Intimate partner violence: Epidemiology and health consequences

INTRODUCTION — Intimate partner violence (IPV) is a serious, preventable public health problem affecting more than 32 million Americans [1]. In countries around the world, 10 to 69 percent of females report physical assault by an intimate partner at some time in their life [2].

The term "intimate partner violence" describes actual or threatened psychological, physical, or sexual harm by a current or former partner or spouse. IPV can occur among people with any gender identities and sexual orientations and does not require sexual intimacy.

Abusive relationships often begin as verbal and emotional abuse but may become physical. Most females who are victims of physical aggression experience multiple episodes of aggression over time [3]. "Intimate terrorism," in which a passive victim in an abusive relationship lives in constant fear of the next episode of abuse, is the classic IPV paradigm. However, IPV may be mutual/bidirectional ("situational violence") or may take the form of "violent resistance," in which the identified victim fights back [4].

The underlying psychological dynamic in most types of violence is power and control of the victim by the abuser. The assumption that within a heterosexual relationship all violence is initiated by males and directed towards females is not correct, although females are far more likely to experience IPV than males [2].

This topic will review the epidemiology and health consequences of intimate partner violence. Screening and diagnosis of IPV is discussed separately, as is management for patients in whom IPV is diagnosed. (See "Intimate partner violence: Diagnosis and screening" and "Intimate partner violence: Intervention and patient management".)

EVOLVING FRAMEWORK FOR UNDERSTANDING GENDER AND IPV — The majority of existing literature on intimate partner violence (IPV) preceded nonbinary gender identification in research; studies did not routinely record gender identity and sexual orientation and assumed different-gender relationships. More recent studies show IPV is at least as common in same-gender relationships as different-gender relationships, with some studies demonstrating that LGBTQ+ minorities experience higher rates of IPV compared with heterosexual and cisgender individuals [5,6]. This topic has been updated to reflect self-identification of gender with the understanding that demographic data among historic studies may have gathered only binary gender identity information.

As an example of this evolving framework, the World Health Organization (WHO) includes IPV as a part of a larger problem referred to as "gender-based violence" [7]. Gender-based violence (GBV) also encompasses rape by strangers, female genital mutilation, sexual harassment in the workplace, selective malnutrition of girls, and human trafficking. It emphasizes the role of society, community, and the political system, rather than individual factors, in promoting and perpetuating violence, thereby highlighting the influence communities can have on addressing violence (table 1) (see "Human trafficking: Identification and evaluation in the health care setting", section on 'Sex trafficking'). The GBV model provides a framework to facilitate understanding IPV in societies worldwide; however, it is limited by the assumption that perpetration occurs only from males to females and that only females are victims. It also focuses more on physical and sexual, rather than emotional, types of IPV. These frameworks will evolve as ongoing research facilitates a broader understanding of IPV impact and groups affected, including survivors of all genders and sexual orientations.

TYPES OF INTIMATE PARTNER VIOLENCE — There are three main types of intimate partner violence (IPV) [8]:

●Psychological/emotional

●Physical

●Sexual

Physical violence occurs less frequently than other forms of IPV and is usually preceded by other forms of control [9]. Experiencing abuse in one domain may increase the risk of other types of abuse. In one study, 68 percent of physically abused females were also sexually abused [10].

Two patterns of violence between couples have been described [2]. "Battering" involves severe and escalating violence with terrorization and increasingly controlling behavior. "Common couple violence" is a more moderate form of IPV in which violence occurs occasionally, triggered by frustration and/or anger.

Psychological/emotional violence — Psychological/emotional violence involves trauma to the victim caused by threats of actions or coercive tactics. Threats of physical or sexual violence use words, gestures, or weapons to communicate an intent to cause physical harm, injury, disability, or death.

Psychological violence may include humiliation, control over what a person can and cannot do, withholding information, isolating the victim from friends and family, denying access to money or other basic resources, or threatening harm to other loved ones (including pets). This type of IPV may also include stalking (repeated behavior that causes victims to experience a high level of fear) [1].

Physical violence — Physical violence is the intentional use of physical force with the potential to cause harm, injury, disability, or death. Physical violence includes scratching, pushing, shoving, throwing, grabbing, biting, strangulating, shaking, slapping, punching, or burning. It may also include using a weapon, restraints, or one's size or strength against another person.

Physical violence varies in frequency and severity, ranging from one hit to chronic severe battering.

Sexual violence — Sexual violence may occur in the context of intimate partners, including date rape, but may also occur between strangers. (See "Evaluation and management of adult and adolescent sexual assault victims in the emergency department" and "Date rape: Identification and management".)

Sexual violence may be divided into three categories:

●The use of physical force to compel a person to engage in a sexual act against their will, whether or not the act is completed.

●An attempted or completed sex act involving a person who is unable to understand the nature of the act, or unable to communicate unwillingness because of illness, disability, the influence of alcohol or other drugs, or intimidation or pressure.

●Abusive sexual contact.

EPIDEMIOLOGY

United States data — Only a small percentage of intimate partner violence (IPV) episodes are reported, so that epidemiologic data are estimates only [11]. Among females in the United States, it has been estimated that approximately 20 percent of sexual assaults, 25 percent of physical assaults, and 50 percent of stalking episodes are reported [1]. Even fewer IPV incidents against males are reported. There are limited data from survey studies suggesting higher rates of IPV among people with nonmajority gender identities and sexual orientations. Specifically, transgender/gender-nonconforming people experienced higher rates of violence than cisgender peers [5,12].

The National Intimate Partner and Sexual Violence Survey conducted in 2011 was performed as an anonymous random digit telephone survey, to relieve the stigma of reporting and obtain more reliable data than previously available. The survey identified the following [13]:

●One in three females (32 percent) and one in four males (28 percent) in the United States have experienced rape, physical violence, and/or stalking by an intimate partner in their lifetime, and almost one-half of all people have experienced psychological violence (table 2).

●Individuals often experience their first episode of IPV in adolescence; thus, primary prevention efforts must begin early (figure 1).

●Among female survivors, rape occurred before age 25 years in 80 percent and before age 18 years in 40 percent. Among male survivors, approximately 30 percent experienced their first rape at age 10 years or younger.

●For over 50 percent of female survivors, rape was perpetrated by intimate partners or acquaintances. For nearly 50 percent of male survivors, rape was perpetrated by acquaintances.

●Violence was less common among White and Latino individuals than those who identified as African American, Native American, or Native Alaskan.

●Violence interfered with work or health for 1 in 3 females and 1 in 10 males.

In a 2012 telephone survey of a random sample of females receiving primary care through the US Veterans Health Administration, the overall prevalence of past year IPV was 18.5 percent and was higher (11.2 to 25.5 percent) for those under age 55 years [14].

Data from another United States study indicate that, in households with one female adult with children, IPV was 10 times more likely to occur than in households with married adults and children, and six times more likely than in households with one female and no children [15].

Some studies suggest that the incidence of IPV in men who have sex with men (MSM) may be similar to the incidence in heterosexual females [16]. One survey found that almost 25 percent of MSM aged 18 to 44 years reported lifetime nonvolitional sex [17].

Homicide — A cross-sectional study of 178,940 intentional violent deaths reported in a national database from 2015 to 2019 identified that 9.5 percent of violent deaths were related to IPV [18]. The most common IPV-related fatality was single suicide (45 percent) followed by intimate partner homicide (31 percent).

Another study found that 44 percent of females murdered by their intimate partner had visited an emergency department within two years of the homicide, and 93 percent had at least one injury visit, suggesting ongoing violence occurred before the homicide and presenting an opportunity for providers to intervene. By contrast, only 4 percent had visited a violence shelter in the preceding year [19].

Worldwide data — The World Health Organization (WHO) sponsored a survey of over 24,000 females in 10 countries (15 sites) to investigate physical and sexual IPV [20]. Lifetime prevalence of physical or sexual IPV ranged from 15 to 75 percent; the prevalence was 50 to 75 percent in 6 of the 15 sites. In almost all sites, the risk of partner-related physical or sexual violence far exceeded the risk of other violence. Physical violence only was the most common pattern of IPV, although 30 to 56 percent of females in most sites experienced both physical and sexual violence.

In another report from WHO, rates of reported assault by a partner in the past month in some countries were as high as 52 percent, with physical assault part of a continuing pattern of abuse [2]. Various types of abuse coexist, with overlap between psychological, physical, and sexual abuse.

Homicide — In a systematic review, with data obtained from 66 countries including the 2010 Global Burden of Disease Study, 13.5 percent (95% CI 9.2-18.2) of homicides were attributed to an intimate partner, with recognition that this is likely an underestimate due to unknown data regarding victim relationships [21]. The proportion of female homicides attributable to IPV (38.6 percent) was six times higher than for male homicides (6.3 percent), but since homicide rates are four times higher in males than females, in absolute numbers, there are three IPV-related homicides in females for every two IPV-related homicides in males.

Pregnancy — IPV often begins or increases during pregnancy and the postpartum period [22-25]. The relationship between IPV and pregnancy is illustrated by the following findings:

●In one review of the obstetrical literature, physical abuse occurred during 7 to 20 percent of pregnancies [24]. A United States national survey found that abuse was reported at least once during 4 to 8 percent of pregnancies. [26].

●People with an unintended pregnancy have a higher risk (threefold greater in one study) of physical abuse compared with those whose pregnancy was planned [27]. Of note, one-half of pregnancies in the United States are unintended [28].

●Abused pregnant people have a threefold higher risk of being victims of attempted/completed homicide than nonabused people with similar demographic characteristics [29].

●In a study of United States death certificates for females aged 10 to 54 years, assuming a conservative estimate of misidentification of pregnancy, the risk of homicide for pregnant/postpartum individuals was 1.84 times that of nonpregnant/nonpostpartum females [30].

Reproductive coercion — People in relationships where IPV is present are more likely to have difficulty obtaining and or using contraception, potentially resulting in more pregnancies which can increase the difficulty of leaving the abusive partner [31].

In a cross-sectional study of nearly 1300 females aged 16 to 29 seeking care in reproductive care clinics in California, 53 percent reported physical or sexual violence from an intimate partner, and one third of those also reported reproductive control (pregnancy coercion or birth control sabotage) [32].

RISK FACTORS — Intimate partner violence (IPV) cuts across sex, racial, ethnic, and socioeconomic boundaries. Although no individual has absolute immunity from involvement with IPV, certain groups are at greater risk for IPV victimization or perpetration. Some risk factors, such as childhood physical or sexual victimization, increase the likelihood for both IPV victimization and perpetration.

Contributing risk factors, while associated with a greater likelihood of IPV victimization or perpetration, are not themselves causes of IPV [3]. According to an ecological model of IPV, a combination of individual, relationship, community, and societal factors contributes to the risk of being a victim or perpetrator of IPV, and these can interrelate in an intersectional way. Understanding these multilevel factors can help identify various points to target preventive interventions.

Risk factors for victimization

Individual factors

●Prior history of IPV [3,19]

●Female [33]

●Young age (<24) [22,34]

●At-risk alcohol use or drug use

●High-risk sexual behavior

●Witnessing or experiencing violence as a child [35]

●History of depression [36] or chronic mental illness [37]

●Being less educated [26]

●Unemployment or being below the poverty line [22]

●For females in the United States, being Native American, Alaska Native, or African American [26]

Relationship factors

●Partners with income, educational, or job status disparities

●Dominance and control of the relationship by a male partner

●Excessive jealousy or possessive behavior

Community and societal factors

●Poverty and associated factors (eg, overcrowding) [38]

●Lack of institutions or community norms that shape social interactions

●Weak community sanctions against IPV (eg, police unwilling to intervene)

●Traditional gender norms (eg, females should stay at home and not enter the workforce, should be submissive)

●In some cultural traditions, notions of male/family honor and female chastity

●Social isolation, restricted movement outside the home, and lack of usual access to in-person health care and support services, such as during the COVID-19 pandemic with "stay at home" orders and quarantines [39-41]

Risk factors for perpetration — Many of the factors associated with risk for IPV victimization are also factors for perpetration. A few are of particular relevance to perpetrators:

●Exposure to childhood violence [35]

●Unresolved posttraumatic stress disorder (PTSD), especially related to returning veterans [42]

●Recent job loss or instability [9]

●Substance use disorder

Male survivors — Although people identifying as female are more likely to be survivors than people identifying as males, one study in an urban emergency department suggests that the dynamics present when males are victims are similar to those of female victims [43]. Risk factors associated with IPV in males were young age, African American race, being single, and being without health insurance. The most common forms of assault were slapping, grabbing, and shoving (60.6 percent). Thirty-seven percent of cases involved a weapon; 7 percent of victims described being forced to have sex.

HEALTH EFFECTS — Many common physical and psychological health conditions are associated with intimate partner violence (IPV) and can be exacerbated by the context of violence [44]. General conclusions about the impact of IPV on health issues are [3]:

●The severity of abuse correlates with the impact on physical and mental health

●The impact of multiple episodes and types of abuse over time is cumulative

●The effect of abuse persists long after the abuse has terminated

The Behavioral Risk Factor Surveillance System, a large telephone survey in the United States, correlated violence reported in the prior year with patient medical records [44]. Compared with nonabused females, those who reported IPV in the past year were at significantly increased risk for multiple medical and psychosocial problems. While IPV may lead to direct physical injury, "functional" physical ailments (eg, chronic pain syndromes, gastrointestinal disorders) are a more common physical outcome [3]. The health consequences of IPV are similar comparing same-sex and opposite-sex victims [45].

Trauma-informed care (TIC) is an approach to understanding and managing individuals with a history of trauma. It is a wholistic framework that considers the effects of trauma on health from neurobiology, child development, epigenetics, and posttraumatic stress disorder (PTSD) perspectives [46,47]. TIC takes into account the intersecting health effects of traumas, including IPV as well as historical, community, and discriminatory traumas.

Physical — Many physical consequences of IPV depend upon the severity and frequency of abuse. In a survey of adults experiencing IPV, at least 42 percent of females and 20 percent of males sustained injuries during their most recent victimization [1]. Most injuries were minor, including scratches, bruises, and welts, although some had more serious injuries, including knife wounds and broken bones. In attempted strangulation, red eyes, neck swelling, petechiae, and ecchymoses on the neck may be seen (picture 1); however, no visible injury is seen in the majority of these cases.

In addition to the direct injury consequences of the assault itself, multiple chronic medical conditions are associated with IPV [3,48,49]. Data from a random sample of females in a large United States health plan, comparing those who reported IPV in the past year and those who reported never having experienced IPV, indicate the following relative risks (RR) [48]:

●Headaches (RR 1.57)

●Back pain and other musculoskeletal pain (RR 1.61-1.71)

●Chest pain (RR 1.53)

●Gynecological disorders including menstrual disorders, pelvic pain, and dyspareunia (RR 1.84)

●Sexually transmitted infections, including HIV/AIDS (RR 3.15)

●Gastrointestinal disorders (reflux) (RR 1.76)

●Urinary tract infection (RR 1.79)

●Acute respiratory infection (RR 1.33)

In addition, in females, there is an association between exposure to IPV and the development of type 2 diabetes and cardiovascular disease, as well as an increased risk of all-cause mortality [50].

Psychological — Physical and sexual violence is typically accompanied by emotional or psychological abuse [1,51]. In addition, exposure to IPV is associated with a higher risk of developing psychiatric illnesses, including major depressive disorder (MDD) and anxiety [52].

As examples:

●In a retrospective cohort study of females in the United Kingdom with no mental illness at baseline, IPV exposure was associated with an increased risk of being diagnosed with a serious mental illness, including anxiety, depression, or schizophrenia (RR 3.08, 95% CI 2.19-4.32) [52].

●In a cross-sectional study of Australian females, those reporting at least one type of gender-based violence (GBV; which may include IPV with physical violence, rape, sexual assault, and/or stalking) were over four times more likely to report a severe current mental disorder than females who did not identify GBV [51].

●In a cross-sectional study of females who experienced IPV, 75 percent reported symptoms of PTSD and 54 percent reported symptoms of MDD. Among these individuals, comorbid PTSD and MDD were common and led to greater maladaptive issues than either diagnosis alone [53].

In addition to anxiety and depression, other psychological and psychosocial consequences for victims of IPV include [48,54,55]:

●Substance use

●Eating disorders

●PTSD

●Sleep disorders

●Suicide attempts

●Low self-esteem

●Fear of intimacy

●Family and social problems

Psychological and psychosocial consequences are similar for males experiencing IPV. In a meta-analyses, IPV involving men who have sex with men (MSM) was associated with an increased risk of substance use disorder, depression, and risky sexual behavior (unprotected anal intercourse) [56].

In addition, the combination of IPV and PTSD has also been associated with biologic effects, including changes in morning cortisol levels and cellular components of the immune system; these may potentially impact cardiovascular and immune function [57,58].

Pregnancy — Pregnancy morbidity and mortality has been associated with IPV.

A national survey revealed that experiencing IPV in the year prior to pregnancy increased the likelihood of high blood pressure or edema; vaginal bleeding; severe nausea, vomiting, or dehydration; kidney infection or urinary tract infection; preterm delivery; low birth weight infant; and an infant requiring intensive care unit care [59,60]. Other pregnancy complications, such as abruption, fetal fractures, premature labor, and perinatal death, have also been associated with IPV [57]. The risk for postpartum depression is two- to threefold higher in people who have experienced psychological or physical abuse during pregnancy compared with those who have not [61].

Children — Children may become injured during IPV incidents between their parents/caregivers, either in the act of defending the parent/caregiver or unintentionally.

IPV increases the relative risk for child maltreatment [62,63]. In one study, children with an abused female parent were 57 times more likely to have been harmed, compared with children without an abused female parent [64].

The Adverse Childhood Events Study has shown that adverse childhood events including abuse and neglect, but especially witnessing partner violence among parents/caregivers, are linked to adult poor health [58]. It is hypothesized these childhood events lead to maladaptive coping behaviors and changes in stress response at the level of the hypothalamic-pituitary-adrenal axis that can adversely impact general health and increase the risk for PTSD [65,66]. (See "Intimate partner violence: Childhood exposure", section on 'Effects' and "Posttraumatic stress disorder in adults: Epidemiology, pathophysiology, clinical features, assessment, and diagnosis" and 'Risky health behaviors' below.)

Disability — A cross sectional study in a family medicine clinic revealed a twofold increase in the incidence of disability in those exposed to IPV, compared with those without an IPV history [67]. Disability was associated with heart or circulatory disease, back pain, chronic pain, arthritis, nerve system damage, asthma, emphysema, and depression or another mental illness.

In addition to disability as a potential consequence of IPV, persons with disabilities, and intellectual disability in particular, may be at greater risk for IPV [68]. As well, persons with disabilities are more likely to experience difficulty in accessing services, when needed, for reporting and intervening in IPV.

Risky health behaviors — IPV is associated with a variety of negative health behaviors that further increase health risks. The more severe the violence, the stronger its relationship to negative health behaviors among victims [49,69]. The increase in negative health behaviors has been increasingly understood as maladaptive "coping mechanisms" for survival in these extreme situations, some of which are not in the patient's control. Such adverse health behaviors include:

●High-risk sexual behavior – Decreased condom use; early sexual debut; choosing unhealthy sexual partners; multiple sex partners; trading sex for food, money, or drugs

●Using or misusing harmful substances – Cigarette smoking, alcohol and/or drug use disorders, driving after drinking alcohol or while otherwise impaired

●Unhealthy diet-related behaviors – Fasting, vomiting, abusing diet pills, overeating

●Nonadherence to health recommendations

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Sexual assault".)

SUMMARY

●The term "intimate partner violence" (IPV) describes actual or threatened psychological, physical, or sexual harm by a current or former partner or spouse. IPV can occur among people with any gender identity and sexual orientation and does not require sexual intimacy. (See 'Introduction' above.)

●Three main types of IPV are psychological, physical, and sexual. Psychological violence relates to threats of actions or coercive tactics, including stalking. Physical violence is the intentional use of physical force with the potential to cause harm, injury, disability, or death. Sexual violence includes use of force to compel a sexual act, a sexual act with a person who is unable to consent, or abusive sexual contact. (See 'Types of intimate partner violence' above.)

●Sexual and physical IPV assaults are greatly underreported. A United States survey found that 24 percent of females and 12 percent of males acknowledged a lifetime threatened or completed physical or sexual IPV. Worldwide, lifetime prevalence of physical or sexual IPV in women ranges from 15 to 75 percent. IPV was a factor in approximately 20 percent of United States homicides, with three-quarters of the victims being female. (See 'Epidemiology' above.)

●IPV often begins or escalates during pregnancy and pregnancy can result from reproductive coercion when IPV is already occurring. Other risk factors include being a young female, alcohol or drug use, being less educated, and family history or prior exposure to violence. (See 'Risk factors' above.)

●IPV is associated with an increased incidence of medical problems and pregnancy complications, understood as biologic responses to toxic stress. IPV victims have significantly increased psychological illness, including major depression and posttraumatic stress disorder (PTSD). Additionally, IPV is associated with a variety of negative health behaviors, understood as maladaptive "coping mechanisms" for survival, including high-risk sexual behavior, substance use, eating disorders, and nonadherence to health recommendations. (See 'Health effects' above.)