Angioedema Without Wheals: Challenges in Laboratorial Diagnosis

Global frequency, diagnosis, and treatment of hereditary angioedema with normal C1 inhibitor

Background

Hereditary angioedema (HAE) is a rare genetic disease, most frequently associated with deficiency or dysfunction in the C1 inhibitor protein. HAE with normal C1 inhibitor (HAE-nC1INH) lacks standardized diagnostic tests, limiting precise prevalence estimates and development of specific treatment guidelines.

Objective

This study sought to describe the global frequency, diagnostic pathway, and current treatment patterns of HAE-nC1INH.

Methods

Board-certified HAE-treating physicians from accredited Angioedema Centers of Reference and Excellence (ACAREs) were invited to complete a 27-item online survey between December 2022 and April 2023.

Results

Thirty physicians from 30 ACAREs across 15 countries reported a mean of 71 (range, 11-148) patients with HAE assessed/treated within the previous 12 months. On average, physicians estimated 24% (range, 2-44%) of patients with HAE were diagnosed with HAE-nC1INH, most of whom were adults (88%). To diagnose HAE-nC1INH, physicians most commonly assessed family history and plasma C4 levels (90% each), and C1 function and quantitative levels (87% each). On-demand and prophylactic treatment patterns varied widely across countries, with an average (range) of 56% (33-100%) of patients receiving on-demand treatment only, and 37% (0-67%) receiving both on-demand and prophylactic treatment. Physicians identified the greatest unmet needs in HAE-nC1INH management as treatment specifically indicated for this patient population and availability of an oral treatment.

Conclusion

HAE-nC1INH may be more prevalent than previously reported. Importantly, our findings revealed varying diagnostic and treatment approaches. Validated, accessible diagnostic biomarkers and clinical outcomes derived from rigorous clinical trials assessing mechanistically based treatments would advance understanding and management of HAE-nC1INH.

Amlodipine-Associated Angioedema: An Integrated Pharmacovigilance Assessment Using Disproportionality and Interaction Analysis and Case Reviews

Background: Amlodipine has recently been incidentally reported with angioedema and is frequently prescribed with renin-angiotensin-aldosterone system inhibitors (RAAS-i) for hypertension management. While RAAS-i drugs are known to cause angioedema, the risk associated with amlodipine alone or in combination with RAAS-i drugs remains unclear. This study aimed to evaluate the association between amlodipine use and angioedema using pharmacovigilance data. Methods: We analyzed adverse event reports from the US FDA Adverse Event Reporting System using both frequentist and Bayesian approaches. Drug-drug interactions were assessed using multiplicative models. Additionally, we conducted a systematic review of published case reports of amlodipine-associated angioedema. Results: Among 29,661,136 reports, 2076 cases of angioedema were identified (1067 with amlodipine alone, 1009 with amlodipine-RAAS-i combinations). Significant safety signals were detected for amlodipine alone and in combination with aliskiren, specific ACE inhibitors (quinapril, benazepril, trandolapril, fosinopril, perindopril), and certain ARBs (candesartan, losartan). No significant interactions were observed between amlodipine and RAAS-i drugs except for the amlodipine-trandolapril combination. A review of published cases demonstrated definite causality in two cases and possible association in others, with most patients presenting with oropharyngeal/facial edema and achieving complete recovery following drug discontinuation and standard therapy. Conclusions: Our findings suggest a potentially increased risk of angioedema with amlodipine, both as monotherapy and in specific RAAS-i combinations. While these results should not discourage appropriate clinical use, they emphasize the importance of monitoring for angioedema, particularly during therapy initiation. The findings from this study need to be validated in prospective studies for further elucidation of the underlying mechanisms.

Validating and utilizing dried blood spots for family screening: Screening Programme Providing Outreach for Testing Hereditary Angioedema (SPPOT-HAE)

Background

Hereditary angioedema (HAE) is a rare genetic disorder with potentially life-threatening consequences, traditionally diagnosed by conventional laboratory methods that can be resource intensive and inconvenient. Incorporating dried blood spot (DBS) tests may be a promising alternative for diagnosing HAE and family screening.

Objective

This study aimed to validate DBS with conventional laboratory assays among confirmed C1 esterase inhibitor (C1-INH) HAE patients and assess the utility of DBS in a Screening Programme Providing Outreach for Testing Hereditary Angioedema (SPPOT-HAE).

Methods

In part 1, 16 Chinese C1-INH-HAE patients from 7 families participated in the validation of DBS for detecting C4, C1-INH, and functional C1-INH (fC1-INH). The results were compared with conventional laboratory assays. In part 2, DBS was utilized in family screening for HAE in a large Chinese family with relatives previously refusing testing.

Results

The study found strong correlation between conventional assays and DBS in measuring C4 (r = 0.870, P < .0001), C1-INH (r = 0.978, P < .0001), and fC1-INH (r = 0.756, P < .0001). There were no false-negative results from the DBS for C4, C1-INH or fC1-INH. SPPOT-HAE successfully recruited 9 additional relatives for family screening, of whom 22% were confirmed to have HAE. The use of DBS in an outreach program overcame barriers of prior family screening initiatives.

Conclusion

This is the first study to validate measurement of fC1-INH using DBS in C1-INH-HAE with conventional assays. An outreach program using DBS is a promising strategy overcoming previous barriers of family screening. Further large-scale, multicenter studies are required to establish the role of DBS, compare cost-effectiveness with prior strategies, and maximize diagnosis in resource-constrained countries.

A clinical evaluation of patients with known mutations (plasminogen and factor XII) with a focus on prophylactic treatment

BACKGROUND

Hereditary angioedema with normal C1-inhibitor (HAE-nC1-INH) is a rare genetic disease. The symptoms can resemble other forms of hereditary angioedema (HAE), but the specific laboratory values are inconspicuous. The knowledge about treatment strategies in HAE-nC1-INH remains insufficient; most of the drugs are only licensed and approved for other types of HAE.

METHODS

An analysis of all patients with HAE-nC1-INH was carried out in a certified angioedema treatment center in southern Germany. Only patients with a confirmed HAE-nC1-INH mutation were included. The impact of disease was monitored with validated questionnaires.

RESULTS

Eighteen patients were included: two families with a factor XII mutation and seven families with a plasminogen mutation. All individuals received icatibant for on-demand therapy-efficient treatment response was reported. Three patients were severely affected, and prophylaxis was initiated with lanadelumab. According to the questionnaires, the clinical course and symptoms improved significantly under this prophylactic regime.

CONCLUSION

This is one of the first descriptions of the clinical outcomes as a response to prophylactic treatment with lanadelumab in HAE-nC1-INH patients with a known mutation. The therapeutic management of HAE-1 and HAE-2 should also be the basis of HAE-nC1-INH, including prophylaxis.

Assessment of clinical phenotypic characteristics of patients with angioedema without wheals in a turkish population

Background: Angioedema (AE) is defined as localized, self-limited swelling of subcutaneous tissues and mucosa. Objective: The aim of this study was to compare the phenotypic characteristics of patients with AE without wheals. Methods: This prospective study included adult patients with recurrent AE without wheals. Demographic and laboratory data of the patients were recorded in the patient file when they presented to the outpatient clinic between August 2018 and August 2020. The patients were contacted by phone to evaluate whether their AE had gone into remission between October 2023 and January 2024. The phenotypic characteristics of AE subtypes were compared. Results: The study included a total of 143 patients. The average age, age of onset of AE, rates of diabetes mellitus, hypertension and coronary artery disease were higher in the patients with angiotensin-converting enzyme inhibitor (ACEI) use related acquired AE (AAE) (AAE-ACEI). The rates of allergic rhinitis, drug allergy, atopy, and aeroallergen sensitivity, and the median total immunoglobulin E level were higher in patients with idiopathic histaminergic AAE (AAE-IH). The rate of face and/or perioral AE attacks was higher in the patients with AAE-ACEI, AAE-IH, and idiopathic non-histaminergic AAE. The rate of AE attacks in limbs, abdominal, genital and other parts of the body was higher in patients with hereditary AE (HAE). The baseline AE activity score was lower in the patients with AAE-IH and higher in the patients with HAE. In long-term follow-up, the remission rate of AE attacks was significant higher in patients with AAE-ACEI and AAE-IH. Conclusion: The phenotypic characteristic features of Turkish patients with AE without wheals may vary, depending on the underlying AE pathogenesis. C1 inhibitor level and function, complement C4 and C1q, and genetic tests contributed to the diagnosis; other laboratory tests did not contribute to the diagnosis.

Exploring disease-specific metabolite signatures in hereditary angioedema patients

Introduction

Hereditary angioedema (HAE) is a rare, life-threatening autosomal dominant genetic disorder caused by a deficient and/or dysfunctional C1 esterase inhibitor (C1-INH) (type 1 and type 2) leading to recurrent episodes of edema. This study aims to explore HAE patients' metabolomic profiles and identify novel potential diagnostic biomarkers for HAE. The study also examined distinguishing HAE from idiopathic angioedema (AE).

Methods

Blood plasma samples from 10 HAE (types 1/2) patients, 15 patients with idiopathic AE, and 20 healthy controls were collected in Latvia and analyzed using LC-MS based targeted metabolomics workflow. T-test and fold change calculation were used to identify metabolites with significant differences between diseases and control groups. ROC analysis was performed to evaluate metabolite based classification model.

Results

A total of 33 metabolites were detected and quantified. The results showed that isovalerylcarnitine, cystine, and hydroxyproline were the most significantly altered metabolites between the disease and control groups. Aspartic acid was identified as a significant metabolite that could differentiate between HAE and idiopathic AE. The mathematical combination of metabolites (hydroxyproline * cystine)/(creatinine * isovalerylcarnitine) was identified as the diagnosis signature for HAE. Furthermore, glycine/asparagine ratio could differentiate between HAE and idiopathic AE.

Conclusion

Our study identified isovalerylcarnitine, cystine, and hydroxyproline as potential biomarkers for HAE diagnosis. Identifying new biomarkers may offer enhanced prospects for accurate, timely, and economical diagnosis of HAE, as well as tailored treatment selection for optimal patient care.

Hong Kong-Macau Severe Hives and Angioedema Referral Pathway

Background

Urticaria (defined as the presence of hives, angioedema, or both) can be caused by a variety of etiologies ranging from more common conditions such as chronic spontaneous urticaria (CSU) to rarer conditions such as hereditary angioedema (HAE). Specialist referral may be necessary in cases of severe urticaria or HAE, but access to specialist services remains limited in certain regions, such as the Greater Bay Area (GBA) of China. To address this, the Hong Kong-Macau Severe Hives and Angioedema Referral Pathway (SHARP) was initiated by the Hong Kong Institute of Allergy and Macau Society of Dermatology to promote multidisciplinary collaboration and regional exchange of expertise in the diagnosis and management of severe urticaria.

Methods

A nominated task force of dermatologists and immunologists who manage patients with severe urticaria formulated the consensus statements (CS) using the Delphi method. The consensus was defined a priori as an agreement of ≥80%.

Results

A total of 24 CS were formulated, including four statements on classifications and definitions, seven statements on diagnosis, and 13 statements on management and referral. The definitions for acute/chronic urticaria and severe CSU were stated. Unnecessary investigations and inappropriate medications were discouraged. The characteristics and recommended approach to suspected bradykinergic angioedema were specified. Stepwise treatment options using second-generation antihistamines, omalizumab, or cyclosporin for patients with CSU were addressed, and the importance of access to HAE-specific medications was emphasized. Furthermore, an integrated referral pathway for patients with severe hives and angioedema was constructed.

Conclusion

The SHARP provides guidance for the management and specialist referral of patients with severe hives and angioedema in Hong Kong and Macau.

Epidemiology, Management, and Treatment Access of Hereditary Angioedema in the Asia Pacific Region: Outcomes From an International Survey

BACKGROUND

Hereditary angioedema (HAE) is a rare genetic disease with significant morbidity and mortality for which early diagnosis and effective therapy are critical. Many Asia Pacific (AP) countries still lack access to diagnostic tests and evidence-based therapies. Epidemiologic data from the AP is needed to formulate regional guidelines to improve standards of care for HAE.

OBJECTIVE

To investigate the estimated minimal prevalence, needs, and potential interventions for the diagnosis and management of HAE in the AP.

METHODS

A structured questionnaire was distributed to representative experts from member societies of the Asia Pacific Association of Allergy, Asthma and Clinical Immunology. Patient profiles and the presence of diagnostic facilities or tests, regional and national HAE guidelines, and patient support groups were reported and compared.

RESULTS

Completed questionnaires were received from 14 representatives of 12 member countries and territories, representing 46% of the world population. Overall minimal prevalence of HAE in the AP region was 0.02/100,000 population, with significant heterogeneity across different centers. Only one-half and one-third had registered on-demand and prophylactic medications, respectively. Few had patient support groups (58%) or regional guidelines (33%), and their existence was associated with the availability of HAE-specific medications. Availability of C1-inhibitor level testing was associated with a lower age at HAE diagnosis (P = .017).

CONCLUSIONS

Hereditary angioedema in the AP differs from that in Western countries. Hereditary angioedema-specific medications were registered in only a minority of countries and territories, but those with patient support groups or regional guidelines were more likely to have better access. Asia Pacific-specific consensus and guidelines are lacking and urgently needed.

A Case of Refractory Angioedema

Angioedema is an acute disorder that affects mucous membranes and the deepest layers of the skin along with underlying tissue, marked by rapid swelling, large welts, and pain. There are 3 major subtypes of angioedema: mast-cell mediated, bradykinin-mediated, and multifactorial or unclear mechanism subtype. The most common subtype of bradykinin-mediated angioedema is ACE-inhibitor induced, which disproportionately affects African-Americans. It is most often self-limiting and usually responds to the withdrawal of the offending agent. The prolonged duration of angioedema is uncommon in the absence of a persistent stimulus, though it is more likely when there is an abnormality of the metabolic pathways, such as in hereditary angioedema or other gene polymorphisms affecting the complement system. We present a case of severe angioedema that persisted for over a month and required a tracheostomy to manage the airway.