Intimate Partner Violence: A Bibliometric Review of Literature

Intimate partner violence (IPV) is a worldwide public health problem. Here, a bibliometric analysis is performed to evaluate the publications in the Intimate Partner Violence (IPV) field from 2000 to 2019 based on the Science Citation Index (SCI) Expanded and the Social Sciences Citation Index (SSCI) databases. This work presents a detailed overview of IPV from aspects of types of articles, citations, h-indices, languages, years, journals, institutions, countries, and author keywords. The results show that the USA takes the leading position in this research field, followed by Canada and the U.K. The University of North Carolina has the most publications and Harvard University has the first place in terms of h-index. The London School of Hygiene and Tropical Medicine leads the list of average citations per paper. The Journal of Interpersonal Violence, Journal of Family Violence and Violence Against Women are the top three most productive journals in this field, and Psychology is the most frequently used subject category. Keywords analysis indicates that, in recent years, most research focuses on the research fields of “child abuse”, “pregnancy”, “HIV”, “dating violence”, “gender-based violence” and “adolescents”.

According to the literature, America is the earliest region to study IPV. E.J. Alpert. proposed in 1995 that physicians can play an important role in the early intervention of IPV through querying women who were treated for emergency care [45]. Over the ensuing few years, many strategies were proposed to prevent IPV, such as training programs [46], abuse screening [7,38,40], and reducing poverty and alcohol consumption [41]. Since the WHO released the "World report on violence and health" in 2002, more and more countries joined the IPV research. The collaborations between regions or countries also are increasing.
Recently, bibliometric analysis has been an effective tool to quantitatively analyze academic publications to evaluate the research trends in different research fields, such as health care science services [47][48][49][50][51], Psychology [52,53], Economics [54,55], Energy [11,51,56,57] and Ecology [58,59]. Bibliometrics, first proposed by Alan Pritchard in a paper in 1969, is defined as "the application of mathematics and statistical methods to books and other media of communication" [60]. To our knowledge, this is the first time assessing the IPV research field using bibliometric methods. The aim of this research is to provide a broad overview on the IPV research area, including the following aspects: (1) the main contributors: country, institute, research group; (2) collaboration patterns: cooperation between countries; (3) the most productive journals; (4) top papers with highest citation numbers; (5) research trends by analyzing the author keywords. This study demonstrates the research focuses and hotspots of IPV research, which enable readers to understand the trajectories, key elements on the theoretical and practical contributions, and the future challenges of IPV.

Methods
The analysis was based on the papers related to "Intimate Partner Violence" which were obtained from the Science Citation Index-Expanded (SCI-E) and Social Sciences Citation Index (SSCI) during the period from 2000 to 2019. The data was retrieved through the "Web of Science Core collection" by searching the title, abstract, author keywords and KeyWords plus with the search formula of "Intimate partner violence" or "Intimate partner abuse" or "spous* violence" or "spous* abuse" or "wife violence" or "wife abuse" or "husband violence" or "husband abuse" on 20 July 2020. The data of the top 25 authors in "Intimate Partner Violence" and citation analyses were acquired on 20 July 2020. Keywords and international cooperation were analyzed using the Derwent Data Analyzer (DDA) software. The Impact Factor (IF) for each journal was determined according to the report from the 2019 Journal Citation Reports (JCR). Note that some related publications that do not use the above search formula may not be included in this analysis.
The top 30 most productive countries in the IPV research field are shown in Table 1. The USA led the list with the most publications (7947) and highest h-index (149). Canada was in the second position, but the amount of publications is only 12% of that from the USA. Other productive countries include the UK (899), Australia (631), Spain (554), South Africa (513), and Sweden (352). Switzerland took the first position of average citations per paper (71.73). The UK is listed in the second position (29.

Cooperation of Countries
Shown in Table 1, all the countries from Africa had a very high share of internationally collaborative papers, especially Kenya and Uganda. Ten European countries held a relatively high share of cooperative publications. Especially, Switzerland had an 84.17% share of co-author papers with other countries or regions. It is worth mentioning that, although the USA was the most active country-collaborating with 119 other countries or regions-over 80% of the papers published independently were from the USA. Altogether, most productive countries had frequent cooperation with other countries or regions.
The academic collaboration network of the top 15 most productive countries is shown in Figure 2. Derwent Data Analyzer (DDA) software was applied to draw the network diagram on the basis of a co-occurrence matrix. The size of the nodes is according to the number of publications and the thickness of the connecting lines represent the frequency of cooperation. It is clearly demonstrated that the USA cooperated most frequently with South Africa, India, the UK, and Switzerland with strong collaboration relationships. Furthermore, the USA, the UK, Australia, South Africa, Germany, and Switzerland had the biggest collaboration network within the top 15 most productive countries.

Contribution of Leading Institutes
A total of 6684 institutes have participated in the study of IPV. The top 20 productive institutes, which were from the top four most productive countries, are shown in Table 2. Among them, seventeen institutes are located in the USA, one in the Canada, the UK and Australia respectively, which indicates again that the USA dominates the IPV research area. The University of North Carolina ranks first in terms of total publications, followed by Johns Hopkins University and the University of Michigan. The London School of Hygiene and Tropical Medicine holds the first position for average citations per paper (ACCP). Harvard University has the highest h-index value. It is worth noting that there is no institute from Asia, Africa or Oceania on this list. We expect more countries will increase their funding input and strengthen international and domestic cooperation to prevent IPV. Additionally, we analyzed the share of cooperative publications between institutes (see Table 2). It can be seen that all 20 of the most productive institutions have very high collaboration rates, especially the University of California-San Diego and Harvard University. It suggests that IPV research requires the cooperation of multiple institutions such as: universities, hospitals, and sectors of government and non-government.

Contribution of Leading Authors
The top 25 most productive authors are shown in Table 3, based on the number of publications. J.C. Campbell led the list with 151 papers followed by J.G. Silverman (94) and G.L. Stuart. (87). Regarding the average citation per paper, C. Watts ranked first with 71.92 followed by R. Caetano (64.27), and R. Jewkes (62.19). The highest h-index was achieved by J.C. Campbell (43). Among these top 25 productive authors, 18 authors were in the USA, two in the UK and Spain, and one in Canada, South Africa, and Australia, respectively.

Contribution of Leading Research Areas and Journals
Twelve thousand three hundred and seventy-five papers related to IPV have been published in about 103 research areas in SCI and SSCI databases, among which the top 20 are listed in Table 4. 'Psychology' ranked in the first position in terms of the total publications and h-index, followed by 'Family Studies', Public Environmental Occupational Health' and 'Criminology Penology'. 'General Internal Medicine' led the list of the ACCP (45.38), followed by 'Neurosciences Neurology', and 'Pediatrics'.  Table 5. Approximately 48% of the papers were published in these top 50 productive journals. The top five journals produced 2590 papers with a 21.15% share of the publications. A bubble chart of the top 50 productive journals by year is shown in Figure 3. The Journal of Interpersonal Violence, the Journal of Family Violence and Violence Against Women were the top three most productive journals, with a sharp increase in IPV research outputs during the last decade. It can be clearly seen that there were few articles sparsely distributed in most of the top 50 journals from 2000-2007, however, there has been a rapid growth in publications since 2008. It is clear to see that more and more research workers have contributed to the 'International Journal of Environmental Research and Public Health'. It is worth noting that Lancet (IF = 60.392), one of the most authoritative academic journals in the world medical community and one of the most influential SCI journals, is in the 46th position on the list. This suggests that IPV is a popular and important research area.

An Analysis of Keywords
To elucidate the main focus and research trend of IPV research, 10,085 author keywords from 12,375 papers were analyzed. The raw data were cleaned to ensure that keywords with the same meanings were represented by one unified word. Among the author keywords, 6794 (68%) were used only once and 1279 (13%) used twice. However, the top 30 most used author keywords appeared 16,614 (35%) times. The large number of once-only author keywords may indicate a wide range of interests in IPV research. As a bubble chart can clearly express in 3D values, using the bubble size as the third dimension, one can be applied to track research frontiers [51,[61][62][63]. The top 30 author keywords by year are shown in Figure 4. Using visual bubble charts, the development trend of research can be clearly presented. Note that the number on the bubble represents author keyword occurrence frequencies and the number of publications.

An Analysis of the Most Cited Papers
Although the citation impact of a paper depends on many factors [64], it is still a measure of its influence in this research field. The top 20 most highly cited publications are presented in Table 6. The most highly cited paper was "Health consequences of intimate partner violence." published in the Lancet by Campbell, J.C. It led the list of total times cited with 1865 and held the second position for annual citations. "The Epidemiology of Depression Across Cultures" [65], authored by Kessler and Bromet, took the first position for annual citations with 128.00. "Prevalence of intimate partner violence: findings from the WHO multi-country study on women's health and domestic violence" authored by Garcia-Moreno, C., et al., ranked in the third position with annual citations of 106. 46.
Among these top 20 papers, eight were published in Lancet, and one in Psychological Bulletin, the American Journal of Preventive Medicine, the Annual Review of Public Health, Jama-Journal of the American Medical Association, the Clinical Psychology Review, the Archives of Family Medicine, the Annals of the New York Academy of Sciences, Pediatrics, Child Abuse and Neglect, Aggression and Violent Behavior, the Archives of Internal Medicine, and the Bulletin of The World Health Organization, respectively. The USA contributed nine of them, followed by South Africa (4), Switzerland (3) Canada (2), Australia (1) and Ireland (1), and again indicated that the USA was the leading country in this research field. It is worth noting that three papers from South Africa were related to the study of the relationships between IPV and HIV infection and prevention in South Africa. Through analyzing the publications about IPV, we found that 1547 papers were associated with HIV research and a 34% share of the publications was related to Africa. It suggested that more and more scholars agree that HIV and IPV are related to some extent [19,21,[66][67][68].

Discussion
One hundred and fifty-one countries contributed 12,357 publications to Intimate Partner Violence (IPV) research from 2000 to 2019, indicating that IPV is a global public health problem and attracting worldwide attention. It is clear that the number of publications has increased steadily since the WHO released the first World Report on Violence and Health in 2002. The number of papers from 2010-2019 was 9884, which represented 80% of the total number of publications. Also, the number of countries which were involved in IPV research increased every year, except for several fluctuations, which indicates that more and more countries have put their efforts to study and prevent IPV.
North America, Western Europe, and Australia were the most active regions in the research of IPV. This was further confirmed by the most active institutions and authors. There was no institute from Asia and Africa in the top 20 most productive institutions. China and India, as the world's most populous countries, had very low productivity. One possible reason might be the traditional culture difference, funding input, and economic level. Another possible reason is that while the WoS database is comprehensive, some journals published from India, China, and other Asian and African countries are not indexed in WoS. Furthermore, as most SCI papers are published in English, some non-native English-speaking researchers might not produce high quality papers due to the language problem to some extent. These thoughts might explain the low productivity from Asia and Africa.
The obvious change in the number on the bubble of the author keywords showed the trend of IPV research: "intimate partner violence" (4399 times) was the most frequently used keyword and increased sharply during the last ten years (2008-2019), followed by "domestic violence" (2166 times), "child abuse" (985 times), "violence" (650 times), "sexual violence" (611 times), and "HIV/AIDs" (605 times). It is worth mentioning that, among the top 30 author keywords, five were related to "woman", including "women", "pregnancy" "violence against women", "battered women" and "women's health" and two were related to adolescents and children, including "adolescents" and "child abuse", which indicates that the biggest victims of IPV are women and children. Studies on the impact of children and young adolescent's exposure to IPV have attracted great attention from the scholars over the last two decades [33,34,36,69,70]. This trend reflects on the one-in-four of the total 12,357 papers being related to children. Additionally, "child abuse" "pregnancy", "HIV", "dating violence", "gender-based violence" and "adolescents" were used at a very low frequency during 2000-2007 but increased rapidly during the last decade, which might be the new emerging research direction.
The top 20 cited publications are shown in Table 6. The article with the highest citation was a review article published in 2002 and discussed the increased health problems caused by IPV [14]. Overall, five papers were published in 2002. Therefore, 2002 was a milestone year in IPV research. The article "The world report on violence and health" analyzed and summarized the main points of the first report on violence and health released by the WHO in 2002 [4]. "Prevalence of intimate partner violence: findings from the WHO multi-country study on women's health and domestic violence" was published in Lancet in 2006 and discussed the prevalence of IPV in 10 mainly low and middle-income countries [5]. The report, "Prevalence and health effects of intimate partner violence and non-partner sexual violence", was released by the WHO in 2013 and demonstrated that 30% of all women from over 80 countries have experienced violence by an intimate partner [10]. The WHO, with other agencies, launched a RESPECT women program to prevent violence against women in 2019 [71].

Conclusions
Here, we presented a general overview of the Intimate Partner Violence (IPV) research area in terms of leading countries, institutes, and research trends. The USA definitely led IPV research with the most publications and highest h-index. There was no doubt that more and more countries have been participating in IPV research. Since IPV is a world health issue, we expect that, as more and more researchers join this research area, more results will be published based on the collaboration between different research groups all over the world, which will continue to make an effort to stop or prevent IPV. Needless to say, how to prevent IPV more effectively is still a big challenge, although many scholars have made various suggestions to intervene or stop IPV. Furthermore, more and more researchers have recognized that IPV is associated with women's vulnerability to HIV. We expect more research will focus on these areas.
This study can help potential researchers to quickly understand IPV globally. It also can provide useful information for relevant research in terms of identifying the research trends and potential collaborators, for example. Additionally, this study can help policy makers improve policymaking to prevent IPV.
Author Contributions: Author Contributions: Y.W. (Yuehua Wan) designed the study. J.C. and H.F. responsible for data collection. Y.W. (Yanqi Wu) analyzed, interpreted the data, and wrote the manuscript. All authors have read and agreed to the published version of the manuscript.