FROM BLOOD

Most pregnant women with a history of immune thrombocytopenia purpura need no treatment. Of those who do, neonatal outcomes were comparable for mothers who received treatment with intravenous immunoglobulin and for those who received corticosteroids, results of an observational study indicate.

Though limited by its retrospective design and low event rates that limit inferences about treatment effects, this observational study – the first to compare the effectiveness of treatment with IVIg to treatment with corticosteroids for immune thrombocytopenia purpura (ITP) in pregnancy – shows that outcomes did not significantly differ with the two regimens. The findings also highlight the need for ongoing neonatal platelet count monitoring throughout the first week of life, regardless of the maternal platelet count, the investigators said.

A review of medical records at two tertiary care centers identified 235 pregnancies in 195 women with a history of ITP. No treatment was required in 137 pregnancies. Of the remaining 98 pregnancies in 91 women, 47 (48%) were treated initially with intravenous immunoglobulin (IVIg) and 51 were treated initially with corticosteroids, reported Dongmei Sun, MD, of University of Western Ontario, London, and colleagues ( Blood. 2016;128[10]:1329-35 ).

The two treatment groups had similar mean maternal platelet counts at birth (68.7 x 109/L and 77.3 x 109/L for IVIg and corticosteroids, respectively). The proportion of mothers who achieved a platelet count response did not significantly differ (38% vs. 39%), the researchers reported.

“The sole difference between treatments was a higher maternal composite outcome noted in the IVIg group,” they wrote, referring to a secondary composite outcome of postpartum hemorrhage, predelivery platelet transfusion, peripartum transfusion of any blood product, or postpartum reduction in the hemoglobin concentration of 30 g/L or more. That composite outcome occurred in 46.8% of pregnancies in the IVIg group and 23.5% in the corticosteroid group.

Adverse events were reported in 13% of cases in each group, and included hemolytic anemia, headache, and “other” in those treated with IVIg, and hyperglycemia requiring treatment, hyperglycemia with neonatal hypoglycemia, infection, and “other” in those receiving corticosteroids.

No severe or fatal maternal, fetal, or neonatal hemorrhages occurred, but two newborns did experience intracranial hemorrhage. No maternal or neonatal deaths occurred, the investigators said.

In 203 neonates for whom platelet counts were available, 56 (28%) had a count of less than 150 x 109/L and 18 (9%) had a count of less than 50 x 109/L.

Nadir platelet counts occurred at birth for 30% of neonates. In two cases, the nadir occurred as late as day 6 postnatally. Of note, a drop in platelets to below 150 x 109/L was found in 9 (11%) of 129 neonates who had a normal cord platelet count and had a repeat count.

ITP occurs in 1 to 10 of every 10,000 pregnancies, and about one-third of cases require intervention. IVIg and corticosteroids are acceptable treatments, but most data on their effectiveness are extrapolated from nonpregnant patients and the treatments have not been adequately assessed in pregnancy, the investigators said. The current study was designed to compare the efficacy of the two treatments for maternal ITP.

Study subjects were women with singleton pregnancies with an ITP diagnosis either before or during pregnancy.

At less than 40% in both groups, the response to ITP therapies was lower than has been reported for nonpregnant patients, the investigators noted.

“Our observation of a relative resistance to ITP treatment during pregnancy requires further validation in prospective studies. We speculate that increased potency of antiplatelet antibodies during pregnancy, pregnancy-associated changes in platelet turnover, or altered drug metabolism may contribute to the lower response rates we observed,” they wrote.

With respect to corticosteroids, this “may warrant consideration of starting therapy earlier in the third trimester to maximize the likelihood of reaching target platelet counts in time for delivery and raises the possibility that lower corticosteroid doses are ineffective in this setting,” they added.

“Also of significance is the finding that 9 neonates (11%) with normal cord platelet counts were found to have a reduction in their platelet count on repeat measurement. These findings highlight the need for determination of cord platelet counts in all neonates born to mothers with active or previous ITP and the need for continued monitoring of the neonatal platelet count during the first week of life, despite normal cord platelet counts,” they wrote.

“Prospective studies are needed to better characterize the safety of these regimens, to determine the optimal dose of corticosteroids, to identify risk factors for neonatal thrombocytopenia, and to explore new therapeutic options,” they concluded.

Among the options worth exploring are rituximab, a monoclonal antibody against B-cell surface antigen CD20, for which “pregnancy data are accumulating,” and romiplostim, a thrombopoietin receptor agonist, which has been used in a few cases without reported fetal complications, they noted.

This study was supported by Canadian Blood Services Small Projects Fund and Canadian Institute of Health Research/Canadian Blood Services New Investigator Award. Individual authors reported receiving support from the Canadian Institutes of Health Research and McMaster University. The authors reported having no other disclosures.

sworcester@frontlinemedcom.com

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