Silvia Costa

Development of methods to objectively identify time spent using active and motorised modes of travel to work: how do self-reported measures compare?

BackgroundActive commuting may make an important contribution to population health. Accurate measures of these behaviours are required, but it is unknown how self-reported estimates compare to those derived from objective measures. We sought to develop methods for objectively deriving time spent in specific travel behaviours from a combination of locational and activity data, and to assess the convergent validity of two self-reported estimates.MethodsIn 2010 and 2011, a sub-sample of participants from the Commuting and Health in Cambridge study concurrently completed objective monitoring using combined heart rate and movement sensors and global positioning system devices and reported their past-week commuting in a questionnaire (modes used, and usual time spent walking and cycling per trip) and in a day-by-day diary (all modes and durations). Automated and manual approaches were used to objectively identify total time spent using active and motorised modes. Agreement between self-reported and objectively-derived times was assessed using Lin’s concordance coefficients, Bland-Altman plots and signed-rank tests.ResultsCompared to objective assessments, day-by-day diary estimates of time spent using active modes on the commute were overestimated by a mean of 1.1 minutes/trip (95% limits of agreement (LOA): -7.7 to 9.9, p < 0.001). The magnitude of overestimation was slightly larger, but not significant (p = 0.247), when walking or cycling was used alone (mean: 2.4 minutes/trip, 95% LOA: -6.8 to 11.5). Total time spent on the commute was overestimated by a mean of 1.9 minutes/trip (95% LOA: -15.3 to 19.0, p < 0.001). The mean differences between self-reported usual time and objective estimates were -1.1 minutes/trip (95% LOA: -8.7 to 6.4) for cycling and +2.4 minutes/trip (95% LOA: -10.9 to 15.7) for walking. Mean differences between usual and daily estimates of time were <1 minute/trip for both walking and cycling.ConclusionsWe developed a novel method of combining objective data to identify time spent using active and motorised modes, and total time spent commuting. Compared to objectively-derived times, self-reported times spent active commuting were slightly overestimated with wide LOA, suggesting that they should be used with caution to infer aggregate weekly quantities of activity on the commute at the individual level.

Physical activity during the early years: a systematic review of correlates and determinants

CONTEXT Being physically active during the early years (age 0-6 years) is vital for healthy development. Identifying correlates and determinants of physical activity (PA) is crucial to guide effective interventions. This systematic review synthesized studies investigating potential correlates and determinants of PA during the early years, accounting for different types of PA assessment. EVIDENCE ACQUISITION Nine electronic databases were searched from inception year (1900) until September 2014; data were analyzed/interpreted in April 2015. The following inclusion criteria were used: written in English, published in peer-reviewed journals, participants not in statutory/school education, and an observational design investigating associations between an exposure/variable, and a quantitative measure of PA. Correlates/determinants of total, moderate to vigorous, and light PA were reported using an ecologic model. EVIDENCE SYNTHESIS Of 22,045 identified studies, 130 were included. All took place in high-income countries and few (6%) were of high quality. Correlates of total PA were sex (male, ++); parental PA (+); parental support (+); and time outdoors (+). Determinants of total PA were sex (+) and time spent playing with parents (+). The only correlate of moderate to vigorous PA was sex (male, ++). No determinants of moderate to vigorous or light PA were found. PA correlates/determinants were relatively consistent between objective and subjective PA measures. CONCLUSIONS Numerous studies investigated potential correlates and determinants of PA, but overall quality was low. A small number of demographic/biological and social/cultural factors were associated with PA. There is a need for high-quality studies exploring correlates/determinants across all domains of the ecologic model.

Physical Activity, Sedentary Time, and Fatness in a Biethnic Sample of Young Children.

Purpose This study aimed to investigate associations of objectively measured physical activity (PA) and sedentary time with adiposity in a predominantly biethnic (South Asian and White British) sample of young children. Methods The sample included 333 children age 11 months to 5 yr who provided 526 cross-sectional observations for PA and body composition. Total PA volume (vector magnitude counts per minute), daily time at multiple intensity levels (the cumulative time in activity >500, >1000, >1500, …, >6000 counts per minute), and time spent sedentary (<820 counts per minute), in light PA (820–3907 counts per minute) and in moderate-to-vigorous PA (≥3908 counts per minute) were estimated with triaxial accelerometry. Indicators of adiposity included body mass index, waist circumference, and the sum of subscapular and triceps skinfold thicknesses. Statistical analyses were performed using multilevel regression and isotemporal substitution models adjusted for confounders. Effect modification by ethnicity was examined. Results There was no evidence for effect modification by ethnicity (P interaction ≥ 0.13). In the whole sample, the accumulated time spent above 3500 counts per minute (i.e., high light-intensity PA) was inversely associated with the sum of skinfolds (&bgr; = −0.60 mm, 95% confidence interval [CI] = −1.19 to −0.021, per 20 min·d−1), and the magnitude of association increased dose dependently with PA intensity (peaking for time spent >6000 counts per minute = −1.57 mm, 95% CI = −3.01 to −0.12, per 20 min·d−1). The substitution of 20 min·d−1 of sedentary time with moderate-to-vigorous PA was associated with a lower sum of skinfolds (−0.77 mm, 95% CI = −1.46 to −0.084). Conclusions High light-intensity PA appears to be beneficial for body composition in young South Asian and White British children, but higher-intensity PA is more advantageous.

Accelerometer data requirements for reliable estimation of habitual physical activity and sedentary time of children during the early years - a worked example following a stepped approach.

ABSTRACT This study presents a worked example of a stepped process to reliably estimate the habitual physical activity and sedentary time of a sample of young children. A total of 299 children (2.9 ± 0.6 years) were recruited. Outcome variables were daily minutes of total physical activity, sedentary time, moderate to vigorous physical activity and proportional values of each variable. In total, 282 (94%) provided 3 h of accelerometer data on ≥1 day and were included in a 6-step process: Step-1: determine minimum wear-time; Step-2: process 7-day-data; Step-3: determine the inclusion of a weekend day; Step-4: examine day-to-day variability; Step-5: calculate single day intraclass correlation (ICC) (2,1); Step-6: calculate number of days required to reach reliability. Following the process the results were, Step-1: 6 h was estimated as minimum wear-time of a standard day. Step-2: 98 (32%) children had ≥6 h wear on 7 days. Step-3: no differences were found between weekdays and weekend days (P ≥ 0.05). Step-4: no differences were found between day-to-day variability (P ≥ 0.05). Step-5: single day ICC’s (2,1) ranged from 0.48 (total physical activity and sedentary time) to 0.53 (proportion of moderate to vigorous physical activity). Step-6: to reach reliability (ICC = 0.7), 3 days were required for all outcomes. In conclusion following a 7 day wear protocol, ≥6 h on any 3 days was found to have acceptable reliability. The stepped-process offers researchers a method to derive sample-specific wear-time criterion.

A community-based motivational personalised lifestyle intervention to reduce BMI in obese adolescents: results from the Healthy Eating and Lifestyle Programme (HELP) randomised controlled trial.

Objective Approximately 7% of children and young people aged 5–15 years in the UK have obesity at a level likely to be associated with comorbidities. The majority of multicomponent lifestyle programmes have limited applicability and generalisability for British adolescents. The Healthy Eating and Lifestyle Programme (HELP) was a specific adolescent-focused intervention, designed for obese 12 to 18-year-olds seeking help to manage their weight. Participants were randomised to the 12-session HELP intervention or standard care. The primary outcome was difference in mean body mass index (BMI) (kg/m2) between groups at week 26 adjusted for baseline BMI, age and sex. Subjects 174 subjects were randomised (87 in each arm), of whom 145 (83%) provided primary outcome data at week 26. Results At week 26 there were no significant effects of the intervention on BMI (mean change in BMI 0.18 kg/m2 for the intervention arm, 0.25 kg/m2 for the control arm; adjusted difference between groups: −0.11 kg/m2 (95% CI −0.62 to 0.40), p=0.7). At weeks 26 and 52 there were no significant differences between groups in any secondary outcomes. Conclusion At minimum this study reinforces the need for higher level, structured interventions to tackle the growing public health burden of obesity in the UK and internationally. The HELP intervention was no more effective than a single educational session for reducing BMI in a community sample of obese adolescents. Further work is needed to understand how weight management programmes can be delivered effectively to young people from diverse and deprived backgrounds in which childhood obesity is common. The study has significant implications in terms of informing public health interventions to tackle childhood obesity. Trial registration number ISRCTN: ISRCTN99840111.

Childcare in Infancy and Later Obesity: a Narrative Review of Longitudinal Studies

Purpose of ReviewThe purpose of this review was to summarize the current literature on the longitudinal relationship between non-parental childcare during infancy and later obesity.Recent FindingsEleven studies met the inclusion criteria, comprising 74 associations relevant to the review. Studies were highly heterogeneous in terms of defining childcare, categorizing different types of childcare, assessing obesity, and age at measurement of outcome and exposure. Most of the associations were either non-significant (42 associations, 57%) or showed a significant association between increased exposure to childcare and greater obesity (30 associations, 41%). There were very few examples of associations indicating that childcare was associated with lower obesity.SummaryThere is limited research on the longitudinal relationship between childcare in infancy and later obesity. Existing studies showed mixed results, similar to recent reviews reporting on cross-sectional studies and older ages. The different definitions of childcare and wide variety of measures of exposure make comparisons between studies challenging.

P04 Rct of a motivational lifestyle intervention (the healthy eating and lifestyle programme (help)) for obese young people

Aims To assess whether a motivational multi-component lifestyle intervention delivered in the community was effective in reducing body mass index (BMI) and improving related health outcomes in obese adolescents. Methods 174 obese adolescents (13–17 years old; 109 females) from a UK community setting were randomised into intervention or control arms. Intervention participants received 12 sessions across 6 months, addressing lifestyle behaviours and focusing on motivation to change and self-esteem rather than weight change. The intervention was delivered by trained Graduate Health Workers in community settings. Control participants received a single 2 h nurse-delivered session providing didactic weight management advice. The primary outcome was BMI change at 6 months. Secondary outcomes included body fat (impedance;), dieting behaviours, self-esteem and quality of life. Random-effects linear regression was used to detect differences in end-point outcomes between Intervention and control groups, adjusting for sex, age, and outcome value at the beginning of the intervention. The primary analyses used the intention to treat sample. Results 145 (83.3%) adolescents completed the intervention. Mean BMI across the whole group was 32.3 kg/m2 (SD 4.4) at start and 32.6 kg/m2 (SD 4.7) at the end of the intervention. We found no significant difference in the primary outcome (BMI) at 6 months: effect estimate -0.06 (95% CI: -0.57 to 0.45) p = 0.8). No significant differences were observed for changes in secondary outcomes (all p > 0.4) between intervention and control groups at 6 months. Fidelity monitoring showed moderately strong fidelity to treatment. The process evaluation found that participants and their families found the intervention highly engaging, respectful and helpful in making behavioural changes. Discussion We did not find evidence that a motivational multi-component lifestyle modification intervention delivered in the community was effective in reducing BMI or improving health and well-being in a community sample of obese adolescents, despite moderately strong fidelity and process evidence that young people used the intervention to make changes in their lifestyle. Our findings suggest that obesity interventions with a strong theoretical basis and evidence of effectiveness when delivered by trained psychologists may not be effective when delivered at lower intensity in the community by entry-level health workers.

Relationship between children's physical activity, sedentary behavior, and childcare environments: A cross sectional study

The purpose of this study was to investigate the relationship between the childcare environment and physical activity and sedentary behavior of toddlers and preschoolers. A total of 68 toddlers (1.0–2.9 years) and 233 preschoolers (3.0–5.9 years) were recruited from 11 childcare services in 2013 within the Illawarra and Shoalhaven region of NSW, Australia. For this study analysis was conducted in 2016. The childcare environment was assessed using the Environment and Policy Assessment Observation (EPAO) instrument, and childcare services categorized as low, medium, or high based on their scores. Time spent in physical activity and sitting was assessed over one week using activPAL accelerometers. Relationship between EPAO and childrens physical activity and sedentary behavior was assessed using multilevel mixed-effects linear regression. Toddlers who attended high EPAO services sat more (8.73 min [− 10.26, 27.73]) and stood less (− 13.64 min [− 29.27, 2.00]) than those who attended low EPAO services. Preschoolers who attended high EPAO services sat less than those in low and medium services (mean [95%CI] = − 7.81 min [− 26.64, 11.02]). Sub-categories of the EPAO that were associated with less time sitting were: sedentary environments for toddlers and portable play equipment for preschoolers. This study extends previous research by identifying differences between toddlers and preschoolers physical activity and sedentary behaviors in relation to childcare environments. A greater understanding of how the childcare environment relates to sitting time for both toddlers and preschool aged children is needed.

G324 Prevalence of thinness in adolescent girls in low and middle-income countries and associations with national wealth, food security, gender inequity and income inequality: A cross-sectional study

Background Adequate nutrition during adolescence is important for optimal physical and cognitive development and for pregnancy either during adolescence or later life. Thinness amongst adolescent girls in low and middle income countries (LMIC) has been little studied. Methods We used BMI data from 40 LMIC from the Global School Health Survey to estimate the prevalence of moderate and severe thinness in 12–18 year olds using the WHO 2007 growth reference. Self-report data on going to bed hungry was used as a proxy for household food insecurity. We used multi-level models to assess whether national wealth (gross domestic product, GDP), income inequality (Gini index), national gender inequality (Gender Inequality Index (GEI)) and food security (Global Food Security Index (GFSI)) were associated with undernutrition. Results Prevalence rates of moderate and severe thinness across 61,603 girls from 40 countries were 6.30% (95% CI: 5.71, 6.95) and 1.34% (1.12, 1.59) respectively. The prevalence of combined moderate and severe thinness demonstrated wide variation between countries; countries in Asia were found to have highest prevalence (nearly 20% in Sri Lanka). Combined moderate/severe thinness was more common amongst early (12–14 years) than later adolescents (15–18 years). Going to bed hungry sometimes was associated with increased risk of moderate/severe thinness (OR: 1.102; 95% CI 1.007, 1.206). A significant inverse relationship was found between thinness and GDP (OR: 0.94; 95% CI: 0.88, 0.99) and GFSI (OR: 0.96; 95% CI: 0.93, 0.99) but not Gini or GEI. Conclusion Thinness is still prevalent in adolescent schoolgirls in LMIC, and poses a significant threat to their health and that of the next generation. New attention is needed to public health nutrition interventions for adolescent girls in LMIC. Our study provides the first systematic data on adolescent thinness to guide regional and national nutrition strategies and provides data to allow for future epidemiological comparisons.

Deriving and evaluating new accelerometer cut-points in young children - a comment on Johansson et al (2014)

We read Johansson et al.s (1) article with great interest, as validation of accelerometers for children under 3 years of age is urgently needed. However, several methodological issues warrant serious consideration. Among the remarks listed on Table ​Table1,1, three main issues deserve highlighting: Table 1 Description of main methodological and inconsistency issues in Johansson et al.s study Only a few inappropriate tests were used for ‘agreement’ between cut-points and Childrens Activity Rating Scale (2); agreement of categorical classification was not tested (e.g. Cohens kappa (4)) and Spearmans rank measures strength of association not agreement between two scale measures (in contrast to Lins concordance coefficient (3)). Because strong correlations do not warrant strong agreement (3), conclusions regarding agreement should not be drawn; Not providing sensitivity/specificity and area under the curve values for sedentary behaviour, light- and high-intensity physical activity in the cross-validation denies the reader a chance to evaluate the validity and reliability of derived cut-points outside of the calibration sample, and subsequently their utility in other free-living populations; Although differences in epoch durations (among others) may hinder direct comparisons, whether or not the derived cut-points show advantages/disadvantages over already published cut-points (e.g. through sensitivity/specificity) is neither discussed nor demonstrated. Clear and detailed information on the protocols/procedures used together with thorough evaluations of new cut-points/equations (including how these improve on existing ones) is imperative and should be encouraged to move the paediatric physical activity measurement field forward (5). This will avoid introducing confusion not only in the measurement literature (5), but also into research investigating the influences on young childrens physical activity/sedentary behaviour, their relationship with health/disease and the effectiveness of interventions.