The Thai Violence Risk Scale (TVRS) persons with schizophrenia: Development and initial validation

Abstract

Introductions : Persons with schizophrenia have a clear association with increased violence in community than the general population. At present, there has not been any scale developed to estimate risk of violence, particularly in persons with schizophrenia.

Objectives : To develop a clinically useful for evaluation violence risk among persons with schizophrenia, and to carry out an initial validation of the scale.

Setting : Out patient department of a psychiatric hospital

Research design : Instrument development

Sample : Persons with schizophrenia who had committed violence (n = 300)

Methods : A 29-item Thai Violence Risk Scale (TVRS) was constructed on the base of the literature review and Psychology of Criminal Conduct (PCC) as guideline for selection of significant characteristics and circumstances that are risk factors associated with violence among persons with schizophrenia in community. Scale development procedures composed of 10 steps guide by Crocker and Algina. Content validity of the TVRS was evaluated by nine content experts, internal consistency was evaluated with Cronbach alpha, and construct validity was evaluated with exploratory factor analysis (EFA).

Results : The number of 29 items in the item pool of the first draft of the TVRS was reduced to 27 items in content validity step with an I-CVI score ranged from .78 - 1.0 and an S-CVI/Ave score of .86. After completing item analysis, the number of 27 items in the second draft scale was reduced to 17 in this step. Cronbach’s alpha coefficient of the second draft scale was high (α = .92). Findings from the EFA (varimax rotation) showed that the TVRS was composed of 2 factors. Factor I was the characteristics (15 items) and factor II was the circumstances (2 items).

Conclusions : The suitability of development procedures of the TVRS that seems to be clinically and practically useful in identifying persons with schizophrenia in community with a particularly high risk for violence.