The prevalence of childhood sexual abuse and adolescent unwanted sexual contact among boys and girls living in Victoria, Australia

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Abstract

Objectives

Childhood sexual abuse (CSA) is associated with both short- and long-term adverse mental and physical health consequences, yet there remains considerable controversy about the prevalence of CSA in the general population. There is also little prospective data on unwanted sexual contact (USC) collected during adolescence.

Methods

Data from a 10-year cohort study of a nationally representative sample of students aged 14-15 years in Victoria, Australia from 1992 to 2003 was used. CSA prior to age 16 was assessed retrospectively at age 24 years using a 6-item validated questionnaire. USC was assessed prospectively via questionnaire at 3 time points during adolescence. Multiple imputation was used to handle missing data.

Results

One thousand nine hundred forty-three of 2032 eligible adolescents participated in at least one wave of the study. One thousand seven hundred forty-five (812 males and 933 females) provided sufficient information to allow for multiple imputation and inclusion in the main analysis. The prevalence of any CSA was substantially higher among girls [17%, 95% confidence interval (CI): 14–20%] than boys (7%, 95% CI: 3–10%), as was the prevalence of USC reported during adolescence (14%, 95% CI 11–16%, versus 6%, 95% CI: 4–8% respectively).

Conclusions

These findings highlight the high prevalence of childhood sexual abuse and unwanted sexual contact among girls as well as boys.

Practice implications

In order to accurately inform early recognition, intervention and education programs for individuals with a history of CSA the frequency of sexual abuse must first be precisely quantified. Developing more standardized approaches will be important in order to improve our understanding of the extent of this problem.

Introduction

In 2004 the World Health Organization (WHO) declared childhood sexual abuse (CSA) “a silent health emergency” of international importance (The World Health Organization [WHO], 2004). The long-term negative consequences of CSA are extensive, including an increased risk for substance abuse, obesity, violence, depression, and suicide (Dube et al., 2005, Hussey et al., 2006, Mullen et al., 1996, Paolucci et al., 2001, Senn et al., 2008). However, there remains considerable debate about the prevalence of CSA in the general population and therefore the extent to which it pervades the community is uncertain (Leserman, 2005, Sapp and Vandeven, 2005). For girls, estimates of prevalence within nationally representative, community-based populations range from 11 to 32% (Gustafson and Sarwer, 2004, Leserman, 2005, Sapp and Vandeven, 2005). Less is known about the prevalence of CSA among boys, which is reflected by estimates ranging from 4% to 76% in one systematic review (Holmes & Slap, 1998). Reasons for this wide range include variations in the definition of sexual abuse and population sampling. In large (>1000 participants) population-based studies of CSA among boys in the United States and Canada, the estimated prevalence ranges from 4% to 16% (Holmes & Slap, 1998). The WHO guidelines for prevention of child maltreatment reinforce that defining the nature and extent of CSA is essential to the planning and implementation of effective prevention and treatment response interventions (The World Health Organization [WHO], 2006).

There are several methodological explanations for widely disparate prevalence estimates of CSA (Sapp & Vandeven, 2005). There is considerable variation in how CSA is defined (Haugaard, 2000). While there is no universal definition of CSA, few studies have adopted previously validated definitions. Furthermore, few definitions have distinguished between sexual abuse with and without physical contact, and there has been limited detail regarding the specific types of sexual abuse experienced (Gustafson & Sarwer, 2004). Detailed information regarding abuse is relevant given that certain types of abuse have been associated with more negative long-term outcomes (Senn et al., 2008, Senn et al., 2007). Furthermore, many estimates are derived from clinic-based samples, which have limited generalizability (Gorey & Leslie, 1997).

Most studies of CSA have extensive missing data, either due to non-response, or refusal to answer questions. Missing data threatens to undermine even the most rigorous study design, especially when the missingness is ignored (Greenland and Finkle, 1995, Schafer and Graham, 2002). Gorey and Leslie (1997) reviewed 16 studies and found that the response rate varied between 25 and 98%, and was inversely related to the estimated prevalence of CSA. While there is no panacea for handling missing data (Altman & Bland, 2007) the method of multiple imputation is increasingly used as an approach for recovering information from study participants with incomplete data (Carlin et al., 2008, Schafer, 1997, Schafer and Graham, 2002). To our knowledge, this approach has not been used previously to assist with prevalence estimations of CSA.

The primary purpose of this study was to estimate the prevalence of CSA among girls and boys using a representative sample from the general population, and a validated definition of CSA collected retrospectively. The secondary aim of this study was to investigate unwanted sexual contact measured in adolescence using a prospective self-administered measure. The specific aims were (1) to compare the prevalence of overall and different types of CSA among boys and girls, and (2) to estimate the prevalence of unwanted sexual contact in adolescence, using data drawn from a 10-year (8-wave) population-based study of the health and wellbeing of young Australians.

Section snippets

Design and participants

The Victorian Adolescent Health Cohort (VAHCS) is a representative sample of young Australians living in the state of Victoria who have been followed across 8 waves of data collection since 1992. The methodology of this study has been described previously (Coffey et al., 2003, Patton et al., 2002, Patton et al., 2007, Sanci et al., 2008). Briefly, the cohort was defined with a two-stage cluster sample in which two classes during year 9 were selected at random from each of 44 schools drawn from

Results

Of the 1943 individuals (943 males and 1000 females) enrolled in the study, 1520 (696 males and 824 females) were interviewed at wave 8, of whom 1509 (691 males and 818 females) responded to at least 1 question pertaining to CSA. Those missing information on CSA were more likely to be male (58% versus 46%), born outside of Australia (30% versus 12% respectively), and to have left school before year 11 (16% versus 8%) (p < 0.001). The parents of those who were missing were more likely to have

Discussion

The primary purpose of this study was to estimate the prevalence of CSA among girls and boys in a large representative sample from the general population using a validated retrospective questionnaire. The WHO guidelines for prevention of child maltreatment specifically recommend that information gathering, either through epidemiological research or facility-based surveillance, with widespread availability of results, be a priority (WHO, 2006). Accurate estimation of prevalence helps inform

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      The long term negative effects of CSA have been found to be extensive, including increased risk for violence, depression and suicide [2]. A 2010 Australian study, surveying 1745 adolescents (812 males and 933 females) found 17% of females and 7% of males were identified as having some type of unwanted sexual contact (touching, fondling, kissing, display of sex organs, etc.) prior to age sixteen [1]. Studies have found that children involved in sexual abuse rarely acknowledge their own victimisation for several reasons; this could include fear, shame and normalisation of sexual behaviours.

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    This work was supported by a National Health and Medical Research Council Capacity Building Grant in Population Health Research (ID: 436914, authors: EM, JC, and GP). Dr Olsson is supported by an Victorian Health Promotion Foundation Research Fellowship. Professor Patton is supported by an Australian National Health and Medical Research Council Senior Principal Research Fellowship.

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