Implications of sex offender classification on reporting demographic characteristics, health, and criminal careers: results from an Australian jurisdiction

Gullotta et al. BMC Medical Research Methodology https://doi.org/10.1186/s12874-020-00960-w (2020) 20:97 RESEARCH ARTICLE Open Access Implications of sex offender classification on reporting demographic characteristics, health, and criminal careers: results from an Australian jurisdiction Mathew Gullotta1*, David Greenberg2,3, Armita Adily1, Jesse Cale4 and Tony G. Butler1 Abstract Background: Cross-sectional and retrospective offence data are often used to classify sex offenders in epidemiological and survey research, but little empirical evidence exists regarding the practical implications of this for applied research. This study describes the classification of sex offenders from a cohort of prisoners recruited as part of an Australian inmate health survey and the implications for reporting results. Methods: Data-linkage was used to join the New South Wales (NSW) Inmate Health Surveys to the states reoffending database to identify men with histories of sexual offending. Sex offenders were classified into men who sexually offended against children only (ChildSOs), against adults only (AdultSOs), and men who sexually offended against both children and adults (Age-PolySOs). Results: Using historical offending data rather than the current offence information only, an additional 35.4% of men with histories of sexual offences were identified. Differences were found between the three sex offender subgroups in terms of demographic characteristics, health, and criminal careers. Age-PolySOs reported higher educational attainment, were less likely to report being self-employed, single marital status, and having children. Half the ChildSOs self-reported a mental health issue and half of the ChildSOs and Age-PolySOs reported four or more chronic health conditions. Age-PolySOs were older than the other sex offender groups when committing their first non-sexual, non-violent crime (M = 43.2 years, SD = 13.8); violent crime (M = 39.5 years, SD = 11.1); and sexual crime (M = 47.8 years, SD = 11.2). Age-PolySOs also committed more sexual offences (M = 5.91, SD = 11.2) compared to those who only offended against one victim age group. Conclusion: These findings suggested that historical offending records should be used to more accurately identify sex offender subgroups and that differences in demographic, health, and criminal careers exist for the different sex offender subgroups. Keywords: Adult sex offender, Child sex offender, Classification, Data linkage, Health, Polymorphous, Specialisation * Correspondence: 1 Kirby Institute, University of New South Wales, Sydney, Australia Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Gullotta et al. BMC Medical Research Methodology (2020) 20:97 Background Sex offenders have been studied extensively by researchers from disciplines including criminology, psychology, and psychiatry. The focus of that research includes describing demographic information [1], criminal careers [2] including recidivism, psychological and psychiatric aspects [3], risk assessment, and the management and treatment of sex offenders [4]. Criminological and health research on specific offender groups such as sex offenders requires classifying individuals using either official records - from the police, corrective services departments, and/or the courts - or selfreported offending [5]. The index offence (also referred to as the most serious or cardinal offence) for the current episode of incarceration is commonly used as the basis for classifying offenders into different groups based on offence type. This can be problematic as it focuses on an offence at a single point in time and does consider other crimes which may have been committed in the past, potentially overlooking those with serious historical crimes such as sexual offences. Furthermore, the most serious offence reflects a subjective political view of sentencing and there does not appear to be a standardized or universally accepted hierarchy of offence seriousness. Men who commit sexual offences are often classified into one homogeneous group: ‘sex offenders’. This lumping together of those who have commited a sexual offence into one amorphous group may occur due to small sample sizes, limited access to historical offending data, or for convenience. Notwithstanding the theoretical implications, this practice can result in important differences between different sex offender subgroups being overlooked and potentially incorrect conclusions being drawn, depending on the focus of the research [6, 7]. Psychological (and more recently criminological) research has produced three broad groupings of studies that have classified male sex offenders into subgroups [5, 8]. The most common classification differentiates between men who commit sexual offences against children (ChildSOs), men who commit sexual offences against adults (AdultSOs), and those who switch between age groups (age-polymorphous – (Age-PolySOs)). ChildSOs and AdultSOs have been studied extensively and differences between these two groups are well documented in terms of their demographic characteristics and the nature and extent of criminal behaviour (e.g., age of offending onset, frequency, versatility and specialisation of offending) [9–11]. ChildSOs often achieve higher academically and professionally, have different social and intimate relationships, and are less likely to abuse alcohol and substances than AdultSOs [9, 12]. ChildSOs are also likely to have a later onset for sexual offending – in part to do with more successfully evading detection, and also Page 2 of 12 to unique offending opportunity structures that present later in life - tend to be less versatile in their offending (i.e., commit only few different types of crime); sexually offend for longer periods (i.e., from age of onset to age of desistance); and, have more victims than AdultSOs [2, 13 (...truncated)