Intimate Partner Violence: A Literature Review

Intimate Partner Violence (IPV) is the most prevalent type of violence against women worldwide. It is defined as a “behavior by an intimate partner or ex-partner that causes physical, sexual or psychological harm, including physical aggression, sexual coercion, psychological abuse, and controlling behaviors” [1]. The United Nations has defined violence against women as “any act of gender-based violence that results in or is likely to result in, physical, sexual or psychological harm or suffering to women, including threats of


INTRODUCTION
Intimate Partner Violence (IPV) is the most prevalent type of violence against women worldwide. It is defined as a "behavior by an intimate partner or ex-partner that causes physical, sexual or psychological harm, including physical aggression, sexual coercion, psychological abuse, and controlling behaviors" [1]. The United Nations has defined violence against women as "any act of gender-based violence that results in or is likely to result in, physical, sexual or psychological harm or suffering to women, including threats of such acts, coercion or arbitrary deprivation of liberty, whether occurring in public or in private life" [2].
The percentage of women experiencing violence in various parts of the world has been recorded. Different factors appear to influence the incidence of this worldwide problem. However, there are no single studies that summarize findings on the subject. The aim of this article was to review available knowledge regarding Intimate Partner Violence. There is a need to understand this problem so that viable solutions and or preventive measures could be implemented.

Searching Strategy
The literature search was conducted in English and Spanish using EBSCO (Psychology and Behavioral Sciences Collection, Academic Search Premier, and Fuente Academica Premiere) and Scopus. It included the keywords "Intimate, Partner, Violence, IPV" and thematic issues on the subject, such as "depression, anxiety, body, ache." Only the findings of empirical studies were considered. The articles ranged from 2004 to 2020. The analysis of full texts of articles was carried out several times and data were extracted according to the aim of this study.

Percentage of Women Experiencing Violence
Data presented by Women UN (2019) indicates that approximately 35 percent of women worldwide have experienced some form of violence in their lifetime [3]. Onethird of women worldwide who have ever been involved in a relationship have experienced physical or sexual violence inflicted by an intimate partner [4].
With a focus on the Americas, the percentage of women who have experienced physical or sexual IPV in the past 12 months progressively increases as one examines data from North, Central and South America (1.1% in Canada, 6.6% in the United States, 7.8% in Costa Rica, and 27.1% in Bolivia) [5]. Compared to countries in Central and South America, Bolivia reports the highest percentage (52.3%) of women ever experiencing physical violence by an intimate partner. However, the percentage of women reporting ever experiencing sexual violence by an intimate partner was similar across nations (i.e., Bolivia 15.2%, Nicaragua 13.1%, Guatemala 12.3%, Colombia 11.8%, Ecuador 11.5%, El Salvador 11.5%, Haiti 10.8%, and Peru 9.4%). Moreover, the percentage of women who reported ever experiencing IPV in the form of emotional abuse (insults, humiliation, intimidation, and threats of harm) also occurred relatively equally across nations (e.g., Nicaragua 47.8%, El Salvador 44.2%, Guatemala 42.2%, Colombia, 41.5%, Ecuador 40.7%), with a few exceptions (Haiti 17.0%, Dominican Republic 26.1%) [6].
Data from Colombia indicates that 31.1% of women in that country reported experiencing economic or patrimonial violence from an intimate partner, 7.6% experienced IPV in the form of sexual violence, and 64% experienced psychological violence from a partner [7]. Similar numbers have been recorded in Ecuador. The National Institute of Statistics and Censuses (INEC 2019) notes that 43 out of 100 women in the country have experienced some form of IPV. Of this group, 40.8% of women reported experiencing psychological violence (e.g., humiliation, insults, being threatened with a weapon), 25% said they were victims of physical violence and 8.3% were victims of sexual violence [8].

Social Norms and Sociodemographic Factors
Women must contend with societal norms related to domestic violence. For example, in some countries, male dominance or patriarchal systems in which the wife is considered a possession or property of the husband are considered the societal norm. Some studies have shown that social attitudes justifying and or accepting IPV in some developing nations or specific localities increase the incidence of this problem in those areas. Women in these places are likely more tolerant of this problem if it were to happen to them and are less likely to leave a violent relationship [9 -12]. Likewise, exposure to violence perpetrated by political groups (e.g., police, armed forces) also seems to increase the prevalence of IPV in nations [13 -15].
Sociodemographic factors also appear to affect the prevalence of IPV. Studies around the globe indicate that a low level of education in women may put them at a higher risk for IPV [16 -19]. This low level of educational attainment could be related to existent socioeconomic disadvantages, a culturally upheld belief that women do not need education because their assigned role is to stay at home and take care of household duties, including the raising of children, and a lack of a network of support that could potentially encourage their educational advancement. For example, a recent study suggested that Latinas who experience IPV "tend to be younger, have more socioeconomic disadvantage, and are fearful of seeking help from authorities" [20].
The marital status of female victims of IPV has been extensively studied, with common findings of IPV appearing to happen less often to married women in comparison to divorced or separated women in most countries [21,22]. However, the findings must be considered within cultural contexts. As previously stated, in some countries, married women are viewed as property of the husband, and physical aggression or violence towards the wife is tolerated or accepted within the culture. In general, cohabitating couples worldwide report higher rates of IPV. The higher rates could be related to socioeconomic status or to the perception that the relationship is less permanent. More studies need to address the contributing factors as to why cohabitating women tend to have a higher rate of IPV compared to married women, as well as examine the norms by varying cultures and their effect on IPV. Single women typically report less rates of IPV in comparison to married, divorced or separated women. However, this trend appears to vary by country. Single women in Canada and Australia, for example, report higher rates of IPV in comparison to married women in these two nations [22]. Possible contributing factors for the increase in IPV among single women in Canada and Australia could be related to age or to lifestyle choices. Riskier lifestyles could potentially expose younger women to a greater chance of experiencing intimate partner violence. Latin American and Caribbean nations, data indicate that IPV typically occurs more often among urban women in comparison to rural women [23]. Nonetheless, some studies in the United States suggest that IPV typically occurs more often in rural settings and small towns [24,25]. Further studies are needed to address the underlying causes of the link between sociodemographic factors and IPV.

Childhood Victimization
In addition to possible social factors influencing the rates of IPV, women impacted by childhood victimization can experience long term negative effects, and data suggest that "childhood victimization and domestic violence are highly correlated" [26]. For example, women who witnessed IPV during their childhood are more prone to experiencing IPV as adults [27 -30]. Similarly, studies suggest that women who have been physically abused [31 -34] or sexually abused [35 -38] in childhood also are more likely to experience IPV in adulthood.

Mental Health
Research has shown that women who experienced IPV report increased levels of mental health symptomatology. For example, women who were abused by an intimate partner reported increased symptoms of depression, anxiety [39,40], and obsessive-compulsive characteristics [40]. Similarly, women exposed to IPV and who present depressive symptoms exhibit significant weight gain [41]. Low-income post-partum women in Brazil who experienced IPV are at a greater risk of presenting suicidal ideation [42], and women living in poverty in Nicaragua who were victims of IPV and perceived they did not receive social support from their families were more likely to indicate they had attempted suicide at some point in their lives [43]. There appears to be a bidirectional relationship between IPV and mental health problems. More specifically, at least one study has shown that women who experienced child abuse and subsequently developed mental health illnesses (i.e., Post Traumatic Stress Disorder, symptoms of depression, binge drinking) were more likely to experience IPV during adulthood [44].

Health Complains and Illnesses
In addition to mental health ailments, women victims of intimate partner violence (IPV), in its many forms, have selfreported having frequent health complaints and illnesses. Because of the complexity of physical ailments and symptoms, research studies are limited in addressing the specific correlations of physical health and IVP [45]. For example, Onur et al. (2020) wrote that women diagnosed with Fibromyalgia Syndrome (characterized by chronic musculoskeletal pain) also reported being victims of partner violence (physical, social, economic, and emotional) [46]. Raya et al. (2004) observed that Andalusian women victims of IPV perpetration were more likely to suffer from hypertension and asthma [47]. More recently, Soleimania et al. (2017) observed that Iranian women who had experienced IPV in the form of psychological abuse had a greater incidence of somatic symptoms than women who had not experienced any form of abuse [48]. There appears to be an additive effect on the body when it comes to experiencing abuse. Women who have experienced various forms of abuse in their life (e.g., child abuse, past IPV, present IPV, and financial problems) have reported higher levels of somatic complaints in comparison to women who had only experienced IPV [49]. At least one study noticed that there was a greater incidence of type 2 diabetes in women who reported experiencing physical intimate partner violence [50].

Utilization of Health Care Providers
Aside from the various somatic complaints that are being described by women who have experienced IVP, Lo Fo Wong, et al. (2007), observed that women who had been physically and psychologically abused by their partners used healthcare providers more often and were also prescribed pain medication more frequently [51]. Also, Comeau, et al. (2012) noticed that women who had been abused by their intimate partners used antidepressants to deal with symptoms of depression [52]. Lastly, higher use of anxiolytics and antidepressants also has been observed in women who had suffered intimate partner violence [53].

Use of Cigarettes
Aside from using various types of medications, Sullivan et al. (2015) noticed that women who had been victims of IPV tend to smoke greater quantities of cigarettes in comparison to women who have not experienced violence [54]. Furthermore, it has also been observed that women who experienced perinatal IPV were twice as likely to smoke cigarettes in comparison to women without a history of IPV [55]. It is worth noting that smoking during pregnancy is a strong predictor of low birth weight [55 -57] and preterm birth [58]. Children born under these circumstances are more prone to being described as having more social problems, attention problems, as well as anxiety and depression by age 7 [59] and low birth weight adolescents show increased levels of mental health problems (emotional symptoms, social problems, and attention deficit) [60].

Current Scenario
Many contributing factors impact women suffering from intimate partner violence. These influences could be cultural, socioeconomic, political, and educational, to name a few. Major findings support the notion that women, who are less educated, socioeconomically disadvantaged, reside in patriarchal societies, or cohabitate are at greater risk of IPV. Another contributing factor is mental health symptomology. Further analysis is needed to better understand the correlation between mental health issues and IPV. Is poor mental health a precursor to IPV, or is IPV a potential cause for poor mental health? Various cultures have differing views pertaining to the topic of mental health and address this problem differently. Without proper treatment and proper advocacy for mental health, some women may feel caught in a cycle of hopelessness, stay in abusive relationships, and contribute to the social perception that IPV is an acceptable way of life.
With the current global crisis of COVID-19 and governments issuing stay-at-home orders, psychologists predict an increase in intimate partner violence. The Secretary-General of the United Nations stated the orders have led to a "horrifying global surge" in IPV [61]. Because of the difficulty to flee from the abusers, women may be at an even higher risk of "IPV-related health issues" [61]. The global pandemic is a major contributing factor to job loss, economic stress, and evictions. Economic crisis can potentially negatively impact relationships, regardless of marital status. With the looming effects of the pandemic, the World Health Organization will need to consider the level of depression, anxiety, stress, marital status, and socioeconomic status in women across varying cultures, and how the pandemic may have contributed to an increase in IPV.

Interventions
Empirically validated interventions aimed to address IPV are scarce. One study observed positive results through the implementation of a culturally relevant program with immigrants of Mexican origin. Specifically, the study observed that Latino men benefited from attending group sessions aimed to address, among others, their histories of childhood maltreatment, their challenges encountering different gender roles as they moved to the United States, their sense of control over their wives, and the development of "unequal but nonabusive relationships". The program included teaching men non-aggressive strategies and problem-solving skills through role-plays. Through these interventions, men became more understanding of their wives' experiences, as they transition to the United States, learned the impact of their aggressive behavior, and also learned to cooperate more within the home [62]. In addition to this report, another study focused on the empowerment of Latino women through the Moms' Empowerment Program. This intervention included providing advocacy services and social support to women. It targeted women's self-blame for experiencing IPV and helped women set forth goals to promote change in their lives while focusing on preserving their children's safety. Overall, the program appeared to be successful in helping reduce women's exposure to mild violence and physical assaults [63]. Another recent study carried out in Brazil observed positive results with the implementation of cognitive-behavioral interventions in women victims of IPV. Thirteen sessions with a weekly frequency, which included, among others, psychoeducation, problem-solving, and cognitive restructuring, showed effectiveness in reducing women's anxiety and depression and increasing their life satisfaction [64]. Aside from individual or group interventions, one study carried in Ghana examined the utilization of community-based structures (i.e., police, health and welfare organizations, and religious leaders) to raise awareness to the problem of violence against women, to guide talks about gender equality, challenge social norms that endorse violence, provide counseling services to couples experiencing IPV, and create referral structures to help victims.. The prevalence of IPV in the communities that received these types of interventions was lower than that of those areas that did not receive these services [65].

CONCLUSION
IVP is a complex issue that needs continued research and attention to provide better interventions. Global findings indicate that certain cultural groups are more tolerant of this problem and that they may tend to normalize it and/or accept it. Overall, IPV is more widespread in developing nations, especially those experiencing political-related-violence. Considering these findings, World Health Organization surveys and future studies should consider assessing the incidence of IPV among immigrants to the United States with histories of having experienced political violence. A study in 2008 showed that eleven percent of immigrant Latinos to the United States had experienced political violence in their countries of origin. Latino women who had lived this type of violence also reported experiences of feeling discriminated [66]. Future studies should focus their attention on clarifying these findings and their possible relationship with IPV, so that prompt interventions with immigrant populations could be developed.
A recent study shows that Hispanics and Blacks in the United States constantly worry about possibly experiencing violence perpetrated by police, a form of political violence. Hispanics worry about police violence four times more than Whites and Blacks worry about this type of violence five times more than Whites [67]. Considering these results, the WHO should also explore if reports of police brutality in black or immigrant communities in the United States correlate to rates of IPV in these communities.
Although there is ample information about the various factors associated with IPV, only a few studies have focused on examining empirically validated interventions to address it. Without this knowledge, it would be impossible to truly know if available interventions work or not. Research findings suggest that women, and in particular women from marginalized groups, should receive assistance and guidance to gain access to higher education institutions. Their educational attainment likely will become a protective factor in their life that could prevent them from ever experiencing IPV. Parity in access to higher-paying jobs likely could help reduce the prevalence of IPV. Well-implemented cultural change strategies also appear to be a solution to the problem of IPV. Societal structures (e.g., law, religion) and organizations (e.g., welfare) seem to be key participants in the development of respectful and nonviolent relationships between men and women that likely could prevent IPV from ever taking place. Early detection of violence within the home and follow-up interventions could prevent children from normalizing such behavior. Health care system screenings could detect early signs and symptomatology of IPV. These screenings could potentially ensure that multisystem interventions be implemented to disrupt the development of IPV and provide survivors with needed support. Lastly, research suggests that governments and their officials should refrain from endorsing politically violent acts. Governmental acts of violence likely could endorse or ignite the problem of IPV in nations.

CONSENT FOR PUBLICATION
Not applicable.