Table 1.
Characteristics† of the study sample: 1590 included and 1938 excluded European adolescents from the Healthy Lifestyle in Europe by Nutrition in Adolescents (HELENA) study
| HELENA participants | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Included (n 1590) | Excluded (n 1938) | |||||||||
| Variables | Median or Mean | P25, P75 or sd | n | Median or Mean | P25, P75 or sd | n | P for difference‡ | |||
| Age (years) | 14·7 | 13·7, 15·7 | 1590 | 14·7 | 13·7, 15·8 | 1938 | >0·9 | |||
| Anthropometric characteristics | ||||||||||
| BMI-SDS§ | 0·3 | 1·1 | 1590 | 0·7 | 1·1 | 1938 | <0·0001 | |||
| Overweight (%)∥ | 16·4 | 1590 | 28·7 | 1938 | <0·0001 | |||||
| BF%¶ | 21·6 | 16·2, 27·1 | 1554 | 23·9 | 17·0, 30·7 | 1781 | <0·0001 | |||
| Socio-economic characteristics | ||||||||||
| Maternal overweight (%)†† | 10·6 | 1590 | 12·2 | 1938 | <0·0001 | |||||
| Paternal overweight (%)†† | 15·8 | 1590 | 14·0 | 1938 | <0·0001 | |||||
| High maternal education (%)‡‡ | 68·6 | 1519 | 62·0 | 1796 | <0·0001 | |||||
| High paternal education (%)‡‡ | 65·5 | 1476 | 59·4 | 1726 | <0·0005 | |||||
| High familial affluence (%)§§ | 33·5 | 1590 | 26·2 | 1938 | <0·0001 | |||||
| Migrant (%)∥∥ | 7·8 | 1568 | 6·6 | 1856 | 0·2 | |||||
| Health-related characteristics | ||||||||||
| Ever smoked (%) | 34·9 | 1590 | 40·5 | 1938 | <0·0001 | |||||
| Physical activity (min/week)¶¶ | 540 | 270, 995 | 1495 | 600 | 270, 1115 | 1546 | 0·02 | |||
| Nutritional knowledge††† | 60·9 | 47·8, 69·6 | 1567 | 60·9 | 47·8, 69·6 | 1858 | 0·9 | |||
P25, 25th percentile; P75, 75th percentile; SDS, standard deviation score; BF%, body fat percentage.
†Values are presented as weighted median with P25 and P75, mean and standard deviation, or frequency.
‡Significant differences between groups tested using the Kruskal–Wallis test for non-normally distributed variables, ANOVA for normally distributed variables and the χ 2 test for categorical variables.
§BMI-SDS calculated using Z-values for BMI, calculated via the LMS method by Cole et al. ( 38 ).
∥Derived from the sex- and age-specific cut-offs proposed by the International Obesity Taskforce, which correspond to an adult BMI cut-off of 25 kg/m2( 38 ).
¶Estimated according to the equations of Slaughter et al. ( 39 ).
††Obtained from questions about adolescents’ perception.
‡‡Higher secondary education and higher education or university degree.
§§Based on information about family car ownership, having an own bedroom, Internet availability and computer ownership.
∥∥Participant was born outside the country in which they lived during the study.
¶¶Moderate-to-vigorous physical activity.
†††Percentage of correctly answered questions in the nutritional knowledge test.