Global output of research on the health of international migrant workers from 2000 to 2017

In the past decade, there has been a significant increase in research about international migration due to its enormous economic, social, cultural, and health impact on both sending and receiving countries [1]. The term international migrant refers to any person who is moving or has moved across international borders [2, 3]. The total number of international migrants has reached 258 million in 2017 [4, 5]. Of this large number of international migrants 106 million were born in Asia, 61 million were born in Europe, 38 million were born in Latin America and the Caribbean, and 36 million were born in Africa. At the country level, India was the largest country of origin of international migrants (17 million), followed by Mexico (13 million). Other countries of origin with large migrant populations include the Russian Federation (11 million), China (10 million), Bangladesh (7 million), Syrian Arab Republic (7 million), and Pakistan and Ukraine (6 million each).

International migrants comprise a wide range of populations, such as workers, refugees, students, undocumented migrants and others. Each type of migrants has different health needs and stressors. Health needs of this large number of people are important public health challenges faced by both sending and destination countries. Migration for work is the most common form of migration, particularly in a globalized world with profound economic and political disparities. Geographic proximity and historical links are also important motivating factors for the flow of migrant workers, particularly within the same region [3, 5].

The term migrant worker refers to all international migrants who are currently employed or are unemployed and seeking employment in their present country of residence [6]. According to the International Labour Organization [6], there are 150.3 million migrant workers in the world, with most living in high-income countries and many engaged in the service sector. Gender distribution showed that 55.7% of international migrant workers are males and 44.3% are females. Almost half of the migrant workers are concentrated in Northern America, Northern, Southern and Western Europe. The Arab region accounts for 11.7% of all migrant workers. Most international migrant workers are found in agricultural, construction, food processing, and other low-skilled jobs. It is estimated that 16.7 million international migrants were part of the agricultural labor workforce worldwide [6].

International migrant workers contribute positively to the economic situation of source countries through sending remittances [7, 8]. Furthermore, migrant workers develop skills, learn new technologies, and make new social and professional connections that could benefit their home countries upon their return [9]. However, the health of migrant workers and the families they leave behind have not been given enough consideration by health-system planners in both sending and destination countries. Migrant workers are most vulnerable to health risks because they are often engaged in what is known as 3-D jobs—dirty, dangerous, and demanding (sometimes degrading or demeaning) [6]. For example, international migrant workers face several occupational hazards due to lack of training and/or appropriate safety measures [10]. Female migrant workers may be subjected to various types of violence and sexual exploitation [11, 12]. Furthermore, migrant workers might face cultural and language barriers which could negatively affect the quality of healthcare services they receive [13‐17]. A new dimension in the field of migrant workers health is the exploitation and abuse of labor and sex trafficked men, women and children, with negative health consequences on individuals and national health security [18‐20]. In developed countries, such as the USA and UAE, there are employer agencies that recruit international workers from low- and middle-income countries (LMIC) by making fraudulent and false promises. Those migrant workers might end up being abused, slaved, mistreated, and deprived of basic medical and healthcare services. It is common for female migrant workers in some destination countries to end up as victims to sexual violence and harassment [21].

Despite the large numbers of migrant workers and the serious health threats they are facing, there has not been any assessment of the peer-reviewed literature on the health of migrant workers. Unfortunately, certain governments have the misconception that research about migrant workers could negate developmental gains or damage their political and human right reputation [22]. Furthermore, a recent study on the global migration health called for research assessment of migration health of all categories of international migrants to spot gaps for intervention and future policy implementation [23]. Therefore, the aim of this study was to assess and analyze the global output of research on the health of international migrant workers to spot research gaps, enrich the international research agendas pertaining to migration health, and create a research repository on this topic. Specifically, the study will examine the growth of publications, authorship analysis, geographical distribution, international research collaboration, important themes discussed, and highly cited articles. The overall aim of this study is to provide baseline data on health-related research issues on international migrant workers for future planning and comparison. Furthermore, this study is in agreement with the 2030 global agenda of health and human rights set in Sustainable Development Goals (SDGs) [24].

The current study aimed to analyze and assess published literature on the health of migrant workers. Such analysis helps in addressing and optimizing clear strategies in both sending and destination countries to protect migrant workers. The current study showed that the volume of the retrieved literature was relatively low. A bibliometric analysis of literature on global migration health conducted by Sweileh et al. showed that a volume of more than 20,000 documents was published on global migration health from 2000 to 2016 [23]. This means that literature on the health of migrant workers represents less than 5% of the overall literature. The relatively lower volume of literature on health of migrant workers could be due to the limited number of worldwide scholars interested in the health of migrant workers. Furthermore, the health issues of migrant workers are usually hidden ones and might be difficult to research given the idea that migrant workers tend not to talk about their negative experiences to avoid losing their jobs [56]. A third potential reason is the fact that serious health issues of massive numbers of refugees dominated the field of migration health [1].

Analysis of research domains of the retrieved literature showed that research about occupational health dominated the field. However, the number of publications could be much higher if research about migrant workers was not complicated by issues related to employees and hidden working conditions [56]. Migrant workers often serve in jobs that natives are reluctant to perform [57]. Thus, migrants are more often exposed to potentially health-damaging work environments than native workers [58]. A review study on the occupational health of migrant workers in the USA showed that the proportion of fatal and nonfatal workplace injuries has been increasing among migrant workers due to the shift in hazardous jobs to the immigrant workforce [59].

Publications in communicable diseases among migrant workers were also evident in the retrieved literature. One concern of health officials in destination countries is that the sending countries tend to have higher prevalence of infectious diseases and less screening systems, which increases the risk of disease importation [60]. The focus on infectious diseases among migrant workers is also based on the idea that migrant workers might have higher risk of infections than non-migrants probably due to risky sexual behaviors, socio-economic factors, their living conditions and financial, language and cultural barriers to healthcare access [61‐63]. Both sending and destination countries need to have an improved screening and preventive measures to limit potential spread of certain serious infections carried by travelers [64]. For example, the rapid spread of pandemic (H1N1) influenza in Mexico led to fears among health officials in North America of potential transmission of the diseases by Mexican migrant workers. To avoid negative opinion and to contain the spread of the infection, health officials in Mexico and North America immediately implemented screening of migrant workers both at departure and arrival points.

The retrieved literature also included relatively good volume of publications on mental health of migrant workers and their families. The cultural shock and acculturative stress in addition to barriers to access healthcare services increase the risk of depression, stress and risk of suicide among migrant workers [65‐68]. Furthermore, work environment that might include physical abuse and harassment is a potential cause for negative mental health outcomes [37]. The presence of several documents about occupational health in the top ten cited documents emphasized the good share of research on occupational health in the retrieved documents.

The current study showed relatively lower research activity on NCDs on migrant workers. One potential reason for that is the fact that migrant workers are usually young and might not have a high prevalence of NCD compared to elderly people. However, migrant workers might get engaged in risky life style such as chronic tobacco smoking or alcohol abuse that could lead to NCD [69]. Furthermore, those with existing chronic illness might experience deterioration of their chronic disease due to interrupted healthcare services or lack of access to medications and medical follow up [70‐72]. Another important factor when considering NCD among migrant workers is affordability to cover for medications when needed which ultimately affects the health of migrant workers [55]. Maternal and reproductive health research domain was also dwarfed on the expense of occupational health and mental health domains. Female migrant workers often face more barriers related to reproductive healthcare, access to health services, child care, family planning services, prenatal care, and unplanned pregnancies than do native-born women [73, 74].

The current study showed that countries, researchers, and institutions in high-income destination countries contributed to a large percentage of retrieved documents. In destination countries, migration has important public health consequences that can affect the national healthcare system. Research experts and research budgets in destination countries are key reasons for the prominent research role of these countries. The findings in the current study showed that China is one of the top ten active countries in research about health of migrant workers. China has become not only a source, but also a destination for migrants from all over the world. There are 60 million overseas Chinese around the world according to the Annual Report on Chinese International Migration [75]. Other Asian countries such as Malaysia, India, and Thailand were also among top ten active countries in producing research about health of migrant workers. This was unsurprising given that more than 100 million of international migrants came from Asia [3, 76].

Despite that the Arab region with approximately 11% of the global migrant workforce had limited and even negligible contribution to literature on health of migrant workers. However, there is frequent worldwide media coverage around the South Asian construction workers building the football stadiums for the 2022 football world cup in Qatar.

The contribution of source countries to literature on migrant workers was low due to the that most of the source countries are poor or undergoing internal civil war or regional conflicts, which limits research productivity from such countries. Effective international health planning that covers migrant workers requires a certain extent of international research collaboration among different countries. Such collaboration was absent which affects collaborative efforts of screening migrant workers for potential contagious diseases that might spread by travelers. Furthermore, collaboration between sending and destination countries is required to set plans to face mental health problems for migrants and families they leave behind. Furthermore, both sending and destination countries need to collaborate to increase awareness of migrant workers about their legal and human rights at working places. Of paramount importance is the efforts directed to increase awareness about potential labor trafficking and exploitation into sex industry or dangerous labor. Finally, sending countries need to collaborate with destination countries to attract back skilled migrant workers to ensure sustainable development in sending countries.

The current study, up to the author’s best knowledge, is the first bibliometric analysis of literature on the health of migrant workers. However, the current study has a few limitations. Bibliometric analysis only picks up published literature in academic journals. There are some reports in grey literature, which may be informative for the field, but were missed in this analysis. In the current study, the research strategy was designed to retrieve the maximum number of documents with minimum false positive and negative results. However, the presence of false positive and negative results is always a possibility. The use of Scopus might have created some bias towards destination countries because journals indexed in Scopus are mainly in English and produced by developed countries. Finally, data obtained might have some percentage of errors due to Scopus updating process. Therefore, a margin of error needs to be considered when interpreting top active authors, institutions, and countries. The overlap due to intra-country collaboration needs to be considered since more than one active author might share similar research output. All these limitations are typical of any bibliometric analysis and are not unique to the current study [26, 41, 77‐80].

The current study showed that research on migrant workers’ health need to be strengthened and encouraged given that the volume and growth rate were relatively inadequate. Attention to research gaps such as the focus on NCD and maternal and reproductive health is also needed. International research collaboration and research networks that include countries of origin and receiving countries were deficient. Building such collaboration and networks require recruitment of large numbers of scholars from different parts of the world to the subject of migration health in general and migrant workers’ health in particular.