Impact of a nationwide school policy on body mass index in Danish school children: An interrupted time series analysis.

Objectives: A new school policy mandating 45 min physical activity daily during school was introduced in Denmark in 2014. We aimed to evaluate the effect of this policy on BMI in school-aged children. It was hypothesized that the school policy would decrease BMI, especially in the obese fraction of the population (90th percentile BMI). Study design: This register-based study was conducted as a natural experiment. Methods: Analyses were based on data from The National Child Health Register that contains nationwide data on height and weight from mandatory preventive health examinations completed by school nurses or medical doctors during pre-preparatory classes (0th-3rd grade) and lower secondary education (7th-9th grade). A total of 401,517 children were included in the analyses with annual repeated cross-sectional data covering the period from 2012 to 2018. The effect of the school policy was evaluated using an interrupted time series approach comparing pre- and post-policy slopes in BMI, stratified by sex and age-group. Results: In boys, no significant differences were observed in mean BMI slopes from pre-to post-policy in either age-group. In girls, post-policy slopes were significantly higher compared to pre-policy in both age-groups (0th-3rd grade: ß:0·034 kg/m2, 95%-CI: (0·024; 0·043), p-value: <0·001; 7th-9th grade: ß:0·066 kg/m2, 95%-CI: (0·028; 0·103), p-value: 0·001). No significant differences in slopes were observed in BMI at the 90th percentile from pre-to post-policy for both sexes and across both age-groups. Adjustment for leisure-time physical activity as a potential time-varying confounder did not alter the findings. Conclusions: In conclusion, we did not detect a significant decrease in BMI levels among school-aged children following the introduction of a nationwide school policy specifying daily physical activity in school. If anything, a small positive change in BMI was observed in girls. More research is needed to understand whether structural changes similar to this requirement are able to prevent overweight and obesity in children and adolescents.

Association between recent exposure to continuous glucose monitoring-recorded hypoglycaemia and counterregulatory and symptom responses to subsequent controlled hypoglycaemia in people with type 1 diabetes.

AIM: Experimental hypoglycaemia blunts the counterregulatory hormone and symptom responses to a subsequent episode of hypoglycaemia. In this study, we aimed to assess the associations between antecedent exposure and continuous glucose monitoring (CGM)-recorded hypoglycaemia during a 1-week period and the counterregulatory responses to subsequent experimental hypoglycaemia in people with type 1 diabetes. MATERIALS AND METHODS: Forty-two people with type 1 diabetes (20 females, mean ± SD glycated haemoglobin 7.8% ± 1.0%, diabetes duration median (interquartile range) 22.0 (10.5-34.9) years, 29 CGM users, and 19 with impaired awareness of hypoglycaemia) wore an open intermittently scanned CGM for 1 week to detect hypoglycaemic exposure before a standardized hyperinsulinaemic-hypoglycaemic [2.8 ± 0.1 mmol/L (50.2 ± 2.3 mg/dl)] glucose clamp. Symptom responses and counterregulatory hormones were measured during the clamp. The study is part of the HypoRESOLVE project. RESULTS: CGM-recorded hypoglycaemia in the week before the clamp was negatively associated with adrenaline response [ß -0.09, 95% CI (-0.16, -0.02) nmol/L, p = .014], after adjusting for CGM use, awareness of hypoglycaemia, glycated haemoglobin and total daily insulin dose. This was driven by level 2 hypoglycaemia [<3.0 mmol/L (54 mg/dl)] [ß -0.21, 95% CI (-0.41, -0.01) nmol/L, p = .034]. CGM-recorded hypoglycaemia was negatively associated with total, autonomic, and neuroglycopenic symptom responses, but these associations were lost after adjusting for potential confounders. CONCLUSIONS: Recent exposure to CGM-detected hypoglycaemia was independently associated with an attenuated adrenaline response to experimental hypoglycaemia in people with type 1 diabetes.

Counterregulatory hormone and symptom responses to hypoglycaemia in people with type 1 diabetes, insulin-treated type 2 diabetes or without diabetes: the Hypo-RESOLVE hypoglycaemic clamp study.

AIM: The sympathetic nervous and hormonal counterregulatory responses to hypoglycaemia differ between people with type 1 and type 2 diabetes and may change along the course of diabetes, but have not been directly compared. We aimed to compare counterregulatory hormone and symptom responses to hypoglycaemia between people with type 1 diabetes, insulin-treated type 2 diabetes and controls without diabetes, using a standardised hyperinsulinaemic-hypoglycaemic clamp. MATERIALS: We included 47 people with type 1 diabetes, 15 with insulin-treated type 2 diabetes, and 32 controls without diabetes. Controls were matched according to age and sex to the people with type 1 diabetes or with type 2 diabetes. All participants underwent a hyperinsulinaemic-euglycaemic-(5.2 ± 0.4 mmol/L)-hypoglycaemic-(2.8 ± 0.13 mmol/L)-clamp. RESULTS: The glucagon response was lower in people with type 1 diabetes (9.4 ± 0.8 pmol/L, 8.0 [7.0-10.0]) compared to type 2 diabetes (23.7 ± 3.7 pmol/L, 18.0 [12.0-28.0], p < 0.001) and controls (30.6 ± 4.7, 25.5 [17.8-35.8] pmol/L, p < 0.001). The adrenaline response was lower in type 1 diabetes (1.7 ± 0.2, 1.6 [1.3-5.2] nmol/L) compared to type 2 diabetes (3.4 ± 0.7, 2.6 [1.3-5.2] nmol/L, p = 0.001) and controls (2.7 ± 0.4, 2.8 [1.4-3.9] nmol/L, p = 0.012). Growth hormone was lower in people with type 2 diabetes than in type 1 diabetes, at baseline (3.4 ± 1.6 vs 7.7 ± 1.3 mU/L, p = 0.042) and during hypoglycaemia (24.7 ± 7.1 vs 62.4 ± 5.8 mU/L, p = 0.001). People with 1 diabetes had lower overall symptom responses than people with type 2 diabetes (45.3 ± 2.7 vs 58.7 ± 6.4, p = 0.018), driven by a lower neuroglycopenic score (27.4 ± 1.8 vs 36.7 ± 4.2, p = 0.012). CONCLUSION: Acute counterregulatory hormone and symptom responses to experimental hypoglycaemia are lower in people with type 1 diabetes than in those with long-standing insulin-treated type 2 diabetes and controls.

Effect of nationwide school policy on device-measured physical activity in Danish children and adolescents: a natural experiment.

Background: A new Danish school policy with a requirement for 45 min physical activity daily during school hours was introduced in 2014. The objective of this natural experiment was to evaluate the effect of this nationwide school policy on physical activity in Danish children and adolescents. Methods: Four historical studies completed between 2009 and 2012 comprised the pre-policy study population. Post-policy data were collected in 2017/18. All post-policy schools were represented in the four pre-policy studies. Age-groups and seasons were matched. In total, 4816 children and adolescents aged 6-17 were included in the analyses (2346 pre-policy and 2470 post-policy). Children and adolescents were eligible if they had accelerometer measurements and did not have any physical disabilities preventing activity. Physical activity was measured by accelerometry. Main outcome was any bodily movement. Secondary outcomes were moderate to vigorous physical activity and overall movement volume (mean counts per minute). Findings: The school policy interrupted a linear decreasing pre-policy trend in physical activity during school hours. All activity outcomes increased post-policy during a standardized school day (8:10 am-1 pm). Increases were more pronounced in the youngest children. Specifically, we observed a daily increase during a standardized school day in 2017/2018 of 14.2 min of movement (95% CI: 11.4-17.0, p < 0.001), 6.5 min of moderate to vigorous physical activity (95% CI: 4.7-8.3, P < 0.001), and 141.8 counts per minute (95% CI: 108.5-175.2, P < 0.001). Interpretation: A national school policy may be an important strategy to increase physical activity during school hours among children and adolescents. Funding: The Danish Foundation TrygFonden has funded the PHASAR project (ID 115606).

Real life evaluation of sodium-glucose cotransporter 2 inhibition in type 1 diabetes and the risk of diabetic ketoacidosis.

BACKGROUND: The indication for treatment of type 1 diabetes(T1D) with the sodium-glucose cotransporter 2 inhibitor (SGLT2i) dapagliflozin has been withdrawn in Europe likely because of concern for diabetic ketoacidosis (DKA). We calculated the incidence of DKA in people with T1D treated with SGLT2i in Denmark. METHODS: Clinical data from adults with T1D in Denmark were collected from nine outpatient clinics. Electronic health records made the search for DKA accurate. RESULTS: From a population of 10.500 we observed 134 people treated with SGLT2i over a total period of 222 patient-years. Of those 72% were female, mean age (SD) was 51.4 (13.6) years and median duration of treatment (median, IQR) with an SGLT2i were 12.0 (6.0-29.0) months. The incidence of DKA was zero%. CONCLUSION: In 134 people with T1D treated with SGLT2i we found that none of the participants developed DKA during the treatment.

Consistent Effects of Hypoglycemia on Cognitive Function in People With or Without Diabetes.

OBJECTIVE: Hypoglycemia poses an immediate threat for cognitive function. Due to its association with acute cognitive impairment, the International Hypoglycemia Study Group (IHSG) defines a blood glucose level <3.0 mmol/L as "level 2 hypoglycemia." In the current study we investigated whether having diabetes, type of diabetes, or hypoglycemia awareness moderates this association. RESEARCH DESIGN AND METHODS: Adults with type 1 diabetes with normal (n = 26) or impaired (n = 21) hypoglycemic awareness or with insulin-treated type 2 diabetes (n = 15) and age-matched control subjects without diabetes (n = 32) underwent a hyperinsulinemic-euglycemic-hypoglycemic glucose clamp (2.80 ± 0.13 mmol/L [50.2 ± 2.3 mg/dL]). At baseline and during hypoglycemia, calculation ability, attention, working memory and cognitive flexibility were measured with the Paced Auditory Serial Addition Test (PASAT) and the Test of Attentional Performance (TAP). RESULTS: For the whole group, hypoglycemia decreased the mean ± SD proportion of correct answers on the PASAT by 8.4 ± 12.8%, increased reaction time on the TAP Alertness task by 32.1 ± 66.6 ms, and increased the sum of errors and omissions on the TAP Working Memory task by 2.0 ± 5.5 (all P < 0.001). Hypoglycemia-induced cognitive declines were largely irrespective of the presence or type of diabetes, level of symptomatic awareness, diabetes duration, or HbA1c. CONCLUSIONS: IHSG level 2 hypoglycemia impairs cognitive function in people with and without diabetes, irrespective of type of diabetes or hypoglycemia awareness status. These findings support the cutoff value of hypoglycemia <3.0 mmol/L (<54 mg/dL) as being clinically relevant for most people with diabetes.

Glycaemic thresholds for counterregulatory hormone and symptom responses to hypoglycaemia in people with and without type 1 diabetes: a systematic review.

AIM/HYPOTHESIS: The physiological counterregulatory response to hypoglycaemia is reported to be organised hierarchically, with hormone responses usually preceding symptomatic awareness and autonomic responses preceding neuroglycopenic responses. To compare thresholds for activation of these responses more accurately between people with or without type 1 diabetes, we performed a systematic review on stepped hyperinsulinaemic-hypoglycaemic glucose clamps. METHODS: A literature search in PubMed and EMBASE was conducted. We included articles published between 1980 and 2018 involving hyperinsulinaemic stepped hypoglycaemic glucose clamps among people with or without type 1 diabetes. Key exclusion criteria were as follows: data were previously published; other patient population; a clamp not the primary intervention; and an inadequate clamp description. Glycaemic thresholds for counterregulatory hormone and/or symptom responses to hypoglycaemia were estimated and compared using generalised logrank test for interval-censored data, where the intervals were either extracted directly or calculated from the data provided by the study. A glycaemic threshold was defined as the glucose level at which the response exceeded the 95% CI of the mean baseline measurement or euglycaemic control clamp. Because of the use of interval-censored data, we described thresholds using median and IQR. RESULTS: A total of 63 articles were included, whereof 37 papers included participants with type 1 diabetes (n=559; 67.4% male sex, aged 32.7±10.2 years, BMI 23.8±1.4 kg/m2) and 51 papers included participants without diabetes (n=733; 72.4% male sex, aged 31.1±9.2 years, BMI 23.6±1.1 kg/m2). Compared with non-diabetic control individuals, in people with type 1 diabetes, the median (IQR) glycaemic thresholds for adrenaline (3.8 [3.2-4.2] vs 3.4 [2.8-3.9 mmol/l]), noradrenaline (3.2 [3.2-3.7] vs 3.0 [2.8-3.1] mmol/l), cortisol (3.5 [3.2-4.2]) vs 2.8 [2.8-3.4] mmol/l) and growth hormone (3.8 [3.3-3.8] vs. 3.2 [3.0-3.3] mmol/l) all occurred at lower glucose levels in people with diabetes than in those without diabetes (all p≤0.01). Similarly, although both autonomic (median [IQR] 3.4 [3.4-3.4] vs 3.0 [2.8-3.4] mmol/l) and neuroglycopenic (median [IQR] 3.4 [2.8-N/A] vs 3.0 [3.0-3.1] mmol/l) symptom responses were elicited at lower glucose levels in people with type 1 diabetes, the thresholds for autonomic and neuroglycopenic symptoms did not differ for each individual subgroup. CONCLUSIONS/INTERPRETATION: People with type 1 diabetes have glycaemic thresholds for counterregulatory hormone and symptom responses at lower glucose levels than people without diabetes. Autonomic and neuroglycopenic symptoms responses are generated at about similar levels of hypoglycaemia. There was a considerable variation in the methodology of the articles and the high insulin doses in most of the clamps may affect the counterregulatory responses. FUNDING: This article has received funding from the Innovative Medicines Initiative 2 Joint Undertaking (JU) under grant agreement no. 777460. REGISTRATION: This systematic review is registered in PROSPERO (CRD42019120083).

35 Years of health surveys in Denmark: a backbone of public health practice and research.

Denmark has a 35-year history of monitoring health status in the general population through health surveys. In this commentary, we outline the development of health surveys in Denmark from the beginning in 1987 to the present time. We describe how the current systematic framework for the Danish National Health Survey (DNHS) developed. We discuss the methodological basis for the DNHS and describe its application in public health practice and research. Over the years, the DNHS has become an important part of the Danish public health environment. Challenges for the DNHS in the future are to adapt to new trends in public health and at the same time to be able to monitor important changes consistently over time.

Feasibility of home-based sampling of salivary cortisol and cortisone in healthy adults.

OBJECTIVE: Salivary cortisol and cortisone are used as biomarkers of physiological stress. Careful sampling of saliva for profiling of awakening response and the diurnal slope can be challenging in free-living environments, and validated sampling protocols are lacking. Therefore, we investigated (1) the level of compliance to a three-day home-based salivary sampling protocol, and (2) the within subject day-to-day variability of cortisol and cortisone outcomes and the required measuring days to obtain high reproducibility. RESULTS: Nineteen healthy adults (mean age: 42, 50% females) participated. Participants collected in total 434 salivary samples out of 456 scheduled (four samples per day over three consecutive days at two time points). We found high level of compliance to the proposed free-living salivary sampling protocol with 18 (95%) and 16 (84%) participants being compliant to numbers and timing of samples, respectively. The area under the curve for the morning salivary samples and peak-to-bed slope had moderate reproducibility for cortisol and cortisone (intraclass correlation coefficient: 0.51-0.68, and mean coefficient of variation: 14.7%-75.3%). Three-to-four measuring days were required for high reproducibility of the area under the curve for the morning salivary samples and peak-to-bed slope using this free-living salivary sampling protocol. Trial registration Clinical trial registered with www.clinicaltrials.gov (NCT03788525).

Children's moderate-to-vigorous physical activity on weekdays versus weekend days: a multi-country analysis.

PURPOSE: The Structured Days Hypothesis (SDH) posits that children's behaviors associated with obesity - such as physical activity - are more favorable on days that contain more 'structure' (i.e., a pre-planned, segmented, and adult-supervised environment) such as school weekdays, compared to days with less structure, such as weekend days. The purpose of this study was to compare children's moderate-to-vigorous physical activity (MVPA) levels on weekdays versus weekend days using a large, multi-country, accelerometer-measured physical activity dataset. METHODS: Data were received from the International Children's Accelerometer Database (ICAD) July 2019. The ICAD inclusion criteria for a valid day of wear, only non-intervention data (e.g., baseline intervention data), children with at least 1 weekday and 1 weekend day, and ICAD studies with data collected exclusively during school months, were included for analyses. Mixed effects models accounting for the nested nature of the data (i.e., days within children) assessed MVPA minutes per day (min/day MVPA) differences between weekdays and weekend days by region/country, adjusted for age, sex, and total wear time. Separate meta-analytical models explored differences by age and country/region for sex and child weight-status. RESULTS/FINDINGS: Valid data from 15 studies representing 5794 children (61% female, 10.7 ± 2.1 yrs., 24% with overweight/obesity) and 35,263 days of valid accelerometer data from 5 distinct countries/regions were used. Boys and girls accumulated 12.6 min/day (95% CI: 9.0, 16.2) and 9.4 min/day (95% CI: 7.2, 11.6) more MVPA on weekdays versus weekend days, respectively. Children from mainland Europe had the largest differences (17.1 min/day more MVPA on weekdays versus weekend days, 95% CI: 15.3, 19.0) compared to the other countries/regions. Children who were classified as overweight/obese or normal weight/underweight accumulated 9.5 min/day (95% CI: 6.9, 12.2) and 10.9 min/day (95% CI: 8.3, 13.5) of additional MVPA on weekdays versus weekend days, respectively. CONCLUSIONS: Children from multiple countries/regions accumulated significantly more MVPA on weekdays versus weekend days during school months. This finding aligns with the SDH and warrants future intervention studies to prioritize less-structured days, such as weekend days, and to consider providing opportunities for all children to access additional opportunities to be active.

Hyperinsulinaemic-hypoglycaemic glucose clamps in human research: a systematic review of the literature.

AIMS/HYPOTHESIS: The hyperinsulinaemic-hypoglycaemic glucose clamp technique has been developed and applied to assess effects of and responses to hypoglycaemia under standardised conditions. However, the degree to which the methodology of clamp studies is standardised is unclear. This systematic review examines how hyperinsulinaemic-hypoglycaemic clamps have been performed and elucidates potential important differences. METHODS: A literature search in PubMed and EMBASE was conducted. Articles in English published between 1980 and 2018, involving adults with or without diabetes, were included. RESULTS: A total of 383 articles were included. There was considerable variation in essential methodology of the hypoglycaemic clamp procedures, including the insulin dose used (49-fold difference between the lowest and the highest rate), the number of hypoglycaemic steps (range 1-6), the hypoglycaemic nadirs (range 2.0-4.3 mmol/l) and the duration (ranging from 5 to 660 min). Twenty-seven per cent of the articles reported whole blood glucose levels, most venous levels. In 70.8% of the studies, a dorsal hand vein was used for blood sampling, with some form of hand warming to arterialise venous blood in 78.8% of these. Key information was missing in 61.9% of the articles. CONCLUSIONS/INTERPRETATION: Although the hyperinsulinaemic-hypoglycaemic clamp procedure is considered the gold standard to study experimental hypoglycaemia, a uniform standard with key elements on how to perform these experiments is lacking. Methodological differences should be considered when comparing results between hypoglycaemic clamp studies. PROSPERO REGISTRATION: This systematic review is registered in PROSPERO (CRD42019120083).

The potential for improvement of outcomes by personalized insulin treatment of type 1 diabetes as assessed by analysis of single-patient data from a randomized controlled cross-over insulin trial.

AIMS: The evidence for optimal insulin treatment in type 1 diabetes is mainly based on randomised controlled trials applying a parallel-group design. Such trials yield robust general results but crucial individual treatment effects cannot be extracted. We aimed to assess the potential for further improvement of outcomes by personalized insulin therapy by analyzing data from a cross-over trial at individual level. METHODS: Post hoc analysis of data from a two-year multicentre, prospective, randomised, open, blinded endpoint (PROBE) trial (the HypoAna trial). In a cross-over design 114 patients with type 1 diabetes and recurrent severe hypoglycemia were treated with basal-bolus therapy based on analog (detemir/aspart) or human (NPH/regular) insulin aiming at maintenance of baseline HbA1c levels. For each patient a superior outcome was defined as fewer events of severe hypoglycemia defined by need for third party treatment assistance or a more than 0.4% (4.4mmol/mol) lower HbA1c. RESULTS: Only one quarter had comparable outcome of the two treatments in terms of rate of severe hypoglycemia or HbA1c. Twice as many patients had superior outcome of analog-based as compared to human insulin-based insulin treatment. The rate of severe hypoglycemia with the superior treatment was lower compared to the rates obtained with analog insulin and with human insulin (0.67, 1.09, and 1.57 episode per patient-year, respectively (p<0.0001)). CONCLUSIONS: Personalized insulin treatment of type 1 diabetes based on single-patient evidence may improve outcomes significantly compared to a general treatment approach.

Impact of the TCF7L2 genotype on risk of hypoglycaemia and glucagon secretion during hypoglycaemia.

INTRODUCTION: In healthy carriers of the T allele of the transcription factor 7-like 2 (TCF7L2), fasting plasma glucagon concentrations are lower compared with those with the C allele. We hypothesised that presence of the T allele is associated with a diminished glucagon response during hypoglycaemia and a higher frequency of severe hypoglycaemia (SH) in type 1 diabetes (T1DM). MATERIAL AND METHODS: This is a post hoc study of an earlier prospective observational study of SH and four mechanistic studies of physiological responses to hypoglycaemia. 269 patients with T1DM were followed in a one-year observational study. A log-linear negative binomial model was applied with events of SH as dependent variable and TCF7L2 alleles as explanatory variable. In four experimental studies including 65 people, TCF7L2 genotyping was done and plasma glucagon concentration during experimental hypoglycaemia was determined. RESULTS: Incidences of SH were TT 0.54, TC 0.98 and CC 1.01 episodes per patient-year with no significant difference between groups. During experimental hypoglycaemia, the TCF7L2 polymorphism did not influence glucagon secretion. DISCUSSION: Patients with T1DM carrying the T allele of the TCF7L2 polymorphism do not exhibit diminished glucagon response during hypoglycaemia and are not at increased risk of severe hypoglycaemia compared with carriers of the C allele.

Glucose-dependent insulinotropic polypeptide augments glucagon responses to hypoglycemia in type 1 diabetes.

Glucose-dependent insulinotropic polypeptide (GIP) is glucagonotropic, and glucagon-like peptide-1 (GLP-1) is glucagonostatic. We studied the effects of GIP and GLP-1 on glucagon responses to insulin-induced hypoglycemia in patients with type 1 diabetes mellitus (T1DM). Ten male subjects with T1DM (C-peptide negative, age [mean ± SEM] 26 ± 1 years, BMI 24 ± 0.5 kg/m(2), HbA1c 7.3 ± 0.2%) were studied in a randomized, double-blinded, crossover study, with 2-h intravenous administration of saline, GIP, or GLP-1. The first hour, plasma glucose was lowered by insulin infusion, and the second hour constituted a "recovery phase." During the recovery phase, GIP infusions elicited larger glucagon responses (164 ± 50 [GIP] vs. 23 ± 25 [GLP-1] vs. 17 ± 46 [saline] min ⋅ pmol/L, P < 0.03) and endogenous glucose production was higher with GIP and lower with GLP-1 compared with saline (P < 0.02). On the GIP days, significantly less exogenous glucose was needed to keep plasma glucose above 2 mmol/L (155 ± 36 [GIP] vs. 232 ± 40 [GLP-1] vs. 212 ± 56 [saline] mg ⋅ kg(-1), P < 0.05). Levels of insulin, cortisol, growth hormone, and noradrenaline, as well as hypoglycemic symptoms and cognitive function, were similar on all days. Our results suggest that during hypoglycemia in patients with T1DM, exogenous GIP increases glucagon responses during the recovery phase after hypoglycemia and reduces the need for glucose administration.

A Longitudinal Study of Objectively Measured Built Environment as Determinant of Physical Activity in Young Adults: The European Youth Heart Study.

BACKGROUND: This longitudinal study aimed to examine if a Movability Index (MI), based on objectively measured built environment characteristics, was a determinant for objectively measured physical activity (PA) among young adults. METHODS: Data collected from 177 persons participating in the Danish part of the European Youth Hearth Study (EYHS) was used to examine the effect of the built environment on PA. A MI was developed using objectively measured built environment characteristics, and included residential density, recreational facilities, daily destinations and street connectivity. RESULTS: Results showed a positive cross-sectional association between MI and PA. PA decreased from baseline to follow-up. MI increased, primarily due to participants relocating to larger cities. An increase in MI from baseline to follow-up was associated with a reduced decrease in PA for females. CONCLUSIONS: Our findings suggest that the built environment is a determinant for PA, especially for females. The found gender differences might suggest the need to develop gender specific environmental indices in future studies. The validity of the measures can be further improved by creating domain specific PA measures as well as domain specific environmental indices and this can potentially reveal more specific built environment determinants for PA.

The effect of multiple reminders on response patterns in a Danish health survey.

BACKGROUND: Reminders are routinely applied in surveys to increase response rates and reduce the possibility of bias. This study examines the effect of multiple reminders on the response rate, non-response bias, prevalence estimates and exposure-outcome relations in a national self-administered health survey. METHODS: Data derive from the Danish National Health Survey 2010, in which 298,550 individuals (16 years of age or older) were invited to participate in a cross-sectional survey using a mixed-mode approach (paper and web questionnaires). At least two reminders were sent to non-respondents, and 177,639 individuals completed the questionnaire (59.5%). Response patterns were compared between four groups of individuals (first mailing respondents, second mailing respondents, third mailing respondents and non-respondents). RESULTS: Multiple reminders led to an increase in response rate from 36.7 to 59.5%; however, the inclusion of second and third mailing respondents did not change the overall characteristics of respondents compared with non-respondents. Furthermore, only small changes in prevalence estimates and exposure-outcome relationships were observed when including second and third mailing respondents compared with only first mailing respondents. CONCLUSIONS: Multiple reminders were an effective way to increase the response rate in a national Danish health survey. However, when differences do exist between respondents and non-respondents, the results suggest that second and third mailings are unlikely to eliminate these differences. Overall, multiple reminders seemed to have only minor effect on response patterns and study conclusions in the present study.

Intervention effects on adolescent physical activity in the multicomponent SPACE study: a cluster randomized controlled trial.

BACKGROUND: Multicomponent school-based interventions have the potential to reduce the age-related decline in adolescents' physical activity (PA), yet there is not consistent evidence to guide non-curricular and school environment interventions. The aim of this study was to assess the effectiveness of a multicomponent environmental school-based intervention, designed to reduce the age-related decline in PA among adolescents. METHODS: A cluster randomized controlled trial was conducted with 7 intervention and 7 control schools. Baseline measurements were carried out in spring 2010 with 2 years of follow-up. A total of 1,348 students (11-13 years, in grade 5 and 6) enrolled in the study at baseline. The 14 schools included in the study were located in the Region of Southern Denmark. The intervention consisted of organizational and physical changes in the school environment with a total of 11 intervention components. The primary outcome measure was overall PA (cpm, counts per minute) and was supported by analyses of time spent in MVPA, and time spent sedentary. Furthermore, a secondary outcome measure was PA in school time and during recess. PA was measured using accelerometer (Actigraph GT3X). RESULTS: A total of 797 students completed the trial and had valid accelerometer data. No significant difference was found for overall PA with an adjusted difference of -19.1 cpm (95% CI: -93, 53) or for school time activity with an adjusted difference of 6 cpm (95% CI: -73, 85). A sensitivity analysis revealed a positive significant intervention effect of PA in recess with an adjusted difference of 95 cpm. CONCLUSIONS: No evidence was found of the overall effect of a non-curricular multicomponent school-based intervention on PA among Danish adolescents. The intervention was positively associated with PA during school time and recess, however, with small estimates. Lack of effect on overall PA could be due to both program theory and different degrees of implementation. TRIAL REGISTRATION: www.Controlled-Trials.com ISRCTN79122411.

Association between body mass index and caries among children and adolescents.

OBJECTIVE: The aim of this article was to examine the relationship between childhood caries, body mass index (BMI) and subsequent changes in BMI over 6 years, and to investigate whether these associations were modified by social class. METHODS: Data were from the European Youth Heart Study (EYHS) merged with data on caries experience from the Danish National Board of Health, (SCOR register). RESULTS: At baseline, 26.2% of the children/adolescents were caries free and 39% at follow-up. A larger percentage of normal weight children/adolescents were caries free, compared with the overweight/obese group of children/adolescents. The linear regression analysis showed that childhood caries was generally not associated with either BMI or subsequent changes in BMI. However, among children whose mothers were well educated, there was an inverse association between caries at baseline and subsequent changes in BMI over a period of 6 years, for example, a high caries experience was associated with a smaller increment in BMI, compared with the group of children with a low caries experience. No association was found for those with lower SES. CONCLUSION: An inverse association between caries and subsequent changes in BMI was found, but only among children with well-educated mothers, suggesting that high caries experience may be a marker for low future risk of overweight among the more advantaged. Associations did not appear to be significant among the less advantaged; however, numbers in this group were low, and an association may have been overlooked. Hence, more studies are needed to confirm these findings.

Between-school variation in physical activity, aerobic fitness, and organized sports participation: a multi-level analysis.

A large proportion of a child's day is spent at school interacting with certain physical surroundings, teachers, and school friends. Thus, schools could have a marked impact on establishing physical activity habits. The aim of the present study was to assess between-school variation in physical activity, aerobic fitness, and organized sports participation. Altogether, we tested 1766 nine- and fifteen-year-old children attending 242 school classes at 35 different schools in Denmark in 1997-2003. The intra-class correlation coefficient (ICC) for objectively assessed physical activity ranged between 0.06 and 0.18 depending on the dimension of physical activity and the time considered (i.e. school time vs. leisure time). For aerobic fitness, an ICC of 0.10 was observed, whereas that for organized sports participation ranged between 0.01 and 0.10 depending on the age group. Studying between-school variation in physical activity provides information about the extent to which children adjust their physical activity habits according to the social and environmental circumstances that they share, and helps to plan future school-based physical activity studies, especially in terms of sample size and power calculation.

SPACE for physical activity--a multicomponent intervention study: study design and baseline findings from a cluster randomized controlled trial.

BACKGROUND: The aim of the School site, Play Spot, Active transport, Club fitness and Environment (SPACE) Study was to develop, document, and assess a comprehensive intervention in local school districts that promote everyday physical activity (PA) among 11-15-year-old adolescents. The study is based on a social ecological framework, and is designed to implement organizational and structural changes in the physical environment. METHODS/DESIGN: The SPACE Study used a cluster randomized controlled study design. Twenty-one eligible schools in the Region of Southern Denmark were matched and randomized in seven pairs according to eight matching variables summarized in an audit tool (crow-fly distance from residence to school for 5-6th graders; area household income; area education level; area ethnicity distribution; school district urbanity; condition and characteristics of school outdoor areas; school health policy; and active transport in the local area). Baseline measurements with accelerometers, questionnaires, diaries, and physical fitness tests were obtained in Spring 2010 in 5-6th grade in 7 intervention and 7 control schools, with follow-up measurements to be taken in Spring 2012 in 7-8th grade. The primary outcome measure is objective average daily physical activity and will be supported by analyses of time spent in moderate to vigorous activity and time spent sedentary. Other secondary outcome measures will be obtained, such as, overweight, physical fitness, active commuting to/from school and physical activity in recess periods. DISCUSSION: A total of 1348 adolescents in 5-6th grade in the Region of Southern Denmark participated at baseline (n = 14 schools). The response rate was high in all type of measurements (72.6-97.4%). There were no significant differences between intervention and control groups at baseline according to selected background variables and outcome measures: gender (p = .54), age (p = .17), BMI (p = .59), waist circumference (p = .17), physical fitness (p = .93), and physical activity (accelerometer) (p = .09). The randomization and matched pair design produced equivalent groups according to central outcome measures and background variables. The SPACE for physical activity Study will provide new insights on the effectiveness of multicomponent interventions to improve adolescents' physical activity level. TRIAL REGISTRATION: Current Controlled Trials ISRCTN79122411.