Patterns of farm exposure are associated with reduced incidence of atopic dermatitis in early life

BACKGROUND

Farm exposures may reduce the risk of atopic dermatitis (AD) in children, but this is controversial and US data are limited.

OBJECTIVE

This study was conducted to identify patterns of farm exposure in Wisconsin family farms that modify AD incidence and prevalence in early childhood.

METHODS

Environmental exposures, health history, and clinical outcomes were prospectively recorded for 111 farm families and 129 non-farm families enrolled in the Wisconsin Infant Study Cohort birth cohort study. Exposures from the prenatal and early postnatal (2-month) visits were evaluated together with parental report of AD diagnosis by a health care provider through age 24 months. Latent class analysis was performed with prenatal and early postnatal farm-exposure variables to assign farm children to 3 classes.

RESULTS

Overall, children of farm families had reduced AD incidence (P = .03). Within farm families, exposures including poultry (3% vs 28%; P = .003), pig (4% vs 25%; P = .04), feed grain (13% vs 34%; P = .02), and number of animal species were inversely associated with AD incidence. Among the latent class groups, children in families with diverse or more intense farm exposures (classes A and B) had reduced AD incidence, whereas low-exposure (class C) infants had AD incidence similar to that in nonfarm children.

CONCLUSIONS

Infants in Wisconsin farm families had reduced AD incidence, and patterns of farm exposures further defined AD risk. These findings suggest that exposure to diverse farm animals, feed, and bedding during the prenatal period and in early infancy reduce the risk of early-onset AD, a phenotype associated with multiple other atopic diseases.

Respiratory health, allergies, and the farm environment: design, methods and enrollment in the observational Wisconsin Infant Study Cohort (WISC): a research proposal

Epidemiologic and cross-sectional studies suggest that early life farming and animal exposures are associated with major health benefits, influencing immune development and modifying the subsequent risk of allergic diseases, including asthma. The Wisconsin Infant Study Cohort (WISC) study was established in central Wisconsin to test the hypothesis that early life animal farm exposures are associated with distinct innate immune cell maturation trajectories, decreased allergen sensitization and reduced respiratory viral illness burden during the first 2 years of life. Beginning in 2013, a total of 240 families have been enrolled, 16,522 biospecimens have been collected, and 4098 questionnaires have been administered and entered into a secure database. Study endpoints include nasal respiratory virus identification and respiratory illness burden score, allergic sensitization, expression of allergic disease, and anti-viral immune response maturation and profiles. The WISC study prospective design, broad biospecimen collections, and unique US rural community will provide insights into the role of environmental exposures on early life immune maturation profiles associated with protection from allergic sensitization and significant respiratory viral disease burden. The WISC study findings will ultimately inform development of new strategies to promote resistance to severe respiratory viral illnesses and design primary prevention approaches for allergic diseases for all infants.

Maternal prepregnancy body mass index and offspring attention-deficit/hyperactivity disorder: a quasi-experimental sibling-comparison, population-based design

BACKGROUND

High maternal prepregnancy body mass index (BMI) has been associated with increased risk of offspring attention-deficit/hyperactivity disorder (ADHD). However, whether this effect is attributable to maternal or familial level confounds has been little examined.

METHODS

The present study sought to examine these associations, utilizing data from the medical records of a health care system which treats 350,000 patients annually and a sibling-comparison design in a sample of 4,682 children born to 3,645 mothers.

RESULTS

When examining the overall maternal effect, a linear association was observed between maternal prepregnancy BMI and child ADHD [b = 0.04, 95% confidence interval (95% CI) = 0.02-0.06, p = .0003], such that a one-unit (i.e. 1 kg/m2 ) increase in prepregnancy BMI was associated with a 4% increase in the odds of ADHD (exp b = 1.04). However, when the model was reparameterized to take full advantage of the sibling design to allow for the examination of both maternal and child-specific effects, the child-specific prepregnancy BMI effect was not reliably different from zero (b = -0.08, 95% CI = -0.23 to 0.06, p = .24). In contrast, at the maternal-level, average prepregnancy BMI was a reliably non-zero predictor of child ADHD (b = 0.04, 95% CI = 0.02-0.06, p < .0001) with each one-unit increase in maternal prepregnancy BMI associated with a 4.2% increase in the odds of ADHD (exp b = 1.04, 95% CI = 1.02-1.06).

CONCLUSIONS

The association between maternal prepregnancy BMI and offspring ADHD may be better accounted for by familial or maternal confounds rather than a direct causal effect of BMI.

Evaluation of the factor structure of the child-reported parenting questionnaire in the National Longitudinal Survey of Children and Youth

BACKGROUND

The effect of parenting behaviours is important in child health and development research. This study evaluates three child-reported parenting behaviour scales (nurturance, rejection and monitoring) in the Canadian National Longitudinal Survey of Children and Youth (NLSCY).

DATA AND METHODS

The sample consisted of two longitudinal cohorts (n = 1,164) who were interviewed at ages 10 to 11, 12 to 13, and 14 to 15. The factor structure of each scale was evaluated using confirmatory factor analysis with weighted least squares estimation on polychoric correlation matrices.

RESULTS

The 7-item NLSCY Parental Nurturance model appeared to be a good fit to the data for children aged 10 to 11 and 12 to 13, but not for those aged 14 to 15. The 7-item Parental Rejection model was not a good fit to the data across any of the three time points. The 5-item Parental Monitoring model was a good fit to the data across all three time points. Removal of one item from the nurturance and one item from the monitoring scale improved the fit to the data.

INTERPRETATION

The revised models appeared to be useful in assessing parental nurturance and monitoring. The model for parental rejection was not confirmed for this sample of adolescents.