Prevalence of food sensitization and probable food allergy among adults in India: the EuroPrevall INCO study.

BACKGROUND: Data are lacking regarding the prevalence of food sensitization and probable food allergy among general population in India. We report the prevalence of sensitization and probable food allergy to 24 common foods among adults from general population in Karnataka, South India. METHODOLOGY: The study was conducted in two stages: a screening study and a case-control study. A total of 11 791 adults in age group 20-54 were randomly sampled from general population in South India and answered a screening questionnaire. A total of 588 subjects (236 cases and 352 controls) participated in the case-control study involving a detailed questionnaire and specific IgE estimation for 24 common foods. RESULTS: A high level of sensitization (26.5%) was observed for most of the foods in the general population, higher than that observed among adults in Europe, except for those foods that cross-react with birch pollen. Most of the sensitization was observed in subjects who had total IgE above the median IgE level. A high level of cross-reactivity was observed among different pollens and foods and among foods. The prevalence of probable food allergy (self-reports of adverse symptoms after the consumption of food and specific IgE to the same food) was 1.2%, which was mainly accounted for cow's milk (0.5%) and apple (0.5%). CONCLUSION: Very high levels of sensitization were observed for most foods, including those not commonly consumed in the general population. For the levels of sensitization, the prevalence of probable food allergy was low. This disassociation needs to be further explored in future studies.

The prevalence and distribution of food sensitization in European adults.

BACKGROUND: Complaints of 'food allergy' are increasing. Standardized surveys of IgE sensitization to foods are still uncommon and multicountry surveys are rare. We have assessed IgE sensitization to food-associated allergens in different regions of Europe using a common protocol. METHODS: Participants from general populations aged 20-54 years in eight European centres (Zurich, Madrid, Utrecht, Lodz, Sophia, Athens, Reykjavik and Vilnius) were asked whether they had allergic symptoms associated with specific foods. Weighted samples of those with and without allergic symptoms then completed a longer questionnaire and donated serum for IgE analysis by ImmunoCAP for 24 foods, 6 aeroallergens and, by allergen microarray, for 48 individual food proteins. RESULTS: The prevalence of IgE sensitization to foods ranged from 23.6% to 6.6%. The least common IgE sensitizations were to fish (0.2%), milk (0.8%) and egg (0.9%), and the most common were to hazelnut (9.3%), peach (7.9%) and apple (6.5%). The order of prevalence of IgE sensitization against different foods was similar in each centre and correlated with the prevalence of the pollen-associated allergens Bet v 1 and Bet v 2 (r = 0.86). IgE sensitization to plant allergen components unrelated to pollen allergens was more evenly distributed and independent of pollen IgE sensitization (r = -0.10). The most common foods containing allergens not cross-reacting with pollens were sesame, shrimp and hazelnut. DISCUSSION: IgE sensitization to foods is common, but varies widely and is predominantly related to IgE sensitization to pollen allergens. IgE sensitization to food allergens not cross-reacting with pollens is rare and more evenly distributed.

Infant antibiotic use and wheeze and asthma risk: a systematic review and meta-analysis.

Our aim was to systematically review and meta-analyse longitudinal studies on antibiotic use and subsequent development of wheeze and/or asthma with regards to study quality, outcome measurement, reverse causation (RC; wheezing/asthma symptoms have caused prescription of antibiotics) and confounding by indication (CbI; respiratory tract infections leading to antibiotic use may be the underlying cause triggering asthma symptom development). English-language papers and studies published before November 1, 2010 with longitudinal observational design were included. Study quality was assessed using the Newcastle-Ottawa scale. We identified 21 longitudinal studies. The effect of antibiotic use on wheeze/asthma risk varied between studies. 18 studies were eligible for meta-analysis showing pooled OR 1.27 (95% CI 1.12-1.43) for wheeze/asthma. When we eliminated studies with possible RC and CbI, the pooled risk estimate in the nine remaining studies was attenuated to OR 1.12 (95% CI 0.98-1.26). Definition of wheeze/asthma and age at follow-up differed between studies. Three studies focused on wheeze/asthma beyond 5-6 yrs of age with the presence of active symptoms and/or medication (pooled OR 1.08, 95% CI 0.93-1.23; dominated by one study). RC and CbI lead to overestimation of the association between antibiotic use and subsequent development of wheeze/asthma. Association was weak when fully adjusted for these types of bias. Heterogeneity of disease definition between studies could affect the results.

Fatty acids in breast milk and development of atopic eczema and allergic sensitisation in infancy.

BACKGROUND: One of the explanations for the increasing prevalence of atopic diseases is a relative low perinatal supply of n-3 fatty acids. However, this does not explain the protective effects of whole-fat dairy products or high levels of transfatty acids in breast milk, observed in some studies. We evaluated the role of perinatal supply of fatty acids in the early development of atopic eczema and allergic sensitisation. METHODS: Fatty acids, including n-3 long-chain polyunsaturated fatty acids (LCPs) as well as ruminant fatty acids (rumenic acid, cis-9,trans-11-C18:2 conjugated linoleic acid; and vaccenic acid, trans-11-C18:1), were determined in breast milk sampled at 1 month postpartum from 310 mother-infant pairs in the KOALA Birth Cohort Study, the Netherlands. Children were followed for atopic outcomes until 2 years of age. RESULTS: Higher concentrations of n-3 LCPs as well as ruminant fatty acids were associated with lower risk of (1) parent-reported eczema, (2) atopic dermatitis (UK Working Party criteria), and (3) sensitisation at age 1 year (as revealed by specific serum IgE levels to cow's milk, hen's egg and/or peanut). In multivariable logistic regression analysis, the inverse associations between ruminant fatty acid concentrations in breast milk and atopic outcomes were found to be independent from n-3 LCPs. CONCLUSIONS: The results confirm a protective role of preformed n-3 LCPs in the development of atopic disease. Moreover, this is the first study in humans confirming results from animal studies of protective effects of ruminant fatty acids against the development of atopic manifestations.

The EuroPrevall-INCO surveys on the prevalence of food allergies in children from China, India and Russia: the study methodology.

BACKGROUND: Very little is known regarding the global variations in the prevalence of food allergies. The EuroPrevall-INCO project has been developed to evaluate the prevalence of food allergies in China, India and Russia using the standardized methodology of the EuroPrevall protocol used for studies in the European Union. The epidemiological surveys of the project were designed to estimate variations in the prevalence of food allergy and exposure to known or suspected risk factors for food allergy and to compare the data with different European countries. METHODS: Random samples of primary schoolchildren were recruited from urban and rural regions of China, Russia and India for screening to ascertain possible adverse reactions to foods. Cases and controls were then selected to answer a detailed questionnaire designed to evaluate the possible risk factors of food allergies. Objective evidence of sensitisation including skin-prick test and serum specific IgE measurement was also collected. RESULTS: More than 37 000 children from the three participating countries have been screened. The response rates for the screening phase ranged from 83% to 95%. More than 3000 cases and controls were studied in the second phase of the study. Further confirmation of food allergies by double blind food challenge was conducted. CONCLUSIONS: This will be the first comparative study of the epidemiology of food allergies in China, India, and Russia using the same standardized methodology. The findings of these surveys will complement the data obtained from Europe and provide insights into the development of food allergy.

The EuroPrevall surveys on the prevalence of food allergies in children and adults: background and study methodology.

BACKGROUND: The epidemiological surveys in children and adults of the EU-funded multidisciplinary Integrated Project EuroPrevall, launched in June 2005, were designed to estimate the currently unknown prevalence of food allergy and exposure to known or suspected risk factors for food allergy across Europe. We describe the protocol for the epidemiological surveys in children and adults. This protocol provides specific instructions on the sampling strategy, the use of questionnaires, and collection of blood samples for immunological analyses. METHODS: The surveys were performed as multi-centre, cross-sectional studies in general populations. Case-control studies were nested within these surveys. The studies in children aged 7-10 years and adults aged 20-54 years were undertaken in eight centres representing different social and climatic regions in Europe. RESULTS: After a community-based survey collecting basic information on adverse reactions to foods, all those stating they had experienced such reactions, as well as of a random sample of those stating 'no reactions' to foods, completed a detailed questionnaire on potential risks and exposures. Also a blood sample was taken to allow serological analysis to establish patterns of food and aeroallergen sensitization. We also included a questionnaire to schools on their preparedness for dealing with food allergy amongst pupils. Subjects reporting adverse reactions to foods and sensitized to the same food(s) were called in for a full clinical evaluation that included a double blind placebo controlled food challenge (DBPCFC), following a protocol which is described in detail elsewhere. CONCLUSIONS: The outcome of these studies will help to improve our understanding of several important aspects of food allergies in the European Community, providing for more well-informed policies and effective measures of disease prevention, diagnosis and management.

Cytokines and soluble CD14 in breast milk in relation with atopic manifestations in mother and infant (KOALA Study).

BACKGROUND: Conflicting evidence exists concerning the protective role of breastfeeding in allergy and atopic disease aetiology. Breast milk contains biologically active molecules influencing the innate immune system of newborns. OBJECTIVE: We aim to assess whether cytokines (TGF-beta1, IL-10 and IL-12) and soluble CD14 (sCD14) in breast milk are influenced by maternal atopic constitution and modify the development of atopic manifestations in infants. METHODS: Milk samples were collected at 1 month post-partum of 315 lactating mothers participating in the ongoing KOALA Birth Cohort Study. The cytokines and sCD14 were analysed by ELISA in the aqueous fraction. We compared the concentrations of cytokines and sCD14 in breast milk between mothers with and without an allergic history and also with and without allergic sensitization (specific IgE). Associations of cytokines and sCD14 with the development of eczema, wheezing in the first 2 years of life and allergic sensitization of infants at the age of 2 years were analysed by multivariate logistic regression analyses to correct for confounders. RESULTS: We found higher sCD14 levels in mothers with a positive vs. negative allergic history (7.6 vs. 7.0 microg/mL; P = 0.04) and in mothers who were sensitized vs. non-sensitized (7.8 vs. 7.1 microg/mL; P = 0.03). None of the studied immune factors were associated with infant's atopic outcomes. IL-10 was not detected above the detection limit of 0.2 pg/mL. CONCLUSION: Taking together the results of the present and previous studies, we conclude that there is no convincing evidence for a relation between TGF-beta1, sCD14, IL-10 or IL-12 in breast milk and atopic manifestations in infants.

Do parents with an atopic family history adopt a 'prudent' lifestyle for their infant? (KOALA Study).

BACKGROUND: Atopic parents may adopt lifestyle characteristics that allegedly protect against atopic disease. If this is true, infants from atopic parents will be characterized by low-risk behaviour. Consequently, aetiologic studies on lifestyle factors and allergic disease in childhood may be biased by confounding by indication. OBJECTIVE: We explored whether the prevalence of 'prudent' lifestyle characteristics differs between atopic and non-atopic families. METHODS: Information about a family history of atopic manifestations and lifestyle characteristics was collected by repeated questionnaires in the Dutch KOALA Birth Cohort Study in 2469 infants from families with divergent lifestyle practices (conventional vs. alternative). RESULTS: In conventional lifestyle families, infants were less often exposed to environmental tobacco smoke when parents were atopic than when they were non-atopic (10.0% vs. 14.7%, P=0.001). In alternative lifestyle families, exposure to smoking was very rare in both groups (1.7% vs. 2.6%). Pets were less often present in families with than without parental atopy (38.8% vs. 51.1%, P=0.008 for conventional lifestyle families; 43.0% vs. 48.4%, P=0.014 for alternative lifestyle families). Infants with atopic siblings had less often been vaccinated according to the standard scheme than infants with non-atopic siblings in conventional lifestyle families (76.6% vs. 85.5%, P<0.001). In alternative lifestyle families, the difference was in the same direction but not statistically significant (30.1% vs. 40.5%, P=0.143). Antibiotic use, breastfeeding and consumption of organic foods were unrelated to a family history of atopic manifestations. CONCLUSION: Some 'prudent' lifestyle characteristics differed between atopic and non-atopic families, depending on whether atopic manifestations were present in parents or older siblings. This has important consequences for the validity in epidemiological studies on the aetiology of allergy in children. Confounding by indication because of a family history of atopic manifestations can best be controlled for by considering atopy in parents and siblings as separate confounders.

A blind spot for secondary gain affecting therapy outcomes.

BACKGROUND: A study to determine whether the expectation for secondary gain held by psychiatric outpatients was associated with therapy outcomes. METHODS: The study was conducted at a Dutch psychiatric outpatient department. Our investigation set out to explore the expectation of obtaining secondary gain by directly asking the patient and clinician via questionnaires whether the patient anticipated to get specific "benefits" from being in therapy. RESULTS: From 166 patients, 70 (42.2%) reported to expect secondary gain while in therapy. We found a significant relation between expectation for secondary gain and treatment outcomes. Patients with expectations for secondary gain were significantly more prone to poor therapy outcome. Only in nine of 147 cases (6%) did patients explicitly express their expectations for secondary gain towards a psychiatrist. Moreover, expectations for secondary gain did not appear to be related to Axis I and Axis II diagnoses. DISCUSSION: Secondary gain appeared to be a "veiled motive" for getting therapy: patients did not express their expectations for secondary gain explicitly towards a psychiatrist. This aspect of veiled motives is of particular relevance in regard to the fact that expectations for secondary gain appeared to affect therapy results.