WAO Anaphylaxis Guidelines-WAO Anaphylaxis Special Committee

Epidemiology7 December 2011

Workshop 25

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”

6

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

JACI;2002:110:647-51Dispensed Self-Injectable Epinephrine

Dispensed Self-Injectable Epinephrine In Children < 5 Years of Age

Events in Established Patients with Peanut and or Tree Nut Allergy

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.

15

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

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