Overnight sleep duration and obesity in 2-5 year-old American Indian children.

BACKGROUND: Sleep has emerged as a potentially modifiable risk factor for obesity in children. OBJECTIVES: The purpose of this investigation was to evaluate the association between overnight sleep duration and obesity among American Indian (AI) children ages 2-5 years. METHODS: Data were examined from the baseline assessment of children enrolling in the Healthy Children, Strong Families study, which is a randomized lifestyle intervention trial in five diverse rural and urban AI communities nationally among children ages 2-5 years. Multivariable models were built to assess the relationship between sleep duration and BMI z-score while controlling for potential sociodemographic and behavioural covariates. RESULTS: Three hundred and ninety-eight children had sufficient data to be included in analysis. In multivariable models controlling for potential covariates, overnight sleep duration was significantly and inversely associated with BMI z-score (B = -0.158, t = -1.774, P = 0.006). Similarly, when controlling for covariates, children who slept 12 or more hours had significantly lower BMI z-scores compared with those who slept 8 to 10 h (P = 0.018) or less than 8 h (P = 0.035); the difference between 12+ hours and 10 to 12-h groups did not reach statistical significance (P = 0.073) but supported a linear relationship between overnight sleep duration and BMI. Weekday-to-weekend variability in overnight sleep duration was not associated with BMI z-score (B = 0.010, t = 0.206, P = 0.837). CONCLUSIONS: Overnight sleep duration is independently and inversely related to BMI z-score among AI children ages 2-5 years, even when controlling for important sociodemographic and obesogenic lifestyle factors. This represents the first report, to our knowledge, of sleep duration as a risk factor for obesity among AI children.

Linking electronic health records with community-level data to understand childhood obesity risk.

BACKGROUND: Environmental and socioeconomic factors should be considered along with individual characteristics when determining risk for childhood obesity. OBJECTIVES: To assess relationships and interactions among the economic hardship index (EHI) and race/ethnicity, age and sex in regard to childhood obesity rates in Wisconsin children using an electronic health record dataset. METHODS: Data were collected using the University of Wisconsin (UW) Public Health Information Exchange database, which links electronic health records with census-derived community-level data. Records from 53,775 children seen at UW clinics from 2007 to 2012 were included. Mixed-effects modelling was used to determine obesity rates and the interaction of EHI with covariates (race/ethnicity, age, sex). When significant interactions were determined, linear regression analyses were performed for each subgroup (e.g. by age groups). RESULTS: The overall obesity rate was 11.7% and significant racial/ethnic disparities were detected. Childhood obesity was significantly associated with EHI at the community level (r = 0.62, P < 0.0001). A significant interaction was determined between EHI and both race/ethnicity and age on obesity rates. CONCLUSIONS: Reducing economic disparities and improving environmental conditions may influence childhood obesity risk in some, but not all, races and ethnicities. Furthermore, the impact of EHI on obesity may be compounded over time. Our findings demonstrate the utility of linking electronic health information with census data to rapidly identify community-specific risk factors in a cost-effective manner.

Effects of endurance exercise training on markers of cholesterol absorption and synthesis.

Abnormal cholesterol metabolism, including low intestinal cholesterol absorption and elevated synthesis, is prevalent in diabetes, obesity, hyperlipidemia, and the metabolic syndrome. Diet-induced weight loss improves cholesterol absorption in these populations, but it is not known if endurance exercise training also improves cholesterol homeostasis. To examine this, we measured circulating levels of campesterol, sitosterol, and lathosterol in 65 sedentary subjects (average age 59 years; with at least one metabolic syndrome risk factor) before and after 6 months of endurance exercise training. Campesterol and sitosterol are plant sterols that correlate with intestinal cholesterol absorption, while lathosterol is a marker of whole body cholesterol synthesis. Following the intervention, plant sterol levels were increased by 10% (p<0.05), but there was no change in plasma lathosterol. In addition, total and LDL-cholesterol were reduced by 0.16 mmol and 0.10 mmol, respectively (p<0.05), while HDL-C levels increased by 0.09 mmol (p<0.05). Furthermore, the change in plant sterols was positively correlated with the change in VO2max (r=0.310, p=0.004), independent of other metabolic syndrome risk factors. These data indicate that exercise training reduces plasma cholesterol despite increasing cholesterol absorption in subjects with metabolic syndrome risk factors.