LAUSR

BACKGROUND AND OBJECTIVES Childhood obesity is increasing in urban India. This study aimed to examine the associations of younger siblings abdominal adiposity with individual, familial and environmental factors, in urban school aged siblings. METHODS AND STUDY DESIGN Weight, height and waist circumference of 2906 siblings aged 3-16 years were measured along with details on demographics, diet, lifestyle, behavior and reported parental anthropometrics. Abdominal adiposity was classified as waist circumference above the age and sex specific 75th percentile value. The associations of various factors with abdominal adiposity in the younger siblings were examined through logistic regression analyses. RESULTS Sibling, familial factors and environmental factors had significant associations with abdominal adiposity. The odds of a younger sibling having abdominal adiposity was greatest (OR=3.16, 95% confidence interval (95% CI): 2.27 to 4.42), when the older sibling had abdominal adiposity, followed by the odds ratio of both parents being overweight (OR=1.63, 95% CI: 1.33 to 1.99) compared to neither being overweight. The influence of abdominal adiposity of the older sibling was greater when the siblings were of the same sex (OR=3.55, 95% CI: 2.24 to 5.65) than when they were of different sex (OR=2.73, 95% CI: 1.67 to 4.46); the odds ratio being highest when both siblings were males. CONCLUSIONS The younger sibling's abdominal adiposity is associated with that of his/her sibling and parental obesity, in addition to other known risk factors in urban south Indian families. Interventions to prevent childhood obesity need to also consider the sibling effect along with the other known factors.