Angioedema Related to Angiotensin-Converting Enzyme Inhibitors: Attack Severity, Treatment, and Hospital Admission in a Prospective Multicenter Study

Angiotensin-Converting Enzyme Inhibitor-Induced Angioedema

Angioedema is a well-recognized and potentially lethal complication of angiotensin-converting enzyme inhibitor (ACEi) therapy. In ACEi-induced angioedema, bradykinin accumulates due to a decrease in its metabolism by ACE, the enzyme that is primarily responsible for this function. The action of bradykinin at bradykinin type 2 receptors leads to increased vascular permeability and the accumulation of fluid in the subcutaneous and submucosal space. Patients with ACEi-induced angioedema are at risk for airway compromise because of the tendency for the face, lips, tongue, and airway structures to be affected. The emergency physician should focus on airway evaluation and management when treating patients with ACEi-induced angioedema.

Over diagnosis of bradykinin angioedema in patients treated with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers

Background

Bradykinin angioedemas are a potentially serious side effect of angiotensin-converting enzyme inhibitors (ACEI) and more controversially of angiotensin II receptor blockers (ARB). Their challenging diagnosis is based on the absence of any recurrence after more than 6 months of drug discontinuation; otherwise mast-cell driven angioedemas as a differential diagnosis must be considered.

Objective

The aim of this study was to determine the prevalence of recurrent angioedema in patients referred for ACEI/ARB-induced bradykinin angioedema, after more than 6 months of drug discontinuation.

Methods

We included ACEI/ARB-treated patients referred for angioedema(s) without hives and unresponsive to antihistamines, after they discontinued ACEI/ARB for at least 6 months. Any C1-inhibitor deficiency was excluded. The primary endpoint was the prevalence of patients with recurrent angioedema after more than 6 months of drug discontinuation and/or developing hives during follow-up. The secondary endpoint was the identification of epidemiological factors associated with any final diagnosis.

Results

Thirty-eight of 93 patients (41%) with a suspicion of ACEI/ARB-induced bradykinin angioedema still had recurrent angioedema (n = 27) or developed hives (n = 2) or both (n = 9) after 6 months of drug discontinuation. Good response to icatibant and facial but not oral localization were predictive for the final diagnosis of ACEI/ARB-induced bradykinin angioedema and mast-cell driven angioedema, respectively.

Conclusion

In patients referred for acquired angioedema without wheals occurring during ACEI/ARB therapy, 59% finally had a diagnosis of ACEI/ARB-induced bradykinin angioedema whereas 41% were rather diagnosed with mast-cell driven angioedema. The overdiagnosis of ACEI/ARB-induced bradykinin angioedema may deteriorate the management of severe cardiovascular conditions.

Profile of serious angioedema requiring an urgent advice from a national reference call center

Angioedema (AE) is a reason for emergency care when it is severe. Care is difficult when the diagnostic is not known before the attack: mast cell (MC) or bradykinin (BK) mediated. One is very common but often benign, the other rare but potentially fatal. The French national reference center of angioedema (CREAK) provides emergency physicians with a hotline and a guideline to help them manage their patients. This study aimed to describe the clinical features of AE episodes prompting a call on the CREAK hotline and classify patients depending on the suspected cause of the AE. This is a retrospective study between March and August 2019. Each physician calling on the CREAK hotline was asked to fill a clinical description form for the AE emergency. Known patients of CREAK was excluded. Eighty four patients were included. Forty one (48.8%) in the angiotensin converting enzyme inhibitors induced acquired angioedema (ACEi-AAE), 39 (46.4%) in the mast cell induced angioedema, and 4 (4.8%) in the Bradykinin mediated angioedema. The mast cell induced angioedema patients have more history of hives (29.3%) than ACEi-AAE (2.4%, P = .0004). ACEi-AAE mainly affected the tongue (58.5% vs 25.6%, P = .003) and larynx (29.3% vs 13%, P = .001). In 65.5% of cases, the etiological diagnosis was not mentioned by the appellant, but made by the hotline. In 31% of cases, the hotline suggested the administration of a specific treatment not previously provided by the caller. All the doctors who called the hotline appreciate this tele-expertise especially in case of ACEi-AAE presumptions. In addition to providing rapid AE expertise, this service also allows to educate physicians in the management of AE irrespective of its origin.

Bradykinin-induced angioedema in the emergency department

Background

Acute airway angioedema commonly occurs through two distinct mechanisms: histamine- and bradykinin-dependent. Although they respond to distinct treatments, these two potentially life-threatening states present similarly. Poor recognition of the bradykinin-dependent pathway leads to treatment errors in the emergency department (ED), despite the availability of multiple pharmacologic options for hereditary angioedema (HAE) and other forms of bradykinin-induced angioedema. Here, we consider the pathophysiology and clinical features of bradykinin-induced angioedema, and we present a systematic literature review exploring the effectiveness of the available therapies for managing such cases.

Methods

PubMed searches using ‘emergency’, ‘bradykinin’ and various therapeutic product names identified studies reporting the efficacy of treatments for bradykinin-induced angioedema in the ED setting. In all, 22 studies met prespecified criteria and are analysed here.

Findings

Whereas histamine-induced angioedema has a faster onset and often presents with urticaria, bradykinin-induced angioedema is slower in onset, with greater incidence of abdominal symptoms. Acute airway angioedema in the ED should initially be treated with anaphylactic protocols, focusing on airway management and treatment with epinephrine, antihistamine and systemic steroids. Bradykinin-induced angioedema should be considered if this standard treatment is not effective, despite proper dosing and regard of beta-adrenergic blockade. Therapeutics currently approved for HAE appear as promising options for this and other forms of bradykinin-induced angioedema encountered in the ED.

Conclusion

Diagnostic algorithms of bradykinin-induced angioedema should be followed in the ED, with early use of approved therapies to improve patient outcomes.

Initial characteristics and follow-up of patients with a diagnosis of angiotensin-converting enzyme inhibitor induced angioedema

Background: A differential diagnosis between angiotensin-converting enzyme inhibitor (ACEi) angioedema (AE) and histaminergic AE (hAE) might be challenging. Follow-up data may help discriminate these conditions but are scarcely reported. Objective: To report on the follow-up of patients with suspected ACEi-AE and to describe the baseline characteristics of AE attacks in patients with a diagnosis of ACEi-AE after follow-up. Methods: Sixty-four patients with suspected ACEi-AE (i.e., with exposure to ACEi before the first attack, no urticaria associated, and normal C1-inhibitor levels) and at least one follow-up visit were included. Data were retrospectively collected at baseline and during the follow-up. Results: After the follow-up, the diagnosis of ACEi-AE was probable in only 30 patients. The remaining patients were reclassified as having probable hAE (21 patients) or undetermined-mechanism AE (13 patients). Patients with ACEi-AE were mostly men (61%), with a median age of 64 years (interquartile range [IQR] ±17 years), with a highly variable delay from ACEi introduction (median: 23 months; interquartile range: 103 months). Attacks preferentially involved lips (50%), tongue (47%), and throat (30%). Interestingly, patients with probable ACEi-AE after a follow-up also frequently presented with a history of allergy and atopic conditions (20%), attacks with preferential evening onset (25%), and spontaneous resolution in < 24 hours (26%), which are usually considered as suggestive of hAE. ACEi-AE attacks responded to icatibant in 79% of the patients. Conclusion: Patients with probable ACEi-AE were mostly men with facial involvement. A third of the patients with an initial suspected diagnosis of ACEi-AE had a final diagnosis of probable hAE. Although a follow-up of all patients should be a standard of care, it is critical to the correct diagnosis in the case of suspected bradykinin-associated AE, which may actually be due to histamine.

Angiotensin-Converting Enzyme Inhibitor-Induced Angioedema

Angioedema is a well-recognized and potentially lethal complication of angiotensin-converting enzyme inhibitor (ACEi) therapy. In ACEi-induced angioedema, bradykinin accumulates due to a decrease in its metabolism by ACE, the enzyme that is primarily responsible for this function. The action of bradykinin at bradykinin type 2 receptors leads to increased vascular permeability and the accumulation of fluid in the subcutaneous and submucosal space. Patients with ACEi-induced angioedema are at risk for airway compromise because of the tendency for the face, lips, tongue, and airway structures to be affected. The emergency physician should focus on airway evaluation and management when treating patients with ACEi-induced angioedema.

Real-world off-label use of icatibant for acute management of non-hereditary angioedema

We retrospectively examined the indications and efficacy of off-label use of the bradykinin B2 receptor antagonist icatibant. The clinical heterogeneity, variability of response to icatibant and lack of efficacy of adrenaline described in this audit highlights both the need for biomarkers that can rapidly distinguish between histaminergic and non-histaminergic angioedema, and for guidelines to improve the utility of icatibant in the non-hereditary angioedema setting.

Clinical Practice Statement: What is the Emergency Department Management of Patients with Angioedema Secondary to an ACE-Inhibitor?

BACKGROUND

Angioedema is a complication that has been reported in up to 1.0% of individuals taking angiotensin-converting enzyme inhibitors (ACE-Is). Importantly, the onset of angioedema can occur anywhere from hours to several years after initiation of therapy with ACE-Is. Although most cases of ACE-I-induced angioedema (ACE-I-AE) are self-limiting, a major clinical concern is development of airway compromise, which can potentially require emergent airway management. The underlying pathophysiology of ACE-I-AE is incompletely understood, but is considered to be due in large part to excess bradykinin. Numerous medications have been proposed for the treatment of ACE-I-AE. This article is an update to the 2011 Clinical Practice Committee (CPC) statement from the American Academy of Emergency Medicine.

METHODS

A literature search in PubMed was performed with search terms angioedema and ACE inhibitors from August 1, 2012 to May 13, 2019. Following CPC guidelines, articles written in English were identified and then underwent a structured review for evaluation.

RESULTS

The search parameters resulted in 323 articles. The abstracts of these articles were assessed independently by the reviewers, who determined there were 63 articles that were specific to ACE-I-AE, of which 46 were deemed appropriate for grading in the final focused review.

CONCLUSIONS

The primary focus for the treatment of ACE-I-AE is airway management. In the absence of high-quality evidence, no specific medication therapy is recommended for its treatment. If, however, the treating physician feels the patient's presentation is more typical of an acute allergic reaction or anaphylaxis, it may be appropriate to treat for those conditions. Any patient with suspected ACE-I-AE should immediately discontinue that medication.

The Influence of ACE Inhibition on C1-Inhibitor: A Biomarker for ACE Inhibitor-Induced Angioedema?

Aims

Angioedema is a rare side effect of angiotensin-converting enzyme (ACE) inhibitors. It remains unclear why it is only induced in a few patients taking ACE inhibitors, often after a long period of uneventful treatment. The aim of this study was to analyze the influence of ACE inhibitor treatment on C1-inhibitor (C1-INH) levels.

Methods

Captopril (5 mg/25 mg) was added to blood samples of 5 healthy subjects. C1-INH levels were measured before and after incubation for 180 min. The second section of the study was done with 17 patients who received therapy with an ACE inhibitor for the first time. C1-INH levels were measured before ACE inhibitor treatment, 24 h after first drug administration, and 4 weeks later.

Results

After incubation of blood samples with 5 mg captopril, there was no detectable change in C1-INH levels. After incubation with 25 mg, C1-INH activity was decreased by an average of 29% and the C1-INH concentration was decreased by an average of 0.06 g/L. In the second study section, inconsistent effects on C1-INH levels were detected. In the majority of patients, 24 h after the first ACE inhibitor administration C1-INH activity was tending to be increased.

Conclusions

A dose-dependent effect on C1-INH levels in captopril-incubated blood samples of healthy test persons was shown. In patients with new ACE inhibitor treatment, heterogeneous reactions of C1-INH values were detected. Larger studies are needed over a longer period of time to find correlations between the effect of ACE inhibitor therapy on C1-INH levels and the clinical course/development of side effects.

ACE inhibitor-mediated angioedema

Angioedema (AE) occurring during ACE inhibitor therapy (ACEi-AE) is a rare complication involving between 0.1 and 0.7% of treated patients. AE can also complicate other therapeutic regimens that block the renin-angiotensin aldosterone system. Other drugs, such as immune suppressors, some type of antidiabetics or calcium antagonists, can increase the likelihood of ACEi-AE when associated to ACEi. There is a clear ethnic predisposition, since African-Americans or Hispanics show a higher prevalence of this condition compared to Caucasians. At least in African-Americans the genetic predisposition accounts for a general higher prevalence of AE, independently from the cause. People that experience ACEi-AE may have some recurrence when they are switched to an angiotensin-receptor blocker (ARB); however, epidemiological studies on large cohorts have shown that angiotensin receptor blockers (ARB) do not increase the likelihood of AE compared to other antihypertensives. Clinical manifestations consist of edema of face, lips, tongue, uvula and upper airways, requiring intubation or tracheotomy in severe cases. Attacks last for 48-72 h and require hospital admission in most cases. Intestinal involvement with sub-occlusive symptoms has also been reported. The pathogenesis of ACEi-AE depends mainly on a reduced catabolism and accumulation of bradykinin, which is normally metabolized by ACE. Genetic studies have shown that some single nucleotide polymorphisms at genes encoding relevant molecules for bradykinin metabolism and action may be involved in ACEi-AE, giving a basis for the ethnic predisposition. Treatment of ACEi-AE is still a matter of debate. Corticosteroids and antihistamines do not show efficacy. Some therapeutic attempts have shown some efficacy for fresh frozen plasma or C1 inhibitor concentrate infusion. Interventional studies with the specific bradykinin receptor antagonist icatibant have shown conflicting results; there might be a different ethnic predisposition to icatibant efficacy which has been proven in caucasian but not in black patients.

Significant predictive factors of the severity and outcomes of the first attack of acute angioedema in children

Background

The initial episode of angioedema in children can be potential life-threatening due to the lack of prompt identification and treatment. We aimed to analyze the factors predicting the severity and outcomes of the first attack of acute angioedema in children.

Methods

This was a retrospective study with 406 children (< 18 years) who presented in the emergency department (ED) with an initial episode of acute angioedema and who had subsequent follow-up visits in the out-patient department from January 2008 to December 2014. The severity of the acute angioedema was categorized as severe (requiring hospital admission), moderate (requiring a stay in the short-term pediatric observation unit [POU]), or mild (discharged directly from the ED). The associations among the disease severity, patient demographics and clinical presentation were analyzed.

Result

In total, 109 (26.8%) children had severe angioedema, and the majority of those children were male (65.1%). Most of the children were of preschool age (56.4%), and only 6.4% were adolescents. The co-occurrence of pyrexia or urticaria, etiologies of the angioedema related to medications or infections, the presence of respiratory symptoms, and a history of allergies (asthma, allergic rhinitis) were predictors of severe angioedema (all p < 0.05). Finally, the duration of angioedema was significantly shorter in children who had received short-term POU treatment (2.1 ± 1.1 days) than in those who discharged from ED directly (2.3 ± 1.4 days) and admitted to the hospital (3.5 ± 2.0 days) (p < 0.001).

Conclusion

The co-occurrence of pyrexia or urticaria, etiologies related to medications or infections, the presence of respiratory symptoms, and a history of allergies were predictors of severe angioedema. More importantly, short-term POU observation and prompt treatment might be benefit for patients who did not require hospital admission.

Angiotensin II receptor blockers are safe in patients with prior angioedema related to angiotensin-converting enzyme inhibitors - a nationwide registry-based cohort study

BACKGROUND

It has long been suggested that angiotensin-converting enzyme inhibitors (ACEi) and angiotensin II receptor blockers (AT2s) have some degree of 'cross-reactivity' in causing angioedema. Therefore, caution has been advised when switching patients with ACEi-related angioedema to an AT2.

OBJECTIVES

To clarify whether AT2s can be used safely in patients with a history of angioedema during ACEi treatment and to estimate the incidence rate of angioedema in patients subsequently treated with other antihypertensive drugs (beta-adrenergic blockers, calcium channel blockers, thiazides and analogues) or no antihypertensives.

METHODS

This is a nationwide retrospective registry-based cohort study of the Danish population during the period 1994 to 2016, and it uses Danish health registries. Propensity score adjusted and conventional proportional hazards regression models have been employed.

RESULTS

A total of 1 106 024 ACEi users were identified. In total, 5 507 (0.5%) of these patients had experienced angioedema during ACEi treatment and were included in the study. The highest risk of angioedema recurrence was associated with continued ACEi use at an adjusted hazard ratio of 1.45 (95% CI, 1.19 to 1.78). An inverse association was found between AT2s and angioedema (adjusted hazard ratio, 0.39; 95% CI, 0.30 to 0.51) compared with other antihypertensives (adjusted hazard ratios, 0.77 to 0.97).

CONCLUSIONS

Compared with other antihypertensive drugs, AT2s do not increase the incidence of angioedema in patients with previous ACEi-related angioedema.

A rare presentation of angioedema with isolated retropharyngeal and supraglottic involvement

Angiotensin converting-enzyme (ACE) inhibitors are commonly prescribed drugs with multiple indications including congestive heart failure, hypertension, and diabetic nephropathy. ACE inhibitor induced angioedema is commonly seen across emergency departments and clinics, with transient swelling of lips, tongue, and other facial structures being the common presentation. Isolated airway obstruction as a result of pharyngeal and laryngeal swelling without facial swelling is a rare presentation. We present a case of a patient on lisinopril therapy for one year who experienced severe airway compromise without the classic symptoms of ACE inhibitor induced angioedema. He required emergent cricothyroidotomy to secure his airway, as fiberoptic laryngoscopy showed 90% obstruction and inability to visualize true vocal cords. His ACE inhibitor therapy was discontinued, and he was discharged home within a few days with no residual symptoms.

Perindopril-induced angioedema of the lips and tongue: a case report

Background

Ace inhibitor-induced angioedema, characterized by sudden-onset swelling of the mucous membrane, skin, or both, is a rare occurrence in the Kingdom of Saudi Arabia. Because of its safety and efficacy, perindopril is a commonly prescribed angiotensin-converting enzyme inhibitor. Here we describe the clinical manifestations, management, and outcome of perindopril-induced angioedema of the lips and tongue in a 65-year-old Saudi man.

Case presentation

A 65-year-old Saudi Arab man presented to an emergency department with lip and tongue swelling and dysphagia. There were no systemic symptoms and no past history of a similar event. He had been consuming perindopril 5 mg and amlodipine 5 mg for the last 3 weeks: brand name, Coveram, from the company Servier (Ireland) Industries Ltd.; one tablet of Coveram contains 3.395 mg perindopril corresponding to 5 mg perindopril arginine and 6.935 mg amlodipine besilate corresponding to 5 mg amlodipine. A physical examination revealed considerable swelling of his lips and tongue.

Examinations of other systems, including his cardiovascular and respiratory systems, revealed unremarkable findings. All laboratory parameters were also normal. Electrocardiography demonstrated sinus rhythm, a normal P axis, and V-rate of 50–99.

A clinical diagnosis of perindopril-induced angioedema was made, and perindopril was discontinued. The angioedema resolved completely after the administration of antihistamines and corticosteroids.

Conclusions

Angioedema caused by angiotensin-converting enzyme inhibitors is an uncommon occurrence in Saudi Arabia. The findings from this case are expected to raise awareness about this condition among clinicians in this country.

[Acquired C1 esterase inhibitor deficiency via bradykinin-mediated angioedema: Four cases]

BACKGROUND

Acquired C1-esterase inhibitor (C1-INH) deficiency angioedema (C1-INH-AAE) is a form of bradykinin-mediated angioedema. This rare disorder is due to acquired consumption of C1-INH, hyperactivation of the classic pathway of human complement, and potentially fatal recurrent angioedema symptoms. Clinical symptoms of C1-INH-AAE are very similar to those of hereditary angioedema (HAE) but usually appear after the fourth decade of life and induce abdominal pain less frequently. Laboratory tests are essential in establishing the diagnosis with low levels or abnormal structure and function of C1-INH. Most patients present C1-INH autoantibodies. Furthermore, C1q is reduced in AAE, contrary to HAE. The long-term prognosis is determined by associated hematologic malignancies.

PATIENTS AND METHODS

We report 4 cases of C1-INH-AAE associated with lymphoproliferative disorders referred to the Reference Centre for Angioedema of Besançon, France. The patients were aged between 60 and 77 years. C1 INH antibodies were found in three patients. Symptoms were triggered by angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) in 3 patients. Hematologic malignancy was present at diagnosis (one case of chronic lymphoid leukemia) or was diagnosed during follow-up (one case of indolent marginal zone non-Hodgkin lymphoma and two cases of monoclonal gammopathy).

DISCUSSION

C1-INH-AAE induced by ACE inhibitors or ARBs may be associated with hematologic malignancies. This form of revelation does not necessarily indicate a diagnosis of ACE or ARBs angioedema, and screening should therefore be performed for C1 Inh and C1q. An underlying hematologic malignancy should be routinely sought and the long-term prognosis determined.

Icatibant for Angiotensin-Converting Enzyme Inhibitor-Induced Angioedema in Intubated Patients: Case Series and Literature Review

Purpose

A case series of icatibant use in intubated patients with angiotensin-converting enzyme inhibitor- (ACEI-) induced angioedema is presented along with a relevant literature review and recommendations for utilization.

Summary

Three intubated patients admitted to the intensive care unit for ACEI-induced angioedema were treated with icatibant. A literature search identified one controlled study and four case reports describing the use of icatibant in intubated ACEI-induced angioedema patients.

Conclusion

Icatibant administration in intubated patients may be beneficial in decreasing time to extubation and length of intensive care unit stay. In the three cases described, icatibant administration did not appear to elicit a response in intubated patients, which has been described in previous case reports. For clinicians considering icatibant in the treatment of ACEI-induced angioedema, earlier administration upon arrival to the ED or immediately upon arriving to the intensive care unit is strongly advised. The suggested benefit of icatibant in intubated ACEI-induced angioedema patients should be verified by randomized clinical trials and cost-benefit analyses should be performed at individual institutions.

An ABC of the Warning Signs of Hereditary Angioedema

Hereditary angioedema (HAE) with C1 inhibitor deficiency is a genetic disorder that clinically manifests with attacks of angioedema in the subcutaneous and submucosal tissues, mainly in the extremities, abdomen, and upper airway. During attacks, vascular permeability is increased due to increased bradykinin (BK). This means that special therapies are needed for attacks that do not respond to traditional antiallergic therapies involving antihistamines, corticosteroids, and epinephrine. The recurring attacks may disable patients and lead to frequent visits to emergency rooms where misdiagnoses are common. HAE attacks may be fatal when upper-airway edema occurs, if proper treatment with a C1 inhibitor concentrate or BK receptor antagonist is not administered or an emergency tracheostomy is not performed. We propose a mnemonic method for the warning signs of HAE for the use as a diagnostic tool, i.e., the so-called "ABC" of the warning signs of HAE. The letters represent the following: A = Angioedema, B = Bradykinin, C = C1 inhibitor, D = Distress factors, E = Epinephrine nonresponsive, F = Family history, and G = Glottis/Gastrointestinal edema. To avoid fatalities, medical staff and patients, including family members, must be aware of HAE. An alphabetical mnemonic method has been developed and we hope it may benefit patients.

Angiotensin-converting enzyme inhibitor-associated angioedema treated with c1-esterase inhibitor: A case report and review of the literature

Case Report:

A 59-year old man currently on >5 years of angiotensin-converting enzyme inhibitor (ACEI) therapy presented to the emergency department with angioedema of the tongue and difficulty swallowing. After receiving conventional therapy of antihistamine, steroids, and epinephrine, the patient's condition continued to deteriorate, with imminent intubation. The patient was treated with a C1-esterase inhibitor (C1-INH) and experienced rapid resolution of symptoms, which avoided airway complications.

Discussion:

Although no therapy has been approved for the treatment of ACEI–associated angioedema (AAE), the conventional therapy (antihistamine, steroids, and epinephrine) often proves ineffective in this bradykinin-mediated angioedema. There are drugs approved and used for hereditary angioedema that may be effective in the acute phase of ACEI-AAE that may prevent the need for further interventions, such as intubation and tracheotomy. These drugs include icatibant, ecallantide, fresh frozen plasma, and C1-INH.

Conclusion:

The literature and clinical evidence indicate C1-INH can be effectively used in the treatment of ACEI-AAE to halt the progression of the condition, prevent airway compromise and the need for intervention, and lead to rapid resolution of symptoms.

Dedicated call center (SOS-HAE) for hereditary angioedema attacks: study protocol for a randomised controlled trial

Background

Despite the availability of guidelines for the specific treatment of hereditary angioedema (HAE) attacks, HAE morbidity and mortality rates remain substantial. HAE attacks are a major medical issue requiring specific treatment as well as a considerable socio-economic burden. We report a protocol designed to test whether a dedicated call centre is more effective than usual practice in the management of patients experiencing an HAE attack.

Methods/design

This prospective, cluster-randomised, single-blind, parallel-group, multicentre trial evaluates the morbidity and consequent socio-economic costs of the management of patients experiencing an HAE attack by a dedicated call centre as compared to usual practice. The trial aims to recruit 200 patients. Patients in the intervention arm are provided with an SOS-HAE card with the call centre’s freephone number that they can access in the case of an attack. The centre’s mission is to provide recommended expert advice on early home treatment. The centre can route the call to a local emergency medical service with competency in HAE management or even arrange for the drugs needed for the specific treatment of an HAE attack to be sent to the emergency department of the local hospital. The primary outcome measure is the number of hospital admissions for an HAE attack. Each patient will be followed up every 2 months for 2 years. The study has been approved by the ethics committee (Comité de Protection des Personnes d’Ile de France 10; registration number: 2012-A00044-39; date of approval: 19 January 2012).

Discussion

The SOS-HAE protocol has been designed to address the handling of attacks experienced by patients with HAE in the home. The proposed trial will determine whether the setting up of a dedicated call centre is more effective than usual practice in terms of reducing morbidity as given by the numbers of hospital admissions. The results are also anticipated to have important implications in terms of socio-economic costs for both healthcare services and patients.

Trial registration

ClinicalTrials.gov NCT01679912.