OUTCOMES OF PATIENTS WITH HEREDITARY ANGIOEDEMA WITH NORMAL C1-INHIBITOR FUNCTION AND ANGIOEDEMA OF UNKNOWN ETIOLOGY

Introduction

Clinical outcomes of patients with hereditary angioedema with normal C1-inhibitor function (HAE nC1-INH) and angioedema of unknown etiology (AE-UNK) in Canada are poorly understood.

Methods

Real-world data on patient characteristics, treatments and outcomes were extracted from electronic heath records of patients with HAE nC1-INH and AE-UNK from Canadian HAE-treating specialist practices.

Results

Of 37 patients with HAE nC1-INH and 23 with AE-UNK, median (range) age at symptom onset was 21.5 (5.0–57.0) and 23.0 years (10.0–54.0), and time to diagnosis from symptom onset was 7.0 (0.0–43.0) and 2.0 years (-10.0–50.0), respectively. Attack characteristics differed between HAE nC1-INH vs. AE-UNK: 65% vs. 26% (p=0.007) reported stress; and 35% vs. 9% (p=0.031) reported estrogen therapy as the predominant attack trigger. Fewer AE-UNK vs. HAE nC1-INH had GI sites affected by attacks (before treatment: p=0.015, after initiation: p=0.032). Pre-diagnosis, most patients received antihistamines. Post-diagnosis, 73% and 74% of HAE nC1-INH and AE-UNK patients received long-term prophylaxis (LTP) (most common were subcutaneous pdC1-INH and tranexamic acid), and 22% and 13% were receiving >1 LTP concurrently. Three-months post-treatment, attack duration and frequency significantly decreased for HAE nC1-INH from 1.00 day (range: 0.00–7.00) to 0.29 (range: 0.02–4.00; p=0.001) and 10.50 attacks (range: 0.00–90.00) to 6.00 (range: 0.00–60.00; p=0.004).

Conclusions

This study demonstrates differing clinical trajectories between HAE nC1-INH and AE-UNK, including attack characteristics, diagnostic delays, and treatment responses. Despite treatment response, many patients still experienced attacks. Unmet need exists for tailored guidelines, therapies, and understanding of pathophysiological differences.