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Background: Hereditary angioedema (HAE) is a rare genetic disease. Patients with type II HAE have normal or elevated C1-inhibitor (C1-INH) levels but C1-INH protein is dysfunctional. C1-INH function requires careful sample handling and technical expertise and may account for the lack of diagnosed patients with type II HAE in resource-limited countries. Objective: We sought to assess the diagnostic performance of elevated C1-INH levels in diagnosing type II HAE. Methods: All patients with confirmed type II HAE in Hong Kong and India were analyzed. Diagnosis was confirmed by persistent low C1-INH function and/or pathogenic SERPING1 gene mutations. Their C1-INH levels were compared with those of matched controls. Results: A total of 31 (14 Chinese, 17 Indian) patients with type II HAE and 31 matched controls were analyzed. Overall, 77.4% (24/31) of patients with type II HAE had elevated C1-INH levels compared with 38.7% (12 of 31) of controls (odds ratio, 2.00; 95% CI, 1.34-2.98; P = .017). C1-INH levels in patients with type II HAE were significantly higher than in controls (52.2 ± 20.0 mg/dL vs 29.1 ±3.6 mg/dL; P < .001). Findings were consistent when C1-INH values in the Chinese and Indian subgroups were analyzed separately. Receiver-operating characteristic curve demonstrated excellent performance for elevated C1-INH levels to diagnose patients with type II HAE with an area under the curve of 0.953 (95% CI, 0.941-0.992; P < .001). Positive and negative predictive values of both a low C4 and an elevated C1-INH level for patients with type II HAE were 100% and 82.9%, respectively. Conclusions: Low C4 and elevated C1-INH levels may be considered as a screening tool for type II HAE, especially in countries where C1-INH function testing is not readily available.

Background: With no approved long-term prophylaxis (LTP) for the prevention of hereditary angioedema (HAE) attacks in Hong Kong, patients rely on compassionate use programs and drug trials. Moreover, studies regarding the use and efficacy of LTP in Asia are lacking. Objectives: Our aim was to assess 2 LTP medications for HAE in Hong Kong: lanadelumab and garadacimab. Methods: A prospective study was performed. Adult patients with a diagnosis of type I or type II HAE with 1 or more expert-confirmed attacks per month were consecutively recruited. The patients had been receiving treatment for at least 6 months. Clinical data were obtained, and questionnaires were administered before treatment periodically for at least 6 months following initiation of LTP. Results: Almost one-third of the patients with HAE experienced frequent attacks and began receiving LTP (8 of the 11 received garadacimab and 3 of the 11 received lanadelumab). At baseline, the time-normalized number of HAE attacks was 2.5 plus or minus 1.3 per month. At month 6, there was an overall reduction of time-normalized number of attacks per month of –2.4 attacks per month (95% CI = –3.3 to –1.5. [P < .01]). The time-normalized number of HAE attacks at month 6 was 0.1 plus or minus 0.1 per month. More than 70% of the patients (8 of 11) were completely attack-free during the 6-month period while receiving LTP, and no patients required hospitalization. LTP improved patients' scores of the Angioedema Quality-of-Life Questionnaire (P < .001) and reduced activity impairment due to health (P = .008). Patients experienced significant improvement across all dimensions of the Treatment Satisfaction for Medication Questionnaire (54.5%-76.8% [P = .002]), and no adverse events were reported. Conclusion: The patients receiving LTP with garadacimab and lanadelumab experienced a significant reduction in number of HAE attacks and improvement in quality of life, and they were satisfied with treatment.