Abstract
In this study, the authors assessed the impact of adjusting for sexual activity on population-based chlamydia incidence and screening rates among adolescents in the province of British Columbia (BC), Canada. They estimated the proportion of adolescent males (15 years-18 years) and females (14 years-18 years) who had ever had sexual intercourse using data from a survey of public school students (Grades 7-12) completed by ∼30,000 BC students in 2003 and 2008. Using provincial chlamydia surveillance and testing data we compared adolescent chlamydia screening and incidence rates by age and gender, using total and sexually active populations as denominators. Using data representing the entire population of BC adolescents they demonstrated that without adjustment for sexual behaviour, adolescent chlamydia incidence and screening rates are substantially under-estimated, particularly at younger ages. Adjusting for sexual behaviour using population survey data is essential for accurately monitoring the population impact of prevention and screening programs among adolescents.