Clusters of health behaviours and their relation to body mass index among adolescents in Northern Finland

Aims To identify clusters of health behaviours among Finnish adolescents and examine whether these clusters are associated with body mass index (BMI). Methods The data, drawn from the prospective population-based Northern Finland Birth Cohort 1986, comprised a total of 7182 adolescents who replied to a follow-up postal questionnaire at the age 15 to 16. The adolescents were asked about multiple health behaviours, such as physical activity, screen time, cigarette smoking, alcohol use and diet. Adolescents who answered the questions concerning all of these variables were included in the study, yielding a final sample of 4305 subjects. K-means cluster analysis was performed to identify group of adolescents with similar health behaviours. Chi-squared tests were performed to analyse the association between the clusters and BMI. Results Two clusters - Healthy Lifestyle and Unhealthy Lifestyle - were identified for both genders. The values of all the studied variables differed significantly between the clusters identified for both boys and girls. No significant relationship between the identified clusters and BMI was found for either boys or girls. Conclusions It is important to consider multiple lifestyle-related behaviours and trying to identify groups that present probability for developing lifestyle diseases.