Overweight does not increase asthma risk but may decrease allergy risk at school age after infantile bronchiolitis

Childhood Obesity, Weight Change, and Pediatric Immune-Mediated Skin Diseases

Whether childhood obesity or weight gain leads to the development of pediatric immune-mediated skin diseases remains unclear. We aimed to determine the associations between body mass index or body mass index changes and the development of 3 main immune-mediated skin diseases-alopecia areata, atopic dermatitis (AD), and psoriasis-by analyzing a longitudinal cohort of 2,161,900 Korean children from 2009 to 2020. The findings indicated that children who were obese had a higher risk of pediatric immune-mediated skin diseases than those with normal weight (P for trend < .01). An increase in body mass index was associated with a higher risk of AD, whereas a decrease in body mass index was correlated with a reduced risk of AD. Children who gained weight, transitioning from normal to overweight, exhibited a higher AD risk than those who maintained a normal weight (adjusted hazard ratio = 1.15, 95% confidence interval = 1.11-1.20). However, those who shifted from being overweight to achieving a normal weight (adjusted hazard ratio = 0.87, 95% confidence interval = 0.81-0.94) had a lower AD risk than children who were overweight who maintained their weight. In summary, early childhood obesity may increase the risk of pediatric immune-mediated skin diseases. Weight gain may increase AD risk, whereas weight loss may lower the risk.

Link between obesity and atopic dermatitis: Does obesity predispose to atopic dermatitis, or vice versa?

Two serious health conditions, obesity and atopic dermatitis (AD), share some pathological features such as insulin resistance, leptin resistance and inflammation, and a growing body of evidence suggests a link between obesity and AD. Obesity predisposes an individual to and/or worsens AD, whereas AD increases the risk of obesity. Obesity and AD's interactions are mediated by cytokines, chemokines and immune cells. Obese individuals with AD are more resistant to anti-inflammatory therapy, while weight loss can alleviate AD. In this review, we summarize the evidence linking AD and obesity. We also discuss the pathogenic role of obesity in AD, and vice versa. Because of the connection between these two conditions, mitigation of one could possibly prevent the development of or alleviate the other condition. Effective management of AD and weight loss can enhance the wellness of individuals with both of these conditions. However, proper clinical studies are warranted to validate this speculation.

Investigating causal relationships between Body Mass Index and risk of atopic dermatitis: a Mendelian randomization analysis

Population studies suggest that atopic dermatitis (AD) is associated with an increased risk of obesity, however a causal relationship between these two conditions remains to be established. We therefore use Mendelian randomization (MR) to evaluate whether obesity and AD are causally interlinked. We used summary statistics extracted from genome wide association studies of Body Mass Index (BMI) and AD. MR analysis was performed in both directions to establish the direction of causality between BMI and AD. We find that genetically determined increase in adiposity is associated with increased risk of AD (odds ratio of AD 1.08 [95% CI 1.01 to 1.14; p = 0.015] per unit increase in BMI). Conversely, genetically determined increased risk of AD is not associated with a higher BMI (change in BMI attributable to AD based on genetic information: 0.00; 95% CI − 0.02 to 0.02; p = 0.862). There was no evidence for confounding of these genetic analyses by horizontal pleiotropy. Our results indicate that the association of AD with obesity is likely to reflect a causal role for adiposity in the development of AD. Our findings enhance understanding of the etiology of AD, and the basis for experimental studies to evaluate the mechanistic pathways by which adiposity promotes AD.

Is atopic dermatitis associated with obesity? A systematic review of observational studies

Obesity has been associated with atopic dermatitis (AD); however, the results have been conflicting. Our aim was to provide an update on current knowledge from observational studies addressing the possible association between obesity and AD. Systematic literature review was performed by identifying studies addressing a possible link between AD and overweight/obesity from PubMed, EMBASE and the Cochrane Library in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. The quality of the included studies was assessed using the Newcastle-Ottawa Scale. A total of 45 studies (comprising more than 90 000 individuals with AD) fulfilled the criteria and were included in the present review. The available studies revealed inconsistencies, but the majority indicated that obesity is associated with AD. Studies addressing obesity in infancy or early childhood (age < 2 years) and AD reported a positive association. From childhood into adulthood, there is a discrepancy in the observations, as the more recent prospective studies found a positive association, whereas this was not observed in older cross-sectional studies. The inconsistency might be explained by the difference in study design, the diagnostic criteria of AD, regional differences, and by the varied definitions of overweight and obesity used in the studies. In Conclusion, overweight/obesity is associated with an increased risk of AD. Large prospective cohort studies are required to confirm the association between AD and obesity and the possibility that weight control in childhood may help to mitigate or reverse AD symptoms.

Weight-for-length, early weight-gain velocity and atopic dermatitis in infancy and at two years of age: a cohort study

Background

Overweight and atopic dermatitis (AD) are major health problems in most industrialised countries, but the relationship between overweight and AD in infants and young children is unclear. We investigated if weight-for-length at birth, in infancy and at two years, as well as early weight-gain velocity, are associated with the development of AD in early life.

Methods

Cohort study of infants (n = 642), all living in south-east Norway, hospitalized with acute bronchiolitis (n = 404) or recruited from the general population (n = 238), examined at mean age 5.1 months (enrolment) and at a two-year follow-up visit (n = 499; 78%) at mean age 24.6 months. Exposures were weight-for-length (g/cm) at birth, enrolment and two-year follow-up, and early weight-gain velocity (gram/month from birth to enrolment). Excessive weight-for-length was defined as weight-for-length >95^th percentile of WHO child-growth standards. Data on weight-for-length at the three time points were obtained for 435, 428 and 473 children. AD was diagnosed according to the Hanifin & Rajka criteria or from a history of physician-diagnosed AD. We performed multivariate analyses with weight-for-length at birth, at enrolment and at the two-year follow-up visit and with early weight gain velocity for the endpoint AD at each visit.

Results

In adjusted analyses, excessive weight-for-length at enrolment was associated with concurrent AD (OR 3.03; 95% CI 1.23–7.50) and with AD at two years (OR 2.40; 1.11–5.17). In infants without AD, weight-for-length at enrolment increased the risk of AD at two years, with OR being 1.02 (95% CI 1.00–1.04) per increased gram/cm. AD at two years was not associated with concurrent excessive weight-for-length, nor was AD at any time associated with weight-for-length at birth or with early weight-gain velocity.

Conclusions

The results suggest that overweight in infancy may contribute to the development of AD in early life, highlighting the need for child health-care professionals to address potential overweight and atopic disease when advising infants’ caregivers.

Trial registration

ClinicalTrials.gov number, NCT00817466, EudraCT number, 2009–012667-34.

Association of atopic dermatitis with being overweight and obese: a systematic review and metaanalysis

BACKGROUND

Previous studies found conflicting results about whether atopic dermatitis (AD) is associated with overweight/obesity.

OBJECTIVE

We sought to examine the relationship between AD and overweight/obesity by performing a systematic review and metaanalysis.

METHODS

Observational studies of the relationship between AD and overweight/obesity were selected from PubMed, Embase, and the Cochrane Library. The quality of evidence was assessed using the Newcastle-Ottawa Scale. Fixed and random effects metaanalyses were performed to estimate pooled odds ratios (ORs). Sensitivity analyses were performed that compared results by location of study, study quality, and between studies in children and adults.

RESULTS

In total, 30 studies were included for review. Patients who were overweight (Cochrane-Mantel-Haenszel [CMH] OR, 1.27 [95% confidence interval {CI}: 1.19-1.36]; random effects OR, 1.23 [95% CI: 1.11-1.41]), obese (CMH OR, 1.68 [95% CI: 1.54-1.84]; random effects OR, 1.47 [95% CI: 1.21-1.79]), or overweight/obese (CMH OR, 1.42 [95% CI: 1.34-1.50]; random effects OR, 1.31 [95% CI: 1.16-1.48]) had higher odds of AD than normal weight patients. In sensitivity analyses, children who were overweight (random effects OR, 1.24 [95% CI: 1.08-1.43]), obese (random effects OR, 1.44 [95% CI: 1.12-1.86]), or overweight/obese (random effects OR, 1.32 [95% CI: 1.15-1.51]) and adults who were obese (random effects OR, 1.56 [95% CI: 1.24-1.95]) or overweight/obese (random effects OR, 1.29 [95% CI: 1.05-1.59]) had higher odds of AD. The association remained significant in North America and Asia but not Europe.

LIMITATIONS

Most studies were cross-sectional.

CONCLUSIONS

Overweight/obesity in North America and Asia is associated with an increased prevalence of AD.