In recent years, studies have been conducted to identify the frequency of violent events among
mental disorder are generally not violent towards others, there is a subgroup of potentially danger- ous patients with a high risk for violence, and this makes it difficult to reduce the stigma associated with this type of disorder (1–3).
Despite differences among countries with respect to legislation and institutionalisation, the data show that, in general, some out-patients with schizophrenia also present violent behaviour. There are retrospective studies indicating a prevalence of violent episodes of around 15% in
6 months and 21.8% in a year in this population (4) The results of these studies were obtained using different methods to measure the existence of any violent episode (ranging from minor episodes such as simple assault to serious violent episodes): self- report using standardised instruments, review of medical records and review of Justice Department databases. In a recent study of 1011 persons with psychiatric disorders receiving treatment in public mental health service systems, Swanson et al. (5) reported a 6-month incidence of violent acts ranging from 18 to 21%, with 3–9% of those being serious violent episodes (assault with a lethal weapon, sexual assault, or assault and battery).
The occurrence of violence in schizophrenia is not explained by a single variable, but is the result of interaction among different factors related to the individual and society. Epidemiological studies conducted in the general population have shown that violent behaviour is associated with younger males with low socioeconomic status, substance abuse problems and a history of violence (6). The population of patients with schizophrenia has the same risk factors as the general population, plus the presence of positive symptoms, poor awareness of the disease and poor treatment compliance, all factors that have been studied by different authors and related to this type of behaviour (7–9). It has been postulated that patients with schizophrenia who take their medication are no more violent than the general population, as the latter variables related to the disorder are not present when the patient is clinically stable (7). Although factors associated with safety concerns in schizophrenia have been identified, more research is needed to identify patients at risk in the context of out- patient clinical settings, and to determine the influence of specific strategies – based either on community, welfare or the legal system – on improving treatment adherence and other risk factors (5). In addition, the relationship between schizophrenia and violent behaviour in compliant patients has not been previously assessed.