Year

2012

Degree Name

Doctor of Philosophy

Department

Faculty Health and Behavioural Sciences

Abstract

Adolescents are an important target group for interventions to reduce the incidence of skin cancer. Despite efforts to improve their sun protection behaviours, there is limited evidence of the effectiveness of programs targeting adolescents. In Australia, adolescents continue to exhibit sub-optimal sun-protection behaviours. One of the main challenges highlighted in studies is the need for the development of behavioural outcome measures to evaluate programs, specifically composite measures of adolescent sun-related behaviours. To facilitate the identification of outcome measures, conceptual models are useful tools as they necessitate the identification of outcomes of interest. However, there has been limited research exploring adolescent sun-related behaviours at a conceptual level. This thesis explored adolescent sun-related behaviours from a conceptual perspective as well as a measurement perspective, addressing major conceptual and methodological limitations of previous research.

This thesis contains two literature reviews and six empirical papers. A systematic literature search was completed to identify composite measures of adolescent sun-related behaviours used to evaluate skin cancer prevention programs (Chapter 2); each measure was compared in terms of the range of behaviours included in the measure, as well as the method used to calculate the composite score. Given the variation in measures identified in Chapter 2, a review of the literature was undertaken to identify a comprehensive conceptual model of adolescent sun-related behaviours. A range of conceptual models were identified; however, the review failed to identify a model specific to adolescent sun-related behaviours. An extended conceptual model of adolescent sun-related behaviours was developed (Chapter 3). To confirm that the range of behaviours in the newly developed conceptual model was accurate, a think-aloud study using a self-report survey of sun-related behaviours was undertaken (Chapter 4). A cross-sectional survey was then conducted using a convenience sample (n= 692) of adolescents, to explore key relationships within the conceptual model. Data were analysed to determine the relationship between sun protection behaviours and sunexposing behaviours with indicators of ultraviolet (UV) exposure (Chapter 5). Since fake tanning products are a relatively recent phenomenon and their relationship with UV exposure is not well understood, the use of fake tanning products among adolescents was then explored in terms of associated sun-protection behaviours (Chapter 6), followed by an exploration of the range of sun-protection behaviours adolescent perform across contexts (Chapter 7). A sub-group from the convenience sample also participated in a concurrent study to determine the validity of adolescent self-report in the school context by comparing observation data to self-report (Chapter 8). Finally, the utility of a composite measure of adolescent sun-related behaviours aimed at detecting behaviour change in evaluating a secondary school based intervention targeting adolescent sun-related behaviours was determined (Chapter 9).

The results suggest adolescents exhibit a range of behaviours that influence their UV exposure from the sun. While composite measures of sun protection behaviours exist, these measures frequently include an incomplete range of sun-protection behaviours and rarely include sun-exposing behaviours. Testing an extended conceptual model of adolescent sun-related behaviours confirmed that differences in sun-protecting behaviours exist across contexts; fake tan use was associated with more frequent sunburns; and the unique contribution of sun-protecting and sun-exposing behaviours to indicators of UV exposure were identified. The validation study of adolescent selfreport yielded conflicting results, indicating adolescent self-report is valid using a diary measure but not using a survey of ‘usual’ behaviours. The utility of a composite measure based on the conceptual model of adolescent sun-related behaviours demonstrated ability to detect small changes in behaviour over time when used to evaluate a program targeting adolescents in secondary schools.

This thesis contributes to our understanding of adolescent sun-related behaviours and their measurement. The development of a conceptual model provides an important contribution to conceptual clarity of adolescent sun-related behaviours. This thesis addressed a gap with regard to our understanding of the range of behaviours adolescents perform in the sun and provided data on the validity of adolescent self-report. Understanding sun-related behaviours are important as adolescents’ exposure to UV radiation from the sun is the primary preventable risk factor for developing both melanoma and non melanoma skin cancers. Since adolescents demonstrate the highest level of risk behaviours in terms of low compliance with recommended sun protection behaviours, long periods of exposure to UV radiation and a high incidence of sunburns they are an important group for skin cancer prevention programs to target. For prevention programs to reverse the current negative trend in behaviours seen among adolescents, innovative program strategies are required. The results presented in this thesis have potential practical implications as they identify an increased range of behaviours that influence UV exposure which program planners can target. Furthermore, the use of a composite measure of sun-related behaviours such as presented in this thesis may provide a useful indicator of the overall effectiveness of skin cancer prevention programs targeting adolescents.

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