The aggressive and/or violent patient presents unique challenges. Like suicidal patients, aggressive individuals are difficult to treat and they tend to elicit strong negative reactions in hospital personnel ranging from anger to fear.⁴² Workplace violence is unfortunately commonplace within the health care setting, and is particularly prominent in the inpatient psychiatry ward and emergency department settings.²⁰ Of the approximately 24,000 annual workplace assaults occurring between the years of 2011 and 2013 in the United States, approximately 75% were within the health care and social service settings.³⁷ The prevalence of verbal and physical assaults reported by emergency nurses within a 12-month period is as high as 100% and 82%, respectively.³⁴ Additionally, a survey of emergency physicians within the state of Michigan showed that 25% of emergency physicians reported being a target of physical assault within 12 months.²⁷ These statistics on workplace violence in health care settings are likely underestimates as events are often underreported to health care supervisors and administrators. Workplace violence occurs so frequently that there is a perception among health care workers that violence is “the norm” and an expected part of their job.⁴⁴

Workplace violence is classified into 4 broad categories that are dependent on the relationship of the perpetrator to the workplace. In type I, which accounts for approximately 80% of workplace homicides, there is not an association between the two. These incidents are generally motivated by theft, with hospitals and pharmacies being susceptible because of their abundance of opioids, equipment, and money. However, this type of violence is no more likely to be experienced in health care settings. Preventive measures include environmental security measures such as metal detectors. In type II, the most common type in the hospital setting, the perpetrator is a patient or customer. In general, these acts of violence occur while workers are performing basic work functions. An example of this would be an intoxicated patient who punches a nurse while obtaining vital signs. In type III, the perpetrator is a current or former employee. In type IV, the perpetrator has a personal relationship with a specific employee but not with the institution.⁴¹ The most common types of hospital violence are incidents of aggression against objects in the hospital (57%), violence directed against the hospital staff (28%), and violence directed against other patients (14%).⁴³

In one study of violence in the emergency department, directors of emergency medicine residency programs were surveyed as to the frequency of verbal threats, physical attacks, and the presence of weaponry in the area. Of the 127 institutions surveyed, 74.7% of the residency directors responded; 41 (32%) reported receiving at least one verbal threat each day; 23 (18%) reported that weapons were displayed as a threat at least once each month. Fifty-five program directors (43%) noted that a physical attack on medical staff members occurred at least once a month.²⁹

These studies underscore the need for timely identification of the potentially violent patient, as well as appropriate management for this diagnostically heterogeneous group.¹³ The assessment and management of the violent patient should include provisions for patient and staff safety as well as a thorough search for the underlying cause of violent behavior.^23,42

The section below addresses the differential diagnosis of violent behavior, predictions of violence, the pharmacotherapy for the treatment of aggressive and/or agitated behavior, and the use of seclusion and physical restraint. It also provides an overview of potential risk factors for violent behavior.

There are many causes of violent behavior; some are social, medical, or biological in nature. The most common characteristic of the violent patient is alteration in mental status. Factors such as metabolic derangements, exposure to xenobiotics (both licit and illicit), withdrawal syndromes, seizures, head trauma, stroke, psychosis, cognitive impairment, and personality disorder all predispose a patient to aggression and violence. Additionally, patients with severe pain, delirium, or extreme anxiety often respond to the efforts of emergency personnel with resistance, hostility, or overt aggression.

The stress-vulnerability model suggests that violence should be considered as the outcome of a dynamic interaction among numerous factors both intrinsic and extrinsic to the individual. Although education theoretically provides alternatives to violence, xenobiotic-induced delirium will render any education ineffective because delirium prevents patients from reasoning or exercising impulse control. Once confused, the patient often misinterprets health care efforts in a paranoid manner, and becomes violent under circumstances that would not normally be sufficient to provoke a violent outburst in that individual. Some patients, on the other hand, come from cultures in which aggressive behavior is more acceptable and/or expected, and these patients require little stress or provocation before responding in what is often perceived as aggression by Western cultural standards.

Although there is a high expectation that violence is predictable, there are no proven predictors of violence. Prior history of violence is postulated as a risk factor for future violence. Patients in police custody are involved in 29% of shootings in emergency departments.³⁷ Predicting violent behavior based on medical diagnosis (eg, patients with HIV) is unfruitful and leads to bias or discrimination. Other factors such as personality disorders, mental illness, dementia, and substance abuse are areas that need further study.⁴² Studies of emergency department violence show the following risk factors: the presence of guns, area of gang activity, low socioeconomic status, and interacting with patients who were recently given bad news.³⁷

There are several structured approaches to violence risk assessment.⁴⁶ Examples are the Psychopathy Checklist–Revised (PCL-R); Historical Clinical Risk Management–20 (HCR-20); Classification of Violence Risk (COVR); Violence Risk Appraisal Guide (VRAG).⁴⁶ Structured approaches tend to have better efficacy for predicting violence than an unstructured approach. However, they also have many shortcomings: the sensitivities and specificities tend to hover around 0.7 and they are time consuming and require specific training to administer, rendering them impractical in the emergency department setting.¹⁶

The association between substance use and violence is well established. Alcohol is found in the offender, the victim, or both in one-half to two-thirds of homicides and serious assaults.^9,38 Substance use is seldom the sole cause, but it contributes to violence in a number of ways. Substance use interacts with other physiologic, cognitive, psychological, situational, and cultural factors including any underlying mental illness. A tripartite model for substance-related violence is described:^18,19

1. 
   

   systemic violence related to the sale and distribution of drugs,

   
   
2. 
   

   economic compulsive violence associated with profit-oriented criminal activity to maintain the expenses of an individual’s drug habit, and

   
   
3. 
   

   psychopharmacologic violence resulting from the direct effects of the particular xenobiotic.

Toxicity causes disinhibition, impulsivity, perceptual disturbance, paranoia, irritability, misinterpretation, affective instability, and/or confusion. For example, synthetic cannabinoids, synthetic cathinones, and phencyclidine are well known to cause agitation, which is often accompanied by violent and uncontrollable behavior.

Withdrawal syndromes also promote aggressive behavior for a multitude of reasons, including physical discomfort, anticipatory anxiety, irritability as a direct result of withdrawal, and withdrawal-related delirium. Patients experiencing any of these symptoms have the potential to become aggressive, verbally abusive, or threatening. Prompt recognition of these syndromes and immediate treatment will prevent some aggressive outbursts or escalation to assaultive behaviors. Well-known xenobiotics that cause irritability and associated behaviors in withdrawal include ethanol, benzodiazepines, and opioids. Because drug use is often concealed, is difficult to ascertain on clinical grounds, and frequently contributes to violent behavior, urine and blood toxicologic studies are useful in enhancing the understanding and long-term treatment of some patients.⁸

The relationship between mental illness and violence is also complex. The impact of present-day media and the counteracting efforts made to destigmatize mental illness often confound this issue. There are several studies showing an association between mental illness and increased risk for violence.³⁸ In one large epidemiologic study, the prevalence of violence for those without mental illness was 2%, whereas schizophrenia was associated with an 8% rate of violent behavior. But, of all respondents reporting violent behaviors, 42% had a substance use disorder. In patients with schizophrenia, having a co-occurring substance use disorder more than tripled the rate of violence.⁴⁵ However, based on a cohort study from the Netherlands, most of the common mental disorders were associated with violence until adjusting for violent victimization, negative life events, and social supports. Then the association of violence with most mental disorders was negligible, with the exception of substance use disorders, which retain a strong association with violent behavior.⁴⁵

In addition to substance abuse and severe mental illnesses, researchers have consistently found a greater prevalence of personality disorders among individuals who become violent in an inpatient setting as compared to nonviolent inpatients.⁷ Antisocial personality disorder is the condition most strongly associated with both substance use and aggression. Patients with either borderline or antisocial personality disorders are at risk for violent behavior as a result of chronic poor impulse control and impaired frustration tolerance in the context of poor coping skills.

Although persons with psychotic disorders are not generally aggressive, there are aspects of their psychosis that place them at risk for aggressive behavior. Hallucinations lead to aggression, such as when patients explicitly follow the instructions of a violent command auditory hallucination. Paranoid ideation that leads an individual to believe that she or he is at imminent risk of bodily harm (“They’re trying to kill me”), sexual victimization (“Men and women are raping me”), or humiliation (“Everyone is laughing at me”) or feeling physically trapped are examples of thoughts that lead psychotic patients to be aggressive.

Delirium from any underlying condition is a cause of aggression. Patients are often suddenly confused, frightened, or frankly psychotic as a result of impaired perception. Violence risk is also associated with cognitive dysfunction such as traumatic brain injury and dementia. These patients are unable to engage in a rational manner and verbal de-escalation is often futile.

Many of the factors correlated with aggression are easy to observe and monitor in the hospital, yet some additional factors are not so easy to detect. One study found that most violent incidents in the hospital occur on Mondays and Fridays, and others have postulated that there is a seasonal variation of violence, with violence occurring more often in extreme temperatures.¹⁰ There is an increase in the frequency of assaults by inpatients during the winter months, and it is hypothesized that increased population density, cold temperature, and less sunlight during the day could account for the increased violence. This finding is in contrast to the literature on outpatient violence, which has reported greater incidence of violence during the warmer months.² However, this same review conceded that any extreme temperature could evoke aggressive urges and frustration.