Hereditary angioedema (HAE) with normal C1 inhibitor (HAE-nl-C1INH) is estimated to affect 1230 to 1331 individuals in the US (ie, approximately 0.37 per 100,000), according to an internet-based survey of US physicians. The results of the survey were recently published in the Journal of Allergy and Clinical Immunology: In Practice.

“To our knowledge, this is the first study surveying US HAE-treating physicians to estimate the prevalence of patients with HAE-nl-C1INH and to provide a comprehensive overview of how patients with HAE-nl-C1INH are diagnosed and treated in the US,” the study authors said. “Results may be useful for the development of studies to assess treatment efficacy and safety, and potentially improve diagnosis and management of this patient population.”

The mean time to establish a diagnosis of HAE-nl-C1INH was approximately 6 years. Physicians often used patient response to medication to inform diagnosis, though the survey highlighted differences in the use of diagnostic tools by low prescribers and high prescribers.

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The most commonly prescribed on-demand therapy to manage acute angioedema symptoms in HAE-nl-C1INH was icatibant, and, in general, high-dose antihistamines were more commonly prescribed than other HAE-specific treatments.

The survey also highlighted differences in treatment patterns between high prescribers and low prescribers. For instance, low prescribers used high-dose antihistamines and corticosteroids more frequently than high prescribers, whereas high prescribers used HAE-specific treatments more frequently than low prescribers.

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Physicians reported that 54% of their patients received long-term preventive treatment, indicating the frequency of acute attacks, attack severity, predictability (or patterns) of attacks, and patient request as the main reasons to start preventive therapy. The most commonly prescribed preventive treatment was lanadelumab, followed by C1 esterase inhibitor.

The authors identified potential participating physicians through the US Hereditary Angioedema Association database and the IQVIA Xponent prescription database. Data were obtained from 113 prescribing physicians for the analysis of HAE-nl-C1INH prevalence. Of these physicians, 20% were included within the 90 highest-prescribing physicians. Moreover, 81 physicians treating patients with HAE-nl-C1INH completed the online survey providing data about treatment patterns.


Riedl MA, Danese M, Danese S, Ulloa J, Maetzel A, Audhya PK. Hereditary angioedema with normal C1 inhibitor: US survey of prevalence and provider practice patterns. J Allergy Clin Immunol Pract. Published online January 30, 2023. doi:10.1016/j.jaip.2023.01.023