Thromboembolic Risk of C1 Esterase Inhibitors: A Systematic Review on Current Evidence

The exact risk of developing a thromboembolic event (TEE) while using complement 1 esterase inhibitors (C1-INHs) is currently undetermined for patients with hereditary angioedema (HAE). This systematic review aimed to define the potential risk of TEEs from these agents.

This evaluation covers publications examining or mentioning the risk of TEEs in association with C1-INHs. A systematic literature search was conducted utilizing PubMed, Scopus, and ProQuest. This review utilized search results through January 2020 and followed the PRISMA recommendations for a systematic review. Articles not available in English and animal or in-vitro studies were excluded. For inclusion, studies had to be open-label, randomized-controlled, cross-sectional, or clinical observational studies. A total of 13 studies met inclusion criteria and yielded 1716 patients receiving at least one dose of C1-INH, though only 41 incidences of thrombosis were documented.

Significant heterogeneity exists in the available literature concerning both study design and the reporting of data; therefore, interpretation of thrombotic risk is difficult. TEEs are rarely reported in the literature, and they seem unlikely to occur in patients without underlying risk factors. Important risk factors include those found in the prescribing information of C1-INHs.