Self Intravenous (IV) Administration of C1-INH Concentrate for Hereditary Angioedema: A Retrospective Analysis of Patient Outcomes

Abstract

Hereditary angioedema (HAE) is a rare and difficult to manage disorder. The availability of C1 inhibitor (C1-INH) concentrate is encouraging the development of improved management strategies based upon patient self IV administration. We conducted a retrospective, case-cohort review of longitudinal data gathered in the routine follow-up of 10 HAE patients (mean age, 35.4 yrs [range, 17-54]; 60% female) trained to self-administer IV C1-INH concentrate (Berinert®/CSL Behring or Cinryze®/ViroPharma) on-demand for acute attacks or ongoing prophylaxis. Patients were taught self IV administration. Four patients were placed on C1-INH prophylaxis (1000U given once weekly, twice weekly, Q3 days or Q4 days) and six used C1-INH on-demand (1000-1500U/attack). Over an average of 16 months, 4 patients on prophylaxis experienced a mean of 0.33 attacks/patient/month. Six patients treated on-demand had a mean of 0.22 attacks/patient/month over an average of 10 months. Thirty-three reported attacks were treated with self IV-administered C1-INH. Administration was in home/school/camp settings in all but 2 attacks: in one, the location of swelling interfered with IV placement and the other was patient preference. Thirty-two of the 33 attacks resolved without further medical intervention; one laryngeal attack was followed by 24-hour hospital observation. Three patients switched C1-INH product during the study, but all remained on home-based treatment. Side effects were infrequent and not serious and there were no reported complications from self-administration of C1-INH. Self-administration of intravenous C1-INH concentrate as prophylaxis or on-demand therapy can be a good option for patients with HAE.