer side effects (6). Long-term UF heparin treatment may result in osteoporosis, and osteoporosis caused by UF heparin during pregnancy may be complicated by spontaneous fractures. Neither osteoporosis nor vertebral fractures were observed in our study, confirming previous findings of less osteoporosis with LMW heparin (6). LMW heparin does not cross the placental barrier during pregnancy, and there is no evidence of teratogenic effects (17). Finally, LMW heparin is not excreted into the milk (17).
In conclusion, treatment with LMW heparin and low-dose aspirin leads to a significantly higher rate of live births in women with recurrent fetal loss associated with antiphospholipid antibodies than that obtained with IVIG. Long-term use of LMW heparin was also associated with few complications and may require less frequent laboratory followup.