Sharon Matthews

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.

Origins of health inequalities in a national population sample.

BACKGROUND Explanations for social inequalities in health are often explored but remain largely unresolved. To elucidate the origins of health inequalties, we investigated the extent to which adult-disease risk factors vary systematically according to social position over three decades of early life. METHODS We used the 1958 birth cohort (all children born in England, Scotland, and Wales on March 3-9, 1958) with data up to age 33 years from parents, teachers, doctors, and cohort members (n = 11,407 for age 33 interview). FINDINGS Social class of origin was associated with physical risk factors (birthweight, height, and adult body-mass index); economic circumstances, including household overcrowding, basic amenities, and low income; health behaviour of parents (breastfeeding and smoking) and of participants (smoking and diet); social and family functioning and structure, such as divorce or separation of participants or their parents, emotional adjustment in adolescence, social support in early adulthood; and educational achievement and working career, in particular no qualifications, unemployment, job strain, and insecurity. With few exceptions, there were strong significant trends of increasing risk from classes I and II to classes IV and V. Self-perceived health status and symptoms were worse in participants with lower class origins. INTERPRETATION An individuals chance of encountering multiple adverse health risks throughout life is influenced powerfully by social position. Social trends in adult-disease risk factors do not emerge exclusively in mid-life, but accumulate over decades. Investment in educational and emotional development is needed in all social groups to strengthen prevention strategies relating to health behaviour, work-place environment, and income inequality.

Cohort study of peanut and tree nut sensitisation by age of 4 years.

Abstract Objective: To determine the prevalence of sensitisation to peanuts and tree nuts in all children born during one year in one geographical area. Design: Birth cohort study with structured review at ages 1, 2, and 4 years. Setting: All children born on the Isle of Wight between January 1989 and February 1990. Subjects: Of 1456 children originally included, 1218 were reviewed at age 4 years. Of these, 981 had skin prick tests. Main outcome measures: Positive skin test results, clinical atopic disease, and risk factors for the development of atopy. Results: 15 of 1218 (1.2%) children were sensitised to peanuts or tree nuts (13 to peanuts). Six had had allergic reactions to peanuts (0.5% of the population), one to hazelnuts, and one to cashew nuts; three had had anaphylactic reactions. Seven children had positive skin test results or detectable IgE to peanuts without clinical symptoms. Two children who reacted to peanut in infancy had lost their sensitivity by 4 years. Family history of atopy, allergy to egg (odds ratio 9.9, 95% confidence interval 2.1 to 47.9, and eczema (7.3, 2.1 to 26.1) were important predictors for peanut allergy. Conclusions: IgE mediated allergy to peanuts is common in early childhood. In many the allergy persists but a minority may develop tolerance. Key messages Key messages This study suggests that 1 in 200 children could have reactions to peanuts and tree nuts by the age of 4 years and a similar number could have asymp- tomatic sensitisation Children with allergy to peanuts invariably have another atopic disorder such as asthma, eczema, or rhinitis Sensitisation to peanuts and tree nuts may coexist

Allergen avoidance in infancy and allergy at 4 years of age.

In an attempt to prevent or reduce the manifestations of atopic disease, a group of infants considered to be genetically at high risk of atopy was entered in a prenatally randomized, controlled study. A prophylactic group (n= 58) was either breast‐fed with their mothers excluding foods regarded as highly antigenic from their diets, or given an extensively hydrolysed formula. In addition, strenuous efforts were made to reduce exposure to the house‐dust mite by application of acaricide to the bedroom and living room carpets and upholstered furniture. A control group (n= 62) was fed conventionally by breast or on formula, and no specific environmental measures were taken. The results (previously reported) after 1 year showed significantly less total allergy, asthma, and eczema in the prophylactic group. Similar results were obtained at 2 years although the reduction in asthma no longer achieved statistical significance. However, there was significantly less sensitization, as shown by a battery of skin prick tests (SPTs), to both dietary allergens and aeroallergens in the prophylactic group. A11 the children have now been reviewed at the age of 4 years, and SPTs to a wide range of dietary allergens and aeroallergens have been performed. The control group continues to show more total allergy (odds ratio [OR] 2.73, 95% confidence interval [CI] 1.21–6.13, P<0.02), definite allergy (allergic symptoms plus positive SPT) (OR 5.6, CI 1.8–17.9, P<0.005), and eczema (OR 3.4, CI 1.2–10.1, P<0.05). More control children have positive SPTs (OR 3.7, CI 1.3–10.0, P<0.02). A dual approach to the prevention of allergic disease, avoiding as far as possible sensitization to food and aeroallergens, significantly reduces the risk of atopic disease. This should be reserved for infants considered at very high risk of atopy, and close medical and dietetic supervision must be available.

Inequalities in self-rated health: explanations from different stages of life.

BACKGROUND Inequalities in health are a major public-health concern. A greater understanding is needed on the relative importance of different causes. We investigated the contribution of risk factors identified at different life stages to inequalities in self-rated health. METHODS We used data from 5606 men and 5799 women in the 1958 British birth cohort followed-up to age 33 years, on health behaviour, education, adolescent health, family structure and social support, work characteristics, and material circumstances. We assessed the contribution of different factors to social-class differences in self-rated health by adjustment of odds ratios (classes IV and V vs I and II). FINDINGS Odds ratios of poor-rated health at age 33 were 3.15 for men and 2.30 for women, which decreased to 2.06 and 1.34, respectively, after adjustment for previously identified factors from birth to early adulthood. Adjustment for adult work characteristics, material circumstances, and health behaviour between ages 23 years and 33 years further decreased the odds ratios to 1.64 (men) and 1.11 (women). Most factors contributed to the reduction in odds ratios, although adolescent socioemotional adjustment, class at birth, educational qualifications, and psychosocial job strain were especially important. Additional key factors for men were adult smoking and job insecurity, and for women, housing during childhood, adult income, and age at first child. INTERPRETATION There was no single cause of health inequality at age 33 years. Explanations spanned from early life to young adulthood. Policy implications include reduction of social differences in material circumstances and of differences in individual skills and resources acquired in early life.

Social inequalities in health: are there gender differences?

Some studies suggest that socio-economic status (SES) inequalities in health are smaller in women than men, but the evidence is inconsistent as to whether this applies across various health measures and life stages. The first aim of this paper was to establish whether the magnitude of social inequality in health differs for men and women during early adulthood, specifically in respect to self rated health, limiting long-standing illness, psychological distress, respiratory symptoms, asthma/wheezing, height and obesity; second, to determine whether explanations for socioeconomic inequality in poor self rated health differ for men and women. Analyses are based on longitudinal data from the British 1958 birth cohort study using information from birth to age 33. When gender differences in inequalities were examined using social class, no significant differences emerged across the seven health measures examined at ages 23 and 33. SES inequalities based on education, however, showed greater inequality among men at age 33 for limiting long-standing illness and respiratory symptoms, but greater inequality among women for poor rated health at age 23 and psychological distress at age 33. Hence, gender differences in the magnitude of health inequality were inconsistent across age and health measures. An analysis of the contribution of explanatory factors to social class differences in self-rated health suggested that causes of inequality were similar for men and women. However, some discrepancies emerged, notably in the greater contribution of job insecurity to class differences for men and in the greater contribution of age at first child for women. The magnitude and explanations for gender differences in SES health inequalities are likely to vary according to life stage and health measure.

Effect of allergen avoidance in infancy on allergic manifestations at age two years

BACKGROUND One hundred twenty children, identified before birth as being at high risk for atopy, were prenatally assigned to prophylactic or control groups. METHODS The infants in the prophylactic group either received breast milk from mothers on an exclusion diet or an extensively hydrolyzed formula. Their bedrooms and living rooms were treated repeatedly with an acaricide, and they used polyvinyl-covered mattresses with vented head areas. The infants in the control group were fed conventionally, and no environmental control was recommended. RESULTS A significant advantage, first demonstrated at 1 year of age, persists for children in the prophylactic group. They have less of any allergy or eczema, but the reduced prevalence of asthma is no longer significant. Only three children in the prophylactic group had positive skin prick test results compared with 16 in the control group, suggesting a significant reduction in sensitization. CONCLUSION A dual approach to allergen avoidance, focusing on foods and aeroallergens, appears to be beneficial in selected high-risk infants. Avoidance of potent allergens in early life increases the threshold for sensitization in these high-risk infants. Whether sensitization has been avoided or merely deferred has yet to be proved.

Primary prevention of asthma and atopy during childhood by allergen avoidance in infancy: a randomised controlled study

Background: Recent increases in the prevalence of asthma and atopy emphasise the need for devising effective methods for primary prevention in children at high risk of atopy. Method: A birth cohort of genetically at risk infants was recruited in 1990 to a randomised controlled study. Allergen avoidance measures were instituted from birth in the prophylactic group (n=58). Infants were either breast fed with mother on a low allergen diet or given an extensively hydrolysed formula. Exposure to house dust mite was reduced by the use of an acaricide and mattress covers. The control group (n=62) followed standard advice as normally given by the health visitors. At age 8, all 120 children completed a questionnaire and 110 (92%) had all assessments (skin prick test, spirometry, and bronchial challenges). Results: In the prophylactic group eight children (13.8%) had current wheeze compared with 17 (27.4%) in the control group (p=0.08). Respective figures were eight (13.8%) and 20 (32.3%) for nocturnal cough (p=0.02) and 11 of 55 (20.0%) and 29 of 62 (46.8%) for atopy (p=0.003). After adjusting for confounding variables, the prophylactic group was found to be at a significantly reduced risk for current wheeze (odds ratio (OR) 0.26 (95% confidence interval (CI) 0.07 to 0.96)), nocturnal cough (OR 0.22 (95% CI 0.06 to 0.83)), asthma as defined by wheeze and bronchial hyperresponsiveness (OR 0.11 (95% CI 0.01 to 1.02)), and atopy (OR 0.21 (95% CI 0.07 to 0.62)). Conclusion: Strict allergen avoidance in infancy in high risk children reduces the development of allergic sensitisation to house dust mite. Our results suggest that this may prevent some cases of childhood asthma.

Egg allergy in infancy predicts respiratory allergic disease by 4 years of age

Sensitization to hen’s egg early in life has been proposed as a predictor for respiratory allergic disease during childhood. However, symptomatic egg allergy in infancy has not been studied in this context. In 1989, a cohort of consecutive births was recruited. Data on family history of atopy and environmental factors were collected. At 4 years of age, 1218 children were seen of whom 981 were skin‐prick tested with a range of food and aero‐allergens. Of the 1218 children, 29 (2.4%) had suffered symptomatic egg allergy (20 during infancy). Egg allergy in infancy was associated with increased respiratory (asthma, rhinitis) allergic disease (odds ratio [OR] 5.0, 95% confidence intervals [CI] 1.1–22.3; p < 0.05) at 4 years of age, with a positive predictive value (PPV) of 55.0%. The addition of infantile eczema to egg allergy increased the PPV to 80% whereas the addition of family history of atopy had no effect. Egg allergy also increased aero‐allergen sensitization (OR 6.1, CI 1.1–37.5; PPV 61.1%; p < 0.05). As a predictor for respiratory allergic disease and aero‐allergen sensitization, it carried a high specificity but poor sensitivity. Hence, egg allergy in infancy, especially when coexisting with eczema, increases respiratory allergic symptoms and aero‐allergen sensitization in early childhood.

Characterization of wheezing phenotypes in the first 10 years of life

Background Childhood wheezing illnesses are characterized into different phenotypes. However, severity of the disease associated with these phenotypes has not been extensively studied.