WAO Anaphylaxis Guidelines-WAO Anaphylaxis Special Committee Epidemiology 7 December 2011 Workshop 25.
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Definition: Epidemiology
• “The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to control of health problems”
• Stedman’s Medical Dictionary
Terminology
• Incidence is the number of NEW EVENTS of a condition in a particular time interval eg per year
• Prevalence is the number of cases of a condition existing in a population at a particular period in time (period prevalence) or particular moment in time (point prevalence)
• Prevalence is dependent on incidence and duration of the condition
World Allergy Organization Guidelines for the Assessment and Management of Anaphylaxis
• Simons FER, Ardusso LRF, Bilo MB, et al…………..WAO Journal 2011;4:13-37
• “Lifetime prevalence based on international studies is estimated at 0.05-2.0%”
Epidemiology of Anaphylaxis: findings of the ACAAI Epidemiology of Anaphylaxis Working Group
• Ann Allergy Asthma Immunol 2006;97:596-602
• Literature review from 1968-2004• “Anaphylaxis is a relatively common problem,
affecting up to 2% of the population”• Prevalence over a lifetime is 0.05-2.0%• “The largest number of incident cases is in
children and adolescents”
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Angioedema
Urticaria
Anaphylaxis (any)
Poulos LM, et al. J Allergy Clin Immunol. 2007;120:878-884.
1993-94 1994-95 1995-96 1996-97 1997-98 1998-99 1999-2000 2000-01 2001-02 2002-03 2003-04 2004-05
Year
12
10
8
6
4
2
0
Ho
spit
aliz
atio
ns
Per
100,
000
Po
pu
lati
on
ICD-10-AM introduced
Australia (1993-2005)
Increasing Anaphylaxis Hospitalizations
ICD-10-AM, International Classification of Diseases, 10th revision, Australian modification.
7
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
Ho
spit
aliz
atio
ns
Per
100
,000
Lin RY, et al. Ann Allergy Asthma Immunol. 2008;101:387-393.
New York (1990-2006)AnaphylaxisAngioedemaUrticariaAllergy unspecified
Trend in Hospitalizations:First 2 Decades of Life
To Determine the Prevalence, Track the Antidote for the Condition
• Patients receiving self-injectable epinephrine from administrative data claims for outpatient treatment over 5 years (1.15 million persons)
• Data from retail pharmacies; patients had to self-pay
• Injectable epinephrine dispensed for outpatients in 0.95% of this population
• Likely an underestimate• JACI 2002;110:647-51
A voluntary registry for peanut and treenut allergy: Characteristics of the first
5149 registrants
• JACI 2001;108:128-32• Structured questionnaire to self-identified
peanut or tree nut allergic patients (n=7000) or health professional members (n= 1000) of the Food Allergy and Anaphylaxis Network and to 4000 members of the AAAAI
• Median age 5 years; mean 8.5 years; just 16 registrants were > 65 years
Self-Reported Information by Questionnaire re Peanut and or Tree Nuts
• Median age of first exposure to peanut was at 12 months; first reaction 14 months
• Median age for first exposure to tree nuts 24 months with first reaction at 36 months
• Isolated peanut allergy 68%• Isolated tree nut allergy 9%• Co-allergy 23%
14
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Self Reported Locations for Reactions to Peanut and Tree Nuts
1st 2nd 3rd 1st 2nd 3rd
HomeSchoolRestaurantRelative/friendOther
Peanut Tree NutsSicherer S, et al. J Allergy Clin Immunol. 2001;108:128-32.
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Severity of an EpisodeNot Predictable
Sicherer SH, et al. J Allergy Clin Immunol. 2001;108:128-132.
*
**
*
*
1st reaction2nd reaction3rd reaction
Severe Epinephrine Severe Epinephrine
Peanuts Tree Nuts
60
50
40
30
20
10
0
Pe
rce
nt
*Indicates a reaction more severe than the previous reaction.
Emergency Department Anaphylaxis: A Review of 142 Patients in a Single Year
• JACI 2001;108:861-6• Data collected from 1998-1999 using ICD-9 codes
(allergy/allergic reaction, anaphylactic shock or reaction, angioedema, urticaria)
• Tertiary referral, university-affiliated teaching hospital in Brisbane, Australia
• ED visits = 162 patients with acute allergic reactions (Urticaria etc) and 142 patients with anaphylaxis
=
Emergency Department Anaphylaxis: A Review of 142 Patients in a Single Year
• Mean age 37 years; F/M 3:2• Potentially life threatening episode = 60 of the
142 patients (1 fatality)• Annual incidence = 1:439 cases in ED and
1:1000 cases in ED = severe ….higher than 1:1100 cases in ED and 1:1500 cases that are severe reported in the literature
• Population incidence = 1:3400 people/year
Emergency Department Anaphylaxis: A Review of 142 Patients in a Single Year
• “One severe case can be expected every week in a moderate-sized department”
• “A precipitant will be recognized in approximately three-forths of cases….”
WAO White Book on Allergy2011
• Potential severe future reactions….”the more rapid the onset, the smaller the dose of the causative agent required to trigger reactions, and previous severe reactions”
• Risk factors for fatal outcomes…”underlying asthma, particularly if poorly controlled, and cardiovascular disease”
• Case fatality rate (proportion of anaphylaxis that is fatal) is < 1% or 1-5.5/million people/year
Fatal Anaphylaxis: postmortem findings and associated comorbid diseases
• Ann Allergy Asthma Immunol 2007;98:252-57• 25 unselected cases over 12 years (2 with
asthma)• Mean age 59 years (17-91)• 17 year old with asthma (shrimp)• 91 year old with ischemic heart disease (ice
cream, possibly peanuts)
Fatal Anaphylaxis (cont.)
• Onset of anaphylaxis in 30 minutes after exposure in 21/25 cases
• Death occurred within 60 minutes in 13/25 cases
• Urticaria was present in 1/25 cases on postmortem exam; 3 cases with flushing or generalized pruritus
Self-Injectable Epinephrine?
• Previous reactions in 8/25 ( one each for radiocontrast material, shrimp, clams, penicillin; 3 for Hymenoptera stings; 1 unknown food)
• Self-administered epinephrine was available and used in 1 case….unknown food
Is There an Effect of Atopy on Anaphylaxis?Yes No
• Foods• Latex• Radiocontrast material• Asthma• Idiopathic anaphylaxis• Exercise induced
anaphylaxis
• Penicillin• Muscle relaxants• Hymenoptera stings• Insulin
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