The development and prediction of atopy in high-risk children: follow-up at age seven years in a prospective randomized study of combined maternal and infant food allergen avoidance

Is atopic dermatitis predictable?

Atopic dermatitis (AD) is a common skin disease which affects 10 to 20% of the population, usually with onset during infancy. The frequency of AD appears to have increased over the past three decades. Attempts to identify parameters predictive of the development of AD have been made by many investigators during the last decades. Although genetic factors remain unmodifiable, avoidance of relevant trigger factors could modify the development of AD. This paper reviews and discusses findings of the last several years and outlines recent advances in genetic studies of AD. In spite of decades of intensive research and newly developed technology, the parental history of AD appears to be the most valuable predictive parameter. However, the predictive capacity is not sufficient to recommend it as screening instrument. At this time, a perinatal screening with the objective of primary prevention of AD does not seem feasible.

Breast-feeding of allergic infants

OBJECTIVE

Infants may have allergic disease even during exclusive breast-feeding. The aim of this study was to evaluate whether allergic infants should continue breast-feeding.

STUDY DESIGN

We studied 100 infants who had atopic eczema during exclusive breast-feeding. The extent and severity of the eczema, allergic sensitization, and the patients' growth and nutrition were assessed during and after cessation of breast-feeding.

RESULTS

The mean body length SD score decreased at the onset of allergic disease, and an association was seen between the duration of symptoms and poor growth (r = -.23, P =.04). Some improvement could be achieved by strict elimination diet by the mothers. The atopic eczema improved significantly after breast-feeding was stopped: SCORAD score 20 (range 15 to 27) during and 7 (range 4 to 11) after breast-feeding; t = 5.38, P <.0001, and the relative length of patients increased, in parallel with improved nutritional parameters.

CONCLUSIONS

Breast-feeding should be promoted for primary prevention of allergy, but breast-fed infants with allergy should be treated by allergen avoidance, and in some cases breast-feeding should also be stopped. This particularly applies to infants with atopic eczema who also have impaired growth.

Is allergy prevention realistic and beneficial?

Allergic diseases among children have shown a marked increase during the last two or three decades, despite increased awareness of possible preventive measures. Preventive efforts have focused on new-borns and infants with a biparental history of allergy as they are at particularly high risk of developing allergic disease (40-60%). No good intervention studies have been performed in the general population, only in high-risk families. Unfortunately, so far known risk factors can only explain a small part of the recent increase in allergic diseases. The most important recommendation for everyone is not to smoke during pregnancy and when living/working with young children. Breast milk is the best for every baby, even from an immunologic aspect. Humidity problems should be reduced in homes, day-care centres and schools. It is probably wise not to keep furred pets indoors in homes when babies have a family history of allergy. However, the effect of such advice should be assessed, including the acceptability, compliance, costs and effectiveness. There is no doubt that we should go on with preventive measures both in babies at high risk of allergy and also in the general population. At the same time, research should try to find even more efficient ways to reduce the current "allergy epidemic".

Is allergy increasing?--early life influences

Data from epidemiological studies conducted in several countries worldwide have revealed that the prevalences of allergic conditions, including allergic rhinitis, asthma and eczema, have increased from the 1940s/50s to the 1990s. These allergic conditions involve specific IgE-mediated responses, and a few studies have demonstrated that IgE levels have increased in some communities over time in a manner similar to the incidences of allergic conditions. The predisposition for atopy appears to be determined in early life, and evidence indicates that events occurring in utero and in infancy can influence the future development of atopy. The intrauterine environment favours TH2 cell development and IgE production and could predispose to atopy. It can be hypothesized that dietary or other factors favouring TH2 proliferation might contribute to the development of atopic disease. Conversely, early infection has been found to have a negative association with the development of atopy, perhaps through promotion of a TH response; the reduction in infection in the very young as a consequence of modern healthcare may have contributed to the increase in atopic disease. Thus, it is a plausible hypothesis that changes in the conditions of the intrauterine environment and/or in infancy (for example, in nutrition and in rates of infection) may explain the observed increases in atopy and allergic conditions.

Special formulas in infant nutrition: a review

Special formulas should only be used by medical prescription and for those lactating infants with diagnosed nutritional problems. Lactose-free formulas or those based on soy are the logical choice when the exclusion of lactose from the diet is considered necessary. At present, there is no concensus on the appropriateness of soy formulas for the treatment and prevention of nutritional allergies and current opinion seems to favour hydrolyzed protein formulas. High-degree protein hydrolysate formulas are used to treat lactating infants with an allergy to cow milk proteins or with serious nutritional problems. These formulas are not without risk, as they may contain residual epitopes capable of provoking a severe allergic reaction. Before using these formulas, allergenicity tests should be performed, particularly for highly sensitive infants. The unpleasant taste and high cost of these formulas, in addition to possible nutritional problems, limit their use in the prevention of atopic disease, although their efficacy is well established. Partially protein hydrolysate formulas are only used for preventive purposes and are not suitable for lactating infants with a proven allergy to cow milk. Although these formulas can reduce the incidence or delay the appearance of certain atopic symptoms, they have not been shown to prevent IgE-mediated allergic reactions to cow's milk and so their effectiveness is open to question.

Prediction of sensitization to inhalant allergens in childhood: evaluating family history, atopic dermatitis and sensitization to food allergens. The MAS Study Group. Multicentre Allergy Study

BACKGROUND

A family history of atopy is a poor predictor of sensitization to inhalant allergens and allergic disease during childhood. We recently identified early sensitization to food allergens, especially hen's egg, as a valuable predictor of subsequent sensitization to inhalant allergens.

OBJECTIVE

(1) Whether prediction will be improved by in vitro allergy tests at 1 year of age in combination with family history and medical history data. (2) Comparison with the capacities of in vitro tests to predict sensitization to aeroallergens.

METHODS

Of an observational birth cohort study (MAS) 49 children who were sensitized to inhalant allergens at 5 years of age and 116 non-sensitized controls were included in the present study. For the prediction of sensitization to inhalant allergens the following prognostic factors were evaluated: atopic family history (FH), atopic dermatitis (AD) during the first year of life, two in vitro allergy tests for specific IgE to common food allergens at 1 year of age (fx5 [Pharmacia] and single allergen specific tests (sIgE) for four allergens) and 'high' total serum IgE, defined by three different cut off points.

RESULTS

The combination of medical history data and laboratory tests resulted in the best predictive discrimination. The positive predictive values (PPV) were higher if sensitization to food was detected by single allergen specific tests (PPV: 66%/75%/100% corresponding to the three evaluated risk groups) than by the qualitative fx5 (PPV: 46%/65%/100%). The negative predictive values were equal for both tests (69 and 92% for the two low risk groups). High total serum IgE had low predictive capacity.

CONCLUSION

During infancy the prediction of sensitization to inhalant allergens should be based on medical history data and allergy tests determining sensitization to food allergens. The in vitro tests improve the predictive discrimination, but the individual risk profile of the child must be considered for a reliable and valid prediction.

Cross sectional study of the relation between sibling number and asthma, hay fever, and eczema

OBJECTIVES

To document the relation between sibling number and atopic disease, and to assess the contribution of possible confounding factors to the protective effect of siblings in relation to asthma and hay fever.

DESIGN AND SUBJECTS

Cross sectional survey by parental questionnaire in Tasmania, Australia, on 6378 children (92% of those eligible) who reached 7 years of age during 1995.

METHODS

Exercise challenge lung function testing was conducted on 428 children. Analyses reported were conducted on singleton births only (n = 6158).

RESULTS

The prevalences of a history of asthma ever, hay fever, and eczema were 27%, 19%, and 22%, respectively. Asthma and hay fever, but not eczema, were inversely related to sibling number, with evidence of a dose-response trend. The mean age at onset for asthma or wheezy breathing decreased as the number of siblings increased. The inverse association between sibling number and asthma or hay fever persisted after adjustment for several confounders, such as parental smoking or breast feeding, but did not persist after adjustment for household size in 1995.

CONCLUSIONS

The protective effect of high sibling number could not be separated from household size at age 7, and it appears to be operating after birth and influences the age at onset of asthma symptoms. Further work to increase knowledge of how the protective effect of the presence of siblings works might have important implications for the understanding of the pathogenesis of asthma.

Food hypersensitivity in children

Adverse reactions to foods involving abnormal immune reactions to food antigens occur in 2-7% of the North American population; the numbers are perhaps higher in children. Both IgE-mediated and non-IgE-mediated allergic responses occur. IgE-mediated allergic responses to foods are the most dramatic and perhaps the most easily diagnosed type of food allergy. Non-IgE-mediated food hypersensitivity is more chronic, less acute, less obvious in its clinical presentation, and often more difficult to diagnose. It usually presents in infants between one week and three months of age with vomiting and diarrhea, although irritability, poor feeding, and failure to thrive are not uncommon. A thorough history and physical examination are often key in establishing a diagnosis of food protein hypersensitivity. In non-IgE-mediated disease, skin tests and immunological studies are not helpful. Eliminating the food allergen is the only means of dealing with a food allergy in most patients. About 85% of infants who have formula protein intolerance will outgrow their symptoms somewhere between 1 month and 3 years of age, older children and adults are somewhat less likely to lose their sensitivity, although approximately one-third will after 1-2 years of dietary restriction.

Growth, development and differentiation: a functional food science approach

Few other aspects of food supply and metabolism are of greater biological importance than the feeding of mothers during pregnancy and lactation, and of their infants and young children. Nutritional factors during early development not only have short-term effects on growth, body composition and body functions but also exert long-term effects on health, disease and mortality risks in adulthood, as well as development of neural functions and behaviour, a phenomenon called 'metabolic programming'. The interaction of nutrients and gene expression may form the basis of many of these programming effects and needs to be investigated in more detail. The relation between availability of food ingredients and cell and tissue differentiation and its possible uses for promoting health and development requires further exploration. The course of pregnancy, childbirth and lactation as well as human milk composition and the short- and long-term outcome of the child are influenced by the intake of foods and particularly micronutrients, e.g. polyunsaturated fatty acids, Fe, Zn and I. Folic acid supplementation from before conception through the first weeks of pregnancy can markedly reduce the occurrence of severe embryonic malformations; other potential benefits of modulating nutrient supply on maternal and child health should be further evaluated. The evaluation of dietary effects on child growth requires epidemiological and field studies as well as evaluation of specific cell and tissue growth. Novel substrates, growth factors and conditionally essential nutrients (e.g. growth factors, amino acids, polyunsaturated fatty acids) may be potentially useful as ingredients in functional foods and need to be assessed carefully. Intestinal growth, maturation, and adaptation as well as long-term function may be influenced by food ingredients such as oligosaccharides, gangliosides, high-molecular-mass glycoproteins, bile salt-activated lipase, pre- and probiotics. There are indications for some beneficial effects of functional foods on the developing immune response, for example induced by antioxidant vitamins, trace elements, fatty acids, arginine, nucleotides, and altered antigen contents in infant foods. Peak bone mass at the end of adolescence can be increased by dietary means, which is expected to be of long-term importance for the prevention of osteoporosis at older ages. Future studies should be directed to the combined effects of Ca and other constituents of growing bone, such as P, Mg and Zn, as well as vitamins D and K, and the trace elements F and B. Pregnancy and the first postnatal months are critical time periods for the growth and development of the human nervous system, processes for which adequate substrate supplies are essential. Early diet seems to have long-term effects on sensory and cognitive abilities as well as behaviour. The potential beneficial effects of a balanced supply of nutrients such as I, Fe, Zn and polyunsaturated fatty acids should be further evaluated. Possible long-term effects of early exposure to tastes and flavours on later food choice preferences may have a major impact on public health and need to be further elucidated. The use of biotechnology and recombinant techniques may offer the opportunity to include various bioactive substances in special dietary products, such as human milk proteins, peptides, growth factors, which may have beneficial physiological effects, particularly in infancy and early childhood.

Determinants of dust mite allergen concentrations in infant bedrooms in Tasmania

BACKGROUND

High exposure to house dust mite allergen during the first year of life has been found to increase the risk of subsequent asthma and mite sensitization. Environmental factors, home construction and cleaning methods used are associated with levels of dust mites in the home.

OBJECTIVE

To investigate determinants of levels of Der p 1 and Der f 1 mite allergens in homes of infants in southern Tasmania.

METHODS

Dust samples were collected from 72 homes of infants participating in the Tasmanian Infant Health Survey (TIHS). The Der p 1 and Der f 1 allergen concentrations in these samples were measured. The TIHS interviewers obtained information from the mothers of the infants via a questionnaire, observed specified aspects of the home environment, and took readings of bedroom temperature and humidity. The effect of each item on allergen concentration in dust from bedroom floors was examined in a variety of ways. Those items which in this study appeared to be significantly related to allergen concentrations plus items which in other studies have been found to be related to allergen concentrations were then investigated further in multivariate models.

RESULTS

Der p 1 allergen concentration (microg/g) and density (microg/m2) in dust from bedroom floors were found to be related to several home environment factors. In the univariate analyses, indoor humidity, 24 h maximum temperature, number of residents and a combination of floor covering and cleaning methods appeared to have a significant effect on allergen levels. These factors remained important in the multivariate model except that indicators for mould in the bathroom and drying washing on an outside line replaced indoor humidity.

CONCLUSION

Features related to home dampness, the number of residents and floor covering and cleaning were major determinants of Der p 1 levels in the bedrooms studied.

Long-lasting sensitization to food during the first two years precedes allergic airway disease. The MAS Study Group, Germany

The purpose of the study was to investigate whether the duration of sensitization to food allergens during early childhood is related to later development of IgE mediated hypersensitivity to inhalant allergens and of allergic rhinitis and asthma in 5-year-old children and whether long-lasting food-sensitization may be used to predict subsequent allergic airway diseases. Five hundred and eight children of a prospective birth cohort study with available serum samples at one and two years of age were included and followed up until five years of age. Specific sensitization to food and inhalant allergens and the occurrence of subsequent allergic airway diseases were determined. Children with a long-lasting sensitization to food allergens (persistently sensitized for more than one year) produced significantly higher total IgE and specific IgE levels than children who were only transiently food-sensitized by two years of age. Children persistently sensitized to food had a 3.4 fold higher risk of developing allergic rhinitis and a 5.5 fold higher risk of developing asthma than infants who were only transiently food sensitized. Persistent food sensitization in combination with a positive atopic family history was a strong predictor for the development of allergic rhinitis and asthma at five years of age. The risks for these children are up to 50%, and 67% respectively. Persistently detectable sensitization to food over more than one year in early childhood is a strong prognostic factor for subsequent allergic airway disease. Persistently food-sensitized children especially in atopic families have to be regarded as a high-risk group and should be considered for preventive measures against respiratory atopy.

The prevalence of and risk factors for atopy in early childhood: a whole population birth cohort study

OBJECTIVES

A birth cohort was followed-up to age 4 years to record the development of allergic disorders and to study the influence of genetic and environmental factors.

METHODS

Information on family history and environmental factors was obtained at birth, and serum cord IgE was measured. At age 4 years, 1218 children were reviewed.

RESULTS

By age 4 years, 27% of the children had symptoms of allergic disease. Period prevalence of asthma increased from 8.7% in infancy to 14.9% at 4 years. Family history of atopy was the single most important risk factor for atopy in children. Sibling atopy was a stronger predictor of clinical disease than maternal or paternal atopy, whereas paternal atopy, male sex, and high cord IgE were significant for the development of allergen sensitization. Children of asthmatic mothers were three times more likely to have asthma (odds ratio [OR]: 3.0, 95% confidence interval [CI]: 1.6-5.8) and rhinitis (OR: 2.9, CI: 1.1-7.4). Formula feeding before 3 months of age predisposed to asthma at age 4 years (OR: 1.8, CI: 1.2-2.6). The effect of maternal smoking on childhood wheeze seen at 1 and 2 years was lost by age 4, except for a subgroup with negative skin test responses (nonatopic asthma). Less than half (46%) of the infantile wheezers were still wheezing at 4 years of age.

CONCLUSION

Family history of atopy remains the most important risk factor for atopy in children, but other markers can be identified with a potential for intervention at an early age.

Health effects of passive smoking .5. Parental smoking and allergic sensitisation in children

BACKGROUND

A systematic review was conducted of the effects of parental smoking on immunoglobulin (IgE) levels, skin prick positivity, and allergic rhinitis or eczema in children. Asthma was excluded in order to distinguish more clearly the effect of passive smoke exposure on allergic sensitisation.

METHODS

Thirty six relevant publications were identified after consideration of 692 articles selected by electronic search of the Embase and Medline databases using keywords relevant to passive smoking in children. The search was completed in April 1997 and identified nine studies of IgE in neonates, eight of IgE in older children, 12 which included skin prick tests, and 10 describing symptoms of allergic disease other than asthma or wheezing. A quantitative meta-analysis was possible only for the studies reporting skin prick tests.

RESULTS

Several large studies failed to confirm early reports of a substantial or statistically significant association of maternal smoking with concentrations of total serum IgE in neonates or in older children. No consistent association emerged between parental smoking and allergic rhinitis or eczema. Few of these studies adjusted for potential confounding variables. The quantity and quality of evidence was greatest for skin prick tests, and studies of parental smoking during pregnancy or infancy were broadly consistent in showing no adverse effect on prick positivity (pooled odds ratio 0.87, 95% confidence interval 0.62 to 1.24). There was much greater and statistically significant (p = 0.002) heterogeneity of odds ratios relating current parental smoking to skin prick positivity.

CONCLUSIONS

Parental smoking, either before or immediately after birth, is unlikely to increase the risk of allergic sensitisation in children.

Prevention of food allergy

Development of a food allergy appears to depend on both genetic factors and exposure-especially in early infancy-to food proteins. In prospective studies, the effect of dietary allergy prevention programmes has only been demonstrated in high-risk infants, i.e. infants with at least one first degree relative with documented atopic disease. High-risk infants feeding exclusively on breast milk and/or extensively hydrolysed formula (eHF) combined with avoidance of cow's milk proteins and solid foods during at least the first 4 months of life are found to have a significant reduction in the cumulative incidence of food allergy, especially cow's milk protein allergy/intolerance (CMPA/CMPI), in the first 4 years of life. As no studies have been conducted pertaining to the preventive effect of avoidance of milk and other foods after the age of 4-6 months, recommendation of preventive elimination diets beyond this age is empirically based. In order to reduce costs and to minimize the risks of stigmatisation and malnutrition, it is important to avoid unnecessary restrictive and prolonged diets. A diet period of 4-6 months appears to be sufficient in the majority of infants. At present, eHF are recommended as a substitute for cow's milk. A few high risk infants may benefit from a maternal diet during lactation, but there is no documented beneficial effect of maternal dieting during pregnancy.

Extensively and partially hydrolysed infant formulas for allergy prophylaxis

The allergy preventive effect of extensively (N) and partially (PH) hydrolysed cows' milk formulas compared with a regular formula (RM) was assessed in 155 infants with a family history of allergy. No cows' milk was given during the first nine months of life and no egg and fish up to 12 months of age. Breast feeding mothers avoided the same foods. At weaning the infants were randomised to one of the formula groups. The cumulative incidence of atopic symptoms at 18 months was 51, 64, and 84% in the N, PH, and RM groups, respectively. From 6 to 18 months there were significantly less cumulative atopic symptoms in the N group compared with the RM group, and significantly less than the PH group up to 6 (N = 25%; PH = 46%) and 9 months (N = 34%, PH = 58%). At 9 months significantly fewer infants in the N group (10%) than in the PH group (33%) had a positive skin prick test to eggs. The findings support an allergy preventive effect of an extensively hydrolysed formula, but not of a partially hydrolysed formula, during the first 18 months of life of high risk infants.

Sensitization to hen's egg at the age of twelve months is predictive for allergic sensitization to common indoor and outdoor allergens at the age of three years

BACKGROUND

Specific predictors for atopic sensitization in early infancy are prerequisites for preventive intervention studies.

OBJECTIVE

To identify predictors of allergic sensitization to common aeroallergens in infancy, 1314 children in five German cities were followed up from birth (1990) to the age of 3 years.

METHODS

Blood samples were taken from cord blood and at follow-up visits at the ages of 1, 2, and 3 years. Total serum IgE and specific IgE antibodies to common food and inhalant allergens were determined.

RESULTS

Among our study population, risk factors for sensitization to indoor and/or outdoor allergens at the age of 3 years were a positive family history, the presence of hen's egg-specific IgE antibodies (> or = 0.35 kU/L), and increased log- [total IgE] levels at the age of 12 months. Elevated cord blood IgE was not associated with sensitization to inhalant allergens at the age of 3 years. Egg-specific IgE greater than 2 kU/L in combination with a positive family history of atopy was a highly specific (specificity, 99%) and predictive (positive predictive value, 78%) marker for sensitization to inhalant allergens at 3 years of age.

CONCLUSIONS

Hen's egg-specific IgE at the age of 12 months is a valuable marker for subsequent allergic sensitization to allergens that cause asthma, allergic rhinitis, and atopic dermatitis.

Atopic dermatitis: an update

This review focuses on recent literature regarding the following clinical features of atopic dermatitis (AD); diagnostic criteria, epidemiology and genetics, provocative factors, predictors of disease development and markers of disease severity, therapy, and prognosis. For example, the frequency of AD appears to be increasing, perhaps in response to provocative factors such as food allergens and house dust mites. Determination of reliable markers for disease development may identify susceptible newborns and facilitate avoidance of relevant triggers. Immunomodulating therapy holds promise in the treatment of refractory AD, and new investigation has led to refinements in conventional modalities such as antihistamines and phototherapy.

Early detection of specific IgE antibody against house dust mite in children at risk of allergic disease

OBJECTIVES

House dust mite (HDM) is a representative inhalant allergen that triggers allergic disease in childhood. The aim of this study is early detection of HDM-specific IgE antibody and prediction of the risk of a positive reaction to this antibody by in vitro parameters in infants with allergic manifestations.

STUDY DESIGN

Levels of HDM IgE in a range below the standard cutoff point of 0.35 U/ml, serum concentrations of IgE, and specific IgE antibodies against egg white, cow milk, and soybeans were determined in 108 infants with allergic manifestations at 6 months of age, and these infants were monitored for conversion of HDM IgE to positive levels greater than 0.35 U/ml up to 5 years of age. The presence of active allergic disease at 5 years of age in relation to HDM-specific IgE was also examined.

RESULTS

We were able to determine reliably the HDM IgE values between 0.23 and 0.35 U/ml, using a fluorescent enzyme immunoassay that measured the intensity of fluorescence. The HDM IgE levels increased, resulting in positive values, in 54 of 108 subjects during the first 5 years of life. In multiple regression analysis, an HDM IgE value between 0.23 and 0.35 U/ml, a high serum IgE level, and a positive reaction to specific IgE antibody against egg white in infants at 6 months of age proved to be significant predictors of the future positive reaction to HDM IgE (p = 0.0006, 0.0043, and 0.0001). In particular, the sensitivity and specificity of specific IgE antibody against egg white for the conversion of HDM IgE to positive values were the best among these indicators. Moreover, active allergic diseases were observed significantly more often in children with positive HDM IgE values than in children with negative HDM IgE values at 5 years of age (p < 0.001 for each).

CONCLUSIONS

A determination of these predictors in infants at 6 months of age can be used for early detection of HDM IgE and would be valuable in a screening test for later allergic disease among infants with allergic manifestations.