Acquired C1 inhibitor deficiency angioedema (AAE-C1INH) patients define meaningful changes for new PRO measures
Background
Angioedema due to acquired C1 inhibitor deficiency (AAE-C1INH) is a rare, severe condition characterized by unpredictable, painful swelling attacks. Unlike hereditary angioedema (HAE), which shares a bradykinin-mediated pathology, AAE-C1INH lacks approved treatments and validated patient-reported outcome (PRO) measures. This gap hinders clinical trial design and effective patient management, as objective measures often fail to capture the full burden of this debilitating disease. Developing a robust conceptual model and adapting existing PRO tools are critical steps towards improving diagnosis, treatment evaluation, and overall patient quality of life for those affected by this challenging condition.
Study Design
This cross-sectional, qualitative study conducted semi-structured interviews with 8 adults living with AAE-C1INH. Participants described disease manifestations and daily life impacts through open-ended questions. Cognitive interviews then assessed their perceptions of clarity, comprehension, and clinically meaningful levels of change for adapted PRO measures, including the Patient Global Impression of Change (PGI-C), Patient Global Impression of Severity (PGI-S), Patient Global Assessment of Status (PGA-S), and Patient Global Assessment of Change (PGA-C). This approach aimed to ensure the PRO tools accurately reflect patient experience.
Results
Participants frequently reported traumatic medical emergencies, diagnostic delays, and consultations with numerous healthcare providers, underscoring the complexity of AAE-C1INH management. Significant daily life impact was common, affecting social and family interactions and treatment adherence in n=7 participants. The most frequently reported attack areas included the abdomen (n=7), face (n=6), and foot/hand (n=5 each). > All 8/8 participants correctly interpreted the PGI-C scale to assess symptoms at a given time post-treatment versus at the time of treatment for a theoretical attack. Regarding meaningful change, 4 of 8 participants considered "a little better" as significant if achieved ≥2 hours post-treatment, while 6 of 6 participants considered "better" as meaningful if achieved ≥4 hours. Most participants also found the PGI-S and PGA measures easy to interpret and highly relevant to their specific symptoms, indicating their potential utility in future clinical assessments.
Key Findings
- AAE-C1INH causes traumatic medical emergencies and significant daily life impact for 7 of 8 patients.
- Abdomen (n=7), face (n=6), and foot/hand (n=5 each) were most common attack sites.
- All 8/8 participants correctly interpreted
PGI-Cfor post-treatment symptom assessment. - "A little better" on
PGI-Cwas meaningful at ≥2 hours post-treatment for 4 of 8 participants. - "Better" on
PGI-Cwas meaningful at ≥4 hours post-treatment for 6 of 6 participants.
Why It Matters
This study provides crucial patient-centric insights into the profound impact of AAE-C1INH on daily life, moving beyond purely clinical metrics. Validating patient-reported outcome measures is a critical step towards developing effective treatments and improving clinical trial design for AAE-C1INH. By establishing what constitutes a "meaningful change" from the patient's perspective, future clinical trials can set more relevant primary endpoints, ensuring that new therapies genuinely improve quality of life. This qualitative work directly informs the clinical outcome assessment strategy for the first phase 3 clinical trial exclusively in AAE-C1INH, accelerating the path to an approved treatment and a more patient-focused standard of care.
acquired angioedema
c1-inhibitor deficiency
angioedema
patient-reported outcomes
qualitative study
rare disease