Heterogeneity and Risk factors of Aggressive Acts among Schizophrenic Inpatients
Date Issued
2005
Date
2005
Author(s)
Chen, Shing-Chia
DOI
en-US
Abstract
Background: Psychiatric inpatients’ aggressive acts can occur frequently and are recognized as a significant problem in psychiatric settings. Understanding of aggressive acts in clinical settings is still incomplete and the clinical care of aggressive acts remains unsatisfactory. It is therefore crucial to establish objective measures and to develop insights into the heterogeneity and related risk factors of aggressive acts, for improvement in the management and prevention of aggressive acts.
Objective: The purpose of this study has a many-fold intention depicted as follows: to describe and characterize schizophrenic inpatients’ aggressive acts, to identify and specify heterogeneity in their structure, and to look for and set up risk factors for prevention. This study investigates four major issues: (1) Establishing an objective behavior rating scale for measuring aggressive acts; (2) Understanding the characteristics and incidence of aggressive acts by inpatients with schizophrenia; (3) Exploration of the heterogeneous structure of aggressive acts by inpatients with schizophrenia; and (4) Identifying the risk factors of aggressive acts of inpatients with schizophrenia.
Method: The “Two-Stage Model of suicide and violence” coined by Plutchik, van Praag, and Conte and MacArthur’s “Violence Risk Assessment Model” have been incorporated in developing the conceptual framework of this study. At first, by back translation, an English version of the violence scale (VS) was translated into Chinese (VS-C) with counts scaling, including three categories of aggressive acts: (1) towards property (AggP), (2) towards others (AggO), and (3) towards self (AggS). The content validity, construct validity, and internal consistency of VS-C were examined. Prospective panel design was used for data collection. Patients fulfilling the DSM-IV criteria of schizophrenia in the acute psychiatric ward of a university teaching hospital were recruited over a one-year period (April 2001 to March 2002) as study subjects, after signing informed consent. The sample size was 107. Aggressive acts were rated daily using the VS-C by participant observation during the hospitalization period. The raw counts of aggressive acts were summed weekly as a data unit. The risk factors of schizophrenic inpatients’ aggressive acts were measured using “Past Month History of Aggressive Acts”, “State-Trait Anger Expression Inventory”, “Patients’ Basic Demographic and Clinical Data”, “Ward Restriction Scale”, and “Psychiatric Symptoms Checklist”. The heterogeneous structure of aggressive acts was assessed by three indicators: (1) the concurrence of specific categories and types of aggressive acts in the initial week after hospitalization, (2) the correlation of the severity of aggressiveness among specific categories and types between past-month and initial-week aggressive acts, and (3) the concordance of specific categories between past-month and initial-week aggressive acts in sensitivity, specificity, and positive and negative predictive value.
The software applications SPSS12.0, S-PLUS6.0, and LISREL8.43 were used for statistical analysis. The statistical methods included descriptive statistics, Chi-square test, Pearson’s correlation, Confirmatory Factor Analysis (CFA), Receiver Operating Characteristic (ROC) curves analysis, multiple regression model and interaction analysis.
Results: There was a Poisson distribution and over-dispersion on aggressive acts found in this study. The VS-C with 16 items showed an acceptable quality, but lacked a high internal consistency value (Cronbach’s α = .67). A shorter version of the VS-C could be drawn with one latent variable of 6 items sharing a core meaning labeled as “common outward aggressive acts.” In this study, participating subjects had a mean age of 33.4 (SD = 11.9). The majority of them was single (68.2%), female (69.2%), unemployed (73.8%), and had an Eastern religious affiliation (57.9%). The average duration of their hospitalization was 4 weeks (SD = 2.4, range = 2 to 13). About one quarter of them were involuntarily admitted (26.2%).
The mean age of the onset of initial nonspecific symptoms was 24.1 years old. Ninety-one out of 107 patients (85.0%) had a history of past-month aggressive acts, and 63 patients (58.9%) exhibited aggressive acts (mean = 10, SD = 9.8, range = 1 to 46) in the initial week after admission. The past-month incidence rate of aggressive acts was in the order of AggO (70.1%), AggP (44.9%), and AggS (32.7%). The initial-week incidence rate of aggressive acts was in the order of AggO (47.7%), AggP (27.1%), and AggS (14.0%). The category AggO occurred more frequently than the other two categories. All aggressive acts decreased during the treatment course of patients’ hospitalization. The incidence rate of aggressive acts that decreased the most, over weeks, were “loud verbal arguments with another person”, “low grade hostility”, and “used property in a threatening manner without damage”. The incidence rate of aggressive acts decreased to 33.3%, 26.8%, and 16.9% in the following second, third, and forth week respectively during hospitalization. Most patients’ aggressive acts were quickly decreased in two weeks.
The study subjects’ aggressive acts were heterogeneous as evidenced by: (1) a high concurrent rate of AggO with AggP (r = .52), especially with physical AggP (r = .51), whereas only physical AggO was concurrent with AggS (r = .24) in the initial week after hospitalization, (2) a high significant correlation of the severity of aggressive acts between corresponding categories of past-month and initial-week aggressive acts (toward property, r= .46 ; toward others, r = .50; toward self, r = .41; and Past-month AggP with AggO, r = .34, and Past-month AggO with AggP, r = .43), whereas the correlation between aggressive acts toward self and the other two categories were all low, and (3) a high concordance rate of corresponding categories of past-month and initial-week aggressive acts (toward property, 72.0%; toward person, 72.6%; toward self, 70.7%). The concordance between past-month AggP and initial-week AggO (64.7%), past-month AggO and initial-week AggP (64.6%) were also high, whereas the concordance between aggressive acts towards the self and other two categories were low.
The risk factors of weekly averages of AggP during hospitalization were weekly averages of past-month AggP, and positive and negative psychiatric symptoms. The risk factors of weekly averages of AggO during hospitalization were weekly averages of past-month AggO, affective psychiatric symptom, and the interaction of weekly averages of past-month AggO and gender factor. The risk factors of weekly averages of AggS during hospitalization were only the weekly averages of past-month AggS. Apparently, the risk factors of these three categories of aggressive acts were different. Globally, the risk factors that significantly predict the single latent factors of “common outward aggressive acts.” were the corresponding category of past-month aggressive acts, psychiatric symptoms, and gender factor.
Discussion: The strength of this study on aggressive acts of inpatients with schizophrenia was a prospective observation study design using an objective measure. Previous studies of patients’ aggressive acts mainly used retrospective reports, which might underestimate the occurrence of patients’ aggressive acts, and which provided a cross-sectional data only. This study revealed information on aggressive acts occurring weekly after admission into the psychiatric ward. In addition, to identify the risk factors of aggressive acts and consider their developmental directions to predict the formation of aggressive acts. This brings insight into the dynamic nature of aggressive acts of schizophrenia inpatients. Further, the incidence rate of aggressive acts decreased of 83.1% after 4 weeks of admission. This information is useful for emphasizing prevention and management of aggressive acts of inpatients with schizophrenia after admission. The specific category of initial-week aggressive acts was accurately predicted around seventy percent of the time by the corresponding category occurring in the past month prior to admission. This evidence is crucial for clinical psychiatric service in the prevention of aggressive acts. AggP was also predicted by high level of the positive and low level of the negative psychiatric symptoms; the AggO was also predicted by high level of the affective psychiatric symptoms. Male patients with a past-month history of AggO predict AggO more accurately than the same for female patients. Gender has no effect on the prediction of the other two categories of AggP and AggS.
The risk factors of aggressive acts among schizophrenic inpatients occurring during hospitalization did not include the personality variable of an anger trait. This might be due to the fact that the acute phase of illness might reduce the effect of the anger trait on aggressive acts. The anger trait may play a role on aggressive acts that occur in the stabilized state of illness. This needs to be studied further.
Subjects
攻擊行為
發生率
異質性
住院病患
精神分裂症
危險因子
aggressive act
incidence rate
heterogeneity
inpatient
schizophrenia
risk factor
Type
other
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