Benefits and risks of danazol in hereditary angioedema: a long-term survey of 118 patients

Background: Hereditary angioedema (HAE) due to C1 inhibitor deficiency is clinically characterized by relapsing skin swellings, abdominal pain attacks, and life-threatening upper airway obstruction. Treatment with androgens prevents attacks for those with this condition. Objective: To examine the benefits and risks of long-term treatment with danazol. Methods: Data were generated retrospectively from 118 German and Danish patients who had HAE due to C1 inhibitor deficiency and were treated with danazol from 2 months to 30 years. The frequency and severity of acute attacks were registered before and during danazol treatment, and adverse effects to the treatment were noted. Data were collected by using standardized questionnaires. Results: In all, 111 of 118 patients responded to danazol. During treatment, 54 of the 118 patients (45.8%) became symptom free or had 1 attack or less per year. In the other patients, hereditary angioedema ran a mild course. The frequency of acute attacks during danazol treatment was reduced to 16.2%, and the attacks were considerably milder than before treatment. Laryngeal edema was reduced to 4.8%. Adverse effects (weight gain, virilization, menstrual irregularities, headache, depression, and/or liver adenomas) occurred in 93 of the 118 patients and led to discontinuation of danazol therapy in 30 patients. Conclusions: Danazol is highly beneficial in patients with frequent and severe attacks of HAE. Because the risk of adverse effects is high, close monitoring of patients is mandatory. However, many patients accept the adverse effects of prophylactic treatment to avoid the distressing and sometimes life-threatening attacks of this condition.