2012 Update: World Allergy Organization Guidelines for the assessment and management of anaphylaxis

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DOI: 10.1097/ACI.0b013e328355b7e4 · Source: PubMed
Abstract
The World Allergy Organization (WAO) Guidelines for the assessment and management of anaphylaxis published in early 2011 provide a global perspective on patient risk factors, triggers, clinical diagnosis, treatment, and prevention of anaphylaxis. In this 2012 Update, subsequently published, clinically relevant research in these areas is reviewed. Patient risk factors and co-factors that amplify anaphylaxis have been documented in prospective studies. The global perspective on the triggers of anaphylaxis has expanded. The clinical criteria for the diagnosis of anaphylaxis that are promulgated in the Guidelines have been validated. Some aspects of anaphylaxis treatment have been prospectively studied. Novel investigations of self-injectable epinephrine for treatment of anaphylaxis recurrences in the community have been performed. Progress has been made with regard to measurement of specific IgE to allergen components (component-resolved testing) that might help to distinguish clinical risk of future anaphylactic episodes to an allergen from asymptomatic sensitization to the allergen. New strategies for immune modulation to prevent food-induced anaphylaxis and new insights into subcutaneous immunotherapy to prevent venom-induced anaphylaxis have been described. Research highlighted in this Update strengthens the evidence-based recommendations for assessment, management, and prevention of anaphylaxis made in the WAO Anaphylaxis Guidelines.

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C
URRENT
O
PINION
2012 Update: World Allergy Organization
Guidelines for the assessment and management
of anaphylaxis
F. Estelle R. Simons
a
, Ledit R.F. Ardusso
b
, M. Beatrice Bilo`
c
,
Vesselin Dimov
d
, Motohiro Ebisawa
e
, Yehia M. El-Gamal
f
,
Dennis K. Ledford
g
, Richard F. Lockey
g
, Johannes Ring
h
,
Mario Sanchez-Borges
i
, Gian Enrico Senna
j
, Aziz Sheikh
k
,
Bernard Y. Thong
l
, Margitta Worm
m
, for the World Allergy Organization
Purpose of review
The World Allergy Organization (WAO) Guidelines for the assessment and management of anaphylaxis
published in early 2011 provide a global perspective on patient risk factors, triggers, clinical diagnosis,
treatment, and prevention of anaphylaxis. In this 2012 Update, subsequently published, clinically relevant
research in these areas is reviewed.
Recent findings
Patient risk factors and co-factors that amplify anaphylaxis have been documented in prospective studies.
The global perspective on the triggers of anaphylaxis has expanded. The clinical criteria for the diagnosis
of anaphylaxis that are promulgated in the Guidelines have been validated. Some aspects of anaphylaxis
treatment have been prospectively studied. Novel investigations of self-injectable epinephrine for treatment
of anaphylaxis recurrences in the community have been performed. Progress has been made with regard to
measurement of specific IgE to allergen components (component-resolved testing) that might help to
distinguish clinical risk of future anaphylactic episodes to an allergen from asymptomatic sensitization to the
allergen. New strategies for immune modulation to prevent food-induced anaphylaxis and new insights into
subcutaneous immunotherapy to prevent venom-induced anaphylaxis have been described.
Summary
Research highlighted in this Update strengthens the evidence-based recommendations for assessment,
management, and prevention of anaphylaxis made in the WAO Anaphylaxis Guidelines.
Keywords
clinical diagnosis of anaphylaxis, epinephrine (adrenaline) in first-line treatment of anaphylaxis,
patient risk factors for anaphylaxis, prevention of anaphylaxis
a
Department of Pediatrics & Child Health and Department of Immunology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada,
b
Ca
´
tedra
Neumonologı´a, Alergia e Inmunologı´a, Facultad de Ciencias Me
´
dicas, Universidad Nacional de Rosario, Rosario, Argentina,
c
Department of Allergy,
Immunology and Respiratory Diseases, University Hospital, Ancona, Italy,
d
Section of Allergy, Asthma and Immunology, Department of Pediatrics and
Medicine, University of Chicago, Chicago, Illinois, USA,
e
Department of Allergy, National Hospital Organization, Sagamihara National Hospital, Clinical
Research Center for Allergy & Rheumatology, Kanagawa, Japan,
f
Pediatric Allergy and Immunology Unit, Ain Shams University, Cairo, Egypt,
g
University
of South Florida Morsani College of Medicine, Tampa, Florida, USA,
h
Department of Dermatology and Allergy, Tech. Universitat Muenchen, Munich,
Germany,
i
Centro Medico Docente La Trinidad, Caracas, Clinica El Avila, Caracas, Venezuela,
j
The Allergy Unit, Verona General Hospital, Verona, Italy,
k
Center for Population Health Sciences, The University of Edinburgh, Edinburgh, UK,
l
Department of Rheumatology, Allergy & Immunology, Tan Tock
Seng Hospital, Singapore and
m
Allergie-Centrum-Charite
´
, Klinik fur Dermatologie und Allergologie, Charite
´
, Universitatsmedizin, Berlin, Germany
Correspondence to Professor F. Estelle R. Simons, Room FE125, 820 Sherbrook Street, Winnipeg, Manitoba, Canada, R3A 1R9. Tel: +1 204 787
2537; fax: +1 204 787 5040; e-mail: lmcniven@hsc.mb.ca
Curr Opin Allergy Clin Immunol 2012, 12:389399
DOI:10.1097/ACI.0b013e328355b7e4
1528-4050
ß 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins www.co-allergy.com
R EVIEW
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
INTRODUCTION
The World Allergy Organization (WAO) Guidelines
for the assessment and management of anaphylaxis
(subsequently referred to as the Guidelines) were
published on 3 March 2011 [1
&&
] in response to
the need for global guidelines on anaphylaxis diag-
nosis and treatment. Unique aspects of the Guide-
lines are summarized below.
The Guidelines were developed without cor-
porate funding in response to absence of global
guidelines for anaphylaxis, absence of national
guidelines in most countries, and for use as an
additional resource in countries with their own
national guidelines. They were based on the best
evidence available from publications in indexed,
peer-reviewed journals to the end of 2010. They
highlighted the role of the allergy/immunology
specialist, particularly in prevention of anaphylactic
episodes; however, they have been widely used by a
broader group of healthcare professionals [1
&&
].
The Guidelines were preceded by documen-
tation of global availability of essentials for assess-
ment and management of anaphylaxis. They
provide a global perspective on anaphylaxis
with regard to vulnerable patients, risk factors
for severe or fatal anaphylaxis, and co-factors
that amplify anaphylaxis sym ptoms, as well as
perspective on mechanisms and triggers. They
emphasize prompt clinical diagnosis, basic initial
treatment, and prevention of anaphylaxis recur-
rences. They are written in a concise format
(22 pages) with recommendations supported by
citation of 150 references, most of which were
published from 2006 to 2010. They include color
illustrations that highlight the key concepts in the
text. They propose a global agenda for anaphylaxis
research (Table 1).
Since co-publication (open access) in the Journal
of Allergy & Clinical Immunology and the World Allergy
Organization Journal in early 2011, the Guidelines
have been disseminated worldwide in a variety of
formats. They have been posted on the WAO web-
site and on WAO member society websites. Sum-
mary posters and pocket cards have been translated
into 10 languages, with additional translations
pending. They have been presented in keynote
and plenary sessions in congresses and meetings
around the globe. They are used in undergraduate
and postgraduate medical courses. They have
become a resource for specialty areas beyond
allergy/immunology, including sports medicine,
for example, the 2012 Olympic Games Therapeutic
Use Exemption Committee. They are also used in
primary care and allied health.
In parallel, progress has been made on the global
agenda proposed for anaphylaxis research (Table 1),
and more than 500 papers on human anaphylaxis
have been published in indexed peer-reviewed
medical journals, hence the need for this Update.
During 2011 and early 2012, members of the WAO
Special Committee on Anaphylaxis independently
searched for and selected relevant publications,
which were then collated and independently ranked
for inclusion in the Update.
Here, we recapitulate the evidence-based recom-
mendations in the Guidelines and support them
with additional recent references. The Update is
intended for use in conjunction wit h the Guidelines
and the references cited therein [1
&&
].
ASSESSMENT OF PATIENTS WITH
ANAPHYLAXIS
Information about patient risk factors, triggers and
mechanisms, and clinical diagnosis [1
&&
,27,8
&
,912,
13
&
,1416,17
&
,1822,23
&
,24
&&
,25] is updated in this
section, which includes case series from five conti-
nents focusing on anaphylaxis in community set-
tings, emergency departments (EDs), and hospitals.
Patient risk factors
Patient risk factors, including age or physiologic
state-related vulnerability, concomitant diseases,
concurrent medications, and co-factors, are similar
worldwide [1
&&
,7,8
&
,912,13
&
,14,15].
Vulnerable patients include infants, teenagers,
pregnant women, and the elderly. Although ana-
phylaxis can be difficult to diagnose in infants, case
series of patients with anaphylaxis, publis hed from
different countries, include infants [27,8
&
], one as
young as 2 weeks of age [5]. Adolescents and young
adults are vulnerable to anaphylaxis because of
KEY POINTS
The World Allergy Organization (WAO) Guidelines for
the assessment and management of anaphylaxis
published in early 2011 remain a useful global
resource on anaphylaxis with regard to patient risk
factors, triggers, clinical diagnosis, treatment,
and prevention.
Since the Guidelines were published, progress in
research that is relevant to human anaphylaxis has
resulted in more than 500 publications in peer-
reviewed, indexed medical journals.
These subsequent publications, many of which are
summarized in this Update, strengthen the evidence
base for the recommendations made in the
Guidelines.
Anaphylaxis and insect allergy
390 www.co-allergy.com
Volume 12 Number 4 August 2012
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
risk-taking behaviors as they transition between
parental control and autonomous decision-making
[1
&&
]. Some are not even aware of their life-threat-
ening allergies and have never been instructed in
allergen avoidance or the need for carrying an epi-
nephrine auto-injector for self-administration [9];
others are aware, but ignore the risks. Anaphylaxis
during labor and delivery can lead to fatality or
permanent disability from hypoxic-ischemic ence-
phalopathy in mothers and especially in neonates.
The most common triggers are intra-partum injec-
tion of penicillin, natural rubber latex, and other
agents encountered in medical or perioperative
settings [1
&&
,10]. In patients with anaphylaxis who
are more than 50 years old, typical triggers are sting-
ing insect venoms, medications, and ‘unknown’
[1
&&
,2,3,11].
In young patients studied prospectively, asthma,
especially when severe or uncontrolled, is strongly
associated with anaphylaxis; additionally, during a
food-induced anaphylactic episode, a history of
asthma is predictive of dyspnea, wheezing, and
respiratory arrest [1
&&
,7]. A history of chronic/relaps-
ing gastrointestinal symptoms is reported to be pre-
dictive of abdominal pain, vomiting, hypotension,
bradycardia, and cardiac arrest [7]. In patients with
anaphylaxis due to insect venom, risk factors for
increased severity include older age, pre-existing car-
diovascular disease or mast cell disorder, elevated
serum baseline total tryptase concentrations, con-
comitant treatment with a beta-adrenergic blocker
and/or angiotensin-converting enzyme (ACE) inhibi-
tor, a previous severe reaction, and the type of sting-
ing insect (honey bees present the highest risk)
[12,13
&
]. Mast cell disorders are associated with
an increased risk of severe or fatal anaphylaxis; of
137 consecutive patients with systemic mastocytosis,
despite taking prophylactic medications, 12% had
one or more life-threatening events [14]. After
Hymenoptera stings, two patients suffered from
severe recurrent hypotensive episodes and required
repeated resuscitation and hospitalization, and two
other patients (one of whom later died) were disabled
by cerebral hypoxia [14].
Co-factors that amplify anaphylaxis [1
&&
] have
been described in nearly 20% of young patients in a
prospective reg istry study. They include exercise,
fever, acute infection such as an upper respiratory
tract infection, premenstrual status, and emotional
stress. Interestingly, these co-factors are also
reported to amplify some of the acute allergic reac-
tions to food that occur during prospective studies
of oral food immunotherapy [1
&&
,8
&
,15].
Triggers and mechanisms
In contrast to older patients [1
&&
,2,3], foods are
consistently reported to be the most common
trigger of anaphylaxis in children and teenagers
[47,8
&
]. In infants, sensitization to one or more
foods is common and is not necessarily accom-
panied by any symptoms; however, in one popu-
lation-based sample, more than 10% of 1-year-olds
had oral challenge-proven clinical reactivity to
uncooked egg, peanut, or sesame [16].
Patients can react clinically to a specific allergen
in different ways, possibly reflec ting the allergen
components to which they are sensitized. As
an example, in different countries, patients with
elevated serum IgE levels to peanut have predom-
inant IgE antibodies directed to different allergen
components, associated with different symptom
patterns. In the US, IgE antibodies directed to
r Ara h 1, 2 and 3 are associated with severe early-
onset symptoms. In Spain, IgE antibodies directed to
r Ara h 9 are associated with later onset of milder
clinical reactivity to peanut and other plant-derived
proteins such as peach. In Sweden, IgE antibodies
directed to r Ara h 8, the Bet v 1 homolog, are also
associated with later onset and milder clinical reac-
tivity to peanut and other plant-d erived proteins
such as hazelnut [17
&
].
Table 1. Progress on the global agenda for anaphylaxis research
Agenda item Progress
Development of instruments to quantify patient-specific risk factors Some
Validation of the clinical criteria for diagnosis Good
Development of rapid in-vitro test(s) to confirm the clinical diagnosis Some
Development of in-vitro tests to distinguish clinical risk of anaphylaxis from asymptomatic sensitization Excellent
Epinephrine research [pharmacology, epidemiology, RCTs (not placebo-controlled) of dose versus
dose and route versus route]
Good
RCTs of second-line medications such as H
1
-antihistamines or glucocorticoids Some
RCTs of immune modulation to prevent anaphylactic episodes Excellent
RCT, randomized controlled trial. Adapted from [1
&&
].
2012 Update: WAO Anaphylaxis Guidelines Simons et al.
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Stinging insect venom-induced anaphylaxis has
been extensively studied in Europe, North America,
and Australia, where flying Hymenoptera insects are
well documented anaphylaxis triggers [1
&&
]. In
North America, stings from nonflying imported fire
ants (Solenopsis species) are also typical triggers, and
in Australia, stings from jumper ants (Myrmecia
species) are also typical triggers [12,13
&
,18].
In a review of nonsteroidal anti-inflammatory
drug (NSAID) hypersensitivity that included non-
cross-reactive NSAID (single NSAID) anaphylaxis,
the authors focused on stepwise investigation,
emphasizing the importance of the history and
the pros and cons of skin tests, specific IgE levels,
and challenge/provocation tests [19].
In a survey of anaphylaxis during anesthesia, of
2516 patients, 72% had an IgE-mediated reaction. In
adults, this commonly involved neuromuscular
blocking agents (58%), latex (20%), or antibiotics
(13%); in children, it commonly involved latex
(42%), neuromuscular blocking agents (32%), or
antibiotics (9%) [20].
A comprehensive review of subcutaneous
immunotherapy (SCIT) with allergens includes
new information about risk factors that increase
the possibility of anaphylaxis during SCIT, and
how to reduce this risk [21]. In one US study [22],
systemic reactions were reported in 4% of 28 000
SCIT injections; 22% of the 773 patients had pre-
viously reacted to SCIT.
Human IgG-mediated anaphylaxis remains an
enigma [1
&&
]. To facilitate its identification,
decreased blood neutrophil Fc gamma RIII expres-
sion without increased IL-4 R alpha expression has
been proposed as a marker [23
&
].
Clinical diagnosis
A poster and pocket card that capture the key
messages in the Guidelines about prompt clinical
diagnosis and initial treatment of anaphylaxis have
been translated into ten different languages [1
&&
]
(Fig. 1).
The clinical criteria for the diagnosis of anaphy-
laxis that emphasize sudden onset of multisystem
symptoms have been validated in a retrospective
cohort study [24
&&
] of ED patien ts, in whom they
had excellent sensitivity [96.7%, 95% confidence
interval (CI) 88.899.9] and good spec ificity
(82.4%, 95% CI 75.587.6). Additionally, use of
these criteria in epidemiologic studies has sign ifi-
cantly improved identification of patients with ana-
phylaxis [25].
Post mortem diagnosis of anaphylaxis can be
difficult when little or no history is available, macro-
scopic signs are absent, and blood or other bio logic
fluids are unavailable or unsuitable for study [1
&&
].
Identification of tissue mast cells, for example, in
the laryngeal wall, by staining for immunohisto-
chemical markers such as CD117, has been proposed
for use in this setting [26].
Serum total tryptase measurements are not help-
ful for confirmation of the diagnosis of anaphylaxis
at the time of the episode because the assay takes
several hours to perform; however, they can be
useful later, more so for confirmation of the clinical
diagnosis of venom or medication-induced anaphy-
laxis than for confirmation of food-induced anaphy-
laxis [1
&&
]. Serial monitoring of tryptase levels at the
time of presentation, 12 h later, and at resolution is
reported to improve the sensitivity of the test [27].
MANAGEMENT OF ANAPHYLAXIS IN
HEALTHCARE SETTINGS
Appropriate preparation is the key to good patient
outcomes in anaphylaxis [1
&&
,28]. In a pediatric ED,
development and implementation of an anaphy-
laxis protocol sign ificantly improved the rate of
epinephrine administration, the rate of admission
to an observation unit, and the duration of obser-
vation in this unit, and there were no significant
adverse effects from epinephrine [29
&&
]. In a retro-
spective study [30] of pediatric ED patients with
food-related allergic reactions, factors that were
independently associated with a higher likelihood
of hospitalization included pre-ED epinephrine
treatment, and epinephrine treatment within 1 h
of triage.
Epinephrine is the preferred vasopressor for
treatment of anaphylactic shock [1
&&
,31]; however,
it is not always given promptly, even in hospitalized
patients. As an example, anaphylaxis can be difficu lt
to diagnose during anesthesia; consequently,
treatment with epinephrine can be delayed. In a
retrospective study [32], 45% of patients with ana-
phylaxis during anesthesia developed shock, circu-
latory instability, or cardiac arrest, yet only 83% of
these patients received epinephrine.
Even if epinephrine has not been given at all,
cardiovascular symptoms, including myocardial
infarction and arrhythmias, can occur during ana-
phylaxis [1
&&
,33]. These complications also occur
after epinephrine overdose, regardless of route of
administration, but especially after an intravenous
bolus dose or overly rapid intravenous infusion
[3436].
In a prospective randomized blinded study
[37] of young patients with acute cutaneous
allergic reactions during food challenges, in com-
parison with diphenhydramine 1 mg/kg, cetirizine
0.25 mg/kg had a similar onset of action, similar
Anaphylaxis and insect allergy
392 www.co-allergy.com
Volume 12 Number 4 August 2012
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Anaphylaxis is highly likely when any one of the following three criteria is fulfilled:
Sudden onset of an illness (minutes to several hours), with involvement of the skin, mucosal tissue,
or both (e.g. generalized hives, itching or flushing, swollen lips-tongue-uvula)
Two or more of the following that occur suddenly after exposure to a
(minutes to several hours):
Reduced blood pressure (BP) after exposure to a
(minutes to several hours):
Or
Or
And at least one
of the following:
Sudden respiratory symptoms
and signs
(e.g. shortness of breath, wheeze,
cough, stridor, hypoxemia)
Sudden skin or mucosal
symptoms and signs
(e.g. generalized hives, itch-flush,
swollen lips-tongue-uvula)
* For example, immunologic but IgE-independent, or non-immunologic (direct mast cell activation)
** For example, after an insect sting, reduced blood pressure might be the only manifestation of anaphylaxis; or,
after allergen immunotherapy, generalized hives might be the only initial manifestation of anaphylaxis.
*** Low systolic blood pressure for children is defined as less than 70 mmHg from 1 month to 1 year less than (70mmHg + [2 × age])
from 1 to 10 years, and less than 90 mmHg from 11 to 17 years. Normal heart rate ranges from 80–140 beats/minutes at age 1-2 years;
from 80–120 beats/minute at age 3 years; and from 70–115 beats/minute after age 3 years. In infants and chilren, respiratory
compromise is more likely than hypotension or shock, and shock is more likely to be manifest initially by tachycardia than by hypotension.
Infants and children: low systolic BP (age-specific)
or greater than 30% decrease in systolic BP***
Adults: systolic BP of less than 90 mmHg or greater
than 30% decrease from that person’s baseline
Sudden respiratory symptoms
and signs
(e.g. shortness of breath, wheeze,
cough, stridor, hypoxemia)
Sudden reduced BP or
symptoms of end-organ
dysfunction (e.g. hypotonia
[collapse], incontinence)
Sudden reduced BP or
symptoms of end-organ
dysfunction (e.g. hypotonia
[collapse], incontinence)
Sudden gastrointestinal
symptoms (e.g. crampy
abdominal pain, vomiting)
1
2
3
Clinical criteria for diagnosis
FIGURE 1. Anaphylaxis diagnosis and treatment. Clinical criteria for the diagnosis of anaphylaxis and initial treatment of
anaphylaxis, as illustrated in the poster and the pocket card based on the 2011 WAO Anaphylaxis Guidelines. The first part of this
figure summarizes a validated approach to the clinical diagnosis of anaphylaxis, which is highly likely when any one of the three
criteria is fulfilled. The second part of the figure summarizes the basic initial treatment which is relatively inexpensive to implement
and should be possible even in a low resource environment. Note that steps 4, 5, and 6 should be performed promptly and
simultaneously as soon as anaphylaxis is diagnosed. If precious minutes are lost early in the diagnosis and treatment of an
anaphylactic episode, subsequent management can become more difficult. Guidelines are not a substitute for appropriate
preparation, good clinical judgment, and strong clinical skills (adapted from [1
&&
]). WAO, World Allergy Organization.
2012 Update: WAO Anaphylaxis Guidelines Simons et al.
1528-4050 ß 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins www.co-allergy.com 393
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
1
2
3
4
5
6
7
O
2
8
9
10
Have a written emergency protocol for recognition and treatment of anaphylaxis and rehearse it regularly.
Remove exposure to the trigger if possible, e.g. discontinue an intravenous diagnostic or therapeutic agent that seems to be
triggering symptoms.
Assess the patient’s circulation, airway, breathing,
mental status, skin and body weight (mass).
Call for help: resuscitation team (hospital) or emergency
medical services (community) if available.
Inject epinephrine (adrenaline) intramuscularly in the
mid-anterolateral aspect of the thigh, 0.01 mg/kg of a
1:1,000 (1 mg/mL) solution, maximum of 0.5 mg (adult)
or 0.3 mg (child); record the time of the dose and
repeat it in 5–15 minutes, if needed. Most patients
respond to 1 or 2 doses.
At frequent, regular interval, monitor patient’s blood
pressure, cardiac rate and function, respiratory status,
and oxygenation (monitor continuously, if possible).
Place patient on the back or in a position of comfort if
there is respiratory distress and/or vomiting; elevate the
lower extremities; fatality can occur within seconds if
patient stands or sits suddenly.
Establish intravenous access using needles or
catheters with wide-bore cannulae (14 - 16 gauge):
When indicated, give 1–2 litres of 0.9% (isotonic)
saline rapidly (e.g. 5-10 ml/kg in the first 5-10 minutes
to an adult; 10 ml/kg to a child).
When indicated, at any time, perform cardiopulmonary
resuscitation with continuous chest compressions
and rescue breathing.
When indicated, give high-flow supplemental oxygen
(6-8 L/minute), by face mask or oropharyngeal airway.
Promptly and simultaneously,
perform steps 4, 5 and 6.
In addition,
5
O
2
0.9%
NaCl
Initial treatment
Anaphylaxis and insect allergy
394 www.co-allergy.com
Volume 12 Number 4 August 2012
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efficacy, longer duration of action, and reduced
sedation profile. A similar number of children in
each treatment group were treated with epinephrine
and glucocorticoids.
MANAGEMENT AT TIME OF DISCHARGE
FROM HEALTHCARE SETTINGS
Information about preparation for self-treatment in
the community [1
&&
,3845], confirmation of the
trigger of an anaphylactic episode [1
&&
,4648,49
&
,
5054], allergen avoidance [1
&&
,5559], pharmaco-
logic prophylaxis [60], and immune modulation
[1
&&
,61
&
,6265,66
&
] is updated in this section (given
below).
Recommendations for prevention and treat-
ment of anaphylaxis recurrences at the time of dis-
charge from the healthcare setting are as follo ws
[1
&&
]:
(1) Medication
(a) self-injectable epinephrine/adrenaline from
an auto-injector or
(b) self-injectable epinephrine from an ampule/
syringe or prefilled syringe (alternative but
not preferred formulations).
(2) Other aspect s of discharge management
(a) anaphylaxis emergency action plan (per-
sonalized, written),
(b) medical identification (e.g. bracelet, wallet
card),
(c) medical reco rd electronic flag or chart
sticker and
(d) emphasis on importance of follow-up inves-
tigations, preferably by an allergy/immu-
nology specialist.
(3) Assessment of sensitization to allergen
(a) bef ore discharge, consider measuring aller-
gen-specific IgE levels in serum for assess-
ment of sensitization to relevant allergens
ascertained from the history of the anaphy-
lactic episode,
(b) at least 34 weeks after the episode, confirm
allergen sensitization using skin tests; if
these tests are negative in a patient with a
convincing history of anaphylaxis, consider
repeating them weeks or months later and
(c) medically supervised challenge/provoca-
tion tests, for example with food or medi-
cation, might also be needed in order to
assess risk of future anaphylactic episodes.
(4) Long-term risk reduction: avoidance and/or
immune modulation
(a) food-triggered anaphylaxis: strict avoi dance
of relevant food(s),
(b) stinging insect-triggered ana phylaxis:
avoidance of stinging insects; subcutaneous
venom immunotherapy (protects up to
90% of adults and 98% of children against
anaphylaxis from future stings),
(c) medication-triggered anaphylaxis: avoid-
ance of relevant medications and use of safe
substitutes; if indicated, desensitization
(using a published protocol) conducted in
a healthcare setting and
(d) unknown or idiopathic anaphylaxis: for fre-
quent episodes, consider glucocorticoid and
non-sedating H
1
-antihistamine prophylaxis
for 23 months; consider measurement of a
baseline tryptase level to identify mastocy-
tosis/clonal mast cell disorders.
(5) Optimal management of asthma and other
concomitant diseases.
Allergy/immunology specialists play a uniquely
important role in preparing the patient for self-treat-
ment in the community, confirmation of the trigger
of an anaphylactic episode, education regarding
allergen avoidance, and immune modulation.
Preparation for self-treatment in the
community
Under-prescription of self-injectable epinephrine
auto-injectors for patients at risk of anaphylaxis
recurrence in the community remains a concern
[1
&&
] and has been described as ‘alarming’ [2,9].
One group of investigators has reported that
patients older than 50 years of age discharged home
from an ED after treatment of anaphylaxis were less
likely to be prescribed self-injectable epinephrine
than those younger than 50 years [11]. It is, how-
ever, possible to demonstrate improvement; in a
prospective study [29
&&
], at the time of discharge
from an ED after anaphylaxis treatment, epineph-
rine auto-injectors were prescribed for 6.7% of
patients before implementation of an anaphylaxis
protocol, and for 54.5% of patients afterwards.
New data lend additional support to the recom-
mendation that patients leaving a healthcare facility
after omalizumab injections should be taught how
to recognize the signs and symptoms of anaphylaxis
and equipped with, and trained to use, self-inject-
able epinephrine [1
&&
,38]. Prescribing self-injectable
epinephrine for patients to use in the event of a
delayed reaction to SCIT warrants further study [39].
Anaphylaxis after sublingual immunotherapy (SLIT)
is rare; nevertheless, as maintenance SLIT is typically
given at home rather than in healthcare setti ngs,
additional efforts are needed to identify risk factors
for adverse effects from SLIT, standardize reporting
2012 Update: WAO Anaphylaxis Guidelines Simons et al.
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Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
of these adverse effects, and provide patients with
written instructions about prompt recognition and
treatment of anaphylaxis [40].
Although epinephrine auto-injectors with
needle protection features that deploy after use have
been introduced, unintentional injections and inju-
ries can still occur if the needle-containing end of
the device is touched before use [41].
Many children and teenagers who experience
anaphylaxis in the community, including some
with throat tightness, difficulty in breathing, diffi-
culty in swallowing, wheezing, or loss of conscious-
ness, fail to use epinephrine, commonly because
they think it is unnecessary [42]. The percentage
of patients requiring more than one dose of
epinephrine during anaphylactic episodes varies
depending on the study [1
&&
]; the second dose is
often administered by a healthcare professional
[6,42].
In a qualitative study [43], most teenagers
reported carrying epinephrine auto-injectors some
of the time; however, only three had used an auto-
injector, and one of these experienced difficulties;
a comprehensive training approach was recom-
mended. In another study [44], children and
teenagers actually performed self-injection of epi-
nephrine during auto-injector training sessions;
apparently, this did not increase their anxiety about
the procedure.
Anaphylaxis education is critically important
for patients, and for those responsible for children
and others at risk [1
&&
]. In this regard, mandatory
education for school personnel about recognition of
anaphylaxis and prompt epinephrine injection has
been reported to improve the standard of care [45].
Confirmation of anaphylaxis triggers
Allergy/immunology specialists play an important
role in identification of clinically relevant allergen
triggers by performing and interpreting skin tests
and measuring specific IgE levels [1
&&
]. These tests do
not distinguish between sensitization associated
with increased risk of anaphylaxis, which is
relatively uncommon, and asymptomatic sens itiz-
ation, which is widespread; therefore, the allergens
selected for testing should be relevant to the history
of the anaphylactic episode [1
&&
,46].
Medically supervised incremental challenge
tests (also described as titrated or graded provoca-
tion tests) to food or medication conduc ted in an
appropriately equipped and staffed healthcare set-
ting are sometimes necessary to determine the risk
of anaphylaxis recurrence in daily life [1
&&
,47,48]. An
algorithm based on six clinica l factors, including
symptoms, sex, and ag e, as well as skin prick tests,
allergen-specific IgE levels, and total IgE level,
improved the prediction of positive food challenge
outcomes, compared with skin prick tests and/or
allergen-specific IgE levels alone [47].
Allergen component-resolved testing might
help to identify patients sensitized to food, latex,
or venom who are at increased risk of anap hylaxis
after exposure to these allergens versus those who
are sensitized but clinically tolerant (i.e. remain
asymptomatic after exposure) to these allergens
[1
&&
,48,49
&
]. For example, patients with elevated
specific IgE levels to food allergen components such
as casein (Bos d 8), ovomucoid (Gal d 1), or r Ara
h 2 are unlikely to tolerate milk, egg, or peanut,
respectively [48,49
&
,50]. The specific IgE ratio of
omega-5 gliadin to wheat has been proposed as a
marker for diagnosis of wheat-dependent, exercise-
induced anaphylaxis and wheat-induced anaphy-
laxis [51], but requires confirmation.
Tests for drug allergy/hypersensitivity are not
universally available; only 74.7% of WAO member
societies report availability of skin testing and
only 67.4% report availability of drug-specific
IgE measurements [52]. The relative risk of acute
systemic reactions from skin tests with beta-lactam
antibiotics is proportional to the pretest probability
of anaphylaxis or other acute systemic reactions as
determined from the history; therefore, preferably,
patients with high pretest probability of such reac-
tions should be skin-tested and monitored in hos-
pital settings [53]. Additional data are needed
regarding the value of skin testing when selecting
a well tolerated radiographic contrast media (RCM)
in patients with a history of anaphylaxis to RCM
[54].
Allergen avoidance
For prevention of food-induced anaphylactic
episodes, strict avoidance of the implicated food
and cross-reacting substances is recommended.
This often leads to stress in affected individuals
and their families and, despite vigilance, uninten-
tional exposures occur [1
&&
]. Depending on dietary
habits and methods of food preparation, people
sensitized to the same food allergen might require
specific, detailed information with regard to avoid-
ance of that allergen [55]. Recall of dietary advice is
variable, and food avoidance may be more stringent
or less stringent than recommended by a healthcare
professional [56]. Unintentional exposures and
clinical reactions are common. Eating away from
home can be dangerous; as an example, although
restaurant staff might appear confident and know-
ledgeable about food allergy and anaphylaxis, many
of them hold serious misconceptions about these
Anaphylaxis and insect allergy
396 www.co-allergy.com
Volume 12 Number 4 August 2012
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
subjects [57]. Persons who are highly sensitized to a
food can experience anaphylaxis after exposure by
any route, for example, ingestion of trace amounts
in presumably ‘safe’ food or medication, or topical
application of soaps or cosmetics [58,59].
Patients who have reacted to a medication such
as an antibiotic or an NSAID should ideally be given
written information about strict avoidance of the
incriminated medications and a list of the alterna-
tive medications (if possible, from a different
pharmacologic class) they are likely to tolerate with-
out adverse effects [1
&&
,19].
Additional prospective studies of pharmacologic
premedication to preven t allergic reactions to diag-
nostic and therapeutic agents are necessary. For
those at risk for anaphylaxis to RCM, pharmacologic
premedication might not always be effective [54].
For those receiving snake antivenom, pretreatmen t
with epinephrine, an H
1
-antihistamine and a glu-
cocorticoid, has been reported to reduce the risk of
acute reactions, and to be safe [60].
Immune modulation
Natural desensitization is possible in some carefu lly
selected and monitored pediatric patients with a
history of clinical reactivity to baked milk or baked
egg [50,61
&
,62]. As an example, if a child with a
history of clinical reactivity to milk can sub-
sequently tolerate small amounts of unintentionally
ingested, extensively heated milk in foods such as
pizza or muffins, this clinical tolerance should be
recognized as a marker of transient IgE-mediated
allergy; moreover, addition of extensively heated
milk to his/her diet might accelerate develop-
ment of tolerance to unheated milk. Conversely,
ongoing reactivity to small amounts of extensively
heated milk portends a more persistent pheno-
type and the need for continued strict dietary avoid-
ance of milk in all forms, even in trace amounts
[61
&
,62].
Medically supervised clinical trials using incre-
mental dosing of specific food through oral, sub-
lingual, or epicutaneous routes are ongoing
[1
&&
,15,61
&
,63]. In the first ever randomized con-
trolled study [63] of peanut oral immunotherapy,
clinical desensitization and concurrent immune
modulation of the allergic response were conclus-
ively demonstrated. Patients with a history of severe
life-threatening anaphylaxis and patients with mod-
erate-to-severe persistent asthma were excluded
from this study; however, adverse events were com-
mon, particularly on the initial dos e escalation day
and on dose build-up days. Long-term immune
tolerance remains to be confirmed [15,63]. Despite
steady progress, food oral immunotherapy is not
yet recommended for use in clinical practice
[1
&&
,61
&
].
An elevated baseline serum total tryptase level is
a predictor of severe insect sting reactions, frequent
systemic reactions during venom immunotherapy,
the possibility of venom immunotherapy failure,
and the risk of relapse if venom immunotherapy
is stopped [12,13
&
,64]. Current strategies for reduc-
ing adverse reactions include pretreatment with an
H
1
-antihistamine or anti-IgE monoclonal antibody
[12]. Patients with honey bee venom allergy and
intense occupational exposure should be treated
with an increased maintenance dose of 200 mcg
honey bee venom [12,65].
In patients sensitized to a medication, when
substitution of an agent from a different pharmaco-
logic class is not possible, rapid desensitization is an
effective means of administering the medication of
interest while minimizing or circumventing adverse
reactions to it [1
&&
,66
&
]. The molecular mechanisms
leading to the temporary tolerance induced by this
approach are incompletely understood. In a 10-year
review of patients sensitized to antibiotics, chemo-
therapeutics such as taxanes and platins, and mono-
clonal antibodies, a full dose of the desired agent
was reached in 99.9% of 796 rapid desensitization
regimens. Reactions that occurred during desensiti-
zation were generally less severe than the initial
reaction. There were no fatalities [66
&
].
CONCLUSIONS
The e vidence base for the recommendations to
improve the assessment, management, and preven-
tion of anaphylactic episodes made in the 2011
WAO Anaphylaxis Guidelines is even stronger
now than at the time they were published. As high-
lighted in this Update, important advances have
subsequently been made in the areas of: validation
of the clinical criteria for diagnosis, use of epineph-
rine, development of in-vitro tests to distinguish
clinical risk from asymptomatic sensitization, and
immune modulation to prevent anaphylaxis.
Additional studies relevant to human anaphylaxis,
particularly prospective studies, are needed.
Acknowledgements
We acknowledge the support of the World Allergy
Organization, and the assistance of Lori McNiven,
Health Sciences Center, Winnipeg, MB, Canada.
Conflicts of interest
M. Beatrice Bilo
`
received funding for Consultancy
provided by Menarini Italy, and payment for lectures,
including service on speakers’ bureaus, funded by
ALK-Abello, Allergopharma, Meda, and Phadia. Richard
2012 Update: WAO Anaphylaxis Guidelines Simons et al.
1528-4050 ß 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins www.co-allergy.com 397