Social capital and adolescent smoking in schools and communities: a cross-classified multilevel analysis.

We sought to determine whether social capital at the individual-, school- and community-level can explain variance in adolescent smoking and accounts for social inequalities in smoking. We collected data as part of the 2005/6 Health Behavior in School-aged Children survey, a nationally representative survey of the health and well-being of high school pupils in Belgium (Flanders). Social capital was assessed by structural and cognitive components of family social capital, a four-factor school social capital scale and a cognitive community social capital scale. We fitted non-hierarchical multilevel models to the data, with 8453 adolescents nested within a cross-classification of 167 schools and 570 communities. Significant variation in adolescent regular smoking was found between schools, but not between communities. Only structural family social capital and cognitive school social capital variables negatively related to regular smoking. No interactions between socio-economic status and social capital variables were found. Our findings suggest that previously observed community-level associations with adolescent smoking may be a consequence of unmeasured confounding. Distinguishing nested contexts of social capital is important because their associations with smoking differ.