Mark S. Tremblay

A comparison of direct vs. self-report measures for assessing height, weight and body mass index: a systematic review.

Obesity is a rapidly increasing public health problem, with surveillance most often based on self‐reported values of height and weight. We conducted a systematic review to determine what empirical evidence exists regarding the agreement between objective (measured) and subjective (reported) measures in assessing height, weight and body mass index (BMI). Five electronic databases were searched to identify observational and experimental studies on adult populations over the age of 18. Searching identified 64 citations that met the eligibility criteria and examined the relationship between self‐reported and directly measured height or weight. Overall, the data show trends of under‐reporting for weight and BMI and over‐reporting for height, although the degree of the trend varies for men and women and the characteristics of the population being examined. Standard deviations were large indicating that there is a great deal of individual variability in reporting of results. Combining the results quantitatively was not possible because of the poor reporting of outcomes of interest. Accurate estimation of these variables is important as data from population studies such as those included in this review are often used to generate regional and national estimates of overweight and obesity and are in turn used by decision makers to allocate resources and set priorities in health.

A comparison of direct versus self-report measures for assessing physical activity in adults: a systematic review

BackgroundAccurate assessment is required to assess current and changing physical activity levels, and to evaluate the effectiveness of interventions designed to increase activity levels. This study systematically reviewed the literature to determine the extent of agreement between subjectively (self-report e.g. questionnaire, diary) and objectively (directly measured; e.g. accelerometry, doubly labeled water) assessed physical activity in adults.MethodsEight electronic databases were searched to identify observational and experimental studies of adult populations. Searching identified 4,463 potential articles. Initial screening found that 293 examined the relationship between self-reported and directly measured physical activity and met the eligibility criteria. Data abstraction was completed for 187 articles, which described comparable data and/or comparisons, while 76 articles lacked comparable data or comparisons, and a further 30 did not meet the reviews eligibility requirements. A risk of bias assessment was conducted for all articles from which data was abstracted.ResultsCorrelations between self-report and direct measures were generally low-to-moderate and ranged from -0.71 to 0.96. No clear pattern emerged for the mean differences between self-report and direct measures of physical activity. Trends differed by measure of physical activity employed, level of physical activity measured, and the gender of participants. Results of the risk of bias assessment indicated that 38% of the studies had lower quality scores.ConclusionThe findings suggest that the measurement method may have a significant impact on the observed levels of physical activity. Self-report measures of physical activity were both higher and lower than directly measured levels of physical activity, which poses a problem for both reliance on self-report measures and for attempts to correct for self-report – direct measure differences. This review reveals the need for valid, accurate and reliable measures of physical activity in evaluating current and changing physical activity levels, physical activity interventions, and the relationships between physical activity and health outcomes.

Body Mass Index in Urban Canada: Neighborhood and Metropolitan Area Effects

OBJECTIVES We investigated the influence of neighborhood and metropolitan area characteristics on body mass index (BMI) in urban Canada in 2001. METHODS We conducted a multilevel analysis with data collected from a cross-sectional survey of men and women nested in neighborhoods and metropolitan areas in urban Canada during 2001. RESULTS After we controlled for individual sociodemographic characteristics and behaviors, the average BMIs of residents of neighborhoods in which a large proportion of individuals had less than a high school education were higher than those BMIs of residents in neighborhoods with small proportions of such individuals (P< .01). Living in a neighborhood with a high proportion of recent immigrants was associated with lower BMI for men (P<.01), but not for women. Neighborhood dwelling density was not associated with BMI for either gender. Metropolitan sprawl was associated with higher BMI for men (P=.02), but the effect was not significant for women (P= .09). CONCLUSIONS BMI is strongly patterned by an individuals social position in urban Canada. A neighborhoods social condition has an incremental influence on the average BMI of its residents. However, BMI is not influenced by dwelling density. Metropolitan sprawl is associated with higher BMI for Canadian men, which supports recent evidence of this same association among American men. Individuals and their environments collectively influence BMI in urban Canada.

Relationships between Parental Education and Overweight with Childhood Overweight and Physical Activity in 9-11 Year Old Children: Results from a 12-Country Study.

Background Globally, the high prevalence of overweight and low levels of physical activity among children has serious implications for morbidity and premature mortality in adulthood. Various parental factors are associated with childhood overweight and physical activity. The objective of this paper was to investigate relationships between parental education or overweight, and (i) child overweight, (ii) child physical activity, and (iii) explore household coexistence of overweight, in a large international sample. Methods Data were collected from 4752 children (9–11 years) as part of the International Study of Childhood Obesity, Lifestyle and the Environment in 12 countries around the world. Physical activity of participating children was assessed by accelerometry, and body weight directly measured. Questionnaires were used to collect parents’ education level, weight, and height. Results Maternal and paternal overweight were positively associated with child overweight. Higher household coexistence of parent-child overweight was observed among overweight children compared to the total sample. There was a positive relationship between maternal education and child overweight in Colombia 1.90 (1.23–2.94) [odds ratio (confidence interval)] and Kenya 4.80 (2.21–10.43), and a negative relationship between paternal education and child overweight in Brazil 0.55 (0.33–0.92) and the USA 0.54 (0.33–0.88). Maternal education was negatively associated with children meeting physical activity guidelines in Colombia 0.53 (0.33–0.85), Kenya 0.35 (0.19–0.63), and Portugal 0.54 (0.31–0.96). Conclusions Results are aligned with previous studies showing positive associations between parental and child overweight in all countries, and positive relationships between parental education and child overweight or negative associations between parental education and child physical activity in lower economic status countries. Relationships between maternal and paternal education and child weight status and physical activity appear to be related to the developmental stage of different countries. Given these varied relationships, it is crucial to further explore familial factors when investigating child overweight and physical activity.

The Canadian Assessment of Physical literacy: Development of a model of children's capacity for a healthy, active lifestyle through a Delphi process

BACKGROUND The Canadian Assessment of Physical Literacy (CAPL) was conceptualized as a tool to monitor childrens physical literacy. The original model (fitness, activity behavior, knowledge, motor skill) required revision and relative weights for calculating/interpreting scores were required. METHODS Nineteen childhood physical activity/fitness experts completed a 3-round Delphi process. Round 1 was open-ended questions. Subsequent rounds rated statements using a 5-point Likert scale. Recommendations were sought regarding protocol inclusion, relative importance within composite scores and score interpretation. RESULTS Delphi participant consensus was achieved for 64% (47/73) of statement topics, including a revised conceptual model, specific assessment protocols, the importance of longitudinal tracking, and the relative importance of individual protocols and composite scores. Divergent opinions remained regarding the inclusion of sleep time, assessment/ scoring of the obstacle course assessment of motor skill, and the need for an overall physical literacy classification. CONCLUSIONS The revised CAPL model (overlapping domains of physical competence, motivation, and knowledge, encompassed by daily behavior) is appropriate for monitoring the physical literacy of children aged 8 to 12 years. Objectively measured domains (daily behavior, physical competence) have higher relative importance. The interpretation of CAPL results should be reevaluated as more data become available.

Associations between obesity and morbidity: effects of measurement methods

A recent systematic review demonstrated that self-reported data typically result in an underestimation of weight and overestimation of height (1). As a result, significant misclassification occurs when body mass index (BMI) categories are estimated from self-reported data and the prevalence of obesity is underestimated (1). Chiolero et al. (2) cautioned researchers in interpreting associations between health conditions and BMI categories when BMI is derived from self-reported values. While it may initially appear intuitive that associations between health conditions and obesity would be underestimated because of this misclassification, using a hypothetical example, Chiolero et al. demonstrated that the opposite is true – the misclassification results in an exaggerated association between obesity and diabetes (2). Using data from Statistics Canada’s 2005 Canadian Community Health Survey (CCHS), a recently published article (3) supports Chiolero et al.’s hypothetical example. The analysis was based on a sample of 2667 respondents aged 40 years or older, from whom both self-reported and measured height and weight were collected. Using logistic regression analyses, associations between BMI categories and selected health conditions were examined. Results revealed that for diabetes, high blood pressure and heart disease, the odds ratios for the overweight and obese categories were substantially higher for models based on self-reported values than those based on measured values (Table 1). Stronger associations were observed for the overweight and obese categories based on self-reported data – because the respondents in them are, in fact, more obese – than for the corresponding categories based on measured values. For example, based on measured values, 29% of respondents were classified as obese, with an average measured weight of 95 kg. Based on self-reported data, only 15% of respondents were classified as obese; however, these respondents substantially under-reported their weights, and based on measured values, their average weight was in fact 98 kg – 3 kg higher than those classified as obese based on measured data. Finally, it is important to note that although associations with obesity-related health conditions were exaggerated when BMI categories were based on self-reported data, this does not imply that the burden of disease (as measured by the number of cases) is overestimated. In fact, because the use of self-reported data underestimates the prevalence of

Effects of physical activity on pediatric reference data for obesity

PURPOSE To examine the influence of physical activity on pediatric obesity reference data for Canada. METHODS The sample included 3527 boys and 3554 girls, 6 to 18 years of age, from the 2004 Canadian Community Health Survey: Nutrition component. The heights and weights of the participants were directly measured, and the body mass index was calculated (BMI: kg/m(2)). Physical activity levels were reported using an interviewer-administered questionnaire. Participants were divided into low and high physical activity groups, based on age-specific physical activity levels (lower and upper quartiles). BMI percentiles (25th, 50th, 75th, 85th, 95th) were generated by sex using the LMS method, separately by physical activity groups. RESULTS There were only minor differences in BMI at the 25th and 50th percentiles between physical activity groups in both boys and girls. However, in boys, the low active group had somewhat higher BMI values at the 85th and 95th percentiles than the high active group after the age of 10 years. In girls, the differences in BMI across groups was similar to that of boys at the 95th percentile, but inconsistent at the other percentiles. CONCLUSION The results suggest that screening for physical activity may be important for the development of national reference data for obesity.

Assessing the Influence of the Transition from Primary to Secondary School on the Volume of Active School Transport and Physical Activity: A Prospective Pilot-Study

Objectives: Active school transport (AST, e.g. the use of non-motorized travel modes such as walking and cycling to travel to/from school) is increasingly promoted as a source of physical activity (PA) in children and youth. This prospective pilot-study assessed the: 1) test-retest reliability of a novel measure of the volume of AST; 2) changes in AST and pedometer-determined PA across the transition from primary to secondary school; and 3) associations between AST and PA at both time points. Methods: 55 grade 6 students were recruited from 4 primary schools in Ottawa (Canada) in May/June, 2012. They were asked to complete a diary indicating their mode of transport to/from school for 1 week, and wear a SC-StepMX pedometer for 8 consecutive days. 48 study packages were returned at baseline and 29 at follow-up (September/ October 2012). For the test-retest assessment, a separate sample of 22 participants completed the diary during 2 consecutive weeks. Results: The weekly volume of AST (e.g. number of active trips X distance) showed high test-retest reliability (ICC=0.87). There were significant decreases in the proportion of children categorized as active travelers (57% to 46%), and in step counts (16,578 ± 3,758 to 14,071 ± 3,680 steps/day) across the school transition. However, in participants reporting at least 1 active trip at both time points (n=11), the volume of AST increased with a moderate effect size (d=0.52), but this change was not statistically significant. While no dose-response association between the volume of AST and PA was evident (probably due to limited statistical power), a gender-adjusted ANOVA indicated that active travelers accumulated an additional 2,207 steps/day at follow-up. Conclusion: These findings suggest that future research is needed to quantify changes in AST across the school transition, and to determine if AST can attenuate the commonly-observed decline in PA levels from childhood to adolescence.

Canadian directive with regard to sedentary behavior in young infants (0-4 years)

La Societe canadienne de physiologie de l’exercice (SCPE) en collaboration avec plusieurs partenaires, intervenants concernes et chercheurs a elabore les premieres directives canadiennes en matiere de comportement sedentaire a l’intention des enfants âges de 0 a 4 ans. Ces directives nationales repondent a une demande des praticiens en sante, des personnes qui prennent soin des enfants et en condition physique desireux d’avoir des directives au sujet du comportement sedentaire durant la petite enfance. L’elaboration des directives a respecte la Grille II d’evaluation de la qualite des recommandations pour la pratique clinique (AGREE). Les recommandations presentees dans cet article sont basees sur les donnees probantes d’une analyse documentaire systematique portant sur les relations entre le comportement sedentaire (surtout le temps passe devant un ecran) et des indicateurs de sante (poids sante, sante des os et du squelette, developpement des habiletes motrices, sante psychosociale, developpement cognit...The Canadian Society for Exercise Physiology (CSEP), with assistance from multiple partners, stakeholders, and researchers, developed the first Canadian Sedentary Behaviour Guidelines for the Early Years (aged 0–4 years). These national guidelines are in response to a call from health and health care professionals, child care providers, and fitness practitioners for guidance on sedentary behaviour in the early years. The guideline development process followed the Appraisal of Guidelines for Research Evaluation (AGREE) II framework. The recommendations are informed by evidence from a systematic review that examined the relationships between sedentary behaviour (predominantly screen time) and health indicators (healthy body weight, bone and skeletal health, motor skill development, psychosocial health, cognitive development, and cardio-metabolic disease risk factors) for three age groups (infants aged 900 domestic and international stakeholders, end-users, and key informants. The final guidelines state: for healthy growth and development, caregivers should minimize the time infants (aged <1 year), toddlers (aged 1–2 years), and preschoolers (aged 3–4 years) spend being sedentary during waking hours. This includes prolonged sitting or being restrained (e.g., stroller, high chair) for more than 1 h at a time. For those under 2 years, screen time (e.g., TV, computer, electronic games) is not recommended. For children 2–4 years, screen time should be limited to under 1 h per day; less is better.