Mikis Stasinopoulos

Gross motor coordination and weight status of Portuguese children aged 6-14 years.

To construct age‐ and gender‐specific percentiles for gross motor coordination (MC) tests and to explore differences in gross MC in normal‐weight, overweight and obese children.

A computerised tailored intervention for increasing intakes of fruit, vegetables, brown bread and wholegrain cereals in adolescent girls

OBJECTIVE To evaluate the effectiveness of a computer-generated tailored intervention leaflet compared with a generic leaflet aimed at increasing brown bread, wholegrain cereal, fruit and vegetable intakes in adolescent girls. DESIGN Clustered randomised controlled trial. Dietary intake was assessed via three 24 h dietary recalls. SETTING Eight secondary schools in areas of low income and/or high ethnic diversity, five in London and three in the West Midlands, UK. SUBJECTS Girls aged 12-16 years participated (n 823) and were randomised by school class to receive either the tailored intervention (n 406) or a generic leaflet (n 417). RESULTS At follow-up 637 (77 %) participants completed both baseline and follow-up dietary recalls. The tailored intervention leaflet had a statistically significant effect on brown bread intake (increasing from 0.39 to 0.51 servings/d) with a smaller but significant increase in the control group also (increasing from 0.28 to 0.35 servings/d). The intervention group achieved 0.05 more servings of brown bread daily than the control group (P < 0.05), which is equivalent to 0.35 servings/week. For the other foods there were no significant effects of the tailored intervention. CONCLUSIONS The intervention group consumed approximately 0.35 more servings of brown bread weekly than the control group from baseline. Although this change between groups was statistically significant the magnitude was small. Evaluation of the intervention was disappointing but the tailored leaflet was received more positively in some respects than the control leaflet. More needs to be done to increase motivation to change dietary intake in adolescent girls.

Centile estimation for a proportion response variable.

This paper introduces two general models for computing centiles when the response variable Y can take values between 0 and 1, inclusive of 0 or 1. The models developed are more flexible alternatives to the beta inflated distribution. The first proposed model employs a flexible four parameter logit skew Student t (logitSST) distribution to model the response variable Y on the unit interval (0, 1), excluding 0 and 1. This model is then extended to the inflated logitSST distribution for Y on the unit interval, including 1. The second model developed in this paper is a generalised Tobit model for Y on the unit interval, including 1. Applying these two models to (1-Y) rather than Y enables modelling of Y on the unit interval including 0 rather than 1. An application of the new models to real data shows that they can provide superior fits.

Short-term secular change in height, body mass and Tanner-Whitehouse 3 skeletal maturity of Madeira youth, Portugal.

Background: Secular trends in height and weight are reasonably well documented in Europe. Corresponding observations for skeletal maturation are lacking. Aim: To assess secular trends in height, body mass and skeletal maturity of Portuguese children and adolescents and to provide updated reference values for skeletal maturity scores (SMSs). Subjects and methods: Data for 2856 children and adolescents of 4–17 years, 1412 boys and 1444 girls, from The ‘Madeira Growth Study’ (MGS; 1996–1998) and from the‘Healthy Growth of Madeira Children Study’ (CRES; 2006) were used. Height and body mass were measured. Skeletal maturity was assessed with the Tanner-Whitehouse 2 and 3 methods. Results: Children from CRES were taller and heavier than peers from MGS. Differences in height reached 5.8 cm in boys and 5.5 cm in girls. RUS SMSs did not differ consistently between surveys boys, while higher RUS scores were observed in CRES girls. Adult RUS SMSs for MGS and CRES combined were attained at 15.8 years in boys and 14.8 years in girls. Corresponding ages for adult Carpal SMSs were 14.4 and 14.0, respectively. Conclusion: The short-term trends for height and mass were not entirely consistent with the trends in RUS and Carpal SMSs and SAs.

Mean and Dispersion Additive Models: Applications and Diagnostics

This paper presents further applications and diagnostics of the ‘Mean and Dispersion Additive Model’ or ‘MADAM’. This is a flexible model for the mean and variance of a dependent variable in which the variance is modelled as a product of the dispersion parameter and a known variance function of the mean, and the mean and dispersion parameters are each modelled as functions of explanatory variables using a semi-parametric Additive model. MADAM’s are fitted using a successive relaxation algorithm which alternates between mean and dispersion model fits until convergence, providing diagnostics for each model. It is shown in the appendix that the algorithm maximises the penalised extended quasi-likelihood of the MADAM.

Determination of adjusted reference intervals of urinary biomarkers of oxidative stress in healthy adults using GAMLSS models

In this study we aimed at identifying main demographic, laboratory and environmental factors influencing the level of urinary biomarkers (DNA-derived 8-oxodG and lipid membrane-derived 8-isoprostane), and deriving their adjusted 95% reference intervals (RI) in a sample of healthy people from the general population. Data from 281 healthy subjects from the Gene Environment Interactions in Respiratory Diseases survey were used in this study. Generalized additive models for location, scale and shape (GAMLSS) were used to find determinants of the biomarkers among gender, age, season and distance from collection (DFC), and to predict their RI. The RI of the biomarkers stratified by season and adjusted for DFC showed a slight statistically significant decrease in the biomarkers at the increasing DFC in two seasons, except the 8-oxodG during the warm season: median levels at the min and max values of DFC were (ng/mgcreat) 7.0–1.1 in the cold and 3.9–3.9 in the warm seasons for 8-oxodG, 0.7–0.2 in the cold and 1.3–0.6 in the warm seasons for 8-isoprostane. Both the biomarkers should be evaluated in association with the DFC and season in large epidemiological studies. The (semi)parametric GAMLSS method is a useful and flexible technique, which makes it possible to estimate adjusted RI.

Biological and environmental determinants of 12-minute run performance in youth

Abstract Background: The 12-minute run is a commonly used indicator of cardiorespiratory fitness in youth. Variation in growth and maturity status as potential correlates of test performance has not been systematically addressed. Aim: To evaluate biological and environmental determinants of 12-minute run performance in Portuguese youth aged 7–17 years. Subjects and methods: Mixed-longitudinal samples of 187 boys and 142 girls were surveyed in 1996, 1997 and 1998. The 12-minute run was the indicator of cardiorespiratory fitness. Height, body mass and five skinfolds were measured and skeletal maturity was assessed. Physical activity, socioeconomic status and area of residence were obtained with a questionnaire. Multi-level modelling was used for the analysis. Results: Chronological age and sum of five skinfolds were significant predictors of 12-minute run performance. Older boys and girls ran longer distances than younger peers, while high levels of subcutaneous fat were associated with shorter running distances. Rural boys were more proficient in the 12-minute run than urban peers. Skeletal maturity, height, body mass index, physical activity and socioeconomic status were not significant predictors of 12-minute run performances. Conclusions: Age and sum of skinfolds in both sexes and rural residence in boys are significant predictors of 12-minute run performance in Portuguese youth.