Suicide Risk among Immigrants and Ethnic Minorities: A Literature Overview

Recent studies have demonstrated that immigrants and ethnic minorities may be at higher risk of suicidal behaviour as compared to the general population. We conducted a literature search to identify studies in English from 1980 to 2017 related to suicide risk among immigrants and ethnic minorities. Six hundred and seventy-eight reports were screened, and 43 articles were included in the qualitative synthesis of the review. Some studies reported lower rates of suicide attempts, while other findings suggested higher rates of suicidal behaviour and deaths among immigrants as compared to the native population. Also, a positive correlation was found between suicidal behaviour and specific countries of origin. Non-European immigrant women were at the highest risk for suicide attempts, a group which included young women of South Asian and black African origin. Risk factors among migrants and ethnic minorities were found to be: language barriers, worrying about family back home, and separation from family. The lack of information on health care system, loss of status, loss of social network, and acculturation were identified as possible triggers for suicidal behaviour. Overall, results suggest that specific migrant populations and ethnic minorities present a higher risk of suicidal behaviour than native populations, as well as a higher risk of death by suicide.


Introduction
Recently, a growing need for a better understanding of mental health issues among immigrants and ethnic minorities has emerged worldwide [1][2][3][4][5]. Europe is now facing the largest migration since the Second World War, resulting in new research questions about the extent of the burden of mental health disorders in migrants [1]. Migrants often experience physical and emotional trauma, including being victims of torture. This may be related to their risk of several psychological problems, such as post-traumatic stress disorder (PTSD), mood and anxiety disorders, and panic attacks, with symptoms of sleeplessness, nightmares, and flashbacks.
Several studies have suggested an increased risk of common mental disorders such as depression as well as psychotic disorders in immigrants as compared to native populations [6,7]. A meta-analysis suggested that migration could be considered a unique risk factor for severe mental health disorders such as schizophrenia [8]. Many studies also focused on women's mental health, and suggested that immigrant women are at higher risk for postpartum depression than non-immigrant women [9].
Recent research has demonstrated that immigrants may be at a higher risk for suicidal behaviour [10,11]. Several authors have also suggested that suicide risk may vary among ethnic minorities [12], and they may have different and more specific risk factors for suicidal behaviour than the general population, such as acculturative stress [13]. As suggested by Wyatt and colleagues [13], acculturation (a process by which subjects acquire the attitudes, values, customs, beliefs, and behaviours of a different culture) may play a role in the development of a suicidal crisis among migrants and ethnic minorities, besides classical psychosocial and psychopathological risk and protective factors [13]. Moreover, the impact of acculturative stress on public health is complex and the underlying theoretical framework, its public health impact, and mental health implications are not yet clear [14,15]. To our knowledge, this is the first study providing a literature overview on suicidal behaviour and specific risk factors both in migrants and ethnic minorities. Thus, the aim of the present paper was to provide an overview of the literature on suicide risk among these two populations and explore potential differences between them.

Search Strategy
In order to provide a novel and timely systematic review concerning suicidal behaviour among immigrants and ethnic minorities, we used the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement for reporting systematic reviews [16]. We conducted a MedLine, Excerpta Medica, PsycLit, PsycInfo, and Index Medicus search to identify all papers and book chapters in English on the main topic for the period from January 1980 to March 2017. We used as specific key words: "suicide" (or suicidal or suicidality), "ethnic minorities" (or ethnicity, ethnic groups, ethnic communities), and "migrants" (or immigrants), including additional references with hand-searched bibliographies of screened articles.

Study Selection
As shown in Figure 1, a total of 998 abstracts were screened through the initial database searches. After duplicates were removed, a total of 678 reports were obtained and full texts were screened with a brief examination of titles and analysis of abstracts. Of these, 77 articles were identified as potentially relevant, and 45 were included in the qualitative synthesis based on the consensus of at least two authors. We gathered data from the initial 77 articles using a template form in Microsoft Excel, according to study characteristics, geographical area of interest, and results.

Eligibility Criteria
Articles that met the following criteria were included: (1) publication in a peer-reviewed journal between 1980 and 2017; (2) publication in English; (3) original study (e.g., not a review); (4) focus on suicidal behaviour; and (5) analysis on immigrants and/or ethnic minority population. The exclusion criteria applied were: failure to report on suicidal behaviour, sampling only from geriatric or paediatric subjects, repeated reports from the same study, and not reporting in English. Thirty-three articles did not fulfil the inclusion criteria, and the remaining 44 were included in the final review.

Study Concept, Quality Assessment and Terminology
The main aim of this research was to examine suicidal behaviour in immigrants and ethnic minority populations, reviewing the recent literature on this topic in order to identify and understand possible risk factors for suicide and attempted suicide in the investigated population.
A quality assessment was performed as shown in Table 1, rating studies with the following criteria: (I) sample size (not reported 0 points, <1000 1 point, ≥1000 2 points, ≥10,000 3 points); (II) study method (1 or 2 points); (III) evidence-based measures assessing suicide or suicide attempts (0 or 1 points); and (IV) reliability of data (1 or 2 points). The maximum score obtainable for each study was 8.
To clarify the terminology used in the article, suicidal behaviours refers to both suicide (resulting in a fatal outcome), attempted suicide, and suicidal ideation (thoughts about suicide such as plans and ideas) [17].
With the term migrant (or immigrant), we refer to the definition of the International Organization for Migration (IOM). Although there is no formal legal definition of an international migrant, most experts agree with IOM, which describes a migrant as any person who is moving or has moved across an international border or within a state away from his/her habitual place of residence regardless of: (1) the person's legal status; (2) whether the movement is voluntary or involuntary; (3) what the causes for the movement are; or (4) what the length of the stay is. In addition, the types of migration can be categorized into short-term migration (within 3 and 12 months), and long-term migration (for a duration of one year or more).

Study Concept, Quality Assessment and Terminology
The main aim of this research was to examine suicidal behaviour in immigrants and ethnic minority populations, reviewing the recent literature on this topic in order to identify and understand possible risk factors for suicide and attempted suicide in the investigated population.
A quality assessment was performed as shown in Table 1, rating studies with the following criteria: (I) sample size (not reported 0 points, <1000 1 point, ≥1000 2 points, ≥10,000 3 points); (II) study method (1 or 2 points); (III) evidence-based measures assessing suicide or suicide attempts (0 or 1 points); and (IV) reliability of data (1 or 2 points). The maximum score obtainable for each study was 8.
To clarify the terminology used in the article, suicidal behaviours refers to both suicide (resulting in a fatal outcome), attempted suicide, and suicidal ideation (thoughts about suicide such as plans and ideas) [17].
With the term migrant (or immigrant), we refer to the definition of the International Organization for Migration (IOM). Although there is no formal legal definition of an international migrant, most experts agree with IOM, which describes a migrant as any person who is moving or has moved across an international border or within a state away from his/her habitual place of residence regardless of: (1) the person's legal status; (2) whether the movement is voluntary or involuntary; (3) what the causes for the movement are; or (4) what the length of the stay is. In addition, the types of migration can be categorized into short-term migration (within 3 and 12 months), and long-term migration (for a duration of one year or more).
The term refugee refers to the definition of the Statute of the United Nations High Commissioner for Refugees (UNHCR), which delineates a crucial legal difference with respect to the migrant population [18]. Although it is common to see the two terms used incorrectly as synonyms, refugees are specifically all persons who are outside their country of origin for reasons of violence, persecution, or conflict. As a result, they require international protection and are covered by international law.
We found some discrepancies with regards to the use of the term ethnic minority. There is no legal definition of ethnic minorities in international law; however, in Europe the definition is provided by the European Charter for Regional or Minority Languages and by the Framework Convention for the Protection of National Minorities. National (ethnic) minorities can be theoretically (not legally) defined as a group of people living within a national state with the following characteristics: (1) status of a minority among the citizen of that state or representing a smaller group than the rest of the population of the state; (2) distinct culture, language, religion and will to preserve them; (3) not in a dominant position; and (4) long-term presence in the territory [19].

Suicide Attempts and Ideation in Immigrants
As shown in Table 1, some studies reported that immigrants have lower rates of suicide attempts than the native population, with annual suicide mortality rates of 1.79 per 100,000 among adolescents with migrant status, compared to 3.05 for native-born individuals [20]. Moreover, a significantly decreased risk of depression was also reported: 10.8% for the migrant group, as compared to 18% for non-migrant group [21]. Conversely, other studies did not find a significant difference in rates among migrants and natives [22], or found mixed results [23][24][25][26]. Taken together, a majority of studies showed higher rates of suicide attempts among immigrants than the native population [27][28][29]. Several years ago, in Sweden, a higher risk ratio (1.3) was found for attempts in both men and women of foreign-born minorities as compared to the native population [30]. In England, suicide rates in migrants ranged from 15 to 17.4%, which are above the native-born rates [31,32]. Filipino migrants working in home care in Israel reported a prevalence of lifetime suicide attempts of 4.5% as compared to a rate of 1.4% in their home country [33]. Similar results were found among ethnic minorities in the Netherlands: Turkish and Surinamese females had a higher risk of attempted suicide, with a rate of 483/100,000 compared to 246/100,000 of Dutch females of the same age [34]. Duldulao and colleagues discovered that first-generation United States-born Asian American women had a significantly higher prevalence of suicidal ideation than their other national counterparts [35]. Overall, data suggested that non-European immigrant women are at the highest risk of suicide attempts [23,32,34], although a positive correlation between suicidal crisis and specific countries of origin was found. A rate of 37.7/1000/year was found for South Asian women as compared to 23.3/1000/year for white women and 23.9/1000/year for black women [36]. Black and Asian minority groups in Europe and the USA were shown to have an increased risk of developing mental health problems as well as a higher risk of associated factors for suicide attempts [23,36,37].

Suicide Deaths in Immigrants
Taken together, results indicated a higher risk of suicide deaths among immigrants and ethnic minorities. Shah and colleagues demonstrated that suicide mortality ratios in foreign males living in England and Wales were generally higher in those of younger age groups (between 20-24 and 50-54 years) born in Eastern European or Caribbean regions. The rates were generally lower in those born in Western Europe in the younger age group, and higher in the age bands of 75-79 and 80-84 years of age. Woman in older age bands (70-74 and 85+ years) and coming from African, Caribbean, and Chinese countries were found to have a higher suicide mortality ratio [38]. Bhui highlighted higher suicide rates among young women of South Asian origin and black African origin, with SMRs (Standardized Mortality Ratios) of 2.8 and 2.7, respectively [39].       ---Epidemiological data on the entire Australia population.
The higher rates of suicide in older males in non-metropolitan areas of Australia is mainly due to the high migrant suicide rates in these regions, but the same it is not true for the higher rates of male youth suicide in non-metropolitan areas.

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Data obtained from the National Coroners' Information System (NCIS).

Second-generation migrants in
Australia had a lower suicide risk compared to first-generation migrants or locals (third-plus-generation), and this evidence could be explained by their better socioeconomic status.  This study examined differences in suicide rates between immigrants and non-immigrant Canadian residents. Immigrants had 50% lower suicide rates, which increased with age and involved predominately males.

Suicidal Ideation and Attempt among Ethnic Minorities
Studies have shown higher rates of suicidal behaviour and self-harm in ethnic minorities. O'Keefe and colleagues reported that American Indian suicidal ideation can be predicted by thwarted belongingness and perceived burdensomeness [40]. The study involved 171 American Indians (representative of 27 different tribes) and employed an online survey based on an empirically supported theoretical model of suicide-the Interpersonal-Psychological Theory of Suicide [72]. The results showed that the interaction of thwarted belongingness and perceived burdensomeness predicted suicidal ideation better than each predictor taken individually [40].
Walker and colleagues investigated the role of acculturation in suicidal-behaviour among African descendants living in the USA, in a sample of 423 adults using the African American Acculturation Scale. Contrary to previous studies, it was found that just religious well-being, and not acculturation, was predictive of suicidal ideation and history of suicide attempt [46].
Else and colleagues identified, among Hawaiian youth, high levels of acculturation as a risk factor for suicide attempts [73]. Moreover, Scheel examined suicidal behaviour among American Indian college students [41]. They found that American Indian college students' suicidality was characterized by: a rate of suicidal ideation comparable to general college students and low rates of awareness of traditional tribal suicide (10%). Moreover, 57% of the participants with suicidal ideation reported that they would not seek help from a mental health professional. Furthermore, they identified that the help-seeking likelihood depended on the cultural commitment. Participants more committed to tribal culture prefer counselling from American Indian counsellors (e.g., tribal healer/medicine man: 22%; American Indian mental health professional from university: 24%; from the campus: 44%; outside the campus: 41%). Less committed participants instead showed a moderate openness to seeking help from non-American Indian counsellors [41].

Suicide Deaths in Ethnic Minorities
Studies have shown increasing rates of suicide deaths, especially in youths from ethnic minorities [42,73]. In Native Hawaiians, death by suicide is a relatively frequent phenomenon among adolescents and young adults, as they have higher lifetime prevalence rates of suicide attempts (12.9%) in comparison with non-Hawaiian students (9.6%) [73].
On the other hand, among the ethnic minorities living in the United Kingdom, black Caribbean (SMR = 0.26) and South Asian (SMR = 0.4) women showed a lower risk of suicide compared to the native population [44]. Black Caribbean and young Black African men (SMR = 2.05) were revealed to have, instead, a higher risk of suicide than the native population [44]. In Hawaiians and other Pacific Islander populations, rates and distribution of suicide deaths were similar to other indigenous population (such as Maori in New Zealand), with a first peak in adolescents and young adults (annual suicide mortality rates per 100,000 by age: 52.8/100,000 for 15-24-year-olds, increasing to 72.4/100,000 for 25-44-year-olds) and then a sharp decline instead of a second peak in the elderly, which is typical of the bimodal distribution in United States and most Western countries [73].
Wong and colleagues focused on youth risk factors for suicide in ethnic minorities among American high school students, using data from the 1999-2009 Youth Risk Behaviour Surveys [42]. Native Hawaiian/Pacific Islander adolescents and multiracial adolescents had a higher prevalence of risk factors for suicide (such as depression, suicide ideation, plans, attempts and/or severe attempts), comparable to that of American Indian/Alaska Native adolescents already known in the literature as an "at-risk population" [42].
Bhui and colleagues also investigated the possible role of ethnicity in suicidal behaviour and related risk indicators among patients within a year of contact with psychiatric services [39,44]. Although they revealed that ethnicity influenced suicide rates and indicators of suicide risk, classical indicators of suicide risk such as "risk-related symptoms" (suicidal ideas, depressive symptoms, emotional distress, and hopelessness) were less common in ethnic groups such as black Africans (SMR 2.05) and South Asians, as compared to white British individuals [44]. Another study conducted by Ngwena in London public health services focused on trends of suicidal behaviour in black and minority ethnic (BME) groups. Among 996 BME patients admitted to the acute psychiatric ward with suicide attempt or self-harm-injury, those of Arab origin and South Americans were more prevalent (28%), followed by Western and Eastern Europeans (26%) [45].
Hunt identified the characteristics of psychiatric patients from ethnic minorities who died by suicide through the observation of 282 suicidal patients from ethnic minorities (6% of total) who had been in contact with mental health services in the 12 months prior to death. In these patients, suicide was characterized by: more violent methods, first episode of self-harm, higher rates of schizophrenia, unemployment, history of violence, and drug misuse [43].

Cultural Stress as Risk Factor for Suicidal Behaviour in Immigrants and Ethnic Minorities
Hagaman and colleagues investigated suicides among Bhutanese refugees resettled in the United States between 2008 and 2011, attempting to identify psychological characteristics and risk factors. Considering the small sample size, they showed a large presence of different post-migration difficulties in the investigated population [48]. The most common risk factor was a language barrier (71%), which seems to contribute to the development of hopelessness. Separation from family (43%) and worrying about family back home (57%) were also recognized as contributing factors to suicidal behaviour. Ngwena suggested other risk factors for self-harm, suicide, or suicide attempt in black and minority ethnic groups: arranged/forced marriage, lack of information on the health care system, loss of status and loss of social network, and also acculturation and thwarted ambition [45]. High levels of acculturation was identified as a risk factor for Hawaiian youth suicide attempts in another study [73]. In African descendants living in the USA, religious well-being was found to be a predictor for suicidal ideation [46].
Wong confirmed that multiracial adolescents more frequently reported a liability to mental disorders and health risk behaviours or dangerous conducts, such as substance use and violence [42]. In addition, immigrant status contributed negatively to acculturative stress, cultural conflicts, and socioeconomic difficulties. In England and Wales, as compared to native white people, suicidal ideation, emotional distress, and hostility were found to be less frequent among black Africans, black Caribbean individuals, and South Asians, while depression and a sense of hopelessness were more prevalent among South Asians [39]. These differences between native people and minorities suggest potentially different pathways to suicidal behaviour among different populations and that cultural stressors play a key role as risk factors for suicidal behaviour.

Discussion
The present overview suggested that findings on suicidal behaviour in immigrants are complex and it is difficult to delineate a theoretical framework explaining findings from the literature. On one hand, several studies found higher rates of suicide attempts among immigrants compared to native populations and that immigrants have a higher risk of experiencing suicidal behaviour than the same population in their home countries [27][28][29]74]. On the other hand, some studies did not reveal differences in suicidal behaviour between immigrant and native populations [22]. However, among the immigrant group and ethnic minorities, specific populations should be considered with regard to their risk of attempting suicide and also for suicide deaths, such as South Asian and black African women [36,39]. In terms of the literature related to immigrants, we found a lack of studies related to suicidal behaviour in ethnic minorities. The highest risk of suicide was found among black Caribbean individuals and young black African men living in the United Kingdom, suggesting that this might be related to specific environmental and psychosocial risk factors [44]. Some authors focused specifically on Native Hawaiians [73] and American Indian/Alaska Native adolescents [42], which have been found to be populations at risk for suicide death.
Various studies have also highlighted that immigrants and ethnic minorities do not receive the same psychiatric care during or after a suicide attempt or are less likely to contact psychiatric services when experiencing suicidal thoughts and/or engaging in suicidal behaviour [33,39,43]. This may lead to a global worsening of their mental health condition and an increased risk of suicide. In addition, if we take into consideration the different rates of suicide attempts and deaths, evidence indicates various patterns and mechanisms.
According to the Interpersonal Psychological Theory of suicide, perceived burdensomeness is a key ingredient for a heightened risk of suicide, together with low belonging, social alienation and the ability to enact self-injury behaviours [72]. Although Joiner's theory holds true for non-minorities and non-immigrants as well, it can provide an explanation of the underlying mechanism related to the increased risk of suicide presented by these populations. Indeed, socioeconomic factors such as poor socio-economic status, social exclusion, discrimination, or deprivation [45,75] are more clearly related to suicidal behaviour rather than the status of migrant itself [25,64]. In conclusion, our findings suggest that migrants and ethnic minorities may be considered as a moderate-high risk group for suicidal behaviour, but this requires further and more specific investigation. Interestingly, ethnicity is related to different risk factors for suicide that are common among general population, such as; suicidal ideas, depressive symptoms, emotional distress, and hopelessness. These risk factors are less common in ethnic groups such as black Africans and South Asians [44]. This suggests that ethnic minorities may manifest a specific phenotype of suicidal behaviour; however, more studies are needed to understand the underlying mechanisms that may explain these differences. Further studies are needed to develop specific suicide prevention strategies targeting ethnic minorities, which represent an effective public health intervention.

Limitations
The present review should be considered in the light of several limitations. First, the articles included in our synthesis were significantly different in terms of sample size, study design, and methodology, and this made it difficult to provide a quantitative synthesis. In addition, the samples included in this review varied widely on age, instruction, culture, traditions, and religious beliefs. Future studies should focus on investigating different rates and patterns of suicidal behaviour in the same population of migrants or ethnic minority longitudinally, in order to evaluate the influence of integration and acculturation on reducing suicidal behaviour.

Conclusions
Taken together, a majority of studies demonstrated higher rates of suicide attempts among immigrants than the native population. Risk factors among migrants and ethnic minorities were found to be: language barriers, worrying about family back home, and separation from family. Lack of information on the health care system, loss of status, loss of social network, and acculturation were identified as possible triggers for suicidal behaviour. Both migrant populations and ethnic minorities may have unique risk factors for suicidal behaviour; however, more studies are needed to clarify them. Additional research is required in order to develop a more reliable and standardized assessment of suicidal behaviour in these populations and to identify dedicated strategies of risk prevention for each group. It is also relevant for future studies to address the specific factors that influence suicidal thoughts and behaviours in each different ethnic group.

Funding:
No author or immediate family member has financial relationships with commercial entities that might represent the appearance of a potential conflict of interest.

Conflicts of Interest:
The authors declare no conflict of interest.