Difficulties in determining the diagnostic accuracy of an instrument to verify suspected sexual abuse in young children: ‘autopsy’ of the PICAS study

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.