Clustering of substance use and sexual risk behaviour in adolescence: analysis of two cohort studies.
Objectives The authors aimed to examine whether changes in health risk behaviour rates alter the relationships between behaviours during adolescence, by comparing clustering of risk behaviours at different time points. Design Comparison of two cohort studies, the Twenty-07 Study (’earlier cohort’, surveyed in 1987 and 1990) and the 11-16/16+ Study …