Laurent Béghin

Sampling and processing of fresh blood samples within a European multicenter nutritional study: Evaluation of biomarker stability during transport and storage

Introduction:Analysis of several biological markers improves the quality and physiologic comprehension of data obtained in epidemiological nutritional studies.Aim:To develop a methodology that guarantees the centralized analysis and quality assurance of the most relevant blood parameters from fresh blood samples in adolescents in a European multicenter study.Materials and methods:Stability of selected nutrients and biomarkers (vitamins, fatty acids, iron metabolism and immunological parameters) chosen with respect to time and temperature of sample transport and storage was evaluated as part of the pilot study of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) project.Results:Routine biochemistry and iron status parameters included in the HELENA Cross-Sectional Study (CSS) protocol could be analyzed within 24 h from fresh blood samples without any stability problems (coefficient of variation (CV)<5%, P<0.05). However, stability tests for lymphocyte subpopulations, vitamin C and fatty acids showed that they are very unstable at room temperature without any treatment. Therefore, a special handling for these samples was developed. Vitamin C was stabilized with metaphosphoric acid and transported under cooled conditions (CV 4.4%, recovery rate >93%, P>0.05). According to the results, a specific methodology and transport system were developed to collect blood samples at schools in 10 European cities and to send them to the centralized laboratory (IEL, Bonn, Germany). To guarantee good clinical practice, the field workers were instructed in a training workshop and a manual of operation was developed.Conclusion:The handling and transport system for fresh blood samples developed for the European multicenter study HELENA is adequate for the final part of the HELENA-CSS and will provide, for the first time, reference values for several biological markers in European adolescents.

Comparison of the IPAQ-A and Actigraph in relation to VO2max among European adolescents: The HELENA study

The purpose was to compare data obtained from a modified, long, self-administered version of the International Physical Activity Questionnaire (IPAQ-A) with objective data obtained in parallel from Actigraph accelerometers, and VO(2)max in adolescents. The study comprised a total of 2018 adolescents (46% male) from ten European cities participating in the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study. Physical activity was assessed over seven consecutive days by accelerometry and expressed as min/day of moderate, vigorous, and moderate to vigorous (MVPA) physical activity (PA). PA was also assessed with the IPAQ-A. VO(2)max was estimated from a 20-m shuttle run test. Poor to fair correlations between the two methodologies were found for the whole study sample and when stratified by age and gender (r(s) = 0.08-0.26, p < 0.01). On average, the self-reported time spent in moderate PA was higher compared to the time measured with the accelerometer, while the differences between both instruments were less clear for vigorous intensity. Adolescents reporting high levels of PA (3rd tertile IPAQ-A) also showed higher levels of PA (accelerometers) in all the study variables (moderate, vigorous and MVPA), compared to adolescents reporting low PA (1st tertile IPAQ-A) (all p < 0.001). Both methods were moderately correlated with estimated VO(2)max. Within the HELENA-study, the IPAQ-A showed the modest comparability with the accelerometer data for assessing PA in each intensity level and was the highest for vigorous intensity. Both instruments are able to detect the adolescents with the highest cardio respiratory fitness, which are the most active adolescents.

Comparison of two ActiGraph accelerometer generations in the assessment of physical activity in free living conditions

BackgroundThe aim of this study was to compare physical activity measured using GT1M ActiGraph and GT3X ActiGraph accelerometers in free living conditions.FindingsTwenty-five adults wore GT1M and GT3X Actigraph accelerometers simultaneously during a typical weekday of activity. Data were uploaded from the monitor to a computer at the end of test (one day). Previously established thresholds were used for defining time spent at each level of physical activity, physical activity was assessed at varying intensities comparing data from the two accelerometers by ANOVA and Bland and Altman statistical analysis. The concordance correlation coefficient between accelerometers at each intensity level was 0.99. There were no significant differences between accelerometers at any of the activity levels. Differences between data obtained in minutes with the GT1M accelerometer and the GT3X monitor were to 0.56, 0.36, 0.52 and 0.44% for sedentary, light, moderate and vigorous, respectively. The Bland and Altman method showed good agreement between data obtained for the two accelerometers.ConclusionsFindings suggest that the two accelerometers provided similar results and therefore the GT3X may be used in clinical and epidemiological studies without additional calibration or validation studies.

Add-on omalizumab in children with severe allergic asthma: a 1-year real life survey

Omalizumab has been shown to reduce exacerbation rates in moderate to severe allergic asthma. Our aim was to evaluate omalizumab efficacy and safety in a real-life setting in severe asthmatic children. 104 children (aged 6–18 years), followed up in paediatric pulmonary tertiary care centres, were included at the beginning of omalizumab treatment. Asthma control levels, exacerbations, inhaled corticosteroid dose, lung function and adverse events were evaluated over 1 year. Children were characterised by allergic sensitisation to three or more allergens (66%), high IgE levels (mean 1125 kU·L−1), high rate of exacerbations (4.4 per year) and healthcare use during the previous year, and high inhaled corticosteroid dose (mean 703 &mgr;g equivalent fluticasone per day). Asthma control levels defined as good, partial or poor, improved from 0%, 18% and 82% at entry to 53%, 30% and 17% at week 20, and to 67%, 25% and 8% at week 52, respectively (p<0.0001). Exacerbation and hospitalisation rates dropped by 72% and 88.5%, respectively. At 12 months, forced expiratory volume in 1 s improved by 4.9% (p=0.023), and inhaled corticosteroid dose decreased by 30% (p<0.001). Six patients stopped omalizumab for related significant adverse events. Omalizumab improved asthma control in children with severe allergic asthma and was generally well tolerated. The observed benefit was greater than that reported in clinical trials. Omalizumab improves asthma control in children with severe allergic asthma and is generally well tolerated http://ow.ly/oLoBp

Recommended levels and intensities of physical activity to avoid low‐cardiorespiratory fitness in European adolescents: The HELENA study

The purpose of this study was to determine the sex‐specific physical activity (PA) intensity thresholds that best discriminate between unhealthy/healthy cardiorespiratory fitness (CRF).

Excessive sedentary time and low cardiorespiratory fitness in European adolescents: the HELENA study

Background The aims of this study were to examine what amount of sedentary time is associated with low cardiorespiratory fitness (CRF) in adolescents and whether this association is independent of physical activity. Methods The study comprised 1808 adolescents aged 12.5–17.5 years from 10 European cities. Sedentary time and moderate-to-vigorous physical activity (MVPA) were measured by accelerometer. CRF was assessed by the 20 m shuttle-run test. Adolescents were divided into two groups (high/low) according to FITNESSGRAM guidelines. Receiver-operating characteristic (ROC) analysis was used to determine thresholds that best discriminate between high and low CRF in adolescents. Results Adolescent girls had more sedentary time than boys (p<0.001). ROC analysis showed that girls spending ≥69% of waking time in sedentary activities had low CRF, but no significant threshold discriminated between high and low CRF in boys. Adolescent girls who exceeded this threshold had lower levels of CRF (p≤0.001) and were more likely to have a low CRF (OR 1.68, 95% CI 1.22 to 2.31) independent of centre, age and body mass index. The negative influence of excessive sedentary time on CRF remained significant (p=0.045) in adolescent girls who did not meet the physical activity guidelines (<60 min/day in MVPA) but was abolished (p>0.05) in those who met the recommendation (≥60 min/day in MVPA). Conclusion Excessive sedentary time is associated with low CRF in adolescent girls but not in boys. However, this adverse effect might be attenuated if adolescent girls meet the current physical activity guidelines.

The International Fitness Scale (IFIS): usefulness of self-reported fitness in youth

BACKGROUND We examined: (i) the usefulness of the International Fitness Scale (IFIS) to correctly rank adolescents into physical fitness levels; (ii) the capacity of the IFIS for predicting cardiovascular disease (CVD) risk; and (iii) the reliability of the IFIS in adolescents. METHODS The study comprised 3059 adolescents (aged 12.5-17.5 years) from nine European countries (HELENA study). Blood samples were collected in one-third of the participants (randomly selected, n = 981). Test-retest reliability of the IFIS was studied in a separate sample of 277 adolescents. Physical fitness-cardiorespiratory fitness (CRF), muscular fitness (MF), speed-agility (SP-AG), flexibility and overall fitness-was self-reported using 5-point Likert-scale questions (1 = very poor, 5 = very good) and measured using standard field-based tests. The CVD risk factors measured included total/central adiposity indices and mean arterial pressure, total and high density lipoprotein cholesterol, triglycerides, insulin resistance (HOMA) and C-reactive protein. RESULTS Analysis of covariance showed that adolescents reporting better fitness had higher measured fitness levels for all the variables studied (all P < 0.001), regardless of gender, age and weight status. Adolescents reporting very good overall fitness, CRF and SP-AG had a healthier cardiovascular profile in eight out of nine CVD risk factors studied. Perfect agreement (same test-retest answer) was observed in 65% of the adolescents and perfect-acceptable agreement (same answer or ±1) in 97% of the adolescents. CONCLUSIONS (i) The IFIS is able to correctly rank adolescents according to their measured physical fitness levels; (ii) adolescents reporting a good/very good overall fitness, CRF or SP-AG have a more favorable cardiovascular profile; and (iii) The IFIS is reliable in adolescents.

Food and nutrient intake, nutritional knowledge and diet-related attitudes in European adolescents

Background and objective:To provide an overview of methods used to assess food and nutrient intake, nutritional knowledge and diet-related attitudes in the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS), with selected results from the feasibility study.Material and Methods:To assess food intake in 13- to 16-year-old adolescents, a previously developed computer-assisted and self-administered 24-h recall was adapted for international use. Food consumption data were linked to national food composition databases to calculate energy and nutrient intakes. To assess nutritional knowledge in pupils not having any special (trained) education concerning ‘nutrition’, a 23-item validated multiple choice questionnaire was adapted. To assess eating attitudes, behaviour and/or putative problems with body weight in adolescents, a validated inventory covering 60 questions or statements was adapted for the study. In a feasibility study, instruments, data collection and processing were tested in one school class in each of the 10 participating European cities.Results and Conclusions:The feasibility study provided plausible results, quite consistent between countries. Against this background and for the first time, standardized and uniform methodology was made available for the main study to assess and characterize dietary intake, nutritional knowledge and eating attitudes.

Comparison of the TriTrac-R3D accelerometer and a self-report activity diary with heart-rate monitoring for the assessment of energy expenditure in children

Determining total energy expenditure (EE) in children under free-living conditions has become of increasingly clinical interest. The aim of this study was to compare three different methods to assess EE triaxial accelerometry (TriTrac-R3D; Professional Products, Division of Reining International, Madison, WI, USA), activity diary and heart-rate (HR) monitoring combined with indirect calorimetry (IC). Twenty non-obese children and adolescents, aged 5.5 to 16.0 years, participated in this study. Results from the three methods were collected simultaneously under free-living conditions during the same 24 h schoolday period. Neither activity diary (5904 (sd 1756) kJ) nor the TriTrac-R3D (6389 (sd 979) kJ) showed statistical differences in 24 h total EE compared with HR monitoring (5965 (sd 1911) kJ). When considering different physical activity (PA) periods, compared with HR monitoring, activity diary underestimates total EE during sedentary periods (P<0.001) and overestimates total EE and PA-EE during PA periods (P<0.001) because of the high energy cost equivalence of activity levels. The TriTrac-R3D, compared with HR monitoring, shows good agreement for assessing PA-EE during PA periods (mean difference +0.25 (sd 1.9) kJ/min; 95 % CI for the bias -0.08, 0.58), but underestimates PA-EE and it does not show good precision during sedentary periods (-0.87 (sd 1.4) kJ/min, P<0.001). Correlation between the vector magnitude generated by the TriTrac-R3D accelerometer and EE of activities derived from HR monitoring is high. When compared with the HR method, the TriTrac-R3D and activity diary are not systematically accurate and must be carefully used for the assessment of childrens EE depending on the purpose of each study.

Main characteristics and participation rate of European adolescents included in the HELENA study

BackgroundParticipation rate and response rate are key issues in a cross sectional large-scale epidemiological study. The objective of this paper is to describe the study population and to evaluate participation and response rate as well as the key nutritional status variables in male and female adolescents involved in the HELENA study.MethodsA multi-stage random cluster sampling with a target sample of 3000 adolescents aged [12.5 to 17.5] years, stratified for geographical location and age, was carried out. Information for participants and non-participants (NP) was compared, and participation and response rates to specific questionnaires were discussed.Results3,865 adolescents aged [12.5 to 17.5] years (1,845 females) participated in the HELENA study, of whom 1,076 (568 females) participated in the blood sampling. 3,528 (1,845 females) adolescents were finally kept for statistical analysis. Participation rates for the schools and classes differed importantly between countries. The participation rate of pupils within the participating classes also differed importantly between countries. Sex ratio, mean age and BMI were similar between NP and participating adolescents within each centre, and in the overall sample. For all the questionnaires included in the database, the response rate of questionnaires was high (more than 80% of questions were completed).ConclusionFrom this study it could be concluded that participation rate differed importantly between countries, though no bias could be identified when comparing the key study variables between participants and non-participants. Response rate for questionnaires was very high. Future studies investigating lifestyle and health in adolescents can optimize their methods when considering the opportunities and barriers observed in the HELENA study.