Study setting and participants
This study is a multi-center, case-control study started in May 2013 and ended in January 2016. Data were obtained from seven qualified forensic institutes located in seven different provinces in China. Targeted participants were individuals with violent behaviors who were suspected to have mental disorders. In China, individuals who are engaged in violent behaviors and suspected to have a mental disorder are required to undergo a forensic psychiatric assessment in order to ascertain their mental status. More details about forensic psychiatric assessment in China can be found in previous literature. The inclusion criteria were individuals who (1) were either female or male, aged over 14, (2) perpetrated any violent criminal acts, including homicide, assault, robbery, arson, and sexual offences, (3) were able to understand and answer the questions in the interview, and (4) were willing to participant in this study. Individuals with incomplete records of the information needed in this study were excluded. The study protocol was approved by the Ethics Committee of the Second Xiangya Hospital. All methods were performed in accordance with relevant guidelines and regulations. Informed consent was obtained from all subjects.
Definition of dual-harm
Dual-harm was defined as the co-occurrence of self-harm and aggression during an individual’s lifetime. In this study, we defined self-harm as any self-directed injurious behavior with suicidal intent but not resulting in death (i.e., suicide attempt or self-directed injurious behaviors, including poisoning, use of asphyxiating gas, use of sharp objects, hanging, jumping from height, and drowning). Aggression in this study was defined as any violent criminal acts towards others, including homicide, assault, robbery, arson, and sexual offences.
Instruments and evaluation
Lifetime history of self-harm was obtained using a self-report questionnaire, which included questions such as “Have you ever made a suicide attempt, for example, cutting yourself or overdosing on drugs?” Violent behaviors were ascertained from the participants’ forensic archives in this study.
Demographic and clinical information was obtained using a standardized data collection form. The demographic information included sex, age, employment status, marital status, place of residence and education levels, and the clinical information included history of mental disorders, family history of mental disorders, history of head trauma, history of alcohol and non-alcohol substance abuse, previous violence behaviors, and lifetime treatment for mental disorders; all the above data were obtained from the participants’ forensic archives.
Each participant was evaluated by at least two senior psychiatrists with the use of the International Classification of Diseases 10 (ICD-10). Diagnoses of mental disorders were made for participants who meet the corresponding diagnostic criteria.
A clinician-rated scale was used to assess the participants’ childhood adverse experiences. This scale was designed by our research team based on previous studies of violence risks associated with the circumstances in China. This scale is used to assess the adverse experiences before the age of 15 years, including child abuse, parental abandonment, parental death, parental separation, parental psychiatric disorder, parental criminal behaviors and parental alcohol/non-alcohol substance abuse. Information regarding childhood adverse experiences was obtained from participants by asking questions such as “During the first 15 years of your life, have you ever been abused by your parents?” and “Have you lost any of your parents because he/she died? ” The total number of childhood adversities that the participant had experienced were recorded and used in subsequent statistical analyses.
The Chinese version of Psychopathy checklist-Revised (PCL-R) was used to assess psychopathic personality traits in this study. The 20-item PCL-R covered four factors of psychopathy, i.e., interpersonal, affective, lifestyle, and antisocial factors; each item was rated on a 3-point scale (0-2), with the total score ranged 0-40. For this scale, higher scores indicated a higher degree of psychopathy, with a cutoff score of 25 suggesting the presence of psychopathy. This scale has demonstrated satisfactory reliability and validity in previous studies.
The 20-item Chinese version of Brief Psychiatric Rating Scale (BPRS) was used to assess psychiatric symptoms in the participants. The BPRS is a well-established clinician-rated tool consisting of 5 subscales: affect (e.g., anxiety, depression), negative symptoms (e.g., withdrawal), positive symptoms (e.g., thought disturbance), activation (e.g., excitement), and resistance (e.g., hostility, suspiciousness). Each item was rated from 1 (no symptom) to 7(extremely severe), and the score of each subscale was calculated by computing the arithmetic mean of the scores of all items included in the subscale.
Categorical variables were presented as number (percentage), and continuous variables were presented as mean±standard deviation. The participants’ education level was categorized into high (years of education >12), intermediate (years of education ranged 6-12), or low (illiterate or years of education <6) levels. The diagnoses were classified into five categories: no mental disorder, schizophrenia spectrum disorders, mood disorders, substance-related disorders and other mental disorders (including personality disorders, neurotic disorders, mental retardation, and other non-specified mental disorders, given the small number of cases). Categorical variables were analyzed using Chi-square test, and Fisher’s exact test was applied as appropriate. The one-sample Kolmogorov-Smirnov test was used to assess the normality of continuous data. Normally distributed data were analyzed using two-simple t-test and non-normally distributed data were analyzed using the Mann-Whitney U test. Binary logistic regression analysis was performed to investigate the association between dual-harm and other factors, with all the categorical variables set as dummy variables. The univariate analysis was first performed to screen potential associated factors, and then the forward stepwise (Likelihood Ratio method) procedures were used to identify independent associated factors for dual-harm. With the type of harm (dual-harm or violence-only) set as the dependent variable, the factors with p <0.1 in the univariate analysis were selected for the multivariable analysis. All analyses were two-sided, and p <0.05 were considered as statistically significant. All data were analyzed using the SPSS software (Version 24.0; IBM).