Short-term sequences of aggressive behavior in psychiatric inpatients with psychotic disorders using Markov models.

Background: Aggression in inpatients with psychotic disorders is harmful to patients and health care professionals.

Aims: The current study introduces a novel approach for assessing short-term sequences of different types of aggression.

Methods: Occurrence and type of aggressive behavior was assessed retrospectively by reviewing hospital charts in a sample of 120 inpatients with psychotic disorders, admitted to the psychiatric wards of an academic hospital using the Modified Overt Aggression Scale (MOAS). Behavioral sequences of verbal aggression, physical aggression against objects, physical aggression against oneself and physical aggression against others were analyzed by using Markov models, a statistical technique providing the probabilities of transferring from one state to another.

Results: The Markov models showed that when patients behave aggressively, they are likely to either show the same type of aggression or to be non-aggressive consecutively. Patients are, however, unlikely to subsequently show another type of aggression. Non-aggressive behavior is very unlikely to result in physical aggression or aggression against objects.

Conclusion: The current study introduced a novel approach on how to investigate aggressive behavior in patients with psychotic disorders. Replication of our results in a bigger sample is needed to reliably develop a day-to-day risk assessment tool for aggressive behavior.