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Study Population

‘’Research, and those pursuing it, should respect the diversity of human society and conditions and the multicultural nature of society. Whenever relevant, it should take account of age, disability, gender, sexual orientation, race, culture and religion in its design, undertaking, and reporting.’’1

Study population refers to the sample of participants that will be recruited to the study.  In the study protocol it is important to specify the characteristics of eligible participants (inclusion criteria) and any specific characteristics that would exclude a participant (exclusion criteria). 

Together the Noclor partners cover a diverse population over a broad geographical area (London and beyond) providing wide-ranging health services (mental health, sexual health, community health, learning disabilities, addictions and substance misuse, primary care, dentistry, offender care). When designing a research study researchers will need to be able to provide the rationale for participant inclusion (e.g involving adults that lack capacity) and exclusion (e.g excluding non-English speaking) and take into consideration any additional legal requirements, ethical principles or regulatory approvals that may be required. 

Adults lacking capacity

When involving adults that lack capacity to consent in health research there are legal requirements and ethical principles that need to be considered during the design stage.

The Mental Capacity Act 2005 (MCA) protects any adult that lack capacity.  The MCA applies to people over age of 16 years who cannot make decisions for themselves because of an impairment or disturbance in the functioning of their mind or brain (i.e they lack capacity). It provides the framework for making decisions in their best interests while protecting them from harm.

The UK law is different depending on the type of study (the source of legal regulation and terminology differ). The research provisions of the MCA (section 30-34) do not apply to Clinical Trial of Investigational Medicinal Products (CTIMPs).

The table below summaries the main differences between CTIMP and non-CTIMP research studies that propose to involves adults lacking capacity to consent.


Research involving adults lacking capacity are regulated by the MCA (which applies to England and Wales only). 

A researcher must seek advice from a consultee during the consent process.

Applications will be reviewed by a REC ‘Flagged’ to review this particular type of research

CTIMPs are regulated by the Clinical Trial Regulations (which applies to the whole of the UK).

The Regulations make a separate provision (in Schedule 1) for adults who are unable to consent for themselves. 

The researcher must seek consent from a legal representative.

 Schedule 1 (Part 5) of the Regulations also outlines the conditions and principles that RECs are required to consider when reviewing a CTIMP involving adults that lack capacity.

Applications will be reviewed by a REC ‘Recognised’ by the United Kingdom Ethics Committee Authority (UKECA) for the review of Clinical Trials of Investigational Medicinal Products (CTIMPs), in accordance with The Medicines for Human Use (Clinical Trials) Regulations 2004.

Difficulties with the English language

The inclusion or exclusion of potential participants who may have difficulties in adequately understanding written or verbal information in English raises ethical issues. Exclusion of non- English speakers may bias the study population and the validity of outcomes in some studies. Whilst the inability to speak English may create a risk or vulnerability that may be difficult to manage within a research project, researchers are encouraged to adopt an inclusive strategy wherever possible, while acknowledging that this ideal may sometimes be impractical.

Where translation is necessary for informed consent or other aspects of a research study, accredited translators should be used wherever possible, ideally trained to the Institute of Linguist’s Diploma in Public Service Interpreting (DPSI) standards or equivalent. 

Prisoners or young offenders

All prisons have healthcare teams. Some of the Noclor partners (the Mental Health Trusts) manage healthcare teams in prisons and young offender institutions across London, Surrey, Kent, Hampshire and Buckinghamshire. Any health research planned within prisons, young offender institutions or probation areas in England and Wales will also require approval from the Her Majesty's Prison and Probation Service (HMPPS). In some cases, approval may also be required from the Ministry of Justice.  For detailed guidance on approval requirements and application procedures, refer to the toolkit published by the Offender Health Research Network ( Click on the OHRN Toolkit tab on the Resource Documents section on this page ).