Objective: Obesity prevention in childhood is important. However, changing children's lifestyle behaviors to reduce overweight is a substantial challenge. Accurately perceiving oneself as overweight/obese has been linked to greater motivation to change lifestyle behaviors. Children and adolescents may be less likely to perceive themselves as overweight/obese if they are exposed to overweight/obese people in their immediate environments. This study examined whether youth who are exposed to overweight parents and schoolmates were more likely to misperceive their own weight status. Design: The Quebec Child and Adolescent Health and Social Survey was a provincially representative, school-based survey of children and adolescents conducted between January and May 1999. Subjects: 3665 children and adolescents (age 9, n=1267; age 13, n=1186; age 16, n=1212) from 178 schools. Mean body mass index (BMI) was 17.5, 20.6 and 22.2 kg/m², respectively. Measurements: The misperception score was calculated as the standardized difference between self-perception of weight status (Stunkard Body Rating Scale) and actual BMI (from measured height and weight). Exposure to obesity was based on parent and schoolmate BMI. Results: Overweight and obese youth were significantly more likely to misperceive their weight compared with non-overweight youth (P<0.001). Multilevel modeling indicated that greater parent and schoolmate BMI were significantly associated with greater misperception (underestimation) of weight status among children and adolescents. Conclusion: Children and adolescents who live in environments in which people they see on a daily basis, such as parents and schoolmates, are overweight/obese may develop inaccurate perceptions of what constitutes appropriate weight status. Targeting misperception may facilitate the adoption of healthy lifestyle behaviors and improve the effectiveness of obesity prevention interventions.

ObjectiveTo determine the association between physical activity (PA) intensities and cardiometabolic risk factors in youth.DesignCross-sectional study using data from the 2008 Healthy Hearts Prospective Cohort Study of Physical Activity and Cardiometabolic Health in Youth.SettingRural and urban communities in Alberta, Canada.ParticipantsA convenience sample of 605 youth aged 9 to 17 years. Youth were on average aged 12.1 years, 248 were boys (41%), and 157 were overweight or obese (26%).Main ExposureActical accelerometer–measured PA intensity.Main Outcomes MeasuresThe primary outcome was body mass index (calculated as weight in kilograms divided by height in meters squared) z score. Secondary outcome measures included waist circumference, systolic blood pressure, and cardiorespiratory fitness (maximal oxygen consumption [[Vdot]O_2max]).ResultsBody mass index z score, waist circumference, and systolic blood pressure decreased and [Vdot]O_2max increased in a dose-response manner across tertiles of vigorous PA (adjusted P < .001). No significant differences in cardiometabolic risk factors were seen across tertiles of moderate or light PA in multivariable analyses. Achieving more than 7 minutes of vigorous PA daily was associated with a reduced adjusted odds ratio of overweight status (0.56; 95% CI, 0.33-0.95) and elevated systolic blood pressure (0.36; 95% CI, 0.16-0.79). The odds of overweight status and elevated blood pressure decreased with increasing time and intensity of PA.ConclusionsOnly vigorous PA was consistently associated with lower levels of waist circumference, body mass index z score, systolic blood pressure, and increased cardiorespiratory fitness in youth. These findings underscore the importance of vigorous PA in guidelines for children and adolescents.

The epidemic rise in the prevalence of obesity and in particular, paediatric obesity has led to concerns that the complications of excess adiposity may well reverse the favourable trends in cardiovascular disease (CVD) mortality observed over the past half-century. Although recent reports suggest that the prevalence of overweight and obesity may have reached a plateau, at least in the USA,^1,2 the continued exposure to excess body fat over prolonged periods of time may have serious deleterious effects on the health and well-being of populations and may lead to a decrease in life expectancy among younger generations.^3,4

Background and objectives: As a result of improved clinical and quality-of-life outcomes compared with conventional hemodialysis, interest in nocturnal home hemodialysis (NHD) has steadily increased in the past decade; however, little is known about the flow of patients through NHD programs or about patient-specific predictors of mortality or technique failure associated with this modality. This study addressed this gap in knowledge. Design, setting, participants, & measurements: This study included 247 NHD patients of the Canadian Slow Long nightly ExtEnded dialysis Programs (CAN-SLEEP) cohort from 1994 through 2006 inclusive. The association between program- and patient-specific variables and risk for adverse outcomes was determined using uni- and multivariable Cox regression. Results: A total of 14.6% of the cohort experienced death or technique failure. Unadjusted 1- and 5-year adverse event-free survival was 95.2 and 80.1%, respectively. Significant predictors of a composite of mortality and technique failure included advanced age (P < 0.001), diabetes (P < 0.001), central venous catheter use (P = 0.01), and inability to perform NHD independently (P = 0.009) and were adjusted for center effect. Weekly frequency of NHD was not predictive. Age and diabetes remained significant with multivariable analysis (hazard ratio 1.07 and 2.64, respectively). Unadjusted 1- and 5-year technique survival was 97.9 and 95.2%, respectively. Only age was a significant predictor of technique failure. Conclusions: NHD is associated with excellent adverse event-free survival. This study underscores the importance of modality-specific predictors in the success of home hemodialysis, as well as favorable baseline characteristics such as younger age and the absence of diabetes.

The Nicotine Dependence in Teens (NDIT) study is a prospective cohort investigation of 1294 students recruited in 1999–2000 from all grade 7 classes in a convenience sample of 10 high schools in Montreal, Canada. Its primary objectives were to study the natural course and determinants of cigarette smoking and nicotine dependence in novice smokers. The main source of data was self-report questionnaires administered in class at school every 3 months from grade 7 to grade 11 (1999–2005), for a total of 20 survey cycles during high school education. Questionnaires were also completed after graduation from high school in 2007–08 and 2011–12 (survey cycles 21 and 22, respectively) when participants were aged 20 and 24 years on average, respectively. In addition to its primary objectives, NDIT has embedded studies on obesity, blood pressure, physical activity, team sports, sedentary behaviour, diet, genetics, alcohol use, use of illicit drugs, second-hand smoke, gambling, sleep and mental health. Results to date are described in 58 publications, 20 manuscripts in preparation, 13 MSc and PhD theses and 111 conference presentations. Access to NDIT data is open to university-appointed or affiliated investigators and to masters, doctoral and postdoctoral students, through their primary supervisor ( www.nditstudy.ca ).