Investigation of the correlation of C1 esterase inhibitor levels and functions with attack severity and frequency in hereditary angioedema

Introduction:
Hereditary angioedema (HAE) affects 1 in 50,000 individuals and is caused by C1 esterase inhibitor protein (C1INH) deficiency or dysfunction. However, the associations between basal C1INH reserve and function at the time of HAE diagnosis and the frequency of exacerbations remains unclear.

Aim:
In this study, we investigated the associations between C1INH level and function at the time of diagnosis and the number of HAE exacerbations.

Material and methods:
This retrospective single-centre study included 53 patients with HAE, followed-up between January 2018 and December 2023. We reviewed the medical records to obtain the demographic characteristics, C1INH level, and activity at the time of diagnosis, and the number and severity of exacerbations.

Results:
The median age of the patients was 41 (31–50) years, and 33 (62.3%) were females. In total, 33 (62.3%) patients had type I HAE, whereas 20 had type II HAE. There was a significant negative correlation between level of C1INH and the number of angioedema exacerbations in type I HAE patients (r = −0.165, p = 0.002). In type II HAE patients, a significant negative correlation was found between level of C1INH function and the number of exacerbations (r = −0.448, p = 0.038). Moreover, there were negative correlations between age and the number of exacerbations (r = −0.311, p = 0.028).

Conclusions:
The basal C1INH reserve level and function at the time of diagnosis and age at symptom onset were negatively correlated with the number of exacerbations in patients with HAE. These findings suggest that the C1INH reserve level and activity at the time of diagnosis are predictors of the disease course in patients with HAE.