Representation of Migrants in Clinical Research in Ireland: A Cross-Sectional Analysis.

Introduction

Clinical trials should ideally consist of participants who reflect the characteristics of the population for whom the knowledge gained from the research is applicable (Muthukumar et al. 2021). Numerous studies have reported the significant underrepresentation of underserved groups in clinical research in countries such as Australia, the United Kingdom (UK), and the Republic of Ireland (Hughson et al. 2016; Bodicoat et al. 2021; Biggs et al. 2024a; Brijnath et al. 2024). The term underserved group refers to segments of the population that are represented in health research at lower levels than expected from population estimates (Bodicoat et al. 2021). Groups identified as underserved in clinical research are diverse and often only categorised based on characteristics such as age, ethnicity, or disability (Bodicoat et al. 2021). Other characteristics, however, including socioeconomic status and geographic location, can also contribute to a group's classification as underserved (National Institute for Health Research 2020).

There are several consequences of underrepresenting underserved groups in clinical research. First, the results of the research may not be generalisable to a broad population because different groups may respond differently to an intervention (e.g. a new drug or medical device) due to variations in physiology or disease state (National Institute for Health Research 2020; Brijnath et al. 2024). Second, being certain that the balance of risk and benefit of an intervention is favourable for a given group can only be achieved by studying the effects of the intervention in a range of diverse groups (National Institute for Health Research 2020). Third, if clinicians lack evidence of the effect of an intervention on a particular group, they may be reluctant to offer the intervention to that group, resulting in clinical opinion replacing evidence (National Institute for Health Research 2020). Moreover, the successful delivery of interventions to target populations is complex, with biological, psychological, sociocultural, and logistical differences having an impact (National Institute for Health Research 2020). Therefore, unless the effectiveness of an intervention has been tested in heterogeneous groups, there is no certainty that it will work in practice (National Institute for Health Research 2020). The COVID-19 pandemic serves as a recent example of this problem: COVID-19 disproportionately affected older populations, migrants, and ethnic minority groups. These groups were underrepresented in COVID-19 research (Biggs et al. 2024a), resulting in a lack of knowledge on which factors were contributing to a greater burden or severity of disease, and which interventions could be effective (Treweek et al. 2020). Without this knowledge, people in these groups can miss out on important benefits of treatments or not be spared harms (Treweek et al. 2020).

This paper focuses on migrants as an underserved group in clinical research. Defined as people who move across international borders for any reason (IOM 2019), a recent WHO report highlighted the health disparities that some migrants experience in host countries (WHO 2022). Due to the cause or nature of migration journeys, some migrants endure a substantial healthcare burden that is insufficiently addressed by research specifically tailored to meet their needs (MacFarlane et al. 2022; WHO 2022). Despite the notable differences in how these groups respond to or engage with healthcare interventions compared to other populations, clinical research often fails to address these disparities (National Institute for Health Research 2020; Bodicoat et al. 2021). As numerous studies have established the persistent underrepresentation of migrants and their consequences, several others have identified a complex array of barriers that hinder their involvement in clinical research. These barriers include language and communication, attitudes and beliefs, lack of trust, lack of knowledge of and access to clinical trials, eligibility criteria, and practical and logistical issues (Hughson et al. 2016; Treweek et al. 2020; Bodicoat et al. 2021; Brijnath et al. 2024). There can also be stigma around specific research topics, such as sexual and reproductive health (Brijnath et al. 2024). Conversely, some studies have highlighted strategies that are in line with Participatory Health Research (PHR) as a research model to enhance the inclusion of migrants, such as building and nurturing relationships with the communities in focus, employing roles like patient navigators or community liaisons to support individuals during the recruitment and consent phases, translating study documents, and adopting communication methods that respect cultural sensitivities (Hughson et al. 2016; Bodicoat et al. 2021; Alarcón Garavito et al. 2025).

Participatory Health Research (PHR) is a research paradigm that has the potential to address the challenges of involving migrants in clinical research as community partners (Roura et al. 2021). The goal of PHR is to do research with, not on, people by maximising the participation of those whose lives or work are the subject of the research in all stages of the research process (Roura et al. 2021). There is evidence that it can be effective in increasing the participation of minority groups in research and testing the generalisability of effective interventions (De las Nueces et al. 2012). Some examples of the success of PHR initiatives include the participation of migrants as partners in the development and implementation of cross-cultural consultations across four European countries and the co-production of a breast screening video by Asian migrant women in the UK (Roura et al. 2021).

In Ireland, the most recent Census of Population in 2022 reported that the population is increasingly diverse, with 20% of the population born in another country (Central Statistics Office 2022). Although two scoping reviews (Villarroel et al. 2019; Cronin et al. 2024a) have shown an increase in migrant health research over time in Ireland, there has been no systematic analysis of the representation of migrants in clinical research and whether/how PHR is being used to support the representation of migrants in clinical research. These gaps mean that first, there is a lack of evidence available to assess whether migrants are adequately represented and included in clinical research in the country, as well as the implications of this.

Second, there is a lack of evidence about whether clinical research is being done with or on migrants in Ireland. Therefore, this study aims to address these two gaps, with the following objectives:

Methods

A database of peer-reviewed migrant health research in Ireland was analysed (Cronin et al. 2024b), and an additional search was performed on ClinicalTrials.gov. These are described in turn below.

The rationale for searching the migrant health research database was that it contained a comprehensive list of 142 peer-reviewed studies from two scoping reviews of migrant health research in Ireland covering the period from 2001 to 2023. The first scoping review included 80 studies published from 2001 to 2017 (Villarroel et al. 2019). The second scoping review was an update and included 62 studies published from 2017 to 2023 (Cronin et al. 2024a). The inclusion criteria for the studies in both scoping reviews were as follows:

Our working definition of clinical research was taken from Ireland’s national funder for health research, the Health Research Board, which defines clinical research according to the definition of the Canadian Institutes of Health Research (see Table 1).

The following criteria were used to classify a study in the Migrant Health Research Database as clinical research:

Each study had to meet either criterion a (as a clinical trial) or criteria b, c, and d (as an observational study) to be categorised as clinical research. For studies categorised as clinical research, information was extracted on the specific disease or condition, whether it was communicable or noncommunicable, and the clinical setting of the study. Each of the clinical research studies was further categorised as a PHR study or not based on their explicit mention of the use of participatory approaches or community involvement in the research process. Also, each study was categorised based on whether it was a clinical trial or not and if it focused primarily on migrant health. The remaining studies in the database were categorised as population health or health services research, guided by the definitions in Table 1.

ClinicalTrials.gov is a website and online database of clinical studies that aims to provide information about clinical research to the public, researchers, and healthcare professionals (U.S. National Institutes of Health 2000). Study sponsors and investigators submit information on clinical research studies to the database, including the results of the studies, where available. Our rationale for using it is that it includes clinical research studies (interventional or observational) that are currently being conducted, will be conducted, or have been completed and is an important source for identifying unpublished clinical research studies.

The search on this website was conducted on the 17th of June 2025. There were no restrictions on the search by study date, study type, study status, or eligibility criteria. The initial search used Ireland as the location to identify the total number of studies registered in Ireland. Subsequently, the search strategy in Table 2 was used, with terms related to migration, ethnicity, and language, and Ireland as the location. The search terms were guided by those used in scoping reviews of migrant health research in Ireland and previous research (Fain et al. 2021; Muthukumar et al. 2021, 2025).

The search results were downloaded in a comma-separated value file format. Each study was categorised as relevant to migrant health based on whether migrants were the primary focus of the study or secondary demographic data were collected that included the migration status or ethnicity of participants. Data from relevant studies were extracted into a data extraction sheet in Excel format with the following headings: study title, study status, migrant variables collected, health condition, study type, and location. The extracted data were manually checked by two independent reviewers (AH and OA).

A descriptive analysis was conducted to categorise studies by type of research and by disease, setting, the use of participatory approaches or community involvement, study design, and whether there was a primary focus on migrant health.

Results

Our analysis of the database of migrant health research in Ireland was based on 141 studies – one study was retracted. Among the 141 studies, 41 (29%) were classified as observational clinical research, 44 (31%) as population health research, and 56 (40%) as health service research. Notably, no clinical trials were identified. Of the 41 observational clinical studies, only one study (1%) was designated as a participatory health research study. This was a study conducted by Brady et al., collaborating with non-governmental, community-based and statutory organisations to develop and pilot standardised data collection tools that were used to create a national surveillance system to monitor HIV testing in the community in Ireland (Brady et al. 2020). Three (7%) of the population health studies and 10 (18%) of the health services research studies were identified as participatory health research.

The total number of clinical research studies in Ireland registered on the ClinicalTrials.gov website was 2499 ( Figure 1). After applying the search terms related to migration in Table 2, there were 75 potentially relevant registered studies. After reviewing these studies, 12 were found to be relevant to migrant health research because they included migrants either as participants or collected secondary data on ethnicity and/or race. Of the 12 relevant studies, three were clinical trials. One of these three trials enrolled a cohort of Asian participants, and two recorded secondary information on ethnicity/race for all the participants. Of the nine observational studies, one included a cohort comprising recent migrants as participants and eight studies recorded secondary data on ethnicity/race for all participants. In addition to the 12 relevant studies, four studies had an inclusion criterion of language proficiency in English and potentially excluded migrants who did not speak English well.

Figure 1. Search results for clinical studies on migrants in Ireland in ClinicalTrials.gov. N = Number of clinical research studies.

Combining the findings from our review of the Migrant Health Research Database in Ireland (N = 41 clinical research studies from 141 studies) and a systematic search of ClinicalTrials. gov (N = 12 studies from 2499 studies conducted in Ireland), there were 53 studies (53/2640, 2%) relating to migrant health. These studies were analysed in detail. The analysis focused on the following characteristics: study title, source, disease/health condition, setting, use of participatory health research approach, whether it is an interventional study (i.e. clinical trial design) and if the study is primarily focused on migrant health. The results are presented in Table 3.

Further analysis described the distribution of diseases and conditions of interest across the 53 clinical research studies ( Table 4). Over a quarter of the studies (15/53, 28%) focused on communicable diseases, most commonly tuberculosis and HIV, and the proportions were similar in both the migrant health research database (12/41, 29%) and ClinicalTrials.gov (3/12, 25%). For non-communicable diseases, over one in 10 studies (6/53, 11%) focused on mental health conditions, including psychiatric disorders such as schizophrenia, affective disorders, depression, and psychosis. All of these studies were identified in the migrant health research database. Almost one in 10 studies focused on cancer (5/53, 9%) and all of these studies were identified in ClinicalTrials.gov.

Table 5 summarises the settings in which the studies were conducted. The majority of studies (39/53, 74%) were conducted in a hospital setting, either as an inpatient, an outpatient or both. Community settings were less common (10/53, 19%), and no studies were conducted in general practice. Other settings included the hospice, accident and emergency department, mental health service and laboratory.

Discussion

Conclusion

In summary, the findings of this analysis indicate that migrants are underrepresented in clinical research in Ireland. We found that migrant health research in Ireland is rarely clinical and that clinical research in Ireland rarely documents the inclusion of migrants in study samples. These results underscore the necessity of ongoing efforts to improve the inclusion of underrepresented groups in clinical trials. In the United Kingdom, several initiatives exemplify efforts to enhance inclusivity in clinical research. Notably, the National Institute for Health Research (NIHR) has established three INCLUDE Frameworks as part of its INCLUDE Initiative. These frameworks encourage researchers to carefully consider factors such as ethnicity, individuals with limited capacity to consent, and those facing socioeconomic challenges in their trials. Furthermore, the STEPUP (Strategies for Trialists to Promote Equal Participation in Clinical Trials for Under-served Populations) initiative offers guidance from the Medical Research Council-NIHR-Trial Methodology Research Partnership (MRC-NIHR-TMRP) to aid in the design of more inclusive clinical trials (Biggs et al. 2024b). Additionally, the SENSITISE project, co-funded by the European Union through the EU ERASMUS+ programme, commenced at the end of 2023 and will continue until the end of 2026. Acknowledging the lack of formal training on inclusivity in clinical trials, the project aims to provide education for students and clinical trial professionals. SENSITISE comprises four work packages, including a free, 12-week, open-access online curriculum focusing on inclusive design, cultural barriers, and case-driven application (Shiely et al. 2024).

The following recommendations emerge from this analysis with the objective of enhancing targeted outreach, education, and policy support for migrants to improve their equitable participation in clinical research.

Redefine research agenda: The emphasis of the clinical research findings from the 53 studies on diseases specific to migrants highlights the viewpoint of Ireland, the host nation. This suggests that it is essential to make practical efforts first to address the health needs that migrants consider a priority and to involve them in the planning, design, execution, and dissemination of research. This can be achieved by adopting frameworks such as INCLUDE and STEPUP in conducting clinical research. (Biggs et al. 2024b).

Build trust: Trust plays a crucial role in research that involves human participants. Establishing trust can be achieved by employing community-based and participatory research methods, which emphasise forming relationships within the community before starting the research (Alarcón Garavito et al. 2025). These methods are also enablers for recruiting participants in clinical research and developing communication strategies for sustaining engagement throughout the trial and beyond (Alarcón Garavito et al. 2025).

Improve the collection and reporting of race/ethnic data in clinical research: Researchers must foresee the potential social and ethical issues linked to population descriptors (Takezawa et al. 2014; Khan et al. 2022). They have a duty to communicate their research findings with precision and to consider how the public might interpret and react to the descriptors used in academic papers and media reports (Takezawa et al. 2014; Khan et al. 2022).

Although various factors and methodological constraints influence the representation of migrants in clinical research, these recommendations call for a significant shift towards implementing carefully designed strategies grounded in relationships among all key stakeholders, such as researchers, community members, healthcare providers, and policymakers. They could help to tackle the complexities of creating clinical research in Ireland that is inclusive of all of its population.