Abstract
Background
Currently, no validated instruments exist for professionals to verify suspected sexual abuse in young children. The aim of the Picture Instrument for Child Sexual Abuse Screening study was to evaluate the diagnostic accuracy of the Sexual Knowledge Picture Instrument (SKPI) in identifying young victims of child sexual abuse (CSA) based on assessments of non-verbal reactions and verbal disclosures.
Methods
Over a 5-year period, 155 children 3–9 years of age were enrolled: 65 children with a suspected history of CSA and 90 without. In line with the study protocol, 50 confirmed cases were expected, but none could be verified. All children underwent SKPI interviews conducted by trained interviewers. Independent conclusions from the Dutch Child Abuse Counselling and Reporting Center (CACRC) and the Dutch National Police Vice Squad, obtained 6 months post-interview, served as the reference standard.
Results
No children from the control group were reported to the CACRC or police. For only 27 of the 65 suspected cases, a reference standard outcome was available, confirming CSA in six children.
Conclusion
Due to the absence of a reliable reference standard, the diagnostic accuracy of the SKPI could not be determined. Beyond organisational challenges and stricter data protection laws, the gap between medical diagnostics, child protection and law enforcement highlights the need for a novel, collaborative approach in this type of research.
Keywords: Child Abuse, Epidemiology, Child Health, Forensic Medicine, Psychology
WHAT IS ALREADY KNOWN ON THIS TOPIC
Despite its serious consequences, sexual abuse in young children often goes unrecognised by medical, forensic and psychological professionals.
No validated diagnostic instruments are currently available for identifying child sexual abuse (CSA) in young children.
WHAT THIS STUDY ADDS
The findings call for strengthening the collaboration and shared practices – including within the legal framework allowed information sharing – between health, law enforcement and statutory child protection agencies.
HOW THIS STUDY MIGHT AFFECT RESEARCH AND PRACTICE
Based on the current scoring method for non-verbal reactions and verbal disclosures, the Sexual Knowledge Picture Instrument (SKPI) should not be used as the sole source of information to confirm or reject suspected CSA.
Further validation studies of instruments such as the SKPI are needed. These require innovative approaches to bridge the perspectives of medical, protection and law enforcement professionals.
Introduction
Child sexual abuse (CSA) is a global problem with profound short-term and long-term physical and psychological consequences.1,5 For medical, forensic and psychological professionals, confirming or rejecting suspicions of CSA in young children is especially challenging. Physical findings are often absent, witnesses are rarely available and professionals must frequently rely on children’s statements.6 However, disclosure is often hindered by fear, shame, guilt, dependency or loyalty toward the perpetrator. Young children’s limited cognitive and verbal abilities further restrict their capacity to articulate what has happened.7,9
Attempts to reduce disclosure barriers have sometimes introduced risks. Misuse of tools such as anatomical dolls or body diagrams has raised concerns about suggestibility and reliability.10,15 In the Netherlands, high-profile cases of sexual offences prompted critical evaluation of investigative practices and the abandonment of several tools.16 17 As in many other countries, these events highlighted the urgent need for validated, structured methods to assess CSA.
Since 2013, the Dutch mandatory reporting code for Domestic Violence and Child Abuse has provided professionals with a stepwise framework to decide whether suspicions should be reported to the local Child Abuse Counselling and Reporting Center (CACRC, in Dutch: Veilig Thuis).18 Following a safety assessment, the CACRC determines whether to conduct its own investigation or involve other agencies, such as the Dutch National Police Vice Squad (DPVS, hereafter referred to as ‘police’) or specialised outpatient medical clinics.19 Currently, each of these professionals employ their own investigative approach, and none use validated diagnostic instruments.20
The Picture Instrument for Child Sexual Abuse Screening (PICAS) study was initiated to address this gap. Its purpose was to validate an updated version of the Sexual Knowledge Picture Instrument (SKPI), designed as a diagnostic tool for young children suspected of CSA.21 The SKPI is a picture book with child-friendly illustrations covering family routines, gender differences and identity, genitals and their functions, reproduction, intimacy and sexual behaviour in adults, and normal physical intimacy among children.22
Earlier research in 2005 suggested that children with CSA histories did not differ significantly in sexual knowledge compared with non-abused children. Instead, they were distinguished by deviant non-verbal reactions during SKPI interviews (eg, defensive, restless or avoidant behaviour).23 In addition, the use of a picture book in some cases lowered the thresholds for disclosure.23 Based on these findings, the current study focused on the diagnostic accuracy of the SKPI by analysing both non-verbal reactions and possible verbal disclosures.
Methods
Study design and participants
The PICAS study was designed as a prospective validation study including children aged 3–9 years. This deviated from the previous age range (2–7 years) used in earlier SKPI research.23 Children under 3 years were excluded due to limited verbal skills and poor ability to sustain attention. The upper limit was extended to 9 years to increase sample size.
Following recommendations by De Vet et al, at least 50 participants were required for a clinical validation study of a diagnostic tool.24 To achieve sufficient precision around sensitivity and specificity estimates, we aimed to recruit 250 children in total. Participants were enrolled in three groups:
Suspected CSA group (n=100): children with suspected CSA were referred to one of three specialised outpatient clinics of the participating Dutch university medical centres (ie, Emma Children’s Hospital at the Amsterdam University Medical Centre (UMC); Sophia Children’s Hospital at the Erasmus UMC and the Wilhelmina Children’s Hospital at the Utrecht UMC) or a CACRC team or the police. Professionals deemed suspicions credible and informed parents about the study.
Case group (n=50): children with confirmed or highly suspected CSA, intended to be recruited via the police.
Control group (n=100): children without a history of CSA, recruited through 31 (pre-)schools across the Netherlands. Parents received study information and completed a questionnaire to rule out CSA history.
All children participated in video-recorded SKPI interviews. The recruited children’s parents/legal guardians were provided with detailed information about the study procedures. Exclusion criteria included insufficient video/audio quality, major visual impairments and diagnosed developmental, psychiatric and/or behavioural disorders.
SKPI interviews and scoring
A professional SKPI user manual was developed, incorporating semi-structured interview questions adapted from the widely used protocol for CSA interviews developed by the USA National Institute of Child Health and Human Development (NICHD).25 26 Standardised scoring lists were created for:
Sexual knowledge
Non-verbal reactions (24 predefined behaviours, coded as ‘present’ or ‘absent’ per picture)
Red flags (interviewer’s overall impression and possible disclosures)
The SKPI pictures and manual, including scoring lists, are presented in onlinesupplemental appendices 1 2.
Interviewers were physicians or master’s students with medical or forensic backgrounds. They received one-on-one training, including practice interviews reviewed by experts. Interviewers were blinded to medical/psychological history, though full blinding to study group was sometimes impossible due to recruitment roles or interview locations.
Interviews lasted 15–30 min and took place in familiar settings (eg, the child’s home). Interviewers scored videos directly afterward using GDPR-compliant software (CASTOR).27 In suspected disclosures, independent experts reviewed the videos. If CSA was confirmed, actions followed the Dutch mandatory reporting code. Any recommended additional steps were taken in consultation with the authorities. Where necessary, professional help was available for all participating children, consisting of feedback to parents and/or current caregivers, and further investigation was carried out by a speciality child abuse outpatient clinic.
To test reliability, 39 suspected and 39 control group interviews were double-rated. Results showed adequate reliability for the verbal scoring form, but lower reliability for the non-verbal and red flag forms, indicating the need for improved manuals and training.28 The reaction form scorings in the control group children were analysed to form a ‘baseline’ of normal and expected reaction scorings.29
The total SKPI test result shall be marked as positive if either or both the non-verbal and red flag scoring forms were scored positive. On the dichotomous red flag form, the result can be either ‘suspected disclosure’ (= positive), or ‘no suspected disclosure’ (= negative). For a positive result on the continuous non-verbal form, we intended to investigate the use of cut-off values in two ways: (1). The total number of non-verbal reactions during the interview, and (2) The number of specific non-verbal reactions to specific images, in the event that certain distinctive reactions were scored only, or mainly in the case group. Poor findings from the reference standard and the small number of confirmed cases, however, prevented us from conducting this investigation.
Reference standard
At least 6 months post-interview, independent conclusions from CACRC and/or police investigations were retrieved as the reference standard.30 Children were categorised as positive (CSA confirmed) or negative (CSA unlikely).
Statistical analysis
We intended to analyse the non-verbal scoring data using a receiver operating curve (ROC), showing the true positive rate (sensitivity) of the non-verbal SKPI score on the Y-axis and the false positive rate (1-specificity) on the X-axis. The area under the ROC curve is a measure of the ability of the instrument to distinguish between the true positive and true negative groups. The larger the area under the ROC curve, the better the performance of the instrument. However, due to insufficient confirmed cases, this analysis could not be performed.
Patient and public involvement
Adult CSA survivors contributed by sharing experiences and feedback on the study methods. Dissemination of results is planned for survivors, parents and caregivers of participants.
Results
Study population
Between 2015 and 2020, 100 children were recruited for the control group and 67 for the suspected CSA group. No children could be enrolled in the intended ‘case group’, as the police were only able to refer suspected—not confirmed—cases of abuse. After excluding 12 children (10% of controls and 3% of suspected CSA group) due to poor recording quality, 155 children remained for analysis (65 suspected CSA, 90 controls). Baseline characteristics of the study population are presented in table 1.
Table 1. Baseline characteristics of the study population.
| Variables | Suspected CSA group (n=65) |
Control group (n=90) |
|---|---|---|
| Male, n (%) | 20 (31) | 45 (50) |
| Age (years), median (IQR) | 5.0 (3.5–7.0) | 5.0 (4.0–7.0) |
| Age groups, n (%) | ||
| 3 years | 16 (25) | 10 (11) |
| 4 years | 12 (18) | 19 (21) |
| 5 years | 8 (12) | 22 (24) |
| 6 years | 8 (12) | 15 (17) |
| 7 years | 7 (11) | 12 (13) |
| 8 years | 14 (22) | 12 (13) |
| Country of birth parents, n (%) | ||
| Dutch (both) | 81 (90) | 57 (88) |
| ≥1 foreign parent | 9 (10) | 8 (12) |
Non-verbal reactions and disclosures
The non-verbal reaction scores of the individual children in the suspected and control group are presented in supplemental tables in onlinesupplemental appendices 3 4, respectively. The median (IQR) number of non-verbal reactions per interview was significantly higher in the suspected CSA group compared with controls (13 [IQR 6–22] vs 4 [IQR 1–8]; p<0.001). Certain reactions, such as crying or sitting hunched over, were observed only among children in the suspected group.
The results of the red flag scoring group are listed in online supplemental appendix 5. Six children in the suspected group made statements suggestive of possible disclosure of CSA.
None of the children in the control group showed concerning findings on the scoring forms, or the parental digital questionnaires. No information was found regarding prior CACRC investigations of suspected sexual abuse in this group.
Reference standard
Follow-up reference information was sought for all 65 children in the suspected CSA group. The flowchart in figure 1 summarises the process of information retrieval in the 65 children in the suspected CSA group:
Figure 1. Flowchart of the Picture Instrument for Child Sexual Abuse Screening study abuse status verification. CACRC, Child Abuse Counselling and Reporting Center; SKPI, Sexual Knowledge Picture Instrument.
The reference standard study could not provide clarity about the abuse status for 38 children.
For 11 of them, referred to us by medical child abuse outpatient clinics, both the local CACRC and the police reported having no information on any investigation of suspected CSA.
Eight children were investigated only at the CACRC (left part of the flow in the diagram of figure 1). For seven of them, the CACRC did not report a conclusion, and in one child CSA was rejected.
26 children were investigated by only the police (middle of the flow in figure 1). For 12 of them, no legal action was taken, that is, no charges were laid; in two investigations, an offender was convicted, thus confirming sexual abuse, and in 12 investigations, no one was convicted.
20 children were investigated by both a CACRC and the police (right part of the flow in figure 1). For eight of them, no conclusion or legal action was reported. For three children, both the CACRC investigation and a conviction based on legal actions by the police confirmed sexual abuse. One child’s investigation by the CACRC confirmed sexual abuse, but, despite high suspicion for CSA, the police, in consultation with the parents, decided not to press charges against the suspected perpetrator. For two children, the investigation by the CACRC confirmed sexual abuse, but after legal actions by the police, the prosecutor found insufficient grounds for conviction. We therefore could not conclude whether sexual abuse had occurred.
Based on the reports from either one or both independent sources, six cases of CSA were confirmed.
The collected reference standard findings per individual child are presented in the final column of the onlinesupplemental appendics 3 5. The SKPI scores of the confirmed cases are reported in the first rows.
From the six children in the suspected CSA group with a positive scoring on the SKPI’s red flag form, one child‘s reference standard, based on both CACRC and police reports, confirmed sexual abuse. One child was examined only by the police, who found no indication that sexual abuse had occurred. For one child, no investigation was conducted by either agency. In the other three children, the available reference standard was found to be inconclusive; two of them were investigated by both the CACRC and police, and one child was investigated only by the CACRC.
Discussion
This study aimed to validate the SKPI as an instrument for medical and psychological professionals to confirm or reject suspected CSA in young children, focussing on non-verbal reactions scorings and disclosures. Although the SKPI provided a structured and child-friendly framework to initiate conversations on sensitive topics, its diagnostic accuracy could not be established.
The primary challenge was the absence of a reliable reference standard. Despite enrolling 65 suspected CSA cases, only 27 had independent conclusions from CACRC or police investigations, and just six were confirmed CSA cases. This limited the statistical power to compare SKPI outcomes of children with a verified abuse status.
Our findings are consistent with earlier suggestions that SKPI interviews can elicit non-verbal cues and, in some cases, disclosures.23 31 However, given the low number of confirmed cases and the high amount of inconclusive reference standard data, the instrument cannot currently be recommended as a standalone diagnostic tool.
Strengths and limitations
Despite our failure to include the number of children specified in the study protocol, the relatively large and diverse study group, including 65 young children with suspected CSA, can be considered a study strength. Additional strong points are the blinding of the interviewers to the child’s medical and psychological history and use of standardised training and semi-structured methods.
Also, video recordings from each interview allowed direct assessment by the interviewer and later verification, reassessment and inter-rater and intra-rater reliability checks. Furthermore, the direct involvement of suspected young CSA victims’ parents and survivors ensures ethical sensitivity and relevance, and this scientific substantiation could contribute to improving the current working methods of professionals.
We had anticipated and taken into account a number of limitations in advance, such as the difficulties in recruiting children because of the sensitive nature of the topic of research. To reach the original target number from the protocol of 250 participants, the upper age limit was raised, from 7 to 9 years. However, children aged 7 to 8 years sometimes found the SKPI childish, suggesting age-specific limitations.
As mentioned in the methods section, blinding the interviewers to the study group was not always possible due to recruitment roles and interview settings. Despite broadening our partnerships with the vice squads in all rural regions within the Netherlands, still much more effort than expected was required to recruit the children for the suspected CSA group. In addition, as described earlier, no children could be included in the intended case group.
During the study, in 2018, a new European Union data protection law came into effect in the Netherlands (GDPR).32 This made it impossible to collect reference standard data in accordance with the study protocol.
It was decided to search for a physician at CACRC and a vice detective at the police in the child’s residential area and to ask them to find relevant conclusions of their investigations on suspected CSA. This resulted in an unexpectedly low number of solid conclusions, reducing the statistic validity of the data.
The involved CACRC professionals concluded that CSA could be neither confirmed nor disproved in most instances because of direct outsourcing to other agencies or an inability to draw their own unequivocal conclusions regarding the suspicion of sexual abuse.
The police apparently did not form their own conclusions during their investigations into suspected sexual abuse, which differed from the information we had received during the development of the study protocol. We were therefore dependent on their decision whether or not to take legal action and to involve a public prosecutor. However, this consultation with a prosecutor rarely took place, usually because the police had not found sufficient evidence regarding a possible perpetrator of the suspected abuse. Those lawsuits that were initiated were often dismissed by the prosecutors, again because of insufficient evidence. We are convinced that the absence of legal action and/or conviction in these cases does not always indicate that the suspected abuse was completely ruled out. Studies from other countries have confirmed that criminal proceedings in cases of CSA are often halted in early stages.33
Conclusions and recommendations
The number of children with confirmed sexual abuse was insufficient to determine the SKPI’s diagnostic accuracy. Therefore, we conclude that the instrument should not be used as the sole basis for confirming or excluding suspected CSA on the basis of the current scoring method for non-verbal reactions and suspected disclosures.
During this study, we, and more importantly, the participating parents and children, were hampered by increased strict rules regarding privacy and a lack of standard and transparent procedures in the Netherlands in cases of suspected CSA. We emphasise the recommendations of the recent Dutch study by Groot et al to develop uniform protocols for professionals.34 A clear timeframe and standardised interviewing methods, such as the NICHD protocol, should be used for this purpose, applied in a multidisciplinary framework.34
We also recommend providing standard follow-up and aftercare to children and parents. Finally, future studies in countries with mandatory reporting systems involving child protective services and public prosecutors, (eg, the USA) may allow for more definitive validation of instruments like the SKPI.
Supplementary material
Acknowledgements
We would like to thank all participating children and their parents. The study described in this article was part of the published PhD thesis ‘PICAS: Validation of the Sexual Knowledge Picture Instrument for child sexual abuse screening’, written by the first author (KH).35
Footnotes
Funding: This study was funded by the Contribute Foundation (n/a), the Healthcare Insurers Innovation Foundation (2.969; 2016/020201) and the Janivo Foundation (2015.444).
Provenance and peer review: Not commissioned; externally peer reviewed.
Patient consent for publication: Not applicable.
Ethics approval: This study involves human participants and was reviewed, approved and monitored by the Institutional Board and Ethics Committee from the Amsterdam University Medical Center, location AMC. (METC, 2015_173). Informed consent was obtained from parents/legal guardians (also see manuscript and former papers on the study).
Data availability free text: All data relevant to the study are included in the article or uploaded as supplementary information. Other PICAS study data may be obtained from a third party and are not publicly available. All study data were stored according to Good Clinical Practice guidelines. Coded data from the subject scoring and questionnaires are stored in the online study database from Castor Castor Electronic Data Capture. For privacy reasons, the video recordings were stored in a separate, locked database on the Amsterdam UMC data server and erased 1 year after the study’s final analysis.
Patient and public involvement: Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods section for further details.
Data availability statement
Data may be obtained from a third party and are not publicly available. All data relevant to the study are included in the article or uploaded as supplementary information.
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