Effectiveness of intravenous immunoglobulin use in heparin-induced thrombocytopenia

Intravenous immunoglobulin improves live birth rates in patients with unexplained recurrent pregnancy loss

This real-world study aimed to assess the clinical efficacy and safety of intravenous immunoglobulin (IVIG) in treating unexplained recurrent pregnancy loss (uRPL) patients. A total of 238 patients with uRPL were enrolled in this retrospective study. According to the treatment, patients were assigned into treatment group (n=184, receiving IVIG+low molecular weight heparin [LMWH]) and control group (n=54, only LMWH). The primary outcome was the live birth rates (LBR) after 24 weeks of gestation. In addition, we performed subgroup analyses to assess the LBR in uRPL patients with age (≥30 years or <30 years), body mass index (BMI, 18-24 kg/m2 or ≥24 kg/m2), number of previous pregnancy losses (2 or ≥3), gestational week of first medication, and IVIG medication regimen during pregnancy. The LBR showed a significant increase after IVIG treatment compared to the control group (77.7 % vs. 53.7 %, P=0.001). Multivariable logistic regression indicated that IVIG was associated with increased LBR (aOR=4.383, 95 %CI 2.024-9.489). Besides, we observed a significantly lower incidence of decreased platelet count (1.6 % vs. 7.4 %, P=0.049) in the treatment group. Subgroup analyses showed that IVIG treatment was associated with improved LBR in uRPL patients with age of <30 years (aOR=4.012, 95 %CI 1.428-11.266), previous pregnancy losses ≥3 times (aOR=17.327, 95 %CI 2.525-118.921), and BMI of 18-24 kg/m2 (aOR=8.914, 95 %CI 2.985-26.618). IVIG treatment significantly improves the LBR in uRPL patients. These findings from real-world data provide evidence for the safety and efficacy of IVIG as a viable treatment for uRPL patients in clinical practice.

Autoimmune Heparin-Induced Thrombocytopenia

Autoimmune thrombocytopenia (aHIT) is a severe subtype of heparin-induced thrombocytopenia (HIT) with atypical clinical features caused by highly pathological IgG antibodies ("aHIT antibodies") that activate platelets even in the absence of heparin. The clinical features of aHIT include: the onset or worsening of thrombocytopenia despite stopping heparin ("delayed-onset HIT"), thrombocytopenia persistence despite stopping heparin ("persisting" or "refractory HIT"), or triggered by small amounts of heparin (heparin "flush" HIT), most cases of fondaparinux-induced HIT, and patients with unusually severe HIT (e.g., multi-site or microvascular thrombosis, overt disseminated intravascular coagulation [DIC]). Special treatment approaches are required. For example, unlike classic HIT, heparin cessation does not result in de-escalation of antibody-induced hemostasis activation, and thus high-dose intravenous immunoglobulin (IVIG) may be indicated to interrupt aHIT-induced platelet activation; therapeutic plasma exchange may be required if high-dose IVIG is ineffective. Also, aHIT patients are at risk for treatment failure with (activated partial thromboplastin time [APTT]-adjusted) direct thrombin inhibitor (DTI) therapy (argatroban, bivalirudin), either because of APTT confounding (where aHIT-associated DIC and resulting APTT prolongation lead to systematic underdosing/interruption of DTI therapy) or because DTI inhibits thrombin-induced protein C activation. Most HIT laboratories do not test for aHIT antibodies, contributing to aHIT under-recognition.

Heparin-Induced Thrombocytopenia: A Review of New Concepts in Pathogenesis, Diagnosis, and Management

Knowledge on heparin-induced thrombocytopenia keeps increasing. Recent progress on diagnosis and management as well as several discoveries concerning its pathogenesis have been made. However, many aspects of heparin-induced thrombocytopenia remain partly unknown, and exact application of these new insights still need to be addressed. This article reviews the main new concepts in pathogenesis, diagnosis, and management of heparin-induced thrombocytopenia.

Intravenous Immune Globulin (IVIG) for Treatment of Autoimmune Heparin-Induced Thrombocytopenia: A Systematic Review

OBJECTIVE

To evaluate intravenous immune globulin (IVIG) for autoimmune heparin-induced thrombocytopenia (aHIT), including platelet recovery, IVIG dose, dosing weight, IVIG product used, and complications reported.

DATA SOURCES

PubMed and EMBASE were searched from inception through June 21, 2020. Search terms included heparin-induced thrombocytopenia, HIT, intravenous immune globulin, IVIG, autoimmune HIT, aHIT, and immune globulin.

STUDY SELECTION AND DATA EXTRACTION

Patients administered IVIG for HIT and diagnosed by immunoassay (optical density ≥2) or positive activation assay were included.

DATA SYNTHESIS

Twenty-four cases were reviewed; 92% had persistent aHIT. Time to IVIG administration post-nonheparin anticoagulant initiation was 9 days (median). Most common IVIG cumulative dose was 2 g/kg (dosed as 1 g/kg/d for 2 consecutive days); 75% had a favorable platelet increase (≥50 × 10⁹/L) within 5 days of initial IVIG dosing.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

aHIT is characterized by critically low platelets, thrombosis, and a persistent delay in platelet recovery despite treatment with a nonheparin anticoagulant. An immunoassay and subsequent confirmatory activation assay (at low, high, and 0 IU/mL unfractionated heparin levels) is recommended to confirm diagnosis. Patients nonresponsive to nonheparin anticoagulants within 5 days of initiation should be evaluated for IVIG treatment (2 g/kg cumulative dose). More data are needed to clarify appropriate IVIG dosing weight, although based on current published literature, it is recommended to use actual body weight.

CONCLUSIONS

Data reported support use of IVIG as adjunctive therapy for patients with aHIT. Judicious IVIG use based on key clinical and laboratory findings is critical.