Clustering of substance use and sexual risk behaviour in adolescence: analysis of two cohort studies

Abstract

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 (‘later cohort’, surveyed 1999 and 2003).

Setting

Central Clydeside Conurbation around Glasgow City.

Participants

Young people who participated in the Twenty-07 and 11-16/16+ studies at ages 15 and 18–19.

Primary and secondary outcomes measures

The authors analysed data on risk behaviours in both early adolescence (started smoking prior to age 14, monthly drinking and ever used illicit drugs at age 15 and sexual intercourse prior to age 16) and late adolescence (age 18–19, current smoking, excessive drinking, ever used illicit drugs and multiple sexual partners) by gender and social class.

Results

Drinking, illicit drug use and risky sexual behaviour (but not smoking) increased between the earlier and later cohort, especially among girls. The authors found strong associations between substance use and sexual risk behaviour during early and late adolescence, with few differences between cohorts, or by gender or social class. Adjusted ORs for associations between each substance and sexual risk behaviour were around 2.00. The only significant between-cohort difference was a stronger association between female early adolescent smoking and early sexual initiation in the later cohort. Also, relationships between illicit drug use and both early sexual initiation and multiple sexual partners in late adolescence were significantly stronger among girls than boys in the later cohort.

Conclusions

Despite changes in rates, relationships between adolescent risk behaviours remain strong, irrespective of gender and social class. This indicates a need for improved risk behaviour prevention in young people, perhaps through a holistic approach, that addresses the broad shared determinants of various risk behaviours.

Article summary

Article focus

• Previous studies have reported clustering of risk behaviours during adolescence.

• Prior studies have not examined whether changes in risk behaviour rates affects relationships between these risk behaviours.

• We examined clustering in early and later adolescent risk behaviours to determine if clustering differed at two different time points, by gender and by socioeconomic status, the latter of which has also tended not to be addressed in previous studies.

Key messages

• Despite changes in health risk behaviour rates, relationships between adolescent risk behaviours remain strong.

• Relationships generally did not vary by gender or social class.

• There is a need for improved risk behaviour prevention in young people, perhaps through a holistic approach that addresses the broad shared determinants of various risk behaviours.

Strengths and limitations of this study

• We compared cohorts of young people from the same geographic area and life stage, surveyed using (near) identical questions, 13 years apart. To our knowledge, this is the first study to examine time trends in associations between substance use and sexual behaviour.

• We examined these associations in both early and late adolescence and by gender and social class, the latter of which has not been previously investigated.

• Although we accounted for loss to follow-up in the 1999/2003 study via weighted analyses, we may not have fully compensated for differential loss to follow-up of adolescents with more ‘risky’ patterns of behaviour.

• Questions on alcohol intake included a more detailed drinking grid in the 1999/2003 study, which possibly encouraging increased reporting in this later cohort, while use of interviewer-administered questionnaires may have led to under-reporting of behaviours.