Hereditary Angioedema With Normal C1 Inhibitor: US Survey of Prevalence and Provider Practice Patterns

Abstract

What is already known about this topic?The diagnosis of hereditary angioedema with normal C1-INH (HAE-nl-C1INH) is challenging because of the lack of confirmatory diagnostic tests.In the absence of robust clinical data, specific recommendations for management are largely based on expert opinion.What does this article add to our knowledge?This article provides prevalence estimates of HAE-nl-C1INH (1,230-1,331) in the United States and describes current diagnoses and management strategies used by physicians.How does this study impact current management guidelines?This study describes diagnostic and management strategies of physicians caring for HAE-nl-C1INH patients, providing real-world data for comparison with current guideline recommendations.Results may be helpful for future clinical studies in this population.BACKGROUND: Hereditary angioedema (HAE) with normal C1-INH (HAE-nl-C1INH) is phenotypically similar to HAE resulting from C1-INH deficiency (HAE-C1INH).Confirmatory diagnostic tests for HAE-nl-C1INH are limited and few clinical study data exist regarding management of the condition.Therefore, survey studies may provide initial estimates of prevalence, diagnosis, and management patterns of this condition.OBJECTIVE: To estimate the prevalence and describe current management patterns for HAE-nl-C1INH in the United States (US).METHODS: We conducted an Internet-based survey of US physicians to estimate the prevalence of the HAE-nl-C1INH population in the United States.Potential participating physicians were identified from the US Hereditary Angioedema Association database and IQVIA Xponent prescription database.Eligible physicians were invited to complete an online survey between June and September 2021.RESULTS: A total of 113 physicians provided data for the estimation of HAE-nl-C1INH prevalence and 81 physicians treating HAE-nl-C1INH patients provided data about treatment patterns.In bias-corrected analysis, we estimated 1,230 to 1,331 HAE-nl-C1INH patients within the United States between May 2019 and April 2020.Mean time to diagnosis for HAE-nl-C1INH was approximately 6 years (range, 2.4-13.5 years).Response to medication was commonly used to inform diagnosis (antihistamine response or nonresponse used by 73% of physician respondents, corticosteroids by 57%, or HAE-specific medications by 74%), and Factor XII genetic testing was used by 43%.CONCLUSIONS: These survey data provide estimates of HAEnl-C1INH prevalence in the United States as well as current diagnosis and management strategies.Results may be useful for developing studies to assess treatment efficacy and safety, and potentially improve the diagnosis for and management of this patient population.

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