Quality control methods in accelerometer data processing: identifying extreme counts

The effects of an active breaks intervention on physical and cognitive performance: results from the I-MOVE study

BACKGROUND

The present quasi-experimental study aimed to evaluate the effects of active breaks intervention (ABs) to promote physical and cognitive improvement in primary school.

METHODS

The active breaks group (ABsG) performed 10 min of ABs three times per school day and the control group (CG) did normal lessons. The baseline and follow-up evaluation was conducted respectively in October 2019 and in May 2021. Cognitive performance was assessed using working memory test, physical performance was analyzed with ActiGraph accelerometers and physical fitness tests, quality of life was monitored using the Paediatric Quality of Life questionnaire (PedsQL) and classroom behavior was collected with an ad hoc questionnaire.

RESULTS

We enrolled 153 children (age: 7.61 ± 1.41, 54.2% males). Working memory significantly increased in the ABsG (ΔWM: 1.30 ± 1.17) than in CG (ΔWM: 0.96 ± 1.20). The 6 min Cooper test increased in the ABsG (Δ: 1.77 ± 136.03) but not in CG (Δ: -156.42 ± 187.53), P < 0.05. The weekly physical activity levels increased in both groups; however, the sedentary behavior significantly increased both in ABsG and CG. Children reported improvements in their quality of school life including feeling better in class and in school when using ABs; moreover, children improved their time on task behaviors in ABsG.

CONCLUSION

The present study has proven to be effective on children's physical and cognitive performance.

Pre-pubertal accelerometer-assessed physical activity and timing of puberty in British boys and girls: the Millennium Cohort Study

BACKGROUND

Early puberty timing is associated with adverse health outcomes. We aimed to examine prospective associations between objectively measured physical activity and puberty timing in boys and girls.

METHODS

In the UK Millennium Cohort Study, physical activity volume and intensities at 7 years were measured using accelerometers. Status of several pubertal traits and age at menarche were reported at 11, 14 and 17 years. Age at menarche in girls was categorized into tertiles. Other puberty traits were categorized into earlier or later than the median ages calculated from probit models, separately in boys and girls. Multivariable regression models, with adjustment for maternal and child characteristics including body mass index (BMI) at age 7 years as potential confounders, were performed to test the associations of total daily activity counts and fractions of activity counts across intensities (in compositional models) with puberty timing, separately in boys (n = 2531) and girls (n = 3079).

RESULTS

Higher total daily activity counts were associated with lower risks for earlier (vs later) growth spurt, body hair growth, skin changes and menarche in girls, and more weakly with lower risks for earlier skin changes and voice breaking in boys (odds ratios = 0.80-0.87 per 100 000 counts/day). These associations persisted on additional adjustment for BMI at 11 years as a potential mediator. No association with puberty timing was seen for any physical activity intensity (light, moderate or vigorous).

CONCLUSIONS

More physical activity regardless of intensity may contribute to the avoidance of earlier puberty timing, independently of BMI, particularly in girls.

Protocol to evaluate the effectiveness and cost-effectiveness of an environmental nutrition and physical activity intervention in nurseries (Nutrition and Physical Activity Self Assessment for Child Care - NAP SACC UK): a multicentre cluster randomised controlled trial

BACKGROUND

One in seven UK children have obesity when starting school, with higher prevalence associated with deprivation. Most pre-school children do not meet UK recommendations for physical activity and nutrition. Formal childcare settings provide opportunities to deliver interventions to improve nutritional quality and physical activity to the majority of 3-4-year-olds. The nutrition and physical activity self-assessment for childcare (NAP SACC) intervention has demonstrated effectiveness in the USA with high acceptability in the UK. The study aims to evaluate the effectiveness and cost-effectiveness of the NAP SACC UK intervention to increase physical activity, reduce sedentary time and improve nutritional intake.

METHODS

Multi-centre cluster RCT with process and economic evaluation. Participants are children aged 2 years or over, attending UK early years settings (nurseries) for ≥ 12 h/week or ≥ 15 h/week during term time and their parents, and staff at participating nurseries. The 12-month intervention involves nursery managers working with a Partner (public health practitioner) to self-assess policies and practices relating to physical activity and nutrition; nursery staff attending one physical activity and one nutrition training workshop and setting goals to be achieved within 6 months. The Partner provides support and reviews progress. Nursery staff receive a further workshop and new goals are set, with Partner support for a further 6 months. The comparator is usual practice. Up to 56 nurseries will be stratified by area and randomly allocated to intervention or comparator arm with minimisation of differences in level of deprivation.

PRIMARY OUTCOMES

accelerometer-assessed mean total activity time on nursery days and average total energy (kcal) intake per eating occasion of lunch and morning/afternoon snacks consumed within nurseries.

SECONDARY OUTCOMES

accelerometer-assessed mean daily minutes of moderate-to-vigorous physical activity and sedentary time per nursery day, total physical activity on nursery days compared to non-nursery days, average serving size of lunch and morning/afternoon snacks in nursery per day, average percentage of core and non-core food in lunch and morning/afternoon snacks, zBMI, proportion of children who are overweight/obese and child quality-of-life. A process evaluation will examine fidelity, acceptability, sustainability and context. An economic evaluation will compare costs and consequences from the perspective of the local government, nursery and parents.

TRIAL REGISTRATION

ISRCTN33134697, 31/10/2019.

Protocol to evaluate the effectiveness and cost-effectiveness of an environmental nutrition and physical activity intervention in nurseries (Nutrition and Physical Activity Self Assessment for Child Care - NAP SACC UK): a multicentre cluster randomised controlled trial

Background One in seven UK children have obesity when starting school, with higher prevalence associated with deprivation. Most pre-school children do not meet UK recommendations for physical activity and nutrition. Formal childcare settings provide opportunities to deliver interventions to improve nutritional quality and physical activity to the majority of 3-4-year-olds. The nutrition and physical activity self-assessment for childcare (NAP SACC) intervention has demonstrated effectiveness in the USA with high acceptability in the UK. The study aims to evaluate the effectiveness and cost-effectiveness of the NAP SACC UK intervention to increase physical activity, reduce sedentary time and improve nutritional intake. Methods Multi-centre cluster RCT with process and economic evaluation. Participants are children aged 2 years or over, attending UK early years settings (nurseries) for ≥ 12 hours/week or ≥ 15 hours/week during term time and their parents, and staff at participating nurseries. The 12-month intervention involves nursery managers working with a Partner (public health practitioner) to self-assess policies and practices relating to physical activity and nutrition; nursery staff attending one physical activity and one nutrition training workshop and setting goals to be achieved within six months. The Partner provides support and reviews progress. Nursery staff receive a further workshop and new goals are set, with Partner support for a further six months. The comparator is usual practice. Up to 56 nurseries will be stratified by area and randomly allocated to intervention or comparator arm with minimisation of differences in level of deprivation.

PRIMARY OUTCOMES

accelerometer-assessed mean total activity time on nursery days and average total energy (kcal) intake per eating occasion of lunch and morning/afternoon snacks consumed within nurseries.

SECONDARY OUTCOMES

accelerometer-assessed mean daily minutes of moderate-to-vigorous physical activity and sedentary time per nursery day, total physical activity on nursery days compared to non-nursery days, average serving size of lunch and morning/afternoon snacks in nursery per day, average percentage of core and non-core food in lunch and morning/afternoon snacks, zBMI, proportion of children who are overweight/obese and child quality-of-life. A process evaluation will examine fidelity, acceptability, sustainability and context. An economic evaluation will compare costs and consequences from the perspective of the local government, nursery and parents.

TRIAL REGISTRATION

ISRCTN33134697.

Joint regression modelling of intensity and timing of accelerometer counts

Accelerometers are commonly used in human medical and public health research to measure physical movement, which is relevant in a wide range of studies, from physical activity and sleep behaviours studies, to identification of movement patterns in people affected by diseases of the locomotor system and prediction of risk of injury in high performance sports. The accelerometer output provides the intensity (activity count) and timing (timestamp) of the movement, which can be used to define bouts of activity (periods of sustained movement of a given intensity). In some contexts, it may be important to include both dimensions to obtain a broader and deeper understanding of the phenomenon under study. Such is the case of a large-scale epidemiological investigation on the daily and weekly physical activity behaviours of school-aged children enrolled in the UK Millennium Cohort Study, which has motivated the present article. I present a statistical approach to joint modelling of intensity and timing of activity bouts that takes advantage of the circular nature of the timing. The model, which accounts for the longitudinal structure of the observations, is remarkably simple to implement using standard statistical software.

Mediterranean diet, physical activity, and family characteristics associated with cognitive performance in Italian primary school children: analysis of the I-MOVE project

Working memory (WM) is a multicomponent system that supports cognitive functioning. It has been linked to a wide variety of outcomes including academic success and general well-being. The present study examined the relations between adherence to the Mediterranean diet (MD) and WM among Italian children, adjusting for important parent characteristics and children's lifestyle habits. Data for this study was obtained from 106 children attending primary school in Imola (Italy) who were part of the I-MOVE study emphasizing school-based physical activity. Children's adherence to the MD was calculated using the KIDMED index (KI) based on the ZOOM-8 questionnaire. Physical activity (PA) levels were assessed using an actigraph accelerometer and WM using the backward digit span test. Univariate regression was used to select significant child-level and family measures associated with WM, which were then tested in a single multivariate regression model. Older age is positively associated with higher WM (β = 0.36; 95% CI 0.25, 0.47). Dietary adherence (KI) (β = 0.07; 95% CI 0.01, 0.14) and engagement in organized PA outside school hours (β = 0.58; 95% CI 0.09, 1.10) are positively related to WM. Among the family measures, father's education was positively associated with WM for high school education and for university vs. middle school or lower, respectively.

CONCLUSION

Adherence to the MD was associated with better WM capacity in primary school children. These findings can be used to guide policymakers in designing health promotion programs and instituting policies emphasizing healthy nutrition to improve physical health and boost cognitive functioning.

WHAT IS KNOWN

• The development of working memory involves the entire childhood with a rapid spurt between 2 and 8 years of age. • Working memory plays a critical role in children's learning and academic performance and underlies higher-order cognitive abilities.

WHAT IS NEW

• Adherence to the Mediterranean Diet was associated with higher working memory capacity in primary school children. • Health promotion interventions based on PA and sound nutrition involving children benefit not only physical and mental health, but also cognitive health.

The impact of COVID-19 on physical activity behaviour in Italian primary school children: a comparison before and during pandemic considering gender differences

BACKGROUND

The World Health Organization stated an average of 60 min of Moderate to Vigorous Physical Activity (MVPA) that children should accumulate every day. Nevertheless physical inactivity is growing and, due to restrictions imposed during pandemic, PA levels of children might be more negatively affected. The study aimed to analyse the impact of COVID-19 on the PA of an Italian sample of primary school children by comparing it before and during COVID-19 considering gender differences.

METHODS

A pre-post analysis (October 2019-January 2021) was conducted using a randomized sample (N = 77) from the I-MOVE study settled in an Italian primary school. Both objective (Actigraph accelerometers) and self-reported (PAQ-c questionnaires) assessments of PA were performed. Changes were compared using T-Student and Chi-Square test. Gender differences were calculated using Anova.

RESULTS

Weekly and daily minutes time spent in MVPA significantly decreased respectively by - 30.59 ± 120.87 and - 15.32 ± 16.21 from before to during pandemic while the weekly time spent in sedentary behaviour increased (+ 1196.01 ± 381.49). PAQ-c scores followed the same negative trend (- 0.87 ± 0.72). Boys seem to have suffered more than girls from the imposed restrictions.

CONCLUSION

These findings outline the need for strategies to promote PA and reduce sedentary behaviours in children to prevent COVID-19 restriction long-term effects.

The Determinants of Health-Related Quality of Life in a Sample of Primary School Children: A Cross-Sectional Analysis

Background: Health-related quality of life (HRQoL) in childhood is a multidimensional construct with many sub dimensions of subjective experience, including physical activity (PA), psychological well-being, social interaction, and school performance, that represents a fundamental health outcome to assess a child’s physical and psycho-social functioning. Our study aims to explore the potential predictors of children’s health-related quality of life, using a convenience sample from the Imola Active Break Study (I-MOVE), considering demographic, anthropometric measures, PA level measured by Actigraph accelerometers, parent-reported/self-reported HRQoL, and body image. Methods: A cross-sectional analysis was conducted among 151 primary school children in Italy. HRQoL was assessed using the Italian version 4.0 of the Paediatric Quality of Life (PedsQL) questionnaire. Results: Children who spent more time partaking in moderate PA were associated with a higher total PedsQL score (p < 0.03). Mother’s body mass index (BMI) was the only variable statistically significant associated with the physical health domain of PedsQL. Parent’s proxy-report perception concerning children’s psychosocial health was statistically relevant. The children’s gender, age, and BMI had no association with any of the HRQoL outcomes. Discussion: Parent proxy-report psychosocial health and mother’s BMI should be considered as predictors of HRQoL for the psychosocial and physical domain. PA should be implemented in order to improve the HRQoL of primary school children.

A dyadic approach for a remote physical activity intervention in adults with Alzheimer's disease and their caregivers: Rationale and design for an 18-month randomized trial

Adults with Alzheimer's disease and related dementia (ADRD) and their caregivers represent a sizeable and underserved segment of the population with low levels of moderate physical activity (MPA). Options for increasing MPA in community dwelling adults with ADRD and their caregivers are limited. A home-based physical activity intervention delivered remotely via video conferencing to groups of adults with ADRD and their caregivers (RGV), represents a potentially effective approach for increasing MPA in this group. We will conduct an 18-month randomized trial (6 mos. Active intervention, 6 mos. Maintenance, 6 mos. no contact) to compare the effectiveness of the RGV approach with usual care, enhanced with caregiver support (EUC), for increasing MPA in 100 community dwelling adults with ADRD and their caregiver. The primary aim is to compare MPA (min/wk.), assessed by accelerometer, across the 6-mo. active intervention in adults with ADRD randomized to RGV or EUC. Secondarily, we will compare adults with ADRD and their caregivers randomized to RGV or ECU on the following outcomes across 18 mos.: MPA (min/wk.), sedentary time (min/wk.), percentage meeting 150 min/wk. MPA goal, functional fitness, activities of daily living, quality of life, residential transitions, cognitive function, and caregiver burden. Additionally, we will evaluate the influence of age, sex, BMI, attendance (exercise/support sessions), use of recorded sessions, self-monitoring, peer interactions during group sessions, caregiver support, type and quality of dyadic relationship, and number of caregivers on changes in MPA in adults with ADRD and their caregiver across 18 mos.

A Multiple Targeted Research Protocol for a Quasi-Experimental Trial in Primary School Children Based on an Active Break Intervention: The Imola Active Breaks (I-MOVE) Study

BACKGROUND

Children and adolescents should perform, according to the World Health Organization guidelines, at least 60 min of moderate-to-vigorous physical activity per-day in order to avoid the risk of metabolic and cardiovascular diseases. The school represents a fundamental setting to conduct interventions to promote physical activity (PA) and contrast sedentary behaviors. Active breaks (ABs), bouts of 10 min of PA conducted inside the classroom, seem to be a good strategy to promote PA and improve classroom behavior. The aim of this study protocol is to describe the design and the assessment of the Imola Active Breaks I-MOVE study.

METHODS

The I-MOVE study is a school-based intervention trial, with a quasi-experimental design, performed in a primary school. It involves one experimental-group performing the intervention, focused on ABs, and one control-group. Nine main outcomes are evaluated: PA and sedentary behaviors; health related fitness; motor control development; dietary patterns; anthropometric evaluation; sociodemographic determinants; cognitive function; time-on-task behavior and quality of life.

CONCLUSIONS

Results from the I-MOVE study will help to clarify the effects of incorporating ABs in the Italian school curriculum as a new public health strategy and an innovative school model oriented to the well-being of children and teachers for the best quality of school life.

Active Breaks: A Pilot and Feasibility Study to Evaluate the Effectiveness of Physical Activity Levels in a School Based Intervention in an Italian Primary School

Background: The school gives access to children, regardless of age, ethnicity, gender and socio-economic class and can be identified as the key environment in which to promote children’s physical activity (PA). The guidelines of the European Union recommend accumulating at least 10-min bouts of PA to reach the daily 60 min. Active breaks (ABs) led by teachers inside the classroom represent a good strategy to promote PA. The aim of this pilot and feasibility study was to evaluate the feasibility and effectiveness in terms of PA level of an AB programme in children aged 8–9 years attending primary school. Methods: A pre-post quasi-experimental pilot and feasibility study was performed in two primary school classes, one of which was assigned to a 14-week AB intervention (AB group) and the other to the control group (CG). At baseline and at follow-up, children were monitored for sedentary and motor activity during an entire week using ActiGraph Accelerometer (ActiLife6 wGT3X-BT). The satisfaction of children and teachers was assessed by self-administered questionnaires. Results: In the pre-post comparison, AB group (n = 16) showed a reduction in the minutes spent in weekly sedentary activity (−168.7 min, p > 0.05), an increase in the number of step counts (+14,026.9, p < 0.05) and in time spent in moderate to vigorous PA (MVPA): weekly MVPA: +64.4 min, daily MVPA: +8.05 min, percentage of MVPA: +0.70%. On the contrary, CG showed a worsening in all variables. ANCOVA analysis, after adjusting for baseline values, showed significant differences between the AB group and CG for time spent in MVPA, percentage of MVPA and step counts. The satisfaction of children and teachers was good. Teachers were able to adapt the AB protocol to the needs of the school curriculum, thus confirming the feasibility of the AB programme. Conclusions: This pilot and feasibility study showed the feasibility and effectiveness of the AB protocol and represented the basis for a future controlled trial.

Physical activity across the curriculum (PAAC3): Testing the application of technology delivered classroom physical activity breaks

Only 43% of children in the U.S., ages 6-11 yrs., meet current physical activity (PA) guidelines. To satisfy the MVPA requirement, schools have begun incorporating MVPA in the form of activity breaks or MVPA academic lessons. We completed two, 3 academic-yr. cluster randomized trials (DK61489, DK85317) called "Physical Activity Across the Curriculum" (PAAC) which involved increasing MVPA in the classroom. Across 3-yrs. teachers in PAAC schools delivered ~60 min/wk. (12 min/day) of MVPA. Although short of our MVPA goal (20 min/d), the PAAC approach substantially increased in-school MVPA. Teacher reluctance to devote additional time to develop and integrate PA lessons into their curriculum was the overwhelming barrier to meeting the MVPA goal. Therefore, to reduce barriers to delivery of classroom PA we developed a 3-academic yr. cluster randomized trial (2 yrs. active intervention, 1 yr. follow-up) to compare the effectiveness and sustainability of technology delivered (PAAC-R) and classroom teacher delivered (PAAC-T) activity breaks for increasing classroom MVPA in elementary school students in grades 2 and 3 at baseline who will progress to grades 4-5. NCT registration: NCT03493139.

Racial and Ethnic Differences Over Time in Outcomes of Infants Born Less Than 30 Weeks' Gestation

OBJECTIVES

To examine changes in care practices over time by race and ethnicity and whether the decrease in hospital mortality and severe morbidities has benefited infants of minority over infants of white mothers.

METHODS

Infants 22 to 29 weeks' gestation born between January 2006 and December 2017 at a Vermont Oxford Network center in the United States were studied. We examined mortality and morbidity rate differences and 95% confidence intervals for African American and Hispanic versus white infants by birth year. We tested temporal differences in mortality and morbidity rates between white and African American or Hispanic infants using a likelihood ratio test on nested binomial regression models.

RESULTS

Disparities for certain care practices such as antenatal corticosteroids and for some in-hospital outcomes have narrowed over time for minority infants. Compared with white infants, African American infants had a faster decline for mortality, hypothermia, necrotizing enterocolitis, and late-onset sepsis, whereas Hispanic infants had a faster decline for mortality, respiratory distress syndrome, and pneumothorax. Other morbidities showed a constant rate difference between African American and Hispanic versus white infants over time. Despite the improvements, outcomes including hypothermia, mortality, necrotizing enterocolitis, late-onset sepsis, and severe intraventricular hemorrhage remained elevated by the end of the study period, especially among African American infants.

CONCLUSIONS

Racial and ethnic disparities in vital care practices and certain outcomes have decreased. That the quality deficit among minority infants occurred for several care practice measures and potentially modifiable outcomes suggests a critical role for quality improvement initiatives tailored for minority-serving hospitals.

Child-care self-assessment to improve physical activity, oral health and nutrition for 2- to 4-year-olds: a feasibility cluster RCT

Background

The Nutrition And Physical Activity Self Assessment for Child Care (NAP SACC) intervention has shown evidence of effectiveness in the USA but not been adapted or assessed for effectiveness in the UK.

Objectives

To evaluate the feasibility and acceptability of implementing NAP SACC in the UK.

Design

Adaptation and development of NAP SACC and feasibility cluster randomised controlled trial (RCT) including process and economic evaluations. Substudies assessed mediator questionnaire test–retest reliability and feasibility of food photography methods.

Setting

Nurseries, staff and parents in North Somerset, Cardiff, Gloucestershire and Bristol.

Participants

Development – 15 early years/public health staff and health visitors, 12 nursery managers and 31 parents. RCT – 12 nurseries and 31 staff, four partners and 168 children/parents. Mediator substudy – 82 parents and 69 nursery staff. Food photography substudy – four nurseries, 18 staff and 51 children.

Intervention

NAP SACC UK partners supported nurseries to review policies and practices and set goals to improve nutrition, oral health and physical activity (PA) over 5 months. Two workshops were delivered to nursery staff by local experts. A home component [website, short message service (SMS) and e-mails] supported parents. The control arm continued with usual practice.

Main outcome measures

Feasibility and acceptability of the intervention and methods according to prespecified criteria.

Data sources

Qualitative data to adapt the intervention. Measurements with children, parents and staff at baseline and post intervention (8–10 months after baseline). Interviews with nursery managers, staff, parents and NAP SACC UK partners; observations of training, workshops and meetings. Nursery environment observation, nursery Review and Reflect score, and resource log. Child height and weight, accelerometer-determined PA and sedentary time, screen time and dietary outcomes using the Child and Diet Evaluation Tool. Staff and parent questionnaires of knowledge, motivation and self-efficacy. Child quality of life and nursery, family and health-care costs. Food photography of everything consumed by individual children and staff questionnaire to assess acceptability.

Results

Thirty-two per cent (12/38) of nurseries and 35.3% (168/476) of children were recruited; no nurseries withdrew. The intervention was delivered in five out of six nurseries, with high levels of fidelity and acceptability. Partners found it feasible but had concerns about workload. The child loss to follow-up rate was 14.2%. There was suggestion of promise in intervention compared with control nurseries post intervention for snacks, screen time, proportion overweight or obese and accelerometer-measured total PA and moderate to vigorous PA. Many parental and nursery knowledge and motivation mediators improved. The average cost of delivering the intervention was £1184 per nursery excluding partner training, and the average cost per child was £27. Fourteen per cent of parents used the home component and the mediator questionnaire had good internal consistency and test–retest reliability. Photography of food was acceptable and feasible.

Limitations

Following nursery leavers was difficult. Accelerometer data, diet data and environmental assessment would have been more reliable with 2 days of data.

Conclusions

The NAP SACC UK intervention and methods were found to be feasible and acceptable to participants, except for the home component. There was sufficient suggestion of promise to justify a definitive trial.

Future work

A multicentre cluster randomised controlled trial to evaluate the effectiveness and cost-effectiveness of NAP SACC UK has been funded by NIHR and will start in July 2019 (PHR NIHR 127551).

Trial registration

Current Controlled Trials ISRCTN16287377.

Funding

This project was funded by the National Institute for Health Research (NIHR) Public Health Research programme and will be published in full in Public Health Research; Vol. 7, No. 13. See the NIHR Journals Library website for further project information. Funding was also provided by the North Somerset and Gloucestershire Councils, Development and Evaluation of Complex Interventions for Public Health Improvement (DECIPHer) (MR/KO232331/1), and the Elizabeth Blackwell Institute.

Cross-sectional analysis of physical activity in 2-4-year-olds in England with paediatric quality of life and family expenditure on physical activity

BACKGROUND

Many children do not meet the recommended level of daily physical activity, even with the widely acknowledged health benefits associated with being physically active. There is a need to establish factors related to physical activity in children so that public health interventions may be appropriately designed. We investigated the association between Pediatric Quality of Life Inventory (PedsQL), family expenditure on physical activity and objectively measured daily physical activity in 2-4-year-old children.

METHODS

Cross-sectional study with a sample of 81 UK preschool children taking part in the NAPSACC UK feasibility randomized controlled trial. Descriptive statistics are presented. We undertook Student t-tests to establish differences in physical activity by gender, age, parental education and nursery versus non-nursery days. Mixed effects linear regressions were used to model the association between minutes spent physically activity, minutes spent in moderate-to-vigorous (MVPA) physical activity and PedsQL scores (physical and psychosocial) and family expenditure on physical activity.

RESULTS

Most children (88.9%) did not engage in the recommended 180 min daily physical activity. There was mean (SD) of 141.9 (33.1) daily minutes of physically activity and 22.2 min per day (SD = 9.9) of MVPA. Boys and older children were more physically active. Children were more active on nursery days. There was no difference in physical activity by parental education. Half of the sample parents (50.6%) spent less than £9.00 weekly on their pre-schooler's physical activity. Children within the highest tertile of PedsQL physical functioning scores had higher levels of MVPA (3.6, 95% CI: - 1.3-8.4, p-value 0.15), although confidence intervals crossed the null in the adjusted model. We found no evidence of an association between positive PedsQL psychosocial scores, or higher parental expenditure on physical activity, with the physical activity variables.

CONCLUSIONS

Children in this sample were not meeting the recommended 180 min of daily physical activity. The 2-4-year-olds were most active on nursery days. There is no evidence of an association between better PedsQL physical scores and higher levels of MVPA. There was no evidence of an association between expenditure on physical activity and time spent physically active. Further examination in larger representative datasets is needed.

Are active children and young people at increased risk of injuries resulting in hospital admission or accident and emergency department attendance? Analysis of linked cohort and electronic hospital records in Wales and Scotland

Introduction

Children and young people (CYP) are encouraged to increase time spent being physically active, especially in moderate and vigorous intensity pursuits. However, there is limited evidence on the prospective association of activity levels with injuries resulting in use of hospital services. We examined the relationship between objectively-measured physical activity (PA) and subsequent injuries resulting in hospital admissions or accident and emergency department (A&E) attendances, using linked electronic hospital records (EHR) from a nationally representative prospective cohort of CYP in Wales and Scotland.

Methods

We analysed accelerometer-based estimates of moderate to vigorous (MVPA) and vigorous PA (VPA) from 1,585 (777 [46%] boys) seven-year-old Millennium Cohort Study members, living in Wales or Scotland, whose parents consented to linkage of cohort records to EHRs up until their 14th birthday. Negative binomial regression models adjusted by potential individual, household and area-level confounders, were fitted to estimate associations between average daily minutes of MVPA, and VPA (in 10-minute increments), and number of injury-related hospital admissions and/or A&E attendances from age nine to 14 years.

Results

CYP spent a median of 59.5 and 18.1 minutes in MVPA and VPA/day respectively, with boys significantly more active than girls; 47.3% of children experienced at least one injury-related admission or A&E attendance during the study period. Rates of injury-related hospital admission and/or A&E attendance were positively associated with MVPA and VPA in boys but not in girls: respective adjusted incidence rate ratios (95% CI) for boys: 1.09 (1.01, 1.17) and 1.16 (1.00, 1.34), and for girls: 0.94 (0.86, 1.03) and 0.85 (0.69, 1.04).

Conclusion

Boys but not girls who engage in more intense PA at age seven years are at higher risk of injury-related hospital admission or A&E attendance when aged nine to 14 years than their less active peers. This may reflect gender differences in the type and associated risks of activities undertaken. EHRs can make a useful contribution to injury surveillance and prevention if routinely augmented with information on context and setting of the injuries sustained. Injury prevention initiatives should not discourage engagement in PA and outdoor play given their over-riding health and social benefits.

Additive quantile regression for clustered data with an application to children's physical activity

Additive models are flexible regression tools that handle linear as well as non-linear terms. The latter are typically modelled via smoothing splines. Additive mixed models extend additive models to include random terms when the data are sampled according to cluster designs (e.g. longitudinal).These models find applications in the study of phenomena like growth, certain disease mechanisms and energy expenditure in humans, when repeated measurements are available. We propose a novel additive mixed model for quantile regression. Our methods are motivated by an application to physical activity based on a data set with more than half a million accelerometer measurements in children of the UK Millennium Cohort Study. In a simulation study, we assess the proposed methods against existing alternatives.

Sex Differences in Mortality and Morbidity of Infants Born at Less Than 30 Weeks' Gestation

OBJECTIVE

To examine whether changes in mortality and morbidities have benefited male more than female infants.

METHODS

Infants of gestational ages 22 to 29 weeks born between January 2006 and December 2016 at a Vermont Oxford Network center in the United States were studied. We examined mortality and morbidity rate differences and 95% confidence intervals by sex and birth year. We tested temporal differences in mortality and morbidity rates between boys and girls by means of a likelihood ratio test (LRT) on nested binomial regression models with log links.

RESULTS

A total of 205 750 infants were studied; 97 048 (47.2%) infants were girls. The rate for mortality and chronic lung disease decreased over time faster for boys than for girls (LRT P < .001 for mortality; P = .006 for lung disease). Restricting to centers that remained throughout the entire study period did not change all the above but additionally revealed a significant year-sex interaction for respiratory distress syndrome, with a faster decline among boys (LRT P = .04). Morbidities, including patent ductus arteriosus, necrotizing enterocolitis, early-onset sepsis, late-onset sepsis, severe intraventricular hemorrhage, severe retinopathy of prematurity, and pneumothorax, revealed a constant rate difference between boys and girls over time.

CONCLUSIONS

Compared with girls, male infants born at <30 weeks' gestation experienced faster declines in mortality, respiratory distress syndrome, and chronic lung disease over an 11-year period. Future research should investigate which causes of death declined among boys and whether their improved survival has been accompanied by a change in their neurodevelopmental impairment rate.

Association of diet in nurseries and physical activity with zBMI in 2-4-year olds in England: a cross-sectional study

BACKGROUND

Childhood obesity tracks into adulthood with detrimental effects on health. We aimed to examine the relationships of diet in childcare settings and daily physical activity (PA) of preschoolers with body mass index z-score (z-BMI).

METHODS

We conducted a cross-sectional study of 150 children aged 2-4-years participating in the Nutrition and Physical Activity Self-Assessment for Child Care (NAP SACC) UK study to examine the associations of their diet in childcare settings and daily PA with z-BMI. Dietary intake was observed and recorded by fieldworkers using a validated tick-list food questionnaire and diet quality was assessed based on adherence to Children's Food Trust (CFT) guidelines. PA was measured using accelerometers. We derived z-BMI scores using the UK 1990 and International Obesity Taskforce growth reference charts. Multilevel regression models were used to estimate associations between diet and PA with z-BMI separately, adjusted for age, gender, ethnicity, parental education level and clustering.

RESULTS

Among children who consumed one main meal or snack at childcare, 34.4% and 74.3% met the standards on fruits and vegetables and high sugar or fat snacks, respectively. Adherence to CFT guidelines was not associated with zBMI. Only 11.4% of children met recommended UK guidelines of three hours per day of physical activity. Minutes spent in light PA (β = 0.08, 95% CI = 0.01, 0.15) and active time (β = 0.07, 95% CI = 0.01, 0.12) were positively associated with UK 1990 zBMI scores.

CONCLUSIONS

The low proportion of children meeting the standards on fruits and vegetables and high sugar or fat snacks and recommended physical activity levels highlight the need for more work to support nurseries and parents to improve preschool children's diet and activity. In our exploratory analyses, we found children with higher zBMI were more physically active which could be attributed to fat-free mass or chance finding and so requires replication in a larger study.

TRIAL REGISTRATION

ISRCTN16287377 . Registered 12 June 2014.

A formative study exploring perceptions of physical activity and physical activity monitoring among children and young people with cystic fibrosis and health care professionals

BACKGROUND

Physical activity (PA) is associated with reduced hospitalisations and maintenance of lung function in patients with Cystic Fibrosis (CF). PA is therefore recommended as part of standard care. Despite this, there is no consensus for monitoring of PA and little is known about perceptions of PA monitoring among children and young people with CF. Therefore, the research aimed to explore patients' perceptions of PA and the acceptability of using PA monitoring devices with children and young people with CF.

METHODS

An action research approach was utilised, whereby findings from earlier research phases informed subsequent phases. Four phases were utilised, including patient interviews, PA monitoring, follow-up patient interviews and health care professional (HCP) interviews. Subsequently, an expert panel discussed the study to develop recommendations for practice and future research.

RESULTS

Findings suggest that experiences of PA in children and young people with CF are largely comparable to their non-CF peers, with individuals engaging in a variety of activities. CF was not perceived as a barrier per se, although participants acknowledged that they could be limited by their symptoms. Maintenance of health emerged as a key facilitator, in some cases PA offered patients the opportunity to 'normalise' their condition. Participants reported enjoying wearing the monitoring devices and had good compliance. Wrist-worn devices and devices providing feedback were preferred. HCPs recognised the potential benefits of the devices in clinical practice. Recommendations based on these findings are that interventions to promote PA in children and young people with CF should be individualised and involve families to promote PA as part of an active lifestyle. Patients should receive support alongside the PA data obtained from monitoring devices.

CONCLUSIONS

PA monitoring devices appear to be an acceptable method for objective assessment of PA among children and young people with CF and their clinicians. Wrist-worn devices, which are unobtrusive and can display feedback, were perceived as most acceptable. By understanding the factors impacting PA, CF health professionals will be better placed to support patients and improve health outcomes.

Neonatal and fetal growth charts to identify preterm infants <30 weeks gestation at risk of adverse outcomes

BACKGROUND

It is unclear whether a neonatal or a fetal growth standard is a better predictor of adverse in-hospital newborn infant outcomes.

OBJECTIVE

We aimed to evaluate and compare the power of birthweight for gestational age to predict adverse neonatal outcomes using neonatal and fetal growth charts. Gestational age-specific birthweight was examined either as a percentile score or as a binary indicator for birthweight <10th percentile (small for gestational age) with the use of 3 fetal growth charts (National Institute of Child Health and Human Development, World Health Organization, and Intergrowth-21st) and 1 neonatal sex-specific birthweight chart.

STUDY DESIGN

Inborn singleton infants from 2006-2014 with gestational age between 22 and 29 weeks and who were enrolled at 1 of the 852 US centers that were participating in the Vermont Oxford Network were studied. Outcomes included death, necrotizing enterocolitis, severe intraventricular hemorrhage, severe retinopathy of prematurity, and chronic lung disease. Receiver operating characteristic curve analysis was used to assess the predictive power of birthweight for gestational age, either as a score or as a small-for-gestational-age indicator, with the use of the 4 charts. We also examined the relative risks of the outcomes by comparing small-for-gestational-age and non-small-for-gestational-age infants with the use of the 4 charts.

RESULTS

The percentage of small-for-gestational-age newborn infants ranged from 25.9-29.7% when with used the fetal growth charts. In contrast, the percentage was 10% when we used the neonatal charts. The areas under the receiver operating characteristic curves were similar across the 4 classification methods and were all <0.60, which suggests a poor predictive power. Small-for-gestational-age status, as classified by the neonatal chart, showed stronger associations with death, necrotizing enterocolitis, severe retinopathy of prematurity, and chronic lung disease, compared with those associations that were based on the other classification methods.

CONCLUSION

Neither the neonatal nor the fetal growth charts are predictive of adverse infant in-hospital outcomes. In contrast to fetal charts, the use of the neonatal charts results in stronger associations between small-for-gestational-age and adverse outcomes.

Associations between objectively measured physical activity and later mental health outcomes in children: findings from the UK Millennium Cohort Study

Background

The beneficial effect of physical activity (PA) on mental health in adults is well established, but less is known about this relationship in children. We examine associations between objectively measured sedentary time, PA and mental health in 11-year-olds from the UK Millennium Cohort Study (MCS).

Methods

Longitudinal data from MCS sweeps 4 (age 7) and 5 (age 11) were used (n=6153). Accelerometer data were collected at MCS4, and mental health was measured at MCS4 and MCS5 using subscales (peer, emotional, conduct, hyperactivity) of the Strengths and Difficulties Questionnaire (SDQ). Associations between mean daily PA minutes at different intensities (sedentary, light, moderate-to-vigorous) at MCS4 and SDQ outcomes at MCS5 (score range 0–10) were estimated using multiple linear regression models, adjusting for SDQ at MCS4 and individual and family characteristics, and stratified by gender.

Results

In fully adjusted models, increased PA at MCS4 was associated with fewer peer problems in boys and girls at MCS5. For each additional 15 min in moderate-to-vigorous physical activity (MVPA), peer problems decreased −0.077 points (95% CI −0.133 to –0.022) in boys. For girls, light PA was associated with decreased peer problems (−0.071 points/30 min, 95% CI −0.130 to –0.013). Greater sedentary time was associated with more peer problems and fewer hyperactivity symptoms in boys and girls. Increased MVPA was associated with more conduct and hyperactivity problems in boys and more hyperactivity in girls.

Conclusions

Increased sedentary time is associated with more peer problems in children, and PA, generally, is beneficial for peer relations in children aged 11.

Using functional data analysis to understand daily activity levels and patterns in primary school-aged children: Cross-sectional analysis of a UK-wide study

Background

Temporal characterisation of physical activity in children is required for effective strategies to increase physical activity (PA). Evidence regarding determinants of physical activity in childhood and their time-dependent patterns remain inconclusive. We used functional data analysis (FDA) to model temporal profiles of daily activity, measured objectively using accelerometers, to identify diurnal and seasonal PA patterns in a nationally representative sample of primary school-aged UK children. We hypothesised that PA levels would be lower in girls than boys at play times and after school, higher in children participating in social forms of exercise (such as sport or play), and lower among those not walking to school.

Methods

Children participating in the UK-wide Millennium Cohort Study wore an Actigraph GT1M accelerometer for seven consecutive days during waking hours. We modelled 6,497 daily PA profiles from singleton children (3,176 boys; mean age: 7.5 years) by means of splines, and used functional analysis of variance to examine the cross-sectional relation of time and place of measurement, demographic and behavioural characteristics to smoothed PA profiles.

Results

Diurnal and time-specific patterns of activity showed significant variation by sex, ethnicity, UK country and season of measurement; girls were markedly less active than boys during school break times than boys, and children of Indian ethnicity were significantly less active during school hours (9:30–12:00). Social activities such as sport clubs, playing with friends were associated with higher level of PA in afternoon (15:00–17:30) and early evenings (17:30–19:30). Lower PA levels between 8:30–9:30 and 17:30–19:30 were associated with mode of travel to and from school, and number of cars in regular use in the household.

Conclusion

Diminished PA in primary school aged children is temporally patterned and related to modifiable behavioural factors. FDA can be used to inform and evaluate public health policies to promote childhood PA.

Anthropometric Charts for Infants Born Between 22 and 29 Weeks' Gestation

OBJECTIVES

Using a large, racially diverse US dataset, we aimed primarily to: (1) fit and validate sex-specific birth weight and head circumference for gestational age charts for infants born at 22 to 29 weeks' gestation; and (2) fit race-specific birth weight and head circumference for gestational age charts.

METHODS

We used data collected between 2006 and 2014 on 183 243 singleton infants without congenital malformations with gestational age between 22 weeks, 0 days and 29 weeks, 6 days from 852 US members of the Vermont Oxford Network. For the sex-specific charts, the final sample size included 156 587 infants who survived hospital discharge. From these 156 587, we abstracted a subset of 47 005 infants to fit sex-specific charts separately for white, black, and Asian infants. For all charts, we applied quantile regression models to predict infants' birth weight and head circumference percentiles from gestational age expressed in days.

RESULTS

We successfully validated the overall sex-specific charts. Over most of the gestational age range, black infants, either girls or boys, had the lowest predicted birth weight as compared with white and Asian infants for many percentiles.

CONCLUSIONS

We fitted and validated new sex-specific charts using a recent, large, and racially diverse dataset. Future steps include using these charts to examine associations of weight and head circumference at birth with mortality and morbidity.

Objectively measured physical activity and sedentary time: cross-sectional and prospective associations with adiposity in the Millennium Cohort Study

OBJECTIVE

To examine whether physical activity (PA) and sedentary time (ST) in primary school-aged children are associated with adiposity at the start of secondary school, and whether these associations differ by sex or ethnic group.

DESIGN

Nationally representative prospective cohort study.

SETTING

Children born across the UK, between 2000 and 2002.

PARTICIPANTS

6497 singleton children.

OUTCOME MEASURES

Measures of adiposity (body mass index (BMI), fat mass index (FMI) and fat free mass index (FFMI))--obtained at 7 and 11 years.

EXPLANATORY MEASURES

Total daily PA (mean counts per minute (cpm)); minutes of moderate-to-vigorous PA (MVPA); and ST. All assessed at 7 years using accelerometers.

RESULTS

In cross-sectional analyses, total PA was inversely associated with FMI (3.7% (95% CI 2.7% to 4.7%) reduction per 150 cpm increase), as was MVPA (4.2% (CI 3.2% to 5.2%) reduction per 20 min/day increase). Associations were stronger in black and South Asian ethnic groups. Total PA and MVPA were not associated with FFMI. ST was positively associated with FMI (1.3% (CI 0.2% to 2.3%) increase per 50 min/day increase) and inversely associated with FFMI (0.5% (CI 0.2% to 0.7%) reduction per 50 min/day increase). Longitudinally, MVPA at age 7 years remained inversely associated with FMI at age 11 years (1.5% (CI 0.4% to 2.6%) reduction per 20 min/day increase). No association was found between total PA and ST and any of the later adiposity measures.

CONCLUSIONS

7-year-old children who are more physically active are less likely to be obese at that age and at age 11 years. These associations were particularly evident in children from black or South Asian ethnicity at age 7 years and in boys at age 11 years. Measurements of fat mass provide valuable insights into ethnic differences in associations between adiposity and activity.

Predictors of non-response in a UK-wide cohort study of children's accelerometer-determined physical activity using postal methods

OBJECTIVES

To investigate the biological, social, behavioural and environmental factors associated with non-consent, and non-return of reliable accelerometer data (≥2 days lasting ≥10 h/day), in a UK-wide postal study of children's activity.

DESIGN

Nationally representative prospective cohort study.

SETTING

Children born across the UK, between 2000 and 2002.

PARTICIPANTS

13 681 7 to 8-year-old singleton children who were invited to wear an accelerometer on their right hip for 7 consecutive days. Consenting families were posted an Actigraph GT1M accelerometer and asked to return it by post.

PRIMARY OUTCOME MEASURES

Study consent and reliable accelerometer data acquisition.

RESULTS

Consent was obtained for 12 872 (94.5%) interviewed singletons, of whom 6497 (50.5%) returned reliable accelerometer data. Consent was less likely for children with a limiting illness or disability, children who did not have people smoking near them, children who had access to a garden, and those who lived in Northern Ireland. From those who consented, reliable accelerometer data were less likely to be acquired from children who: were boys; overweight/obese; of white, mixed or 'other' ethnicity; had an illness or disability limiting daily activity; whose mothers did not have a degree; who lived in rented accommodation; who exercised once a week or less; who had been breastfed; were from disadvantaged wards; had younger mothers or lone mothers; or were from households with just one, or more than three children.

CONCLUSIONS

Studies need to encourage consent and reliable data return in the wide range of groups we have identified to improve response and reduce non-response bias. Additional efforts targeted at such children should increase study consent and data acquisition while also reducing non-response bias. Adjustment must be made for missing data that account for missing data as a non-random event.