Objective: Hereditary angioedema (HAE) is a rare disease with recurrent angioedema (AE) attacks as a result of accumulation of excess bradykinin in the tissues. Both the level and function of C1 inhibitor protein (C1INH) are within the normal range in HAE with normal C1INH (HAE-nC1INH). This study aimed to evaluate the disease control of HAE-nC1INH patients receiving tranexamic acid (TXA) for long-term prophylaxis (LTP).

Materials and Methods: The study was conducted as a retrospective, single-center pilot cohort survey. A total of six patients with HAE-nC1INH receiving TXA were enrolled. The angioedema control test (AECT) and quality of life (AE-QoL) scale, which are used to evaluate disease control, were administered before and after TXA.

Results: The median age at diagnosis of HAE-nC1INH was 45 (IQR, 28-52) years. The median age at onset of the patients` first AE episodes was 31 (IQR, 18-45) years. The median time to diagnosis was 78 (IQR, 28-240) months. FXII mutation was detected in two cases, and the others were HAE-nC1INH with unknown genetic etiology. All patients were receiving 1000-1500 mg/d TXA for LTP, while two patients had received TXA for acute AE attacks. The median duration of TXA LTP therapy was 48 (IQR, 28-72) months. The median number of annual attacks before and after TXA was 36 and 1, respectively. The median AECT score before TXA was 6 (IQR, 3-6), while the median AECT score after TXA was 13 (IQR,11-15). At least a two-fold improvement in terms of minimal clinically important difference was detected in all four sub-headings (function, fatigue, fear, and nutrition) of the AE-QoL scale.

Conclusion: TXA was highly effective in reducing attack frequency and significantly improving disease control in patients with HAEnC1INH. Moreover, substantial improvements were observed across all AE-QoL domains, indicating a marked positive impact on the patients` quality of life.