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- Study of the prevalence and clinical features of food allergies in adults and adolescents from Beira InteriorPublication . Lozoya Ibáñez, Carlos; Barata, Luís Manuel TabordaBackground: Food allergy is an important health problem in western-style countries, and its prevalence has increased in the last three decades. Studies of the prevalence of food allergy in the general population in Portugal are scarce. Thus, the objectives of the present thesis were: a) to design and validate a food allergy study questionnaire for Portuguese adults, b) to determine the prevalence, and clinical characteristics of food allergy in a population of adolescents and adults in Beira Interior, and c) to determine the prevalence, and clinical characteristics of food allergy in the elderly population worldwide by conducting a systematic review of the bibliography and a subsequent meta-analysis of the data. Methods: A 17-item questionnaire was developed and applied by phone to a group of food allergy patients and a group of healthy individuals, with subsequent reassessment (re-test). Face and content validity, intelligibility, construct validity, and test-retest reliability (temporal stability) were analysed. This tool, once validated, was applied in two population-based individuals samples (3,168 adolescents; mean age: 14.3±1.1; 51.7% female; 1.436 adults; mean age of 47 years, median age: 45 years, 50.6% female), registered at participating Healthcare cross-sectional studies performed in various healthcare centres and secondary schools from central Portugal. All randomly selected individuals (1702 adolescents; mean age: 14.9±2.1 years; median age: 14 years; 61.9% female; 840 adults; (mean age: 48 years, median age: 46 years, 51.3% female) replied to the food allergy questionnaire by phone (adults) or in a written form (adolescents). Those who reported an adverse food reaction were invited to come to the hospital, where clinical history was taken, skin prick (SPT) and prick-prick skin (SPPT) tests were performed and food allergen-specific IgE levels (sIgE) were determined. An open oral challenge was performed in selected cases. Cases of positive clinical history of immediate (up to 2 hours after ingestion) reaction in association with positive food sIgE levels and/or skin prick tests were classified as IgE-associated probable food allergy. Cases of positive clinical history of delayed (more than 2 hours after ingestion) and negative food sIgE levels independently of positive SPT or SPPT results were classified as non-IgE associated probable food allergy. A systematic review and meta-analysis on the prevalence and risk factors for food allergy in elderly individuals were conducted. A searched of international electronic databases including MEDLINE, EMBASE, Cochrane Library, CINAHL, AMED and ISI Web of Science, as well as clinical trials databases for published, unpublished and on-going studies from 1980 to 2019. There were no restrictions on the language or geography of publication. The Critical Appraisal Skills Programme (CASP) quality assessment tool was used to appraise the methodological quality of the included studies. A descriptive summary with data tables was elaborated, and when clinically relevant and statistically adequate, a meta-analysis using random-effects modelling was carried out, given the expected clinical, methodological and statistical heterogeneity of the selected studies. The PRISMA checklist guided the reporting of the systematic review. Results: Face and content validity of the questionnaire allowed item reduction from 30 to 17 items with adequate content validity index > 0.78. Construct validity was confirmed in a group of 66 confirmed food allergic patients. Test-Retest Reliability (general temporal stability) of the test had a Spearman correlation coefficient value of 0.845 for the retest. Cohen's Kappa values for the relevant questions were greater than 0.890 for almost all items. No differences were found when sex, age and volunteers’ recruitment origin were analysed. An inverse relationship was found between reliability and retest time interval. The prevalence of probable food allergy in our sample was 1.41% in adolescents and 1% in adults, with fresh fruits and shellfish in adolescents and shellfish and fish in adults as the most frequently implicated foods. IgE-mediated probable food allergy occurred in 1.23% of adolescent and in 0.71% of adult cases, and fresh fruits and shellfish in adolescents and shellfish and peanut in adults were the foodstuffs mainly involved. Cutaneous symptoms were most frequently reported and prevalence values and food types were discrepant between self-reported and probable food allergies in both populations. The prevalence of food allergy in the elderly was 6.46% for self-report, slightly lower than that of SR + food-specific IgE levels (6.95%) and SR + SPT (1.30%). In addition, it was lower than that in non-elderly adults, but higher than in children assessed by self-report outcomes. Finally, it was lower when compared with the other age groups when self-report symptoms were combined with in vitro or in vivo outcome assessment. No results were obtained regarding time and geographical trends, predominant foods, risk and prognostic factors, and clinical manifestations of food allergy in the elderly. There was great heterogeneity both in the systematic review and the meta-analysis, which was lowest for shellfish (I2=0.000%) and highest for fruits (I2=98.205%). Conclusions: Due to the quick and easy implementation, confirmation of face, content and construct validity as well as high temporal reproducibility, the screening questionnaire was a useful study tool for an initial approach to detection of food allergies in adults. The prevalence of probable food allergies in Portuguese adolescents and adults was low, mostly related to fresh fruits, shellfish, nuts and peanut in the former, and to shellfish, fish, peanut and nuts in the latter. Most cases frequently involved cutaneous symptoms. The systematic review allowed us to draw up-to-date estimates of the prevalence of adverse food reactions in elderly individuals, worldwide. However, most of the studies were not focused on the population over 60 years of age, which resulted in an evident lack of information and biases that might affect exposure and outcomes. This fact conditioned the knowledge of the clinical characteristics, implicated foods, evolution and diagnosis of food allergy in these individuals, as well as the development of possible preventative measures focused specifically on the elderly population.