Hong Kong demonstrates effectiveness of Cascade Family screening for Hereditary Angioedema

Published: August 11, 2022

Hereditary angioedema (HAE) is a rare genetic condition characterized by unpredictable and swellings affecting the hands, feet and throat –that can be potentially fatal. Although known to be inherited in an autosomal dominant manner, the diagnosis of HAE is often delayed or even missed - even within families with known HAE patients. HAE is also frequently under-diagnosed in many Asian countries and was virtually unheard of in Hong Kong prior to initiation of formal family screening programs. Furthermore, recommendations on family screening in HAE remain variable, mostly based on expert opinion without a strong evidence base. Studies evaluating the implementation, outcomes and efficacy of family screening for HAE are also lacking.

Wong et al. published a study on a novel HAE screening program that evaluated the efficacy and impact of cascade family screening (CFS). The authors screened for all at-risk relatives of HAE patients in Hong Kong and assessed clinical, psychological and HAE-related outcomes. Patients screened with HAE were provided counselling, medications and a comprehensive management plan shortly after diagnosis. Longitudinal outcomes were analyzed, and results were recently published in The Journal of Allergy and Clinical Immunology: In Practice.

Of 179 relatives, 53% were contactable, of which 68 (67%) agreed to screening. Almost half of those screened (46%) were newly diagnosed. Surprisingly, half (52%) were symptomatic. Symptomatic relatives were followed up for one year. Compared with the year prior to screening, a higher proportion had not experienced symptoms, and an overall reduction in hospital admissions and length of stay was observed. Patients experienced less anxiety and improved angioedema quality of life scores as a result of CFS. CFS did not worsen depression scores. Overall, CFS saved at least HK $1,200 (US $153) in HAE-related costs per patient per year.

This study indicates a key role in HAE family screening for all at-risk relatives, regardless of symptomatology or degrees of relationship. CFS led to a substantial increase in Hong Kong’s reported prevalence of HAE (from 1:640,000 to 1:166,000) in the span of just five years. The authors conclude that CFS is an effective approach, improving clinical and psychological outcomes, and reducing disease-related costs. Replication in other cohorts and international collaborations would be of great interest.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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