WAO Anaphylaxis GuidelinesWAO Anaphylaxis Special Committee Epidemiology 7

WAO Anaphylaxis Guidelines-WAO Anaphylaxis Special Committee Epidemiology 7 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”

Increasing Anaphylaxis Hospitalizations Australia (1993 -2005) Hospitalizations Per 100, 000 Population 12 10 8 Angioedema Urticaria Anaphylaxis (any) 6 4 2 ICD-10 -AM introduced 0 1993 -94 1994 -95 1995 -96 1996 -97 1997 -98 1998 -991999 -2000 -01 2001 -02 2002 -03 2003 -04 2004 -05 Year ICD-10 -AM, International Classification of Diseases, 10 th revision, Australian modification. Poulos LM, et al. J Allergy Clin Immunol. 2007; 120: 878 -884. 6

Trend in Hospitalizations: First 2 Decades of Life 5 Hospitalizations Per 100, 000 4. 5 4 3. 5 New York (1990 -2006) Anaphylaxis Angioedema Urticaria Allergy unspecified 3 2. 5 2 1. 5 1 0. 5 0 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 Year Lin 7 RY, et al. Ann Allergy Asthma Immunol. 2008; 101: 387 -393.

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 -51 Dispensed 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 tree nut 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%

Self Reported Locations for Reactions to Peanut and Tree Nuts 100% 90% Home School 80% 70% Restaurant Relative/friend Other 60% 50% 40% 30% 20% 10% 0% 1 st 2 nd 3 rd 1 st 2 nd Peanut Sicherer S, et al. J Allergy Clin Immunol. 2001; 108: 128 -32. 14 3 rd Tree Nuts

Severity of an Episode Not Predictable 1 st reaction 2 nd reaction 3 rd reaction 60 Percent 50 40 * 30 * 20 * * * 10 0 Severe Epinephrine Severe Peanuts *Indicates a reaction more severe than the previous reaction. Sicherer SH, et al. J Allergy Clin Immunol. 2001; 108: 128 -132. 15 Epinephrine Tree Nuts

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 Allergy 2011 • 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 • • • Foods Latex Radiocontrast material Asthma Idiopathic anaphylaxis Exercise induced anaphylaxis No • • 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