allergy
Optimal skin prick wheal size for diagnosis of cat allergy.

Zarei M, Remer CF, Kaplan MS, Staveren AM, Lin CK, Razo E, Goldberg B.

Department of Allergy, Center for Medical Education, Kaiser Permanente Medical Center, Los Angeles, California, USA.

BACKGROUND: The skin prick test is the diagnostic procedure of choice for determination of immediate hypersensitivity. A wheal diameter of 3 mm or larger is generally accepted as the cutoff for a positive test result, although the validity of this assumption has not been rigorously demonstrated. OBJECTIVE: To determine the skin prick wheal size that best identifies clinical allergy to cat. METHODS: Forty-five patients referred for evaluation of rhinoconjunctivitis underwent determination of atopic status by skin testing using the Greer Dermapik device and a combination of other modalities, including history, in vitro determination of specific IgE level, and nasal challenge with standardized cat pelt extract. Parameters evaluated before and after nasal challenge included symptom score and nasal lavage tryptase and prostaglandin D (PGD2) levels. RESULTS: The widely accepted 3-mm wheal for a positive skin test result to cat is highly sensitive but only moderately specific for diagnosis of cat allergy as evaluated by history, specific IgE level, postchallenge symptom score, and tryptase and PGD2 levels. Optimal cutoffs for a positive skin test result to cat based on receiver operating characteristic analysis and 95% positive predictive value were 5.5 mm or greater for each of these parameters. When a true-positive result for cat allergy was defined as a combination of positive history, specific IgE level, postchallenge symptom score, and tryptase and PGD2 levels and a true-negative result as all of these parameters being negative, a 6-mm cutoff was able to distinguish cat allergic from cat nonallergic individuals. CONCLUSION: In a potentially allergic population undergoing skin prick testing with the Greer Dermapik using standardized extracts, a 3-mm skin prick wheal will overestimate the presence of cat allergy. A 6-mm wheal appears to distinguish those individuals who are cat allergic from those who are not.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15237761&dopt=Abstract allergy medicine



allergy
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 SH, Munoz-Furlong A, Sampson HA.

Department of Pediatrics, Mount Sinai School of Medicine, New York, NY 10029-6574, USA.

BACKGROUND: Allergy to peanuts and tree nuts (TNs) is the leading cause of fatal and near-fatal food allergic reactions. Peanut allergy appears to be increasing in prevalence. OBJECTIVES: We sought to determine the prevalence of self-reported peanut and TN allergy among the general population of the United States in 2002 by sex and age and to compare the results with prevalence estimates obtained 5 years earlier. METHODS: We performed a nationwide, cross-sectional, random telephone survey by using a standardized questionnaire. RESULTS: A total of 4855 households participated (53% participation rate), representing a census of 13,493 individuals. Peanut allergy, TN allergy, or both was self-reported in 166 (1.2%; 95% CI, 1.0%-1.4%) individuals in 155 (3.2%; 95% CI, 2.7%-3.7%) households, overall prevalence rates similar to those reported in 1997. Also similar to the 1997 survey, the severity level was high, with 79% reporting respiratory or multiple organ system reactions and 66% experiencing more than 5 lifetime reactions. Despite the severity and reaction frequency, only 74% of the children and 44% of the adults sought evaluation for the allergy, and fewer than half who did were prescribed self-injectable epinephrine. Applying conservative rules to adjust for persons with unconvincing reactions and a false-positive rate of the survey instrument (7%), a final prevalence estimate of 1.04% (95% CI, 0.9%-1.24%) was obtained. A male predominance of peanut-TN allergy was reported in children younger than 18 years (1.7% vs 0.7%, P =.02), and a female predominance was reported among adults (1.7% vs 0.9%, P =.0008). Although the rate of peanut allergy, TN allergy, or both was not significantly different from 1997 to 2002 among adults, the rate increased from 0.6% to 1.2% among children, primarily as a result of an increase in reported allergy to peanut (0.4% in 1997 to 0.8% in 2002, P =.05). CONCLUSIONS: Self-reported peanut allergy has doubled among children from 1997 to 2002, and peanut allergies, TN allergies, or both continue to be reported by more than 3 million Americans. Considering that reactions are severe and the allergy is persistent, these allergies represent an increasing health concern.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14657884&dopt=Abstract allergy medicine



allergy
Kiwi fruit is a significant allergen and is associated with differing patterns of reactivity in children and adults.

Lucas JS, Grimshaw KE, Collins K, Warner JO, Hourihane JO.

Allergy and Inflammation Sciences, University of Southampton, UK. jlucas1 soton.ac.uk

BACKGROUND: Allergy to kiwi fruit appears increasingly common, but few studies have evaluated its clinical characteristics, or evaluated methods of investigating the allergy. OBJECTIVE: To characterize the clinical characteristics of kiwi fruit allergy and to study the role of double-blind placebo-controlled food challenge (DBPCFC), skin tests and specific IgE in the diagnosis of this food allergy. METHODS: Two-hundred and seventy-three subjects with a history suggestive of allergy to kiwi completed a questionnaire. Forty-five were investigated by DBPCFC, prick-to-prick skin testing with fresh kiwi pulp, and specific IgE measurement. Nineteen subjects were also skin tested using a commercially available solution. RESULTS: The most frequently reported symptoms were localized to the oral mucosa (65%), but severe symptoms (wheeze, cyanosis or collapse) were reported by 18% of subjects. Young children were significantly more likely than adults to react on their first known exposure (P<0.001), and to report severe symptoms (P=0.008). Twenty-four of 45 subjects (53%) had allergy confirmed by DBPCFC. Prick-to-prick skin test with fresh kiwi was positive in 93% of subjects who had allergy confirmed by DBPCFC, and also in 55% of subjects with a negative food challenge. The commercial extract was significantly less sensitive, but with fewer false-positive reactions. CAP sIgE was only positive in 54% of subjects who had a positive challenge. CONCLUSIONS: Kiwi fruit should be considered a significant food allergen, capable of causing severe reactions, particularly in young children. DBPCFC confirmed allergy to kiwi fruit in 53% of the subjects tested, who had a previous history suggestive of kiwi allergy. Skin testing with fresh fruit has good sensitivity (93%), but poor specificity (45%) in this population. CAP sIgE and a commercially available skin test solution were both much less sensitive (54%; 75%) but had better specificity (90%; 67%).

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15248859&dopt=Abstract allergy medicine



allergy
Alphagan allergy may increase the propensity for multiple eye-drop allergy.

Osborne SA, Montgomery DM, Morris D, McKay IC.

North Glasgow University Hospitals, NHS Trust, UK. stuartosborne doctors.org.uk

AIMS: Since its introduction in 1996, brimonidine tartrate 0.2% ophthalmic solution (Alphagan, Allergan) twice daily has become established as an effective intra ocular pressure-lowering treatment. While the efficacy of Alphagan cannot be questioned, we gained the clinical impression that the drug has an unacceptably high rate of allergy. Of greater concern, we suspected that patients suffering from local Alphagan allergy had a higher rate of allergy to subsequently used topical preparations. We analysed data from a large scale study of glaucoma patients to establish whether our suspicions were correct. SUBJECTS AND METHODS: We have created a database of the entire glaucoma treatment histories for consecutive patients attending a single consultant's clinics (DMIM) at Glasgow Royal Infirmary between May 1999 and September 2001. All have undergone medical treatment for primary open angle glaucoma, ocular hypertension, or normal tension glaucoma. Patients with any other form of glaucoma, and patients in whom a full record of treatment was not available were excluded from the study. RESULTS: Alphagan was discontinued due to allergy on 73 per 100,000 patient treatment days. This was a far higher frequency than for other preparations. In patients allergic to both Alphagan and another preparation (Timoptol, Trusopt and Xalatan), the mean interval between the first and second allergy was shorter when Alphagan allergy occurred first. This was statistically significant in Timoptol and Trusopt cross-reactivity. CONCLUSIONS: Alphagan has high allergenicity, and may increase the likelihood of allergy to subsequently used preparations.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15254495&dopt=Abstract allergy medicine



allergy
Prevalence of peanut allergy in primary-school children in Montreal, Canada.

Kagan RS, Joseph L, Dufresne C, Gray-Donald K, Turnbull E, Pierre YS, Clarke AE.

Department of Pediatrics, McGill University Health Care Centre, Montreal, Quebec, Canada.

BACKGROUND: Peanut allergy is receiving increasing attention. Only one study has estimated the prevalence in North America, but it did not corroborate history with diagnostic testing. OBJECTIVE: We estimated the prevalence of peanut allergy in Montreal by administering questionnaires regarding peanut ingestion to children in kindergarten through grade 3 in randomly selected schools. METHODS: Respondents were stratified as follows: (1). peanut tolerant, (2). never-rarely ingest peanut, (3). convincing history of peanut allergy, and (4). uncertain history of peanut allergy. Groups 2, 3, and 4 underwent peanut skin prick tests (SPTs), and if the responses were positive in groups 2 or 4, measurement of peanut-specific IgE were undertaken. Children in group 3 with a positive SPT response were considered allergic to peanut without further testing. Children in groups 2 and 4 with peanut-specific IgE levels of less than 15 kU/L underwent oral peanut challenges. RESULTS: Of the 7768 children surveyed, 4339 responded, 94.6% in group 1. The prevalence of peanut allergy was 1.50% (95% CI, 1.16%-1.92%). When multiple imputation was used to incorporate data on those responding to the questionnaire but withdrawing before testing, the estimated prevalence increased to 1.76% (95% CI, 1.38%-2.21%). When data regarding the peanut allergy status of nonresponders (as declared to the school before the study) were also incorporated, the estimated prevalence was 1.34% (95% CI, 1.08%-1.64%). CONCLUSION: Our prevalence study is the first in North America to corroborate history with confirmatory testing and the largest worldwide to incorporate these techniques. We have shown that, even with conservative assumptions, prevalence exceeds 1.0%.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14657887&dopt=Abstract allergy medicine



allergy
Pharmacist-managed service providing penicillin allergy skin tests.

Wall GC, Peters L, Leaders CB, Wille JA.

Iowa Methodist Medical Center (IMMC), USA. geoff.wall drake.edu

PURPOSE: A penicillin allergy skin-testing service run by pharmacists is described. SUMMARY: A board-certified allergist trained pharmacists at a tertiary care teaching hospital to administer penicillin allergy skin tests and interpret the results. A major objective of the service was to avoid unnecessary use of vancomycin and quinolones in patients claiming but not actually having a penicillin allergy. Patients with a severe type I reaction to penicillin during the preceding five years, patients with a confirmed history of a type II-IV reaction to penicillin, and severely immunosuppressed patients were not eligible for testing. As of July 2003, 26 patients had been enrolled in the service. A type I penicillin reaction was ruled out by the drug allergy history for 3 patients. The results were negative in 22 of the 23 patients who received skin testing, and in 1 the result was indeterminate. A penicillin or a beta-lactam antibiotic was administered to all 26 patients. No patient had a significant adverse reaction to skin testing or drug administration. CONCLUSION: A pharmacist-managed penicillin allergy skin-testing service was well received by physicians and showed potential to avoid unnecessary use of alternative antibiotics.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15259758&dopt=Abstract allergy medicine



allergy
A rational clinical approach to suspected insulin allergy: status after five years and 22 cases.

Bodtger U, Wittrup M.

Steno Diabetes Centre, Gentofte, Denmark. ub-all rh.dk

AIMS: Allergy to recombinant human (rDNA) insulin preparations is a rare complication of insulin therapy. However, insulin preparations contain several allergens, and several disorders can resemble insulin allergy. Studies evaluating the diagnostic procedures on suspected insulin allergy are extremely few. METHODS: Since January 1998, we have used a standardized investigative procedure during admittance to the medical ward allowing observation and repeated recording of reactions to intradermal skin test (performed with a commercially available kit containing isolated insulin allergens). Data on all investigated cases until April 2003 were collected retrospectively, and self-reported efficacy of intervention was compared to clinical data. RESULTS: Twenty-two patients were included. In nine (41%) cases, non-insulin allergic causes were discovered and successfully treated: poor injection technique (n = 5), skin disease (n = 3) and other systemic allergy (n = 1). Nine other patients were found to be allergic to protamine (n = 3) or rDNA insulin (n = 6), and specific treatment was associated with relief in 8 patients (89%). Four patients had local reactions of unknown causes but symptom relief was obtained in three cases by unspecific therapy. Overall, 20 (91%) reported relief of symptoms. CONCLUSION: Our standardized investigative procedure of suspected insulin preparation (IP) allergy was associated with relief of symptoms in > 90% of patients. IP allergy was diagnosed in 41%, and intradermal testing with isolated insulin allergens was a prerequisite in identification of culprit allergen and targeting of treatment.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15606700&dopt=Abstract allergy medicine