Primary ITP (Immune Thrombocytopenia) in Pregnancy

Key points

• Primary Immune Thrombocytopenia (ITP) is an acquired immunological disorder characterised by an isolated low platelet count.
• This condition can be acquired during women's reproductive years and is known to develop in pregnancy, but there are no accurate estimates of UK incidence.
• Additionally, there are no high quality prospective studies or randomised clinical trials to inform management of the mother or delivery.
• This study seeks to estimate the current incidence and describe management and outcomes of severe ITP in pregnancy in the UK.

Surveillance Period

1^st June 2013 – 31^st January 2015

Background

Primary ITP is an acquired immunological disorder characterised by an isolated low platelet count (thrombocytopenia) necessary for normal clotting function. It is defined as a blood peripheral platelet count of <100 x 10⁹/l and the absence of any initiating or underlying cause such as antiphospholipid antibody syndrome, SLE or viral infections^[1]. This condition can be acquired during women's reproductive years and is known to develop in pregnancy. The current incidence of ITP in pregnancy is not yet estimated accurately. Discrepancies in definition and clinical criteria have led to a wide range of estimates reported to be between 0.1 and 1 case per 1000 pregnancies^[2][3]. ITP accounts for 3% of cases of thrombocytopenia in pregnancy^[3].

Current treatment recommendations for ITP in pregnancy are largely based on clinical experience and expert consensus^[1]. There are no high quality prospective studies or randomised clinical trials to inform management of the mother or delivery. First line treatments include corticosteroids and/or immunoglobulin. Second line treatments include combination therapy of high dose methylprednisolone and IVIg, and rarely splenectomy (advised in the second trimester)^[1]. Without clear guidance or a strong evidence base for treatment of this rare condition it is unknown how this patient cohort is currently managed in the UK. This study seeks to estimate the current incidence and describe management and outcomes of severe ITP in pregnancy in the UK.

Objectives

• To use the UK Obstetric Surveillance System to describe the incidence of severe primary ITP in pregnancy in the UK.
• To describe the current drug treatment strategies used to manage severe primary ITP in pregnancy in the UK.

Research questions

• What is the current incidence of severe primary ITP in pregnancy in the UK?
• What indications or factors determine a clinician's decision to commence active treatment of severe primary ITP in pregnancy in the UK?
• How is severe primary ITP managed in pregnancy in the UK?
• What is the current incidence of maternal morbidity and mortality in this cohort of patients?
• What is the current incidence of neonatal morbidity and mortality in this cohort of patients?

Case definition

Any pregnant woman who has been diagnosed with thrombocytopenia with a platelet count of <50 x 10⁹/l at any point in her pregnancy prior to delivery where obstetric and hereditary causes for thrombocytopenia have been excluded (ie. pre-clampsia, HELLP syndrome, acute fatty liver of pregnancy, known antiphospholipid antibody syndrome or hereditary thrombocytopenias).

OR

Any pregnant woman diagnosed with an isolated thrombocytopenia where a clinical decision to treat the thrombocytopenia prior to delivery of the infant has been made.

EXCLUDE

Women with secondary immune thrombocytopenia to systemic lupus erythematosus (SLE), Hepatitis C, CMV, HIV and HAART therapy or any condition where treatment of thrombocytopenia is focused on treatment of the causative disease are excluded from the study.

Funding

This study is funded by the ITP Support Association.

Ethics committee approval

This study has been approved by the NRES Committee North West - Lancaster (study reference 13/NW/0133).

Investigators

Angharad Care, Liverpool Women's Hospital; Zarko Alfirevic, University of Liverpool/Liverpool Women's Hospital; Marian Knight, NPEU; Sue Pavord, Oxford University Hospitals/University of Oxford.

Download the Data Collection Form (DCF)

UKOSS Severe Primary ITP Form