Association Between Atopic Dermatitis and Height, Body Mass Index, and Weight in Children

IMPORTANCE: Atopic dermatitis may be associated with short stature and obesity in children, but most previous studies have been either small or cross-sectional. OBJECTIVE: To evaluate the association between atopic dermatitis and height, body mass index (BMI; calculated as weight in kilograms divided by height in meters squared), and weight throughout childhood. DESIGN, SETTING, AND PARTICIPANTS: TARGet Kids! (The Applied Research Group for Kids) is an ongoing prospective longitudinal cohort study that collects data at routine physician visits throughout childhood. In this cohort, children aged 5 or younger were followed up into adolescence at regular physician visits at general pediatric and family practices in Toronto, Canada, from June 2008 to February 2021. EXPOSURE: Parental report of atopic dermatitis. MAIN OUTCOMES AND MEASURES: Primary outcomes were length-for-age and BMI-for-age z scores. The secondary outcome was weight-for-age z score. Linear mixed effects models were used to estimate associations between atopic dermatitis and each outcome. In secondary analyses, interaction terms were included between atopic dermatitis and age. RESULTS: A total of 10 611 children were included in the analysis, with mean (SD) baseline age of 23 (20) months; 5070 (47.8%) participants were female. Participants were followed for a median (range) of 28.5 (0.0-158.0) months. A total of 1834 (17.3%) children had atopic dermatitis during follow-up. Atopic dermatitis was associated with lower length-for-age z score (-0.13; 95% CI, -0.17 to -0.09; P < .001), higher BMI z score (0.05; 95% CI, 0.01 to 0.09; P = .008), and lower weight-for-age z score (-0.07; 95% CI, -0.10 to -0.04; P < .001) compared with children without atopic dermatitis. The associations between atopic dermatitis and height and BMI changed with age, diminishing by age 14 years and 5.5 years, respectively. Based on World Health Organization growth tables, children with atopic dermatitis were on average 0.5 cm shorter with 0.2 more BMI units at age 2 years and 0.6 cm shorter with no difference in BMI at age 5 years than children without atopic dermatitis after adjusting for covariates. There was no evidence of interaction between atopic dermatitis and age with respect to weight. CONCLUSIONS AND RELEVANCE: In this cohort study, atopic dermatitis was associated with shorter stature, higher BMI, and lower weight in early childhood, but these associations were small and, for height and BMI, attenuated with age and resolved by adolescence.