Objective: Severe school absence may be one underlying cause of poor school performance among overweight and obese children. We examined the associations between school absenteeism and body mass index (BMI) in a nationally representative sample of children.

Methods and Procedures: We analyzed the data of 1,387 children (6-11 y) and 2,185 adolescents (12-19 y), who completed an interview and anthropometric measurement as a part of the National Health and Nutrition Examination Survey, 2005-2008. CDC 2000 growth chart was used to categorize BMI status, and school days missed during the past 12 months was assessed by asking the proxies or interviewees.

Results: The prevalence of obese and overweight were 18.96 (SE=1.44), and 16.41(0.78)% respectively among study populations. The means of school days missed in the last 12 months were not statistically different between normal weight, overweight and obese groups, 3.79 (SE=0.56), 3.86 (0.38) and 4.31 (0.01) days respectively. However, when more than 2 days missed per school month was defined as severe absenteeism, the prevalence of severe absenteeism were 1.57%, 2.99% and 4.94% respectively among 6- 11 years old children with normal, overweight and obese. The adjusted odds of being severe absentee were 2.18 (95% CI = 0.61-7.73) and 3.79 (1.45-9.91) respectively among overweight and obese children compared to normal weight peers (p for trend test < 0.01). No significant association was found among adolescents.

Conclusion: Increased body weight is independently associated with severe absenteeism.