External validity and anchoring heuristics: application of DUNDRUM-1 to secure service gatekeeping in South Wales

AIMS AND METHOD: Structured clinical judgement tools provide scope for the standardisation of forensic service gatekeeping and also allow identification of heuristics in this decision process. The DUNDRUM-1 triage tool was completed retrospectively for 121 first-time referrals to forensic services in South Wales. Fifty were admitted to medium security, 49 to low security and 22 remained in open conditions. RESULTS: DUNDRUM-1 total scores differed appropriately between different levels of security. However, regression revealed heuristic anchoring on the ‘legal process’ and ‘immediacy of risk due to mental disorder’ items. CLINICAL IMPLICATIONS: Patient placement was broadly aligned with DUNDRUM-1 recommendations. However, not all triage items informed gatekeeping decisions. It remains to be seen whether decisions anchored in this way are effective. DECLARATION OF INTEREST: Dr Mark Freestone gave permission for AUC values from Freestone et al. (2015) to be presented here for comparison.