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Background Adaptive clinical trials increasingly aim to detect heterogeneity of treatment effect (HTE) to guide personalized care. However, most adaptive designs rely on predefined subgroups and are limited in their ability to uncover unknown or complex sources of HTE. Bayesian statistical methods offer a flexible alternative, enabling real-time learning and adaptation within trials. This review evaluates Bayesian methods used to detect hidden HTE in adaptive clinical trials, with attention to their methodological innovations, operating characteristics, and consideration of equity and inclusion in trial design. Methods We conducted a systematic search of MEDLINE, Embase, and other databases to identify original studies that developed Bayesian methods for detecting unknown HTE within adaptive clinical trial designs. Eligible studies were reviewed and synthesized based on design features, statistical methodology, operating characteristics, reproducibility, and whether equity-related factors were explicitly considered. Equity considerations included whether studies incorporated variables related to underrepresented populations—such as age, sex, race/ethnicity, or geography—examined intersectional subgroup effects, or explicitly framed their methods as tools to address health disparities. Results Of 2826 screened records, seven studies met inclusion criteria. Bayesian methods included random partition models, spatial models, logistic regression with dimension reduction, adaptive randomization using machine learning classifiers, and adaptive enrichment or platform designs incorporating model averaging or latent subgroup estimation. In simulation studies, these methods often showed improvements in subgroup detection, efficiency, or power relative to non-Bayesian comparators. None were tested using real-world trial data. Reproducibility was limited overall, with analytic code only available for the three most recent studies. Notably, none explicitly framed their methods as tools to address inequities in treatment outcomes across population subgroups. Conclusions The small number of simulation-based studies illustrates preliminary but promising directions for applying Bayesian methods to detect HTE in adaptive clinical trials. While these approaches demonstrate potential to enhance trial adaptability, scalability, and inclusiveness, current evidence remains limited and largely conceptual. Incorporating an equity lens into future methodological development, alongside greater emphasis on empirical validation and open science practices, will be essential to determine their practical value in advancing equitable clinical research.

Background Digital research methods were rapidly adopted into clinical trials and health research during the COVID pandemic in 2020. Current UK policy aims to make digital research methods a norm, but their influence on recruitment, retention, and representation in health research remains largely unknown. Whilst efforts have been made to improve engagement with digital health interventions, less attention has been given to digital research methods—such as informed consent, data collection, and research communications—despite their potential to influence study participation and participant experience. Objective This qualitative study aims to understand the factors influencing the initial uptake and ongoing engagement with digital research methods across diverse populations, capturing experiences and perspectives to inform diverse and efficient health research conduct. Methods Semi-structured interviews were conducted with 50 people who had participated in health research in the past 12 months. Reflective thematic analysis was used to understand factors influencing study engagement from participant perspectives, acknowledging the role of the researcher in data interpretation. Results Three interconnected themes were identified: (1) Digital Positionality: The Interplay of Social Position, Personal Experience, and Identity; (2) Power Redistribution in Research Relationships: Navigating Vulnerability and Agency; (3) Trust Assemblages: How Intersecting Identities Shape Multi-modal Verification Practices in Research Engagement. These themes illustrate how intersecting identity factors and social contexts shape engagement with digital methods in health research. The first theme revealed how factors such as age, social role, migration, and socioeconomic status create pathways towards or away from engagement with digital methods. The second theme highlights how different digital methods can shift power dynamics in participant-research relationships or expose social vulnerabilities. The third theme uncovered the complex ways participants established trust in research, relying on multi-channel trust makers. Conclusions The study reveals intersecting factors shaping participant engagement with digital methods, offering insights to enhance research conduct and increase diversity in health research participation. Future studies should integrate theoretical frameworks to examine these influencers and develop effective approaches for optimising diverse engagement with digital methods.

The importance of conducting inclusive research is well-established, yet recruiting a sample which reflects the distribution of a disease or condition within a target population has proven elusive for many triallists. We draw on our experiences of achieving inclusive recruitment through the intentional protocol design and delivery in the ILANA (Implementing Long-Acting Novel Antiretrovirals) study to highlight some tangible steps that could be extrapolated to trials to aid inclusive recruitment to research and produce findings which can contribute to tackling health inequities. These include the importance of meaningful public involvement from start to finish, drawing on existing data to determine appropriate targets, factoring targets into analysis plans through pre-specified analyses and triangulation with qualitative data, and making targets mandatory (rather than aspirational) through a range of strategies. We believe ILANA offers a proof of concept for triallists seeking to radically improve representation and conduct more equitable RCTs that engage all those who could benefit.

The lack of diversity in clinical studies has significant ethical and health consequences, limiting the development of effective treatments for diverse populations. Homogeneous participation in clinical studies contributes to health disparities, particularly among historically underrepresented groups in the United States (US). Racial, ethnic, and other minoritized populations have long been excluded from clinical research. In response, the US Congress mandated the National Institutes of Health to assess the impacts of insufficient diversity in clinical studies. Despite efforts by the government, non-profit organizations, and industry players to improve diversity in clinical studies, progress has been slow due to fragmented approaches. For instance, the new US administration (2025) has recently released executive orders which threaten to reverse the progress made in inclusive clinical research. The Stanford Think Tank on Diversity and Equity in Clinical Trials, held in September 2023, brought together key partners across multiple sectors and professions to discuss barriers and explore potential solutions to participation in clinical studies. In this commentary, we discuss the importance of collaborative, inclusive strategies in clinical study design to advance equitable health outcomes for all. Further, we discuss potential implications of the government’s dismissal of diversity, equity, and inclusion initiatives on diverse research participation.

Recruitment and retention of participants remain critical challenges in clinical trials, often requiring innovative approaches to ensure sufficient enrolment and sustained engagement. Social media advertising offers the potential to reach target populations quickly by leveraging demographic, geographic and interest-based targeting. This mixed-methods observational study evaluates participant experiences and the effectiveness of various recruitment routes within a trial of a treatment for acne. Demographic variables, including age, ethnicity, acne severity and acne duration, were stratified primary care, secondary care, community and social media recruitment routes and 12 participant interviews were analysed using reflexive thematic analysis. Social media recruitment accounted for over half of participants (53.9%). It was particularly effective in recruiting individuals with higher acne severity (IGA ≥ 3; 57.5% of its recruits, n  = 127), longer duration of disease (> 5 years history of acne; 60.2% of its recruits, n  = 133) and from ethnic minority groups (9.0% of its recruits, n  = 20), the latter being notably higher than the proportion recruited via primary care (1.5% of its recruits, n  = 1). Slight variations in retention by recruitment route were observed, with social media (85%) and primary care (84%) achieving the highest retention rate at the 12-week follow-up. All routes lost between 25 and 32% of participants by the 24-week follow-up, signifying the importance of implementing effective retention strategies to keep participants engaged. Overall, participants found targeted social media advertisements to be an acceptable and convenient recruitment approach; initial signals of trust were provided by high-quality graphics and recognisable NHS and university logos, which coupled with responsive trial staff, were suggested to provide a seamless enrolment experience. This study demonstrates that social media recruitment can be an effective and acceptable component of a multi-route strategy for clinical trial enrolment.

Background Improving the inclusion of under-served groups in clinical trials is increasingly being seen as a priority area for research funders and regulators. Adults who lack capacity to make an informed decision about taking part in trials are recognised as an under-served group. Researchers struggle to navigate the complex ethical, legal, and methodological issues surrounding trials involving adults lacking capacity to consent, leading to frequent exclusion of this population. Researchers have identified a need for greater knowledge about designing and conducting trials involving this population. Building on the CONSULT research programme, we developed stakeholder-informed training to help researchers design more inclusive trials. Methods The CONSULT e-learning was developed in collaboration with a group of researchers with topic expertise and a lay advisory group with lived experience. It was developed over four phases: (1) establishing researchers’ training needs using an online survey; (2) developing the e-learning content including illustrative case studies, videos, and links to resources and further reading; (3) iterative piloting and refining of the content; (4) dissemination of the e-learning and initial evaluation. A set of informational materials about the e-learning were also developed. Results Informed by the stakeholder survey ( n  = 82), the CONSULT e-learning consists of four key modules covering the legal and ethical frameworks, consent and consultation processes, and methodological considerations, with the key role of public involvement threaded throughout. It was launched at a webinar (December 2024), with a post-webinar survey ( n  = 29) showing an increase in awareness about the importance of including adults lacking capacity in trials where they are a relevant population. Researchers also signalled their commitment to changing their research practice, suggesting that the e-learning has a role in facilitating greater inclusion of this under-served population in trials. The CONSULT e-learning is available online: www.capacityconsentresearch.com/training . Conclusions Alongside tools such as the INCLUDE Impaired Capacity to Consent Framework, the CONSULT e-learning course aims to support researchers to develop the knowledge and skills needed to design and conduct higher-quality trials that are more inclusive of adults who lack capacity to consent. Further engagement, including with funders who increasingly require inclusion as a condition of funding, is needed.

Background Participation in clinical cancer research trials should diversely reflect the intersectionality characteristics of the general population for results to be representative and applicable. European migrant populations residing in the United Kingdom (UK) are a group whose participation in clinical research warrants further exploration from a community and clinical perspective. This study aimed to explore the barriers and facilitators of individuals who have migrated to the UK from an EU8 or EU2 (EU8/2) country to participating in clinical cancer research trials to update clinical and research agendas for optimising inclusive engagement strategies. Methods Perspectives of migrant individuals and of clinical research staff were explored to identify barriers and opportunities for optimising engagement. Five focus groups with clinical research staff at four hospitals across the East Midlands and three online focus groups with individuals who had migrated to the UK from Poland, Latvia and Romania were conducted. Data was analysed using template analysis. Results Twenty-two clinical research staff and 17 individuals from EU8/2 countries participated in the study. Three key themes and related subthemes were identified: (1) Ambivalence, misunderstanding and fear shape cancer research perceptions (1.1. a lack of familiarity with cancer research practices; 1.2. Cancer fear may hinder participation); (2) Structural barriers and gaps in cultural competency; and (3) Building trust through community engaged research (3.1.Co-researching with communities; 3.2. Incentivising and legitimising research). Discussion Many migrant participants were unfamiliar with UK-based research practices, and it was suggested that fatalist attitudes towards a cancer diagnosis and mistrust of research generally created apprehension and defensiveness when hearing about clinical cancer research in migrant communities. Migrant individuals and staff endorsed research design strategies which engage community champions (including clinicians); narrate positive stories of cancer research participation; and consider language accessibility and comprehension as key elements of engagement-focused research design.

Background Trials involving adults who lack capacity to consent can be challenging, partly due to the involvement of ‘proxy’ decision-makers. This is usually a family member, who advises the researchers about the person’s wishes. Families can find decision making difficult and some experience a decisional burden. Following the development of a decision aid for family members making trial participation decisions, we are conducting a mixed-methods randomised Study Within a Trial (SWAT) to evaluate its (cost-)effectiveness. This paper reports the feasibility stage conducted in one host study to inform delivery of the main SWAT. Methods Family members approached to act as a consultee for the host study were randomised 1:1 to receive the decision aid booklet alongside standard study information (intervention), or standard information plus a blank notebook (control), and asked to complete the CONCORD scale (Combined Scale for Proxy Informed Consent Decisions) questions about their experience and take part in a semi-structured interview. Acceptability of the SWAT was assessed through exploring recruitment rates and data completeness, and qualitatively through interviews with family members and research staff. Interviews were analysed using a rapid qualitative approach. Results In total, 92 family members were randomised to the SWAT and 16 completed the CONCORD questionnaire. Interviews were conducted with consultees ( n  = 4), and host study staff ( n  = 3) who also provided resource use data. Differences in time staff spent with consultees were small. Key themes included (1) setting up the SWAT and balancing priorities with the host study, (2) differences when recruiting consultees to a SWAT, (3) feasibility and acceptability of the SWAT, (4) challenges of measuring decision quality and (5) views and experiences of the decision support intervention. Conclusion The CONSULT SWAT is feasible, but changes to study processes are needed in advance of the main SWAT. The findings suggest that attempting to seamlessly integrate the SWAT into the host study may have inadvertently led to it becoming ‘invisible’ to consultees. The small number of trials involving participants lacking capacity limits opportunities for developing the evidence-base. Recruitment of host trials continues, with a focus on evaluating the intervention in a broad range of populations and settings. Trial registration The SWAT is registered as SWAT #159 with the Northern Ireland Hub for Trials Methodology Research SWAT repository (registered 09.08.2020).

Background Black adults are underrepresented in cardiovascular disease clinical trials. Individual and social circumstances may limit when they are available to complete trial prescreening requirements. Characterizing preferences related to callback times and the impact of calling during preferred times could inform strategies to improve the recruitment of Black adults into clinical research. Our objectives were to characterize prescreening call preferences and successfully reaching a potential participant among adults inquiring about participation in two trials for Black residents of Boston. Methods The GoFreshRx and GoFresh trials examine the effect of a home-delivered Dietary Approaches to Stop Hypertension (DASH)-patterned grocery intervention on blood pressure among Black adults with or without hypertension treatment in Boston. With the exception of the study population, both trials were identical and used the same recruitment apparatus for outreach. Interested persons completed a common online form for both trials and indicated their preferred callback time. Staff call attempts and participant screening status were logged prospectively. Gender was estimated based on first name, using a published algorithm. Odds ratios (OR) were determined via logistic regression models with adjustment for estimated gender, recruitment source, method of inquiry, and first call during preferred callback time. Results Of 2870 inquiries (September 2022–July 2023), 1740 participants were called and 1286 were reached. Out of the 1740 participants, 25% preferred to be called before noon and 22% after 4 pm, yet only 10% of the latter were called after 4 pm. Calling during preferred times significantly increased the odds of reaching participants (OR: 1.44; 95% CI: 1.12, 1.85) and completing a prescreening interview (OR: 1.39; 95% CI: 1.14, 1.71). Staff outreach 8–12 weeks (vs 0–4 weeks) after inquiry submission was significantly associated with lower odds of completing a prescreening interview (OR: 0.41; 95% CI: 0.23, 0.73). Participants who made inquiries via return mail were significantly less likely to be reached outside work hours (OR: 0.49; 95% CI: 0.27, 0.90) and in the afternoon (OR: 0.51; 95% CI: 0.30, 0.88). Participants recruited through community events were more likely to be reached in the afternoon (OR: 2.71; 95% CI: 1.06, 6.97). Conclusion Contacting participants during their preferred callback time was associated with reaching them and completing a prescreening interview. These data highlight the importance of study teams’ flexibility in outreach time to enhance the recruitment of Black adults into cardiovascular clinical trials.