Mediation analysis of an adolescent HIV/STI/pregnancy prevention intervention

Abstract

Most interventions designed to prevent HIV/STI/pregnancy risk behaviours in young people have multiple components based on psychosocial theories (e.g. social cognitive theory) dictating sets of mediating variables to influence to achieve desired changes in behaviours. Mediation analysis is a method for investigating the extent to which a variable X (e.g. intervention indicator) influences an outcome variable Y (e.g. unprotected sex) by first influencing an intermediate variable M (e.g. self-efficacy to use a condom) and provides a way for empirically validating theoretical hypothesised mediators. In this way, mediation analysis is a critical tool for suggesting which components of complex interventions should be the focus of more efficient and effective interventions in the future. The present study applied multilevel mediation analysis to outcome data from the All4You2! study to begin to examine the relationships between a theory-based HIV/STI/pregnancy prevention curriculum for students attending alternative high schools who were at risk of educational failure. The study targeted psychosocial mediating variables and the primary outcome unprotected sex in the past three months. Results suggest helping young people attending alternative schools identify and avoid exposure to risky situations and improving their self-efficacy to refuse sex should be focal points of future interventions.

Keywords::

• psychosocial mediators
• mediation analysis
• adolescent sexual risk behaviour
• adolescent pregnancy prevention
• randomised controlled trial

Acknowledgements

The study was supported by the National Institute of Child Health and Human Development (HD#041856).

Notes

^1. PRODCLIN (distribution of the PRODuct Confidence Limits for INdirect effects) is a programme written in SPSS, SAS and R that computes confidence limits for the product of two normal random variables. It is used to obtain confidence limits for the indirect effect. Tests of the significance of and confidence limits for indirect effects based on the distribution of the product method have more accurate Type I error rates and more power than other, more commonly used tests.