Biostatistics Research Today is a free monthly online journal that collates and summarizes the latest research about Biostatistics, including details on statistics, uncertainty, probability, modeling. | ||||||||
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Time spent outdoors at midday and children's body mass index.Milne E, Simpson JA, Johnston R, Giles-Corti B, English DR Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, West Perth. lizm@ichr.uwa.edu.au OBJECTIVES: We investigated whether the Kidskin sun protection intervention increased children's body mass index by reducing the time spent outdoors at midday. METHODS: The Kidskin sun protection intervention involved 1614 Australian school children assigned to 1 of 3 groups: a control group, a moderate-intervention group, or a high-intervention group. Schools in the control group received the standard health curriculum and schools in the intervention groups received a multicomponent intervention. Outcomes included time spent outdoors and nevus development (a marker of melanoma risk). Height and weight were measured at 3 time points. Body mass index was transformed into age- and gender-specific z scores; z scores at each age were modeled simultaneously. Time spent outdoors at ages 10 and 12 years was analyzed using a linear mixed effects modeling. RESULTS: The proportion of children who were overweight or obese increased with age. The moderate-intervention and control groups had a minimal increase in z score over time, and the z score for the high-intervention group decreased over time. There were no differences among groups with respect to total time outdoors at any age. CONCLUSIONS: It is possible to reduce the time children spend outdoors when ultraviolet radiation is high without producing an unfavorable effect on the children's body mass index. Published 24 January 2007 in Am J Public Health, 97(2): 306-10.
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