Statistical analysis
Data were analyzed using PASW Statistics 17.0. 
Variables were analyzed descriptively, and results were 
distributed in frequency tables. Data that could not be 
retrieved were classified as lost and excluded from the 
analysis. We controlled data for age, sex, demographic 
characteristics and diagnosis, and a chi-square test and 
the Fisher exact test were used to compare differences 
between groups.
The sample was first divided into aggressive and 
non-aggressive individuals. Aggressive individuals 
were then separated into hostile (verbally aggressive 
and aggressive against objects) and violent (physically 
aggressive). After that, aggressive individuals were 
divided into those that were aggressive against others 
only (hetero-aggressive), and those that were also 
aggressive towards themselves (self-aggressive). The 
groups were compared using the Mann-Whitney U test. 
The level of significance was set at 5% (α = 0.05). 
The prevalence of aggression was described with 95% 
confidence intervals (95%CI).