Several scales have been developed to measure the propensity for, and severity of, violent and aggressive behavior.
The scales listed below are the best in terms of use in prospective studies.

For psychiatric clinicians:

• Overt Aggression Scale
• Overt Agression Scale — Modified

For nurses and other staff:

• Staff Observation of Aggression Scale
• Staff Observation of Aggression Scale — Revised
• The Excited Component from the Positive and Negative Syndrome Scale (PANSS-EC) is a validated scale to assess agitated patients. The PANSS-EC consists of 5 items taken from the PANSS that clinicians can quickly and routinely assess: excitement, tension, hostility, uncooperativeness, and poor impulse control. The 5 items are rated from 1 (not present) to 7 (extremely severe) with scores ranging from 5 to 35 (scores = 20 correspond to severe agitation.

References

Otto RK, Douglas KS: Handbook of Violence Risk Assessment. New York, Routledge, 2010.

Palmstierna T, Wistedt B: Staff observation aggression scale, SOAS: presentation and evaluation. Acta Psychiatrica Scandinavica 1987; 76(6):657-663.

Nijman H, Palmstierna T: Measuring aggression with staff observation. Acta Psychiatrica Scananivica 2002; 412:101-102.

Yudofsky SC,, Slivler JM, Jackson W, et al: The Overt Aggression Scale for the objective rating of verbal and physical aggression. American Journal of Psychiatry 1986; 143:35-39.

Knoedler DW: The Modified Overt Aggression Scale. American Journal of Psychiatry 1989; 146(8):1081.