To map the landscape of decentralised clinical trials (DCTs) by summarising characteristics, methods and reported challenges of published DCTs.

Scoping review, reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews (PRISMA-ScR) checklist.

Ovid MEDLINE and PubMed were searched through to 21 August 2024.

We included reports of completed DCTs (defined as a trial of an intervention, with a comparison arm, in which some or all trial activities occurred away from the trial centre). All intervention types were included.

A single reviewer extracted data to a structured extraction sheet. Descriptive statistics (frequencies) are reported for study characteristics and the terminology used to describe trial methods. Decentralised methods used were coded separately for each trial stage.

53 papers met inclusion criteria. Most studies (34/53) were conducted in the USA. Mental health (18 studies) and COVID-19 (11 studies) were the predominant research areas. 24 (of 53) studies investigated pharmaceutical interventions, while others examined nutritional interventions, medical devices and behavioural interventions. Recruitment, screening and consent were commonly conducted remotely. A range of methods, including online, in-person and telemedicine, was used to collect outcome measures. Several studies experienced challenges related to participant retention and biased recruitment. Terminology regarding decentralisation was inconsistent across studies.

DCTs are rapidly increasing in use, and commonly cited advantages include reduced costs and reduced participant burden. This review identifies key research areas using DCTs and highlights a need for standardised terminology, comprehensive reporting of methods and limitations, and robust regulatory frameworks. Development of formal ethical and reporting standards is essential to ensure effective and responsible implementation of DCTs in clinical research.

Delayed antibiotic prescribing (DAP) has demonstrated efficacy in reducing inappropriate antibiotic use for uncomplicated respiratory tract infections (uRTIs) in primary care across high-income countries. However, evidence regarding its effectiveness in low-income and middle-income countries remains limited. This cluster-randomised controlled trial (cRCT) aims to evaluate the effectiveness of DAP for optimising antibiotic use in primary healthcare institutions (PHIs) in China.

We designed a pragmatic, multicentre, open-label, three-arm cRCT in adult patients with uRTIs. The study will involve 12 PHIs in Korla City of China. Participating institutions will be randomised at a 1:1:1 ratio to three parallel arms: (1) DAP-intervention arm, (2) Immediate antibiotic prescribing comparator arm and (3) Usual care (observational arm). The primary outcome is symptom duration. Secondary outcomes include symptom severity, antibiotic use, adverse events, patient satisfaction and patient belief regarding antibiotic efficacy.

Ethics committee approval of this study was obtained from Peking University Institution Review Board (IRB00001052-24169). The findings will be disseminated through peer-reviewed publications and presentations at scientific conferences.

ChiCTR2500097330.

Saskatchewan is facing a public health crisis driven by high rates of HIV, syphilis and hepatitis C virus (HCV) infections, particularly among people who use drugs. Injection drug use is a major contributor to these syndemic infections, exacerbated by structural barriers such as stigma, poverty and limited culturally safe healthcare. Innovative, community-informed approaches are urgently needed to improve prevention, testing and linkage to care.

This study will implement a rapid assessment and response system in Regina, Saskatchewan, Canada, integrating geospatial mapping of community needle prevalence with pop-up interventions. Needle hotspot maps will be used to guide the deployment of community-based pop-up events offering point-of-care testing for HIV, syphilis and HCV, alongside education on pre-exposure prophylaxis (PrEP) and postexposure prophylaxis (PEP). A convergent participatory mixed-methods design will be used to evaluate feasibility, acceptability and effectiveness, guided by the Reach, Effectiveness, Adoption, Implementation and Maintenance framework. Quantitative data will assess changes in knowledge of PrEP and PEP, satisfaction with the intervention and report new diagnoses and participant demographics descriptively. A qualitative substudy will include 30 participants and will explore experiences with the intervention, barriers to care and perceptions of service delivery.

Ethical approval has been obtained from the research ethics board of the Saskatchewan Health Authority (#24–91). Findings will be disseminated through peer-reviewed publications, conference presentations and community reporting. This study may provide a model of community-based geospatial testing and education that could be scaled up and adapted elsewhere.

Open Science Framework https://doi.org/10.17605/OSF.IO/HVK3B

The SupportBack 2 randomised controlled trial (RCT) compared the clinical and cost-effectiveness of an internet intervention supporting self-management versus usual primary care in reducing low back pain (LBP)-related disability. In this study, we aimed to identify and understand key processes and potential mechanisms underlying the impact of the intervention.

This was a nested qualitative process evaluation of the SupportBack 2 RCT (ISRCTN: 14736486 pre-results).

Primary care in the UK (England).

46 trial participants experiencing LBP without indicators of serious spinal pathologies (eg, fractures, infection) took part in telephone interviews at either 3 (n=15), 6 (n=14) or 12 months (n=17) post randomisation. Five physiotherapists who provided telephone support for the internet intervention also took part in telephone interviews.

An internet intervention ‘SupportBack’ supporting self-management of LBP primarily through physical activity and exercise delivered in addition to usual care, with and without physiotherapist telephone support.

Data were analysed thematically, applying a realist logic to develop context-mechanism-outcome configurations.

Four explanatory themes were developed, with five context-mechanism-outcome configurations. Where benefit was reported, SupportBack appeared to work by facilitating a central associative process where participants linked increases in physical activity or exercise with improvements in LBP, then continued to use physical activity or exercise as key regulatory strategies. Participants who reported little or no benefit from the intervention appeared to experience several barriers to this associative process, including negative expectations, prohibitive beliefs about the cause of LBP or functional limitations preventing engagement. Physiotherapists appeared to provide accountability and validation for some; however, the remote telephone support that lacked physical assessment was viewed as limiting its potential value.

Digital interventions targeting physical activity and exercise to support LBP self-management may rely on mechanisms that are easily inhibited in complex, heterogeneous populations. Future research should focus on identifying and removing barriers that may limit the effectiveness of digital self-management support for LBP.

Increasing physical activity and effectively managing stress can positively impact immunity and may reduce the duration of respiratory tract infections (RTIs). As part of a larger trial, participants accessed a digital behavioural change intervention that encouraged physical activity and stress management to reduce RTIs. We aimed to understand the barriers and facilitators to engaging in physical activity and stress reduction.

A qualitative process analysis from semistructured interviews of the behavioural intervention in a randomised control trial.

Primary care in the UK.

34 participants (aged 18–82 years) in the behavioural intervention arm.

The larger trial involved four interventions: a gel-based antiviral nasal spray; a saline water-based nasal spray; a behavioural intervention; usual care. In this study, we focused on participants allocated to the behavioural intervention. The behavioural intervention included two components: one to increase physical activity (getting active) and another for stress management techniques (healthy paths) to reduce RTIs.

We analysed the interviews using thematic analysis with a critical realist perspective (focusing on). We developed five themes: digital intervention engagement, views on intervention allocation, the role of getting active, the role of healthy paths and benefits reinforcing behaviour. Participants’ views on the relevance and benefit of the behavioural intervention shaped their engagement with the intervention website and behaviour. Facilitators of intervention engagement included awareness of inactivity, goal setting, increasing immunity, positive outcome expectations and benefits from changing behaviour. Barriers to engagement included negative outcome expectations, such as around efficacy of the behaviours.

Overall, the results highlighted the importance of positive expectations for a digital intervention promoting physical activity and stress management for RTI reduction. Future interventions should consider how to clearly communicate a broad range of perceived benefits to users.

The trial was prospectively registered with International Standard Randomized Controlled Trial Number (ISRCTN) registry (17936080).

There is a need for early, non-invasive and inexpensive biomarkers for Alzheimer’s disease (AD), which could serve as a proxy measure in prevention and intervention trials that might eventually be suitable for mass screening. People with Down syndrome (DS) are the largest patient group whose condition is associated with a genetically determined increased risk of AD. The REVEAL study aims to examine changes in the structure and function of the eye in individuals with DS compared with those with mild cognitive impairment (MCI) and cognitively healthy control (HC) individuals. REVEAL will also explore whether these changes are connected to inflammatory markers previously associated with AD.

The protocol describes a cross-sectional, non-interventional, single-centre study recruiting three cohorts, including (1) participants with DS (target n=50; age range, 6–60 years), (2) participants with MCI (target n=50; age range, 50–80 years) and (3) HC participants (target n=50; age range, 50–80 years). The primary research objective is to profile retinal, choroidal and lenticular status using a variety of eye imaging modalities and retinal functional testing to determine potential associations with cognitive status. The REVEAL study will also measure and compare established blood markers for AD and proteomic and transcriptomic marker profiles between DS, MCI and HC groups. Between-group differences will be assessed with an independent sample t-test and ² tests for normally distributed or binary measures, respectively. Multivariate regression analysis will be used to analyse parameters across all three cohorts. Data collection began in October 2023 and is expected to end in October 2025.

The study gained a favourable opinion from Health and Social Care Research Ethics Committee A (REC reference 22/NI/0158; approved on 2 December 2022; Amendment 22/0064 Amend 1, 5 April 2023; Amendment 22/0064 Amend 2; 23 May 2024; Amendment 22/0064 Amend 3; 25 June 2024; Amendment 22/0064 Amend 4; 16 January 2025; Amendment 22.0064 Amend 5; 9 May 2025; Amendment 22.0064 Amend 6; 9 June 2025). The study has also been reviewed and approved by the School of Biomedical Sciences Research Ethics Filter Committee within Ulster University. Findings from the REVEAL study will be presented to academic audiences at international conferences and peer-reviewed publications in targeted high-impact journals after data collection and analysis are complete. Dissemination activities will also include presentations at public events.