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Pragmatic Clinical Trials Unit

Collaborations With Different Types of Studies

The PCTU collaborates in various types of studies described briefly below.  We are particularly interested in collaborating on studies that fall within our key clinical areas.  We have specialists working across a range of methodological strengths.  Please visit our Methodological Strengths and Research page for more information on our methodological work and how to explore a methodological collaboration with us.  

For detail of our ongoing studies please visit Current Studies.

A clinical trial is any research study that prospectively assigns human participants or groups of humans to one or more health-related interventions to evaluate the effects on health outcomes.  A randomised controlled trial is a clinical trial in which randomisation is used to assign participants to interventions.

The PCTU specialises in pragmatic trials, trials designed to support decisions about care options. We have particular expertise in cluster randomised trials, including stepped wedge, trials within cohorts, and other similar designs. We lead and collaborate in Clinical Trials of Investigational Medicinal Products (CTIMPs), non-CTIMPs (including trials of complex interventions) and device studies, whether these are single centre, multi-centre, national or international studies. We do not currently collaborate in early phase (phase I and phase II) trials.

The PCTU has particular expertise in pilot and feasibility studies and welcomes the opportunity to be involved in such studies.

Pilot and feasibility studies address the feasibility of a future study or part of that study, for example the feasibility of an intervention to be evaluated in a future trial. They should therefore focus the key uncertainties that investigators have about the feasibility of the future study or part of it, and the objectives of the study should relate to these key uncertainties. Cluster randomised trials and stepped wedge designs can often benefit from pilot and feasibility studies.   

It is essential to have a very clear description of objectives and the methods to be used to address them at the grant application stage and to avoid unnecessary data collection and analysis that does not address the key uncertainties, otherwise the study can become unwieldy and/or unnecessarily expensive. Pilot and feasibility studies are usually smaller than definitive trials or observational studies that address a clinical question, in terms of number of participants, number of sites and duration of study.

A wide range of studies come under the title observational studies. In fact this term can be used to describe any study in which something is observed or measured on participants. This can include surveys, case control studies, cohort studies and qualitative observational studies. The studies may collect data directly from participants or use routine data. A wide range of funders and funding streams consider funding such studies.

Programme grants involve a programme of inter-connected research projects, which could include feasibility studies, systematic reviews, trials, process evaluations, and qualitative studies. The PCTU collaborates in a considerable number of NIHR Programme Grants for Applied Research. These grants are awarded to research groups who can demonstrate an outstanding track record of achievement in applied health research and have potential to deliver research findings that will benefit patients and the NHS within the relatively near future.

Systematic reviews are literature reviews that collect and critically analyses multiple research studies or papers, using systematic methods selected a priority. Most commonly they are designed to provide a complete summary of current literature relevant to a research question. Systematic reviews of randomized controlled trials are key in the practice of evidence-based medicine.

IPD (Individual participant data) meta-analysis is a specific type of systematic review. Rather than extracting summary (aggregate) data from study publications or from investigators, the original research data are sought directly from the researchers responsible for each study. These data can then be re-analysed centrally and combined, if appropriate, in meta-analyses.


The PCTU collaborates/supports applications to Fellowship funding programmes. These programmes often impose funding constraints that affect the extent of PCTU support/collaboration. There are three models for PCTU collaboration/support. You may want to consider any combination of these models. Note that your application will only be formally linked with PCTU if you use the first model.

The first model is usual PCTU collaboration. PCTU agrees a collaboration tailored to your project in the same way as for non-fellowship funding programmes, and the cost of the support package is calculated as for any other collaboration with PCTU. You will need to check what sort of CTU costs your funder is willing to cover, bearing in mind that a Fellow is often expected to take on many of the research roles him/herself.

The second model is a training package, Inside a Clinical Trials Unit (i-CTU), designed to give participants an insight into the workings of a Clinical Trials Unit and an understanding of how clinical trials are run, including opportunities to observe PCTU activities and one-to-one tutoring/advice from specialist and senior staff, as well as structured learning. For more information, please visit our courses page.

The third model is academic supervision or mentoring. Most fellowship programmes allow the applicant to propose one or more senior academic members of staff as supervisors and/or mentors. Prospective fellows may be seeking a supervisor or mentor with specialist expertise of the kind found in the PCTU – for example in statistics, health economics or trial methodology. The nature of the supervisory/advisory involvement would need to be agreed with the person concerned and detailed in the fellowship application. Please approach prospective supervisors/mentors directly. Please check our Staff List for details of who to contact. Please do not contact staff directly for any other type of collaboration enquiry.

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