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US prevalence of self-reported peanut, tree nut, and sesame allergy: 11-year follow-up

      Background

      Allergy to peanuts and tree nuts (TNs) is the leading cause of fatal allergic reactions in the United States, and the prevalence appears to be increasing.

      Objectives

      We sought to determine the US prevalence of self-reported peanut, TN, and sesame allergy in 2008 and compare results with comparable surveys conducted in 1997 and 2002.

      Methods

      A nationwide, cross-sectional, random telephone survey for peanut and TN allergy was conducted with a previously used questionnaire, with additional questions about sesame.

      Results

      A total of 5,300 households (13,534 subjects) were surveyed (participation rate, 42% vs 52% in 2002 and 67% in 1997). Peanut allergy, TN allergy, or both was reported by 1.4% of subjects (95% CI, 1.2% to 1.6%) compared with 1.2% in 2002 and 1.4% in 1997. For adults, the prevalence was 1.3% (95% CI, 1.1% to 1.6%), which was not significantly different from prior surveys. However, the prevalence of peanut or TN allergy for children younger than 18 years was 2.1% (95% CI, 1.6% to 2.7%) compared with 1.2% in 2002 (P = .007) and 0.6% in 1997 (P < .001). The prevalence of peanut allergy in children in 2008 was 1.4% (95% CI, 1.0% to 1.9%) compared with 0.8% in 2002 (P = not significant) and 0.4% in 1997 (P < .0001). The prevalence of childhood TN allergy increased significantly across the survey waves (1.1% in 2008, 0.5% in 2002, and 0.2% in 1997). Sesame allergy was reported by 0.1% (95% CI, 0.0% to 0.2%).

      Conclusions

      Although caution is required in comparing surveys, peanut allergy, TN allergy, or both continue to be reported by more than 1% of the US population (eg, >3 million subjects) and appear to be increasingly reported among children over the past decade. Sesame allergy is reported much less commonly.

      Key words

      Abbreviation used:

      TN (Tree nut)
      Discuss this article on the JACI Journal Club blog: www.jaci-online.blogspot.com.
      Food allergy significantly affects quality of life, and there is an impression that its prevalence is increasing.
      • Sicherer S.H.
      • Sampson H.A.
      Food allergy.
      • Sicherer S.H.
      • Sampson H.A.
      Peanut allergy: emerging concepts and approaches for an apparent epidemic.
      However, there are few studies that have monitored the prevalence of food allergy in the general population over time while consecutively using the same methods.
      • Sicherer S.H.
      • Muñoz-Furlong A.
      • Sampson H.A.
      Prevalence of peanut and tree nut allergy in the United States determined by means of a random digit dial telephone survey: a 5-year follow-up study.
      • Branum A.M.
      • Lukacs S.L.
      Food allergy among children in the United States.
      • Ben Shoshan M.
      • Kagan R.S.
      • Alizadehfar R.
      • Joseph L.
      • Turnbull E.
      • St Pierre Y.
      • et al.
      Is the prevalence of peanut allergy increasing? A 5-year follow-up study in children in Montreal.
      • Grundy J.
      • Matthews S.
      • Bateman B.
      • Dean T.
      • Arshad S.H.
      Rising prevalence of allergy to peanut in children: data from 2 sequential cohorts.
      • Mullins R.J.
      • Dear K.B.
      • Tang M.L.
      Characteristics of childhood peanut allergy in the Australian Capital Territory, 1995 to 2007.
      • Venter C.
      • Hasan A.S.
      • Grundy J.
      • Pereira B.
      • Bernie C.C.
      • Voigt K.
      • et al.
      Time trends in the prevalence of peanut allergy: three cohorts of children from the same geographical location in the UK.
      We previously reported the prevalence of self-reported peanut and tree nut (TN) allergies in the United States by using a random-calling telephone survey.
      • Sicherer S.H.
      • Muñoz-Furlong A.
      • Sampson H.A.
      Prevalence of peanut and tree nut allergy in the United States determined by means of a random digit dial telephone survey: a 5-year follow-up study.
      • Sicherer S.H.
      • Muñoz-Furlong A.
      • Burks A.W.
      • Sampson H.A.
      Prevalence of peanut and tree nut allergy in the US determined by a random digit dial telephone survey.
      Overall, in 2002 we found that 1.2% (95% CI, 1.0% to 1.4%) of the general US population reported a peanut or TN allergy.
      • Sicherer S.H.
      • Muñoz-Furlong A.
      • Sampson H.A.
      Prevalence of peanut and tree nut allergy in the United States determined by means of a random digit dial telephone survey: a 5-year follow-up study.
      We found that peanut allergy was reported by 0.8% of children younger than 18 years in 2002 compared with 0.4% in 1997 (P = .047). This finding of a doubling in prevalence over a short time period was similar to a report by Grundy et al,
      • Grundy J.
      • Matthews S.
      • Bateman B.
      • Dean T.
      • Arshad S.H.
      Rising prevalence of allergy to peanut in children: data from 2 sequential cohorts.
      who showed that among 2 separate birth cohorts, one from 1989 and another from 1994-1996, living on the Isle of Wight, the rate of peanut allergy for children 3 to 4 years of age increased from 0.5% (6/1,218) to 1% (13/1,273; P = .2). They also reported an increased sensitization rate to peanut from 1.1% to 3.3% (P = .001). Since these last 2 reports, several studies have indicated rates of peanut allergy exceeding 1% among children in Australia,
      • Mullins R.J.
      • Dear K.B.
      • Tang M.L.
      Characteristics of childhood peanut allergy in the Australian Capital Territory, 1995 to 2007.
      Canada,
      • Ben Shoshan M.
      • Kagan R.S.
      • Alizadehfar R.
      • Joseph L.
      • Turnbull E.
      • St Pierre Y.
      • et al.
      Is the prevalence of peanut allergy increasing? A 5-year follow-up study in children in Montreal.
      and the United Kingdom.
      • Hourihane J.O.
      • Aiken R.
      • Briggs R.
      • Gudgeon L.A.
      • Grimshaw K.E.
      • Dunngalvin A.
      • et al.
      The impact of government advice to pregnant mothers regarding peanut avoidance on the prevalence of peanut allergy in United Kingdom children at school entry.
      • Du Toit G.
      • Katz Y.
      • Sasieni P.
      • Mesher D.
      • Maleki S.J.
      • Fisher H.R.
      • et al.
      Early consumption of peanuts in infancy is associated with a low prevalence of peanut allergy.
      Allergy to sesame, often considered an emerging allergen, has been estimated to affect 0.10 to 0.79% of children from studies outside of the United States.
      • Du Toit G.
      • Katz Y.
      • Sasieni P.
      • Mesher D.
      • Maleki S.J.
      • Fisher H.R.
      • et al.
      Early consumption of peanuts in infancy is associated with a low prevalence of peanut allergy.
      • Zuidmeer L.
      • Goldhahn K.
      • Rona R.J.
      • Gislason D.
      • Madsen C.
      • Summers C.
      • et al.
      The prevalence of plant food allergies: a systematic review.
      • Venter C.
      • Pereira B.
      • Grundy J.
      • Clayton C.B.
      • Arshad S.H.
      • Dean T.
      Prevalence of sensitization reported and objectively assessed food hypersensitivity amongst six-year-old children: a population-based study.
      • Dalal I.
      • Binson I.
      • Reifen R.
      • Amitai Z.
      • Shohat T.
      • Rahmani S.
      • et al.
      Food allergy is a matter of geography after all: sesame as a major cause of severe IgE-mediated food allergic reactions among infants and young children in Israel.
      There have not been any follow-up studies to determine the prevalence of peanut or TN allergies in the United States. We therefore undertook the current study by using the same methodologies we applied in 1997 and 2002 to compare the current rates of self-reported peanut and TN allergies with those of the previous surveys. Because sesame allergy is increasingly reported and is potentially severe,
      • Derby C.J.
      • Gowland M.H.
      • Hourihane J.O.
      Sesame allergy in Britain: a questionnaire survey of members of the Anaphylaxis Campaign.
      we added queries about this food in the current study.

      Methods

       Survey methods

      The survey was a nationwide, cross-sectional, computer-assisted telephone interview performed by TMR, Inc, OpinionMD Division (Broomall, Pa). The survey was administered through the same computer-assisted survey technology and the same sampling system as the 2 previous surveys; the company performing the interviews was different but specializes in the same approach as the previously used vendor. The current survey was conducted from September 27, 2008, to December 22, 2008; the first survey was conducted from April 2, 1997, to June 10, 1997,
      • Sicherer S.H.
      • Muñoz-Furlong A.
      • Burks A.W.
      • Sampson H.A.
      Prevalence of peanut and tree nut allergy in the US determined by a random digit dial telephone survey.
      and the second was conducted from June 24, 2002, to August 7, 2002.
      • Sicherer S.H.
      • Muñoz-Furlong A.
      • Sampson H.A.
      Prevalence of peanut and tree nut allergy in the United States determined by means of a random digit dial telephone survey: a 5-year follow-up study.
      The Genesys Sampling System (Fort Washington, Pa) was used to generate a random sampling of telephone numbers, not including cell phones, for the 48 contiguous states. Interviews were conducted by trained telephone medical interviewers. Calling times and patterns were identical to the prior surveys. Briefly, at least 10 attempts were made to contact a resident of each household. Calling was done between the hours of 3 and 9 pm (local time) Monday through Thursday and 10 am until 5 pm Eastern standard time on Saturday to minimize selection bias related to availability.

       Questionnaire contents, selection of eligible respondents, rules for surrogates, definitions, and data processing

      Federal regulations pertaining to consent procedures and subject confidentiality were strictly observed, and the study was approved by the Essex (Lebanon, NJ) and Mount Sinai School of Medicine Institutional Review Boards. Respondents were eligible if they were 18 years of age or older, were living in the household, and understood the questions without a language/mental/hearing barrier. The initial age-eligible household respondent was invited to participate in the survey. If this respondent was not allergic to peanuts, TNs, or sesame, he or she was asked to identify subjects within the household who were allergic. If the affected subject was a minor, the initial respondent acted as a surrogate and completed the interview, or if unable, another adult was sought. If the affected subject or subjects were adults and unavailable, the household was recontacted until the affected subject could be interviewed. However, unlike the previous survey, census data were collected with the initial respondent in the event the affected subject was not available despite multiple attempts. Census data were also collected for all household members if no household resident was allergic to peanuts, TNs, or sesame. In households with 1 or more persons allergic to peanuts or TNs, the entire interview was conducted with each allergic person (or surrogate for children). Details of reactions in adults were only included when the affected adult was personally interviewed. For subjects who reported peanut, TN, or sesame allergy, further specific questions were administered to determine the details of the allergic reactions. Queries regarding sesame allergy were introduced after the peanut and TN allergy queries so as not to alter the comparability of the current survey with previous ones.
      Reactions were considered to be “convincing” if the organ systems affected and symptoms were typical of those involved in allergic reactions (skin with hives and angioedema; respiratory tract with trouble breathing, wheezing, or throat tightness; and gastrointestinal tract with vomiting and diarrhea) and occurred within 2 hours of ingestion. A previous study with these symptoms as criteria for a convincing acute allergic reaction to peanut or TN found that most subjects (93%) had IgE antibody to the implicated food.
      • Sicherer S.H.
      • Burks A.W.
      • Sampson H.A.
      Clinical features of acute allergic reactions to peanut and tree nuts in children.
      Because the survey used a multilevel sampling frame in which households were contacted and then subjects were assessed, potential correlation among family members was addressed by calculating the estimated proportion and its SE by using methods for 2-stage cluster sampling with unequal numbers of secondary units in the clusters. The pairwise comparison of prevalence between any 2 time periods was done with a z test for comparing 2 binomial proportions. The Cochran-Armitage trend test was used to compare prevalence across the 3 survey waves.

      Results

       Participation rate

      A total of 12,683 households were contacted: 6,578 (51.8%) refused to participate, and an additional 807 (6.4%) were ineligible (age <18 years, n = 32; language barrier, n = 775). The total of 5,300 participating households represented a census of 13,534 subjects. The overall participation rate of 5,300 (42%) from the 12,658 households contacted was lower than that for the 2002 survey (52%, P < .001) and the 1997 survey (67%, P < .001).

       Demographic characteristics of participants and reported rates of peanut and TN allergy

      A total of 188 households (3.6%; 95% CI, 3.1% to 4.1%) reported 1 or more subjects with peanut allergy, TN allergy, or both, a rate similar to the 1997 (3.5%) and 2002 (3.3%) studies. Rates of reported allergy to peanut, TN, or both according to age are shown in Table I. Overall, the rate of any peanut allergy, TN allergy, or both among adults (1.3%; 95% CI, 1.1% to 1.6%) was lower than among children younger than 18 years (2.1%; 95% CI, 0.2% to 2.6%; P = .005). The number of subjects reporting allergy to each TN was as follows: walnut, 41; cashew, 29; pecan, 26; almond, 25; pistachio, 19; Brazil nut, 19; hazel nut, 17; Macadamia nut, 17; and pine nut, 11. The distribution of reported peanut and TN allergy according to race/ethnicity and sex according to age is shown in Table II. Race/ethnicity was only determined from the responding household member, and calculations therefore assume all household members are of the same race/ethnicity presented in a manner as previously queried (eg, not differentiating race from ethnicity). There is an overall male predominance of peanut/TN allergy reported in children and female predominance in adults, but these did not reach statistical significance. There were no significant differences in rates of allergy to peanut or TNs by geographic region (data not shown).
      Table IPrevalence of peanut and TN allergy in 2008 by age
      Type of nut allergy
      Total sample populationAny nut
      “Any nut” is reported nut allergy including peanuts, TNs, or unspecified nut.
      Both peanut and TNPeanut onlyTN onlyUnspecified nut
      n = 13,534No.Percent (± 95% CI)No.Percent (± 95% CI)No.Percent (± 95% CI)No.Percent (± 95% CI)No.Percent (± 95% CI)
      Age (y)
       0-5860182.1 (1.3-3.3)40.5 (0.1-1.2)80.9 (0.4-1.8)40.5 (0.1-1.2)20.2 (0.0-0.8)
       6-10861222.6 (1.6-3.8)70.8 (0.3-1.7)111.3 (0.6-2.3)40.4 (0.1-1.2)00.0 (NA)
       11-171,151201.7 (1.1-2.7)20.2 (0.0-0.6)80.7 (0.3-1.4)90.8 (0.4-1.5)10.1 (0.0-0.5)
       18-2045681.8 (0.8-3.4)00.0 (NA)20.4 (0.1-1.6)10.2 (0.0-1.2)51.1 (0.4-2.5)
       21-301,019161.6 (1.0-2.5)30.3 (0.1-0.9)20.2 (0.0-0.7)50.5 (0.2-1.1)60.6 (0.2-1.3)
       31-401,311181.4 (0.8-2.2)30.2 (0.1-0.7)80.6 (0.3-1.2)40.3 (0.1-0.8)30.2 (0.1-0.7)
       41-501,754281.6 (1.1-2.3)30.2 (0.0-0.5)100.6 (0.3-1.1)80.5 (0.2-0.9)70.4 (0.2-0.8)
       51-601,894201.1 (0.7-1.6)30.2 (0.0-0.5)70.4 (0.2-0.8)50.3 (0.1-0.6)50.3 (0.1-0.6)
       61-6461091.5 (0.7-2.8)00.0 (NA)20.3 (0.0-1.2)50.8 (0.3-1.9)20.3 (0.0-1.2)
       ≥652,481321.3 (0.9-1.8)10.0 (0.0-0.2)180.7 (0.4-1.1)110.4 (0.2-0.8)20.1 (0.0-0.3)
      Not reported (<18)4312.3 (0.1-12.3)00.0 (NA)00.0 (NA)12.3 (0.1-12.3)00.0 (NA)
      Not reported (>18)51820.4 (0.1-1.4)00.0 (NA)10.2 (0.0-1.1)10.2 (0.0-1.1)00.0 (NA)
      Overall13,5341941.4 (1.2-1.7)260.2 (0.1-0.3)770.6 (0.5-0.7)580.4 (0.3-0.6)330.2 (0.2-0.3)
      NA, Not applicable.
      “Any nut” is reported nut allergy including peanuts, TNs, or unspecified nut.
      Table IIPrevalence of peanut and TN allergy by race, ethnicity, and sex by age
      Type of nut allergy
      Any nut
      “Any nut” is reported nut allergy including peanuts, TNs, or unspecified.
      Both peanut and TNIsolated peanutIsolated TNUnspecified nut
      Total populationNo.Percent (± 95% CI)No.Percent (± 95% CI)No.Percent (± 95% CI)No.Percent (± 95% CI)No.Percent (± 95% CI)
      Race/ethnicity
       White10,3171451.4 (1.2-1.7)1431.4 (1.2-1.6)20.0 (0.0-0.1)10.0 (0.0-0.1)170.2 (0.1-0.3)
       African American/black1,290241.9 (1.2-2.8)241.9 (1.2-2.8)20.2 (0.0-0.6)00.0 (NA)50.4 (0.1-0.9)
       Hispanic942121.3 (0.7-2.2)111.2 (0.6-2.1)00.0 (NA)00.0 (NA)00.0 (NA)
       Other527101.9 (0.9-3.5)101.9 (0.9-3.5)00.0 (NA)00.0 (NA)00.0 (NA)
       Not reported45861.3 (0.5-2.8)61.3 (0.5-2.8)00.0 (NA)10.2 (0.0-1.2)00.0 (NA)
      Sex/age
       Male (<18 y)1,535372.4 (1.7-3.3)90.6 (0.3-1.1)161.0 (0.6-1.7)90.6 (0.3-1.1)30.2 (0.0-0.6)
       Female sex (<18 y)1,367231.7 (1.1-2.5)30.2 (0.1-0.6)110.8 (0.4-1.4)90.7 (0.3-1.2)00.0 (NA)
       Male sex (>18 y)4,530521.2 (0.9-1.5)40.1 (0.0-0.3)200.4 (0.3-0.7)130.3 (0.2-0.5)150.3 (0.2-0.6)
       Female sex (>18 y)5,315811.5 (1.2-1.9)90.2 (0.1-0.3)300.6 (0.4-0.8)270.5 (0.3-0.7)150.3 (0.2-0.5)
      NA, Not applicable.
      “Any nut” is reported nut allergy including peanuts, TNs, or unspecified.
      The reported rates of allergy in the 3 survey years 1997, 2002, and 2008 are shown in Table III. There were no significant differences in the rates of reported peanut or TN allergy among adults. From 2002 to 2008, there were significant increases of children reported with peanut/TN allergy (from 1.2% to 2.1%, P = .007) and TN allergies (from 0.5% to 1.1%, P = .022), but the increase in peanut allergy in children did not reach statistical significance (from 0.8% to 1.4%, P = .058). There had been significant increases in self-reported total peanut/TN allergy (from 0.6% to 1.2%, P = .023), peanut allergy (from 0.4% to 0.8%, P = .047), and TN allergy (from 0.2% to 0.5%, P = .037) between the earlier surveys from 1997 to 2002,
      • Sicherer S.H.
      • Muñoz-Furlong A.
      • Sampson H.A.
      Prevalence of peanut and tree nut allergy in the United States determined by means of a random digit dial telephone survey: a 5-year follow-up study.
      and therefore the 1997 to 2008 increases were significantly different, with P values of less than .0001. Similarly, trend analysis of the increasing proportions of children reported with any nut, peanut, or TN allergies was significant (P < .0001) across the 3 surveys.
      Table IIIComparison of reported peanut and TN allergies among the 1997, 2002, and 2008 surveys
      CensusAny nutBoth peanut and TNTotal peanutTotal TNUnspecified nut
      Age199720022008199720022008199720022008199720022008199720022008199720022008
      Child <18 y2,9983,1272,91518 (0.6%)37 (1.2%)61 (2.1%)9 (0.3%)13 (0.4%)12 (0.4%)26 (0.8%)40 (1.4%)5 (0.2%)16 (0.5%)31 (1.1%)1 (0%)4 (0.1%)3 (0.1%)
      Adult8,0499,88110,043131 (1.6%)126 (1.3%)133 (1.3%)423 (0.2%)13 (0.1%)59 (0.7%)58 (0.6%)63 (0.6%)59 (0.7%)73 (0.7%)53 (0.5%)17 (0.2%)18 (0.2%)30 (0.3%)
      Unknown98548557615 (1.5%)3 (0.6%)15 (1.5%)3 (0.6%)
      Total12,03213,49313,534164 (1.4%)166 (1.2%)194 (1.4%)432 (0.3%)26 (0.2%)71 (0.6%)84 (0.6%)103 (0.8%)64 (0.5%)89 (0.7%)84 (0.6%)33 (0.3%)25 (0.2%)30 (0.2%)
      Increases in any nut, total peanut, and total TN allergies among children were significantly greater across survey waves (P value trend < .001). Between 2002 and 2008, increases were significant for children for any nut (P = .007) and total TN (P = .022) but not for total peanut (P = .058).

       Adjusted prevalence

      Information about clinical reactions was available for 146 (75%) of 194 subjects (93 adults and 53 children). Reactions were not convincing for 18 adults (nasal symptoms only, n = 3; hives after 2 hours [all also had recurrent reactions], n = 3; gastrointestinal symptoms after 2 hours, n = 6; migraine/headache, n = 3; and convincing symptoms but delayed onset [but all had recurrent reactions], n = 3) and 3 children (nasal symptoms only for 1 and multisystem recurrent reactions for 2 but delayed over 2 hours). Thus 21 (14.4%) of 146 with complete information did not have convincing reactions. If a similar rate of unconvincing reactions occurred among the 48 subjects without clinical details, a total of 27 persons would be excluded, leaving 167 with convincing symptoms for their first reaction. Reducing the total by another 7% to reflect the potential false-positive rate of the survey,
      • Sicherer S.H.
      • Burks A.W.
      • Sampson H.A.
      Clinical features of acute allergic reactions to peanut and tree nuts in children.
      155 persons would remain, resulting in an adjusted prevalence of 1.15% (95% CI, 1.0% to 1.3%), which is not significantly different compared with the adjusted prevalence rate in 1997 (1.1%) and 2002 (1.04%).

       Sesame allergies

      A total of 13 subjects reported allergy to sesame (3 children and 10 adults), 0.1% of each age group (95% CI, 0% to 0.2%). Only 3 persons reported isolated sesame allergy; the remainder also reported allergy to peanut (n = 2), TNs (n = 1), or both/unspecified (n = 7).

      Discussion

      We have focused on peanut and TN allergies during each of 3 periodic US telephone surveys because allergies to these foods are often severe and rarely outgrown.
      • Sicherer S.H.
      • Sampson H.A.
      Peanut allergy: emerging concepts and approaches for an apparent epidemic.
      Our study is particularly unique because we determined peanut and TN allergy prevalence in the general US population using the same methods over time. Except for our national seafood allergy survey,
      • Sicherer S.H.
      • Muñoz-Furlong A.
      • Sampson H.A.
      Prevalence of seafood allergy in the United States determined by a random telephone survey.
      we are not aware of US food allergy prevalence studies that incorporate all age groups with a national sample. In our current study, although the total population prevalence of self-reported peanut allergy, TN allergy, or both did not increase among adults since 1997, there was a significant increase in self-reported allergies among children. In the group younger than 18 years, TN allergies increased from 0.2% in 1997 to 1.1% in 2008, and peanut allergy increased from 0.4% to 1.4%. Although this increase appears remarkable, the current estimate (eg, 1.4% of children affected with peanut allergy) is similar to recent reports from Canada (1.63% of kindergarten through third grade),
      • Ben Shoshan M.
      • Kagan R.S.
      • Alizadehfar R.
      • Joseph L.
      • Turnbull E.
      • St Pierre Y.
      • et al.
      Is the prevalence of peanut allergy increasing? A 5-year follow-up study in children in Montreal.
      the United Kingdom (1.85% of Jewish schoolchildren,
      • Du Toit G.
      • Katz Y.
      • Sasieni P.
      • Mesher D.
      • Maleki S.J.
      • Fisher H.R.
      • et al.
      Early consumption of peanuts in infancy is associated with a low prevalence of peanut allergy.
      1.2% of a birth cohort of 3-year-olds,
      • Venter C.
      • Hasan A.S.
      • Grundy J.
      • Pereira B.
      • Bernie C.C.
      • Voigt K.
      • et al.
      Time trends in the prevalence of peanut allergy: three cohorts of children from the same geographical location in the UK.
      and 1.8% of schoolchildren
      • Hourihane J.O.
      • Aiken R.
      • Briggs R.
      • Gudgeon L.A.
      • Grimshaw K.E.
      • Dunngalvin A.
      • et al.
      The impact of government advice to pregnant mothers regarding peanut avoidance on the prevalence of peanut allergy in United Kingdom children at school entry.
      ), and Australia (1.15% in the Australian Capital Territory
      • Mullins R.J.
      • Dear K.B.
      • Tang M.L.
      Characteristics of childhood peanut allergy in the Australian Capital Territory, 1995 to 2007.
      ), where the studies additionally included evaluations, such as physicians' diagnoses, allergy tests, and food challenges. Hypotheses as to the reason for the increased rate of peanut allergies in children include increased allergenicity of roasted forms of peanut, early introduction of peanut when the immune system is immature, delayed introduction of peanut into the diet, and environmental exposures to peanut without ingestion.
      • Sicherer S.H.
      • Sampson H.A.
      Peanut allergy: emerging concepts and approaches for an apparent epidemic.
      • Lack G.
      Epidemiologic risks for food allergy.
      • Fox A.T.
      • Sasieni P.
      • Du Toit G.
      • Syed H.
      • Lack G.
      Household peanut consumption as a risk factor for the development of peanut allergy.
      Statistics from the United States Department of Agriculture (http://www.ers.usda.gov/Data/FoodConsumption/FoodAvailSpreadsheets.htm; accessed March 21, 2010) indicate relatively level availability of peanut in the United States over the past 40 years and almost a doubling of availability of TNs; it does not appear that availability alone would account for the results noted in this study.
      Only a few other studies have evaluated peanut allergy rates using similar methods over time. Ben Shoshan et al
      • Ben Shoshan M.
      • Kagan R.S.
      • Alizadehfar R.
      • Joseph L.
      • Turnbull E.
      • St Pierre Y.
      • et al.
      Is the prevalence of peanut allergy increasing? A 5-year follow-up study in children in Montreal.
      evaluated Montreal schoolchildren in kindergarten through third grade and reported for the 2000-2002 cohort a peanut allergy rate of 1.50% (95% CI, 1.2% to 1.9%) and in 2005-2007 a rate of 1.63% (95% CI, 1.3% to 2.0%). This increase was not statistically significant. Venter et al
      • Venter C.
      • Hasan A.S.
      • Grundy J.
      • Pereira B.
      • Bernie C.C.
      • Voigt K.
      • et al.
      Time trends in the prevalence of peanut allergy: three cohorts of children from the same geographical location in the UK.
      recently reported their third peanut prevalence study using a birth cohort on the Isle of Wight, United Kingdom. The rates of sensitization to peanut in 3- or 4-years-olds born in 1989, 1994-1996, and 2001-2002 were 1.3%, 3.3%, and 2.0%, and rates of clinical peanut allergy were 0.5%, 1.4%, and 1.2%, respectively. Although rates increased between 1989 and 1994, they stabilized or slightly decreased in the most recent cohort. These results might have been influenced by differences in participant age, participation rates, and selection between their studies, but their more recent results, peanut allergy prevalence rates of 1.2% to 1.4%, are similar to ours. Environmental influences on the outcome of peanut allergy are being aggressively studied,
      • Fox A.T.
      • Sasieni P.
      • Du Toit G.
      • Syed H.
      • Lack G.
      Household peanut consumption as a risk factor for the development of peanut allergy.
      • Sicherer S.H.
      • Wood R.A.
      • Stablein D.
      • Burks A.W.
      • Liu A.H.
      • Jones S.M.
      • et al.
      Immunologic features of infants with milk or egg allergy enrolled in an observational study (Consortium of Food Allergy Research) of food allergy.
      and the influence of recommendations that at-risk families avoid peanut during pregnancy, lactation, and for the first 3 years of a child's life remain uncertain.
      • Venter C.
      • Hasan A.S.
      • Grundy J.
      • Pereira B.
      • Bernie C.C.
      • Voigt K.
      • et al.
      Time trends in the prevalence of peanut allergy: three cohorts of children from the same geographical location in the UK.
      • Du Toit G.
      • Katz Y.
      • Sasieni P.
      • Mesher D.
      • Maleki S.J.
      • Fisher H.R.
      • et al.
      Early consumption of peanuts in infancy is associated with a low prevalence of peanut allergy.
      Given the lack of evidence that extended periods of food allergen avoidance alter atopic disease, prior US recommendations to avoid peanut until age 3 years were rescinded in 2008.
      • Greer F.R.
      • Sicherer S.H.
      • Burks A.W.
      Effects of early nutritional interventions on the development of atopic disease in infants and children: the role of maternal dietary restriction, breastfeeding, timing of introduction of complementary foods, and hydrolyzed formulas.
      We added queries regarding sesame allergy to the 2008 survey because this allergy is increasingly reported from other countries
      • Venter C.
      • Pereira B.
      • Grundy J.
      • Clayton C.B.
      • Arshad S.H.
      • Dean T.
      Prevalence of sensitization reported and objectively assessed food hypersensitivity amongst six-year-old children: a population-based study.
      • Dalal I.
      • Binson I.
      • Reifen R.
      • Amitai Z.
      • Shohat T.
      • Rahmani S.
      • et al.
      Food allergy is a matter of geography after all: sesame as a major cause of severe IgE-mediated food allergic reactions among infants and young children in Israel.
      • Derby C.J.
      • Gowland M.H.
      • Hourihane J.O.
      Sesame allergy in Britain: a questionnaire survey of members of the Anaphylaxis Campaign.
      • Dalal I.
      • Binson I.
      • Levine A.
      • Somekh E.
      • Ballin A.
      • Reifen R.
      The pattern of sesame sensitivity among infants and children.
      and the US prevalence has not been evaluated. We found that that sesame allergy was reported by 0.1% of adults and children. In a population-based study of 6-year-olds in the United Kingdom that included open oral food challenges, 0.1% had sesame allergy.
      • Venter C.
      • Pereira B.
      • Grundy J.
      • Clayton C.B.
      • Arshad S.H.
      • Dean T.
      Prevalence of sensitization reported and objectively assessed food hypersensitivity amongst six-year-old children: a population-based study.
      Studies from Israel that include surveys or allergy tests estimate 0.13% to 0.2% affected children.
      • Du Toit G.
      • Katz Y.
      • Sasieni P.
      • Mesher D.
      • Maleki S.J.
      • Fisher H.R.
      • et al.
      Early consumption of peanuts in infancy is associated with a low prevalence of peanut allergy.
      • Dalal I.
      • Binson I.
      • Reifen R.
      • Amitai Z.
      • Shohat T.
      • Rahmani S.
      • et al.
      Food allergy is a matter of geography after all: sesame as a major cause of severe IgE-mediated food allergic reactions among infants and young children in Israel.
      A questionnaire study of Jewish children in the United Kingdom estimated 0.79% affected.
      • Du Toit G.
      • Katz Y.
      • Sasieni P.
      • Mesher D.
      • Maleki S.J.
      • Fisher H.R.
      • et al.
      Early consumption of peanuts in infancy is associated with a low prevalence of peanut allergy.
      Meta-analyses of population-based studies evaluating perceived allergy, sensitization, or challenge tests indicate prevalence rates of 0.1% to 0.9%.
      • Zuidmeer L.
      • Goldhahn K.
      • Rona R.J.
      • Gislason D.
      • Madsen C.
      • Summers C.
      • et al.
      The prevalence of plant food allergies: a systematic review.
      Although the population prevalence in our study is low relative to peanut/TN allergy, the severity of sesame allergy and the frequency of concomitant allergy with peanuts or TNs should not be underappreciated.
      • Derby C.J.
      • Gowland M.H.
      • Hourihane J.O.
      Sesame allergy in Britain: a questionnaire survey of members of the Anaphylaxis Campaign.
      Our study has several limitations inherent to telephone surveys and to self-reported diagnosis of allergy. Telephone surveys might overrepresent persons with a high socioeconomic status because homes without telephones are excluded and homes with multiple voice lines are more likely to be selected.
      • Waksberg J.
      Sampling methods for random digit dialing.
      We did not query income levels to monitor this effect, although presumably any such bias would be similar across survey waves. Participation in telephone surveys has been decreasing in general, likely because of privacy concerns and increasing use of telephones for marketing and sales.
      • Mellinger-Birdsong A.K.
      • Powell K.E.
      • Iatridis T.
      • Bason J.
      Prevalence and impact of asthma in children, Georgia, 2000.
      Indeed, the overall participation rate in our survey was proportionately lower for each survey wave, as might be expected. Although refusal rates increased, the relative consistency of the results among survey waves suggests the findings are predictive of the larger US population. It should be noted that respondents do not know that the survey entails queries about allergy until after they have agreed or not agreed to participate. An additional possible bias is the migration of households from landlines to cellular telephones; about 15% of households are cellular only.
      • Blumberg S.J.
      • Luke J.V.
      • Davidson G.
      • Davern M.E.
      • Yu T.C.
      • Soderberg K.
      Wireless substitution: state-level estimates from the National Health Interview Survey, January-December 2007.
      However, to maintain comparability with prior surveys, we did not include cellular telephones. An additional subtle bias could include the availability of a household member; we attempted to reduce this concern by calling at different times and days, including weekends and evenings. If the prevalence of peanut/TN allergy is increasing in children and the allergy is not outgrown, we might predict an increase in young adults over the survey waves. This trend was not observed thus far, possibly because of relatively low numbers of subjects surveyed when evaluating subgroups by age, although such a trend will be interesting to follow in future surveys.
      There are also limitations of the survey instrument to identify true allergy. The gold standard for diagnosing food allergy is the double-blind, placebo-controlled oral food challenge.
      • Nowak-Wegrzyn A.
      • Assa′ad A.H.
      • Bahna S.L.
      • Bock S.A.
      • Sicherer S.H.
      • Teuber S.S.
      Work Group report: oral food challenge testing.
      It was clearly not practical in this study to challenge subjects culled from the general population. However, peanut and TN reactions are usually acute and severe, and hence the false-positive rate of historical determination of allergy is generally low. In a study using this questionnaire instrument, 7% of 111 patients with convincing histories of acute reactions to peanut or TNs did not have detectable peanut or TN-specific serum IgE antibody.
      • Sicherer S.H.
      • Burks A.W.
      • Sampson H.A.
      Clinical features of acute allergic reactions to peanut and tree nuts in children.
      Taking these limitations into account and including adjustments in which self-reported reactions that were not convincing were excluded, we conservatively report an overall rate of peanut and TN allergy in the United States of 1.15% (95% CI, 1.0% to 1.3%), representing more than 3 million Americans. It should be appreciated, as described in the results, that many of the subjects excluded because of the unconvincing nature of their reaction had convincing symptoms with a delayed onset, had recurrent reactions, or both; therefore our adjusted prevalence rates are potentially quite conservative. It is also notable, as described above, that our estimates of peanut allergy in children are similar to rates reported from several international studies in westernized countries that included allergy testing and food challenges.
      • Ben Shoshan M.
      • Kagan R.S.
      • Alizadehfar R.
      • Joseph L.
      • Turnbull E.
      • St Pierre Y.
      • et al.
      Is the prevalence of peanut allergy increasing? A 5-year follow-up study in children in Montreal.
      • Mullins R.J.
      • Dear K.B.
      • Tang M.L.
      Characteristics of childhood peanut allergy in the Australian Capital Territory, 1995 to 2007.
      • Venter C.
      • Hasan A.S.
      • Grundy J.
      • Pereira B.
      • Bernie C.C.
      • Voigt K.
      • et al.
      Time trends in the prevalence of peanut allergy: three cohorts of children from the same geographical location in the UK.
      • Du Toit G.
      • Katz Y.
      • Sasieni P.
      • Mesher D.
      • Maleki S.J.
      • Fisher H.R.
      • et al.
      Early consumption of peanuts in infancy is associated with a low prevalence of peanut allergy.
      In summary, we have documented a similar overall rate of peanut and TN allergy in the United States in 2008, as was noted in 1997 and 2002; however, over this 11-year period, there was an apparent increase in self-reported peanut and TN allergies among children. This noted increase must be interpreted with caution because of uncontrolled factors related to sampling and population composition. Sesame allergy is reported by 0.1% of the general population. Our survey has consistently shown that more than 1% of the population or more than 3 million Americans report peanut allergies, TN allergies, or both, representing a significant health burden. Better strategies for prevention and treatment are desperately needed,
      • Sicherer S.H.
      • Sampson H.A.
      Food allergy: recent advances in pathophysiology and treatment.
      particularly if we will be seeing a significant increase of these persistent allergies with time.
      Clinical implications
      Peanut and TN allergies are common, affecting more than 1% of the US population, and the rates appear to be increasing among children.
      We thank Michelle A. Collins, Roger A. Straus, PhD, and Christopher Sutherland, PhD, of TMR, Inc-OpinionMD Division, Broomall, Pa, for assistance with data management and analysis. This research was funded by the Food Allergy Initiative (FAI) , New York. Past surveys were funded by FAI, the Jaffe Family Foundation, and the Food Allergy & Anaphylaxis Network .

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      Linked Article

      • Correction
        Journal of Allergy and Clinical ImmunologyVol. 130Issue 1
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          With regard to the June 2010 article “US prevalence of self-reported peanut, tree nut, and sesame allergy: 11-year follow-up” (J Allergy Clin Immunol 2010;125:1322-6), some of the numbers in the top half of Table II are incorrect. A corrected version of the table appears below.
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