A Survey to Understand C1 Esterase Inhibitor Distribution Patterns and Use in Canada

Hereditary angioedema (HAE) is a rare, genetic condition treated with plasma-derived human C1 esterase inhibitor (C1-INH). Little is known about patient geographic distribution and patterns of use. The project aim was to understand how and where C1-INH product is being used to treat HAE in Canada. An online survey using REDCap was distributed by email to hospitals that had received C1-INH from the blood supplier between December 2019 and November 2020. Hospital demographics, contact information and C1-INH use in-hospital and by patients at home was requested. Descriptive analyses were performed. Calculation of IUs of C1-INH from vial numbers used by hospitals was assumed to follow the national distribution of vial sizes (1500 and 500 IUs). Research Ethics Board approval was not required. Respondents: 83/181 hospitals (47.5%) that received C1-INH responded: 39 from Ontario; 35 from Alberta and British Columbia combined and 9 from other provinces. The 83 hospitals represented 52.3% of the C1-INH product distributed nationally. Patients: 221 patients received 1844 vials (2.6 million IUs) of C1-INH in a hospital setting: 138 in the emergency department (62.4 %), 53 as inpatients (24.0%), and 30 in out-patient clinics (13.6%). The total number of hospital patient encounters was 615 with the out-patient clinic having the highest proportion (52.5%). For home care use, 68 hospitals (81.9%) issued product to 239 patients; 67.8% were female. The most common age category was 30–44 years but in Ontario the age demographic was slightly older (45–59 years). Distribution and use: The total number of C1-INH units issued to all hospitals in Canada was 62,260,000; of which 32,568,000 units were issued to the 83 responding hospitals. There were 2,616,000 IUs of C1-INH transfused in hospitals, 424,500 IUs transferred to other hospitals and 101,000 IU discarded. For home care, 31,395,000 IUs were transfused; hence, home care use accounted for 92% of product issued. This project gives a Canadian snapshot of the distribution and use of C1-INH both in hospitals, and at home for patients with HAE, with most patients residing in three provinces and the majority of product being used for home care. Further information is required to understand the proportion of home product used on-demand versus prophylactically.