Thromboembolic risk of intravenous and subcutaneous immunoglobulin treatment for neuroinflammatory diseases

Rogers, Tobias and White, Laura M and Cooper, Susan and Smith, Hannah and Gosal, David and Keh, Ryan Yann Shern (2026) Thromboembolic risk of intravenous and subcutaneous immunoglobulin treatment for neuroinflammatory diseases. Journal of Neurology, Neurosurgery and Psychiatry, 97 (3). pp. 204-208. ISSN 0022-3050

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Abstract

Background Intravenous immunoglobulin (IVIg) is effective in many neuroinflammatory disorders but carries a risk of thromboembolic events (TEEs). Subcutaneous immunoglobulin (SCIg) is effective, but its thromboembolic risk profile is less well-described, particularly in patients with prominent vascular risk factors. We investigated the thromboembolic risk profile of IVIg and SCIg using a large single-centre retrospective dataset of patients with neuroinflammatory disorders. Methods 243 patients treated with immunoglobulin over a 15-year monitoring period were analysed. Demographic information was used to calculate QRISK3 vascular risk scores. Patients were grouped based on having received IVIg-only, SCIg-only or both IVIg and SCIg (with subgroup analysis of IVIg and SCIg treatment periods). TEE incidence rates were compared. The relationship between QRISK3 and TEE likelihood was analysed. Results A total of 1401 patient-years immunoglobulin treatment data were obtained. The SCIg-only cohort was older with higher QRISK3 scores. More patients on IVIg (n=14) than SCIg (n=2) experienced TEEs on treatment (1.38 vs 0.52 events per 100 patient-years), but this difference was not statistically significant. IVIg-treated patients with TEEs were younger (p=0.039) than SCIg-treated TEE patients. QRISK3 scores broadly correlated with thromboembolic risk across the cohort (p=0.027), but some younger IVIg patients with low QRISK3 scores experienced TEEs indicating that IVIg but not SCIg independently increases thromboembolic risk. QRISK3 scores >10% identified 71% and 100% of TEEs in IVIg-treated and SCIg-treated patients, respectively, but are insensitive (7%) as TEEs are rare events. Conclusions SCIg is at least equivalent in thromboembolic risk to IVIg and may be safer for patients with existing vascular risk factors.