Validation and recalibration of OxMIV in predicting violent behaviour in patients with schizophrenia spectrum disorders

Claudia Simons,Jelle Lamsma,Genetic Risk And Outcome Of Psychosis (Group) Investigators ,Wiepke Cahn,Therese Van Amelsvoort,Rongqin Yu,Frederike Schirmbeck,Agna Bartels-Velthuis,Lieuwe De Haan,Seena Fazel

doi:10.1038/s41598-021-04266-9

Abstract

Oxford Mental Illness and Violence (OxMIV) addresses the need in mental health services for a scalable, transparent and valid tool to predict violent behaviour in patients with severe mental illness. However, external validations are lacking. Therefore, we have used a Dutch sample of general psychiatric patients with schizophrenia spectrum disorders (N = 637) to evaluate the performance of OxMIV in predicting interpersonal violence over 3 years. The predictors and outcome were measured with standardized instruments and multiple sources of information. Patients were mostly male (n = 493, 77%) and, on average, 27 (SD = 7) years old. The outcome rate was 9% (n = 59). Discrimination, as measured by the area under the curve, was moderate at 0.67 (95% confidence interval 0.61–0.73). Calibration-in-the-large was adequate, with a ratio between predicted and observed events of 1.2 and a Brier score of 0.09. At the individual level, risks were systematically underestimated in the original model, which was remedied by recalibrating the intercept and slope of the model. Probability scores generated by the recalibrated model can be used as an adjunct to clinical decision-making in Dutch mental health services.

Highlights

Oxford Mental Illness and Violence (OxMIV) addresses the need in mental health services for a scalable, transparent and valid tool to predict violent behaviour in patients with severe mental illness
In a Dutch sample of 637 general psychiatric patients with schizophrenia spectrum disorders, we evaluated the performance of a newly developed risk assessment tool (OxMIV) in predicting interpersonal violence over 3 years
We found OxMIV performed moderately well, especially considering that it is designed to predict a different outcome

Summary

Introduction

Oxford Mental Illness and Violence (OxMIV) addresses the need in mental health services for a scalable, transparent and valid tool to predict violent behaviour in patients with severe mental illness. We have used a Dutch sample of general psychiatric patients with schizophrenia spectrum disorders (N = 637) to evaluate the performance of OxMIV in predicting interpersonal violence over 3 years. The most widely used tools, such as the Historical, Clinical and Risk Management-20 (HCR-20), Violence Risk Appraisal Guide (VRAG) and Level of Service Inventory (LSI)[2], were developed in other populations and with methods that are considered low quality (e.g., absence of a study protocol, small and selected samples, vague or undefined risk categories)[3] They have rarely been validated in patients with schizophrenia spectrum disorders and have low-to-moderate discrimination across psychiatric populations. We have evaluated the performance of OxMIV in predicting interpersonal violence over a 3-year period in a Dutch sample of general psychiatric patients with schizophrenia spectrum disorders. We explored the feasibility of adjusting OxMIV for this population and outcome

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