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Background: Higher maternal preconception body mass index (BMI) is associated with lower breastfeeding duration, which may contribute to the development of poor child eating behaviours and dietary intake patterns (components of nutritional risk). A higher maternal preconception BMI has been found to be associated with higher child nutritional risk. This study aimed to determine whether breastfeeding duration mediated the association between maternal preconception BMI and child nutritional risk., Methods: In this longitudinal cohort study, children ages 18 months to 5 years were recruited from The Applied Research Group for Kids (TARGet Kids!) in Canada. The primary outcome was child nutritional risk, using The NutriSTEP ® , a validated, parent-reported questionnaire. Statistical mediation analysis was performed to assess whether total duration of any breastfeeding mediated the association between maternal preconception BMI and child nutritional risk., Results: This study included 4733 children with 8611 NutriSTEP ® observations. The mean (SD) maternal preconception BMI was 23.6 (4.4) and the mean (SD) breastfeeding duration was 12.4 (8.0) months. Each 1-unit higher maternal preconception BMI was associated with a 0.081 unit higher nutritional risk (95% CI (0.051, 0.112); p < 0.001) (total effect), where 0.011(95% CI (0.006, 0.016); p < 0.001) of that total effect or 13.18% (95% CI: 7.13, 21.25) was mediated through breastfeeding duration., Conclusion: Total breastfeeding duration showed to mediate part of the association between maternal preconception BMI and child nutritional risk. Interventions to support breastfeeding in those with higher maternal preconception BMI should be evaluated for their potential effect in reducing nutritional risk in young children., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Background: Risk factors for problematic child eating behaviors and food preferences are thought to begin during the preconception period. It is unknown if maternal preconception body mass index (BMI) is associated with child nutritional risk factors (eg, poor dietary intake and eating behaviors)., Objectives: We aimed to determine whether maternal preconception BMI was associated with child nutritional risk., Methods: In this longitudinal cohort study, a secondary data analysis of children ages 18 mo to 5 y were recruited from The Applied Research Group for Kids (TARGet Kids!), a primary care practice-based research network in Canada. The primary exposure was maternal preconception BMI. The primary outcome was parent-reported child nutritional risk score, measured using the Nutrition Screening for Every Preschooler/Toddler (NutriSTEP), an age-appropriate validated questionnaire. Fitted linear mixed effects models analyzed associations between maternal preconception BMI and child nutritional risk after adjusting for covariates., Results: This study included 4733 children with 8611 repeated NutriSTEP observations obtained between ages 18 mo to 5 y. The mean (standard deviation [SD]) maternal preconception BMI was 23.6 (4.4), where 73.1% of mothers had a BMI ≤24.9 kg/m 2 , and 26.9% had a BMI ≥25 kg/m 2 . The mean (SD) NutriSTEP total score was 13.5 (6.2), with 86.6% at low risk (score <21) and 13.4% at high risk (score ≥21). Each 1 unit increase in maternal preconception BMI was associated with a 0.09 increase in NutriSTEP total score (95% confidence interval [CI]: 0.05, 0.12; P ≤ 0.001). After stratification, each 1 unit increase in maternal BMI was associated with a 0.06 increase in mean NutriSTEP total score (95% CI: 0.007, 0.11; P = 0.025) in toddlers and 0.11 increase in mean NutriSTEP total score (95% CI: 0.07, 0.15; P < 0.001) in preschoolers., Conclusion: Higher maternal preconception BMI is associated with slightly higher NutriSTEP total scores. This provides evidence that the preconception period may be an important time to focus on for improving childhood nutrition. This study was registered at clinicaltrials.gov as NCT01869530., (Copyright © 2023 American Society for Nutrition. Published by Elsevier Inc. All rights reserved.)

Measures that can provide reasonably accurate estimates of sugar-containing beverage (SCB) intake among children are needed. The primary objective of this study was to evaluate the relative validity of a short beverage screener (Nutrition and Health Questionnaire, NHQ) compared to a 24-hour recall (Automated Self-Administered 24-h (ASA24) Dietary Assessment Tool-Canada) for assessing parent proxy-reported daily SCB intake among children aged 4-14 years from the TARGet Kids! research network in Toronto, Canada. Children for whom a NHQ completed between March 2018 and June 2019 and an ASA24 completed within one year were included. A total of 471 parents who completed the NHQ beverage screener were also asked to complete the ASA24. One-hundred sixty-three completed the ASA24 and of this group, 109 were analyzed. Estimates of daily intake of 100% juices, sweetened drinks and soda, and total SCBs from the two measures were compared. The mean difference in beverage intake, Spearman correlations, and Bland-Altman plots were estimated for continuous measures. The kappa coefficient, sensitivity, and specificity were calculated for dichotomous measures of any daily intake versus none. The mean difference in total SCB intake between the NHQ and ASA24 was 0.14 cups/day (95% CI 0.01, 0.29) and the correlation was 0.43 (95% CI 0.26, 0.57). Sensitivity and specificity for any daily SCB intake were 0.63 and 0.76, respectively. Overall, parent proxy-reporting of children's total SCB intake from a beverage screener can provide reasonable estimates of SCB intake when detailed dietary assessment is not feasible., Competing Interests: JLM received an unrestricted research grant for a completed investigator-initiated study from the Dairy Farmers of Canada (2011-2012) and Ddrops provided non-financial support (vitamin D supplements) for an investigator initiated study on vitamin D and respiratory tract infections (2011-2015). This does not alter our adherence to PLOS ONE policies on sharing data and materials. No other authors declare competing interests., (Copyright: © 2023 Sharpe et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Adolescents with obesity have lower academic performance, but little is known about the association between body weight in early childhood and school readiness. The objective was to examine the association between age- and sex-standardized body mass index (zBMI) and body weight status and school readiness in young children. Methods: A prospective cohort study in Toronto, Canada, was conducted in young children enrolled in TARGet Kids!. Children's weight and height were measured before the start of kindergarten. Children's school readiness was measured by the Early Development Instrument (EDI), a validated teacher-completed instrument that assesses children's skills and behaviors in five developmental domains in kindergarten. Generalized estimating equations, adjusted for relevant confounders, were used in the analysis. Results: The study included 1015 children (1217 observations): 52% were male and mean age at zBMI was 4.2 years [50 months (SD 12.1)] and school readiness was 5.2 years [62.7 months (SD 6.9)]. There was no evidence found that zBMI was associated with school readiness. However, in a post hoc analysis, being classified as overweight or with obesity in kindergarten was associated with twofold higher odds of vulnerability in school readiness and a lower social competence score compared with their normal weight peers. Conclusions: Being classified as overweight or with obesity was associated with poor school readiness in year 2 of kindergarten. Early interventions to promote healthy growth before school entry may help promote development and school readiness in young children. www.clinicaltrials.gov (NCT01869530).

Objective: The American Academy of Pediatrics recommends developmental surveillance and screening in early childhood in primary care. The 18-month visit may be an ideal time for identification of children with delays in language and communication, or symptoms of autism spectrum disorder (ASD). Little is known about the predictive validity of developmental screening tools administered at 18 months. Our objective was to examine the predictive validity of the Infant Toddler Checklist (ITC) at the 18-month health supervision visit, using school readiness at kindergarten age as the criterion measure., Methods: We designed a prospective cohort study, recruiting in primary care in Toronto, Canada. Parents completed the ITC at the 18-month visit. Teachers completed the Early Development Instrument (EDI) when the children were in Kindergarten, age 4-6 years. We calculated screening test properties with 95% confidence intervals (CIs). We used multivariable logistic and linear regression analyses adjusted for important covariates., Results: Of 293 children (mean age 18 months), 30 (10.2%) had a positive ITC including: concern for speech delay (n = 11, 3.8%), concern for other communication delay (n = 13, 4.4%), and concern for both (n = 6, 2.0%). At follow-up (mean age 5 years), 54 (18.4%) had overall EDI vulnerability, 19 (6.5%) had vulnerability on the 2 EDI communication domains. The ITC sensitivity ranged from 11% to 32%, specificity from 91% to 96%, false positive rates from 4% to 9%, PPV from 16% to 35%, NPV from 83% to 95%. A positive ITC screen and ITC concern for speech delay were associated with lower scores in EDI communication skills and general knowledge (β = -1.08; 95% CI: -2.10, -0.17; β = -2.35; 95% CI: -3.63, -1.32) and EDI language and cognitive development (β = -0.62; 95% CI: -1.25, -0.18; β = -1.22; 95% CI: -2.11, -0.58)., Conclusions: The ITC demonstrated high specificity suggesting that most children with a negative ITC screen will demonstrate school readiness at 4-6 years, and low false positive rates, minimizing over-diagnosis. The ITC had low sensitivity highlighting the importance of ongoing developmental surveillance and screening., (Copyright © 2022 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.)

Background: The primary aim of this study was to determine if screen use in early childhood is associated with overall vulnerability in school readiness at ages 4 to 6 years, as measured by the Early Development Instrument (EDI). Secondary aims were to: (1) determine if screen use was associated with individual EDI domains scores, and (2) examine the association between screen use and EDI domains scores among a subgroup of high screen users., Methods: This prospective cohort study was carried out using data from young children participating in a large primary care practice-based research network in Canada. Logistic regression analyses were run to investigate the association between screen use and overall vulnerability in school readiness. Separate linear regression models examined the relationships between children's daily screen use and each separate continuous EDI domain., Results: A total of 876 Canadian participants participated in this study. Adjusted logistic regression revealed an association between increased screen use and increased vulnerability in school readiness (p = 0.05). Results from adjusted linear regression demonstrated an association between higher screen use and reduced language and cognitive development domain scores (p = 0.004). Among high screen users, adjusted linear regression models revealed associations between increased screen use and reduced language and cognitive development (p = 0.004) and communication skills and general knowledge domain scores (p = 0.042)., Conclusions: Screen use in early childhood is associated with increased vulnerability in developmental readiness for school, with increased risk for poorer language and cognitive development in kindergarten, especially among high users., (© 2022. The Author(s).)

Background: Nutrition in early childhood is important for healthy growth and development. Achieving school readiness is considered one of the most important developmental milestones for young children., Objectives: The purpose of this study is to determine if nutritional risk in early childhood is associated with school readiness in kindergarten., Methods: A prospective cohort study was conducted through The Applied Research Group for Kids (TARGet Kids!) primary care research network in Toronto, Canada, 2015-2020. Nutritional risk was measured (18 mo to 5 y) using validated parent-completed questionnaires called Nutrition Screening for Toddlers and Preschoolers (NutriSTEP). High nutritional risk was categorized as scores ≥21. School readiness was measured using the validated teacher-completed Early Developmental Instrument (EDI), which measures 5 developmental domains in kindergarten (2 y of schooling, ages 4-6 y, before they enter grade 1). Vulnerability indicates scores lower than a population-based cutoff at the 10th percentile on at least 1 domain. Multiple logistic and linear regression models were conducted adjusting for relevant confounders., Results: The study included 896 children: 53% were male, 9% had high nutritional risk, and 17% were vulnerable on the EDI. A 1-SD increase in NutriSTEP total score was associated with 1.54 times increased odds of being vulnerable on the EDI among children in year 2 of kindergarten (P = 0.001). High nutritional risk cutoff was associated with 4.28 times increased odds of being vulnerable on the EDI among children in year 2 of kindergarten (P < 0.001). NutriSTEP total score and high nutritional risk were associated with lower scores on all 5 EDI domains, with the strongest association observed for the domains of language and cognitive development and communication skills and general knowledge., Conclusions: Higher nutritional risk in early childhood is associated with lower school readiness in year 2 of kindergarten. Nutritional interventions early in life may offer opportunities to enhance school readiness. This trial was registered www.clinicaltrials.gov as NCT01869530., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition.)

Objective: To determine if nutritional risk in early childhood is associated with parent-reported school concerns., Design: A prospective cohort study conducted through the TARGet Kids! primary care research network (2011-2018). Nutritional risk was measured between 18 months and 5 years of age using validated parent-completed NutriSTEP® questionnaires with eating behaviour and dietary intake subscores (0 = lowest and 68 = highest total nutritional risk score). Parent-reported school concerns were measured at school age (4-10 years of age) and included: speech and language; learning; attention; behaviour; social relationships; physical coordination; fine motor coordination and self-help skills and independence. The primary outcome was any parent-reported school concerns, and individual school concerns were used as secondary outcomes. Multiple logistic regression models were conducted adjusting for clinically relevant confounders to assess the relationship between nutritional risk and school concerns., Setting: Toronto, Canada., Participants: Children aged 18 months to 10 years., Results: The study included 3655 children, 52 % were male, mean NutriSTEP® score was 14·4 (sd 6·4). Each 1 sd increase in NutriSTEP® total score was associated with a 1·18 times increased odds of school concerns (adj OR: 1·18, 95 % CI 1·07, 1·28, P = 0·0004), and high nutritional risk was associated with a 1·42 times increased odds of school concerns (adj OR: 1·42, 95 % CI 1·13, 1·78, P = 0·002)., Conclusions: Nutritional risk in early childhood was associated with school concerns. Nutritional interventions in early childhood may reveal opportunities to enhance school outcomes.

Background: Few studies have published mediation analyses to quantify the role concurrent BMI plays in the relationship between growth and cardiometabolic risk (CMR) outcomes. Methods: We used data from a longitudinal cohort study conducted in children aged 0-60 months through The Applied Research Group for Kids (TARGet Kids!) in Canada. Four age and sex standardized BMI (zBMI) trajectories were identified using latent class mixed models. CMR were assessed using a CMR score. Concurrent zBMI was the zBMI measured on the same visit as CMR. Mediation analyses were performed comparing each trajectory with the reference trajectory. Results: One thousand one hundred sixty-five children were included. On average, compared with being in the stable low trajectory, being in the catch-up trajectory was associated with an increased CMR score of 0.42, 0.28 of which was mediated through concurrent zBMI [95% confidence interval (CI) 0.17 to 0.41, p  = 0.001]; being in the stable high trajectory was associated with an increased CMR score of 0.23, 0.24 through concurrent zBMI (95% CI 0.18 to 0.31, p  < 0.001). Similarly, being in the rapid accelerating trajectory was associated with an increased CMR score of 1.43, 1.18 of which was through concurrent zBMI (95% CI 0.89 to 1.50, p  < 0.001). Conclusions: There was a strong evidence that the effect of BMI trajectories on CMR was indirect via concurrent BMI. It is important for researchers to choose the most appropriate analytic method based on the study hypothesis to understand the total or direct effect of growth patterns on cardiometabolic disease risk in children.

Background: Rapid growth is associated with increased cardiometabolic risk (CMR) in adolescence and adulthood. Little is known about whether the association between rapid growth and increased CMR originates in early childhood., Objectives: To identify age and sex standardized body mass index (zBMI) trajectories and to examine the association between zBMI trajectories and CMR outcomes in children 0 to 60 months., Study Design: A longitudinal cohort study was conducted through The Applied Research Group for Kids (TARGet Kids!) in Toronto, Canada. Participants had repeated measures of weight and length or height performed from birth to 60 months of age. Latent class mixed modelling was used to identify the zBMI trajectories. Linear regressions were performed to determine the association between zBMI trajectories and the primary outcome, a CMR score, quantified as the sum of age- and sex- standardized waist circumference, systolic blood pressure, glucose, log-triglycerides and negative high-density lipoprotein cholesterol (HDL-C), divided by √5. Secondary outcomes were the individual components of the CMR formula as well as diastolic blood pressure and non-HDL-C., Results: Four BMI trajectories were identified among the 1166 children. After adjusting for all covariates, children in the rapidly accelerating trajectory had increased total CMR score (β = 1.38, 95% CI 0.77; 1.99, P < .001) and increased waist circumference score (β = 2.39, 95% CI 1.92; 2.86, P < .001) compared to the stable low group., Conclusions: Rapid growth during early childhood is associated with increased CMR in preschool children, largely driven by larger waist circumference., (© 2020 World Obesity Federation.)

Introduction: Cow's milk is a dietary staple for children in North America. Though clinical guidelines suggest children transition from whole (3.25% fat) milk to reduced (1% or 2%) fat milk at age 2 years, recent epidemiological evidence supports a link between whole milk consumption and lower adiposity in children. The purpose of this trial is to determine which milk fat recommendation minimises excess adiposity and optimises child nutrition and growth., Methods and Analysis: Cow's Milk Fat Obesity pRevention Trial will be a pragmatic, superiority, parallel group randomised controlled trial involving children receiving routine healthcare aged 2 to 4-5 years who are participating in the TARGet Kids! practice-based research network in Toronto, Canada. Children (n=534) will be randomised to receive one of two interventions: (1) a recommendation to consume whole milk or (2) a recommendation to consume reduced (1%) fat milk. The primary outcome is adiposity measured by body mass index z-score and waist circumference z-score; secondary outcomes will be cognitive development (using the Ages and Stages Questionnaire), vitamin D stores, cardiometabolic health (glucose, high-sensitivity C-reactive protein, non-high density lipoprotein (non-HDL), low density lipoprotein (LDL), triglyceride, HDL and total cholesterol, insulin and diastolic and systolic blood pressure), sugary beverage and total energy intake (measured by 24 hours dietary recall) and cost effectiveness. Outcomes will be measured 24 months postrandomisation and compared using analysis of covariance (ANCOVA), adjusting for baseline measures., Ethics and Dissemination: Ethics approval has been obtained from Unity Health Toronto and The Hospital for Sick Children. Results will be presented locally, nationally and internationally and published in a peer-reviewed journal. The findings may be helpful to nutrition guidelines for children in effort to reduce childhood obesity using a simple, inexpensive and scalable cow's milk fat intervention., Trial Registration Number: NCT03914807; pre-results., Competing Interests: Competing interests: JLM received an unrestricted research grant for a completed investigator-initiated study from the Dairy Farmers of Canada (2011–2012) and Ddrops provided non-financial support (vitamin D supplements) for an investigator initiated study on vitamin D and respiratory tract infections (2011–2015)., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Introduction: School readiness is a multidimensional construct that includes cognitive, behavioural and emotional aspects of a child's development. School readiness is strongly associated with a child's future school success and well-being. The Early Development Instrument (EDI) is a reliable and valid teacher-completed tool for assessing school readiness in children at kindergarten age. A substantial knowledge gap exists in understanding how early child growth, health behaviours, nutrition, cardiometabolic risk and development impact school readiness. The primary objective was to determine if growth patterns, measured by body mass index trajectories in healthy children aged 0-5 years, are associated with school readiness at ages 4-6 years (kindergarten age). Secondary objectives were to determine if other health trajectories, including health behaviours, nutrition, cardiometabolic risk and development, are associated with school readiness at ages 4-6 years. This paper presents the Fit for School Study protocol., Methods and Analysis: This is an ongoing prospective cohort study. Parents of children enrolled in the The Applied Health Research Group for Kids (TARGet Kids!) practice-based research network are invited to participate in the Fit for School Study. Child growth, health behaviours, nutrition, cardiometabolic risk and development data are collected annually at health supervision visits and linked to EDI data collected by schools. The primary and secondary analyses will use a two-stage process: (1) latent class growth models will be used to first determine trajectory groups, and (2) generalised linear mixed models will be used to examine the relationship between exposures and EDI results., Ethics and Dissemination: The research ethics boards at The Hospital for Sick Children, Unity Health Toronto and McMaster University approved this study, and research ethics approval was obtained from each school board with a student participating in the study. The findings will be presented locally, nationally and internationally and will be published in peer-reviewed journals., Trial Registration Number: NCT01869530., Competing Interests: Competing interests: JLM received an unrestricted research grant for a completed investigator-initiated study from the Dairy Farmers of Canada (2011–2012) and Ddrops provided non-financial support (vitamin D supplements) for an investigator-initiated study on vitamin D and respiratory tract infections (2011–2015). PP received unrestricted research grants for completed investigator-initiated studies from Danone Institute of Canada (2002–2004 and 2006–2009), Dairy Farmers of Ontario (2008–2010) and Mead Johnson Nutrition provided non-financial support (Fer-In-Sol liquid iron supplement) (2011–2017) for an ongoing investigator-initiated trial of iron deficiency in young children that was funded by Canadian Institutes of Health Research (FRN # 115059). CBi received a research grant from the Centre for Addiction and Mental Health Foundation (CAMH 2017-2020). CBo reports previously receiving a grant for a completed investigator-initiated study from the SickKids Centre for Health Active Kids (CHAK) (2015–2016) involving the development and validation of a risk stratification tool to identify young asymptomatic children at risk of iron deficiency. These agencies had no role in the design, collection, analyses or interpretation of the results of this study or in the preparation, review or approval of the manuscript. All other authors declare no conflicts of interest., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Introduction: Asthma prevalence is commonly measured in national surveys by questionnaire. The Ontario Asthma Surveillance Information System (OASIS) developed a validated health claims diagnosis algorithm to estimate asthma prevalence. The primary objective was to assess the agreement between two approaches of measuring asthma in young children. Secondary objectives were to identify concordant and discordant pairs, and to identify factors associated with disagreement., Study Design and Setting: A measurement study to evaluate the agreement between the OASIS algorithm and parent-reported asthma (criterion standard). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated. Multivariable logistic regression was used to determine factors associated with disagreement., Results: Healthy children aged 1 to 5 years (n =3642) participating in the TARGet Kids! practice based research network 2008-2013 in Toronto, Canada were included. Prevalence of asthma was 14% and 6% by the OASIS algorithm and parent-reported asthma, respectively. The Kappa statistic was 0.43, sensitivity 81%, specificity 90%, PPV 34%, and NPV 99%. There were 3249 concordant and 393 discordant pairs. Statistically significant factors associated with asthma identified by OASIS but not parent report included: male sex, higher zBMI, and parent history of asthma. Males were less likely to have asthma identified by parent report but not OASIS., Conclusion: The OASIS algorithm identified more asthma cases in young children than parent-reported asthma. The OASIS algorithm had high sensitivity, specificity, and NPV but low PPV relative to parent-reported asthma. These findings need replication in other populations., (© 2019 Wiley Periodicals, Inc.)

Objectives: To determine the association between cow's milk-fat and non-high-density lipoprotein (non-HDL) cholesterol, a marker of cardiovascular disease (CVD) risk in young children, and whether this association is mediated by the typical volume of cow's milk consumed., Study Design: A longitudinal study in 2- to 8-year-old children (n = 2890) was conducted through The Applied Research Group for Kids (TARGet Kids!), a practice-based research network in Toronto, Canada. Generalized estimating equations were used to examine the relationship between parent-reported cow's milk-fat percentage intake and serum non-HDL cholesterol concentrations as well as having high non-HDL cholesterol (≥3.75 mmol/L [145 mg/dL]), adjusting for covariates including age, sex, body mass index z score, breastfeeding duration, mother's ethnicity, and parental history of CVD. Bootstrap resampling (10 000 repetitions) was used to assess whether typical volume consumed mediated the association between cow's milk-fat percentage and non-HDL cholesterol., Results: In total, 156 (5.4%) had high non-HDL cholesterol. Each percent increase in cow's milk-fat was associated with a 0.035 mmol/L (1.35 mg/dL) (P < .001) and 0.024 mmol/L (0.92 mg/dL) (P = .01) increase in non-HDL cholesterol, unadjusted and adjusted for covariates respectively. Cow's milk-fat percentage was not associated with greater odds of having high non-HDL cholesterol. Volume of cow's milk partially mediated the association between cow's milk-fat percentage and non-HDL cholesterol, accounting for 28% of the relationship (P < .001)., Conclusions: Consumption of higher-fat cow's milk was associated with a small increase in non-HDL cholesterol but not greater odds of having high non-HDL cholesterol. Further research is needed to assess this relationship with other CVD risk factors in young children., Trial Registration: ClinicalTrials.gov: NCT01869530., (Copyright © 2019. Published by Elsevier Inc.)

Background: Asthma is the most common chronic illness of childhood and a common reason for hospital admission. Studies suggest that low vitamin D levels may be associated with health service utilization (HSU) for childhood asthma. The primary objective was to determine if vitamin D serum levels in early childhood were associated with HSU for asthma including: a) hospital admissions; b) emergency department visits; and c) outpatient sick visits. Secondary objectives were to determine whether vitamin D supplementation in pregnancy or childhood were associated with HSU for asthma., Methods: Prospective cohort study of children participating in the TARGet Kids! practice-based research network between 2008 and 2013 in Toronto, Canada. HSU was determined by linking each child's provincial health insurance number to health administrative databases. Multivariable quasi-Poisson and logistic regression were used to evaluate the association between 25-hydroxyvitamin D concentrations, vitamin D supplementation in pregnancy, and childhood and HSU for asthma., Results: A total of 2926 healthy children aged 0-6 years had 25-hydroxyvitamin D data available and were included in the primary analysis. Mean (IQR) 25-hydroxyvitmain D level was 84 nmol/L (65-98 nmol/L), 218 and 1267 children had 25-hydroxyvitamin D concentrations <50 nmol/L and <75 nmol/L, respectively. In the adjusted models, there were no associations between 25-hydroxyvitamin D concentrations (continuously or dichotomized at 50 and 75 nmol/L), vitamin D supplementation in pregnancy or childhood and HSU for asthma., Conclusions: Vitamin D blood values do not appear to be associated with HSU for asthma in this population of healthy urban children., (© 2018 Wiley Periodicals, Inc.)

Objective: Upper respiratory tract infections (URTI) are the most common and costly condition of childhood. Low vitamin D levels have been hypothesized as a risk factor for URTI. The primary objective was to determine if serum vitamin D levels were associated with health-service utilization (HSU) for URTI including hospital admission, emergency department visits and outpatient sick visits. The secondary objectives were to determine whether oral vitamin D supplementation in pregnancy or childhood was associated with HSU for URTI., Design: Cohort study. HSU was determined by linking each child's provincial health insurance number to health administrative databases. Multivariable quasi Poisson regression was used to evaluate the association between 25-hydroxyvitamin D, vitamin D supplementation and HSU for URTI., Setting: Toronto, Canada., Subjects: Children participating in the TARGet Kids! network between 2008 and 2013., Results: Healthy children aged 0-5 years (n 4962) were included; 52 % were male and mean 25-hydroxyvitamin D was 84 nmol/l (range 11-355 nmol/l). There were 105 (2 %), 721 (15 %) and 3218 (65 %) children with at least one hospital admission, emergency department visit or outpatient sick visit for URTI, respectively. There were no statistically significant associations between 25-hydroxyvitamin D or vitamin D supplementation and HSU for URTI., Conclusions: A clinically meaningful association between vitamin D (continuously and dichotomized at <50 and <75 nmol/l) and HSU for URTI was not identified. While vitamin D may have other benefits for health, reducing HSU for URTI does not appear to be one of them.

The association between vitamin D and wheezing in early childhood is unclear. The primary objective of this study was to evaluate the association between vitamin D exposure, during both pregnancy and childhood, and early childhood wheezing. Secondary objectives were to evaluate the associations between vitamin D exposures and asthma and wheezing severity. We conducted a cohort study of children (0-5 years) recruited from 2008 to 2013 through the TARGet Kids! primary-care research network. Vitamin D exposures included maternal vitamin D supplement use during pregnancy, child vitamin D supplementation and children's 25-hydroxyvitamin D (25(OH)D) concentrations. The outcomes measured were parent-reported childhood wheezing, diagnosed asthma and wheezing severity. Vitamin D supplement and wheezing data were available for 2478 children, and blood samples were available for 1275 children. Adjusted odds ratios (aOR) were estimated using logistic regression adjusted for age, sex, ethnicity, body mass index, birth weight, outdoor play, breastfeeding duration, daycare status, parental smoking and family history of asthma. Vitamin D supplementation during pregnancy was associated with lower odds of childhood wheezing (aOR=0.65; 95% CI: 0.46-0.93). In early childhood, neither 25(OH)D (aOR per 10 nmol/l=1.01; 95% CI: 0.96-1.06) nor vitamin D supplementation (aOR=1.00; 95% CI: 0.81-1.23) was associated with wheezing. No significant associations were observed with diagnosed asthma or wheezing severity. Vitamin D supplementation during pregnancy was associated with reduced odds of wheezing, but child vitamin D supplementation and childhood 25(OH)D were not associated with reduced wheezing. The timing of exposure may be important in understanding the association between vitamin D and childhood wheezing.

Objective: To determine if children aged 1-6 years from non-Western immigrant families have lower serum 25-hydroxyvitamin D (25(OH)D) levels than children from Western-born families and examine which factors influence this relationship., Design: Cross-sectional study., Setting: Toronto, Canada., Subjects: Healthy children (n 1540) recruited through the TARGet Kids! practice-based research network. Serum 25(OH)D concentrations of non-Western immigrants were compared with those of children from Western-born families. Children from non-Western immigrant families were defined as those born, or their parents were born, outside a Western country. Univariate and multiple linear regression analyses were used to identify factors which might influence this relationship., Results: Median age was 36 months, 51 % were male, 86 % had 'light' skin pigmentation, 55 % took vitamin D supplements, mean cow's milk intake was 1·8 cups/d and 27 % were non-Western immigrants. Median serum 25(OH)D concentration was 83 nmol/l, with 5 % having 25(OH)D < 50 nmol/l. Univariable analysis revealed that non-Western immigrant children had serum 25(OH)D lower by 4 (95 % CI 1·3, 8·0) nmol/l (P = 0·006) and increased odds of 25(OH)D < 50 nmol/l (OR = 1·9; 95 % CI 1·3, 2·9). After adjustment for known vitamin D determinants the observed difference attenuated to 0·04 (95 % CI -4·8, 4·8) nmol/l (P = 0·99), with higher cow's milk intake (P < 0·0001), vitamin D supplementation (P < 0·0001), summer season (P = 0·008) and increased age (P = 0·04) being statistically significant covariates. Vitamin D supplementation was the strongest explanatory factor of the observed difference., Conclusions: There is an association between non-Western immigration and lower 25(OH)D in early childhood. This difference appears related to known vitamin D determinants, primarily vitamin D supplementation, representing opportunities for intervention.

Purpose: Measuring ethnicity accurately is important for identifying ethnicity variations in disease risk. We evaluated the degree of agreement and accuracy of maternal ethnicity measured using the new standardized closed-ended geographically based ethnicity question and geographic reclassification of open-ended ethnicity questions from the Canadian census., Methods: A prospectively designed study of respondent agreement of mothers of healthy children aged 1-5 years recruited through the TARGet Kids! practice-based research network. For the primary analysis, the degree of agreement between geographic reclassification of the Canadian census maternal ethnicity variables and the new geographically based closed-ended maternal ethnicity variable completed by the same respondent was evaluated using a kappa analysis., Results: Eight hundred sixty-two mothers who completed both measures of ethnicity were included in the analysis. The kappa agreement statistic for the two definitions of maternal ethnicity was 0.87 (95% confidence interval, 0.84-0.90) indicating good agreement. Overall accuracy of the measurement was 93%. Sensitivity and specificity ranged from 83% to 100% and 96% to 100%, respectively., Conclusions: The new standardized closed-ended geographically based ethnicity question represents a practical alternative to widely used open-ended ethnicity questions. It may reduce risk of misinterpretation of ethnicity by respondents, simplify analysis, and improve the accuracy of ethnicity measurement., (Copyright © 2014 Elsevier Inc. All rights reserved.)