Specialist Advice Support for Management of Severe Hereditary Angioedema Attacks: A Multicenter Cluster-Randomized Controlled Trial

Study objective: Hereditary angioedema is a rare disease associated with unpredictable, recurrent attacks of potentially life-threatening edema. Management of severe attacks is currently suboptimal because emergency medical teams are often unaware of new specific treatments. The objective of this trial is to test whether a dedicated national telephone care-management strategy would reduce resource use during severe hereditary angioedema attacks.

Methods: We conducted a cluster-randomized multicenter prospective trial of patients with a documented diagnosis of hereditary angioedema (type I, II or FXII hereditary angioedema). Participants were enrolled between March 2013 and June 2014 at 8 participating reference centers. The randomized units were the reference centers (clusters). Patients in the intervention arm were given a national free telephone number to call in the event of a severe attack. Emergency physicians in the SOS-hereditary angiœdema (SOS-HAE) call center were trained to advise or prescribe specific treatments. The primary outcome was number of admissions for angioedema attacks. Economic evaluation was also performed.

Results: We included 100 patients in the SOS-HAE group and 100 in the control group. During the 2 years, there were 2,368 hereditary angioedema attacks among 169 patients (85%). Mean number of hospital admissions per patient in the 2-year period was significantly greater in the usual-practice group (mean 0.16 [range 0 to 2] versus 0.03 [range 0 to 1]); patient risk difference was significant: -0.13 (95% confidence interval -0.22 to -0.04; P=.02). Probabilistic sensitivity graphic analysis indicated a trend toward increased quality-adjusted life-years in the SOS-HAE group.

Conclusion: A national dedicated call center for management of severe hereditary angioedema attacks is associated with a decrease in hospital admissions and may be cost-effective if facilities and staff are available to deliver the intervention alongside existing services.