Acute hospital
A hospital which provides A&E and/or critical care services.
Adherence means sticking to the treatment prescribed, or allocated in a clinical trial and, if appropriate, finishing the course.
Adverse events
Adverse events are undesired effects that may or may not be related to treatment such as dizziness, stomach ache or a rash. A symptom caused by the treatment is a side effect. Serious adverse events (SAEs) in trial participants are reported to the national regulatory authority (MHRA in the UK).
A written description of a change or formal clarification. Substantial amendments require RCE, R&D, MHRA approval (when applicable), non-substantial amendments should be notified to the relevant body.
Annual Safety Report
For studies involving the use of an Investigational Medicinal Product, the annual report must be submitted to the MHRA detailing all SUSARs and SARs that have occurred on that study in the past year.
Acute Physiology And Chronic Health Evaluation
APACHE II Acute Physiology Score
The Acute Physiology Score (APS) is a score ranging from 0 to 60 points, based on weightings for deviations from normal in twelve physiological parameters during the first 24 hours in the critical care unit.
The APACHE II risk prediction model combines the APACHE II score with other factors – admission from theatre following emergency surgery, reason for admission and CPR within 24 hours prior to admission - to calculate the risk of acute hospital mortality for critical care unit admissions.
A score from 0 to 71 consisting of weights for age at admission to the critical care unit (0 to 6 points), severe conditions in the past medical history (0 to 5 points) and the Acute Physiology Score (0 to 60 points).


Bar charts
Used to illustrate the number/percentage of cases in each category of a variable.
Bias results when a particular design or analysis is likely to favour a particular outcome and would, therefore, make those results unreliable. It is important to avoid bias in health research as it can distort the results and could lead to unsafe or ineffective treatments being licensed for use, or useful treatments being overlooked. One way to avoid bias is by using randomisation and by ‘blinding’ participants and their carers.
Blinding/double blinding
Blinding means that trial participants do not know which treatment they are receiving. This helps prevent bias. Double blinding refers to the participant, their doctor and researchers running the trial not knowing which treatment is received by which group until all data have been recorded.
Browser compatibility
The ability of a website to display and function correctly in various client side browsers, such as all versions of Internet Explorer, Firefox, Chrome, Safari etc. At ICNARC, we do not support browsers older than Internet Explorer 6.


C diff
Clostridium difficile
Confidentiality Advisory Group
Calibration plots
Used to show the fit of a risk prediction model. Individuals are ordered according to predicted risk of an outcome and split into five to ten equal sized groups. The combined predicted risk for each group is then plotted against the observed.
Cardiac arrest
A cardiac arrest happens when your heart stops pumping blood around the body due to failure of the heart to contract effectively. If you have a cardiac arrest, you lose consciousness almost at once. A cardiac arrest is different from a heart attack, where blood flow to the muscle of the heart is impaired.
Case mix
The term case mix refers to the type or mix of patients treated by a hospital.
Case Report Forms
Data collection tools provided by the sponsor on which clinical trial data is recorded for each participant
Critical Care Minimum Data Set
Coronary Care Unit
Cerebral Performance Category
The only internationally recognisable scale for assessing outcome following cardiac arrest.
Chief Investigator
Lead investigator with overall responsibility for the research. In a multi-centre study the Chief Investigator has coordinating responsibility for research at all study sites.
Clinical trials
Clinical trials are research studies that compare different treatments and treatment strategies. They test whether one is better or, at times, at least as good as another. No matter how promising a new treatment or treatment strategy may appear, it must go through clinical trials before its benefits and risks can really be known.
Clinical Trials Authorisation
The regulatory approval for a clinical trial of a medicinal product issued by the MHRA.
Clinical Trials Site Agreement
Contract between the legal Sponsor and the hosting research sites.
Clinical Trials Unit
Unit that designs and manages a portfolio of research studies.
Comprehensive Local Research Network
Case Mix Programme
Case Mix Programme Database
Comparative data
Analyses which compare data for a specific participating critical care unit/hospital against other participating critical care units/hospitals.
Comprehensive Clinical Research Network
Research infrastructure embedded in the NHS to support participation in high quality clinical research studies across England. Made up of 25 CLRNs.
Comprehensive Local Research Network
CLRNs are the primary vehicle for providing infrastructure to support study involvement at NHS trusts.
Confidence interval
An interval that has a specified chance (e.g. 95%) of containing the true value of a parameter.
Confidentiality Advisory Group
The Confidentiality Advisory Group provide independent expert advice to the Health Research Authority (for research applications) and the Secretary of State for Health (for non-research applications) on whether applications to access patient information without consent should or should not be approved under Section 251 of the NHS Act (2006).
Coordinated System for gaining NHS Permissions
Standard process for adoption onto NIHR Portfolio in order to access NIHR CRN support and funding. Streamlines process for gaining NHS permissions by collating the information for global and local approvals.
Cerebral Performance Category
Cardiopulmonary resuscitation
Case Report Forms
Critical care unit
Coordinated System for gaining NHS Permissions
Clinical Trials Authorisation
Clinical Trials Site Agreement


Data Analysis Report
Data completeness plots
Used to indicate the percentage of cases (e.g. critical care unit admissions/cardiac arrest team visit records) with complete data for individual variables or for combinations of variables.
Data Monitoring & Ethics Committee
Independent data monitoring committees oversee the progress of trials. They are made up of experts who are independent from the trial and who examine its findings while the trial is still recruiting or in follow-up. If they see evidence that participants are experiencing serious or unexpected side effects, or if it emerges that one treatment being compared is clearly better than the others, they can advise that a trial is stopped.
Data validation
The process of ensuring the quality and reliability of data for a study or audit by checking against dataset rules and definitions
Database of Individual Patient Experience
DIPEx run The Health Experience Research Group, who have created a database of personal and patient experiences through in-depth qualitative research. The results and a wide range of videos of real patient experience are available on their website.
A set of standardised data fields collected for an audit or trial, allowing comparisons between sites to be made.
Denominator data
The lower part of a fraction, e.g. the total number of people in the population
Database of Individual Patient Experience
Data Monitoring & Ethics Committee
Do Not Attempt Resuscitation


Eligibility criteria
These are clearly-defined criteria of who is eligible to take part in a study and who is not as given by the inclusion criteria and exclusion criteria of the study.
European Medicines Agency
Epidemiological study
An epidemiological, or observational, study examines data on individuals with a specific condition and does not intervene in their care, as a clinical trial would. Epidemiological studies examine the effect of certain exposures (e.g. tobacco smoke, long duration of HIV infection) on health outcomes (e.g. cancer).
European Society of Intensive Care Medicine
European Clinical Trials Database
European Clinical Trials Database
Database of all clinical trials in Europe.
European Medicines Agency
A body of the European Union which has a responsibility for the protection and promotion of public health through the evaluation and supervision of medicine for human use.
Event rate
The event rate describes the number of people who experience a particular event (e.g. tumour recurrence) over a given time period.
Evidence base
A collection of the best available scientific research currently available about a health condition. This is used to make decisions about how best to treat and provide care for individuals with that condition, or to prevent it.
Exponentially weighted moving average.
EWMA plots
Used to display observed outcome, predicted risk of outcome and predicted risk of outcome +/- 2 and 3 standard deviations. Observations are exponentially weighted in favour of more recent observations, smoothing observed data. The observed outcome line must cross the 2 standard deviation area of predicted risk of outcome to be considered significantly different.
Exclusion criteria
Determine who is not eligible for a clinical study; e.g. many trials exclude women who are pregnant, or who may become pregnant, to avoid any possible danger to a baby, and people who are taking a drug that interacts with the treatment being studied (see also eligibility criteria and inclusion criteria).


Food and Drug Administration
Food and Drug Administration
The competent authority in the United States, giving authorisation to conduct clinical trials and issuing marketing licences.
Funnel plots
Scatterplots of an outcome ratio (observed outcome divided by predicted outcome) against the number of eligible individuals. Used when observations for different critical care units/hospitals are based on varying sample sizes. Funnel shaped control limits (at 2 and 3 standard deviations) indicate that as sample size decreases, observations must be further from average to be considered significantly different.


Good Clinical Practice
Glasgow Coma Score
Glasgow Coma Score
A neurological scale that aims to give a reliable, objective way of recording the conscious state of a person for initial as well as subsequent assessment.
Good Clinical Practice
This is an international quality standard for the conduct of clinical studies. Randomised Clinical Trials are required by law to conform to Good Clinical Practice.


High dependency unit - a critical care unit providing predominantly level 2 care, with one nurse for every two patients.
Health economics
In some clinical trials the cost of all aspects of the treatments being compared is examined. This is particularly important when there is more than one effective approach to treating a condition.
Health Technology Assessment programme
One of the NIHR research funding streams.
Used to illustrate the distribution of a continuous variable.
Healthcare Resource Group
Health Technology Assessment


ICNARC Coding Method
ICNARC Case Mix Programme Dataset Specification
Intensive Care National Audit & Research Centre
ICNARC Coding Method
A way of recording the reason a patient was admitted to the critical care unit through the use of a tiered numeric coding system. It avoids the need for data collectors to enter the full name of the condition in text format or having to provide a full list of possible conditions in a drop-down list.
ICNARC model
The ICNARC risk prediction model combines the ICNARC physiology score with other factors - age at admission, reason for admission, CPR within 24 hours prior to admission, source of admission and surgical urgency - to calculate the risk of acute hospital mortality for critical care unit admissions.
ICNARC physiology score
A score from 0 to 100 based on weightings for deviations from normal in twelve physiological parameters during the first 24 hours in the critical care unit.
Intensive care unit - a critical care unit providing predominantly level 3 care, with one nurse per patient.
Intensive care unit/High dependency unit - a combined critical care unit providing both level 2 and level 3 care.
Investigational Medicinal Product
Inclusion criteria
These clearly indicate who can join a trial, e.g. the condition and stage of disease they are already at, and their age (see also eligibility criteria and exclusion criteria).
Compensation for damage, loss or injury.
Individual Patient Data meta-analysis
Use of standard systematic review and meta-analysis methods, but also involve the central collection and analysis of the original data from all the relevant trials worldwide, rather than just the published summary statistics.
Informed consent
This refers to a participant in a research study agreeing to take part of their own free will after being given all the important facts about that study, and after they have had the chance to ask questions and have them satisfactorily answered and understood.
Integrated Research Application System
A system for completing applications for the permissions and approvals required for health and social care research in the UK. The various applications (REC, MHRA, R&D etc.) can be made through this single system.
Interim analysis
An analysis of trial data which is undertaken before the end of the trial.
International Standard Randomised Controlled Trial Number
Numeric system for the identification of randomised controlled trials worldwide. Allows the identification of trials and provides a unique number that can track all publications and reports resulting from each trial.
Interquartile range
The range from the lower quartile (value below which 25% of the data lie) to the upper quartile (value above which 25% of the data lie).
An intervention is a measure which is introduced and evaluated through a clinical trial with the aim of improving health. It could be a treatment (e.g. drug A vs. drug B), a treatment strategy (e.g. a drug vs. a surgical technique), a different screening approach, or prevention measure.
Investigational Medicinal Product
An unlicensed new drug or a drug tested outside its licence, or existing drugs tested against each other for their efficacy/safety.
Researcher conducting the (clinical) study, those researchers leading the team are referred to as CI or PI.
Investigator Site File
A file designed for use in organising and collating all essential documentation required to conduct the study in accordance with the principles of GCP and the applicable regulatory requirements.
Interquartile range
Integrated Research Application System
International Standard Randomised Controlled Trial Number


Length of stay
London School of Hygiene & Tropical Medicine


Mental Capacity Act
The ‘average’ value (obtained by summing all values and dividing by the number of values).
The value below which 50% of the data lie.
Mental Capacity Act
Act of the Parliament of the United Kingdom applying to England and Wales. Its primary purpose is to provide a legal framework for acting and making decisions on behalf of adults who lack the capacity to make particular decisions for themselves.
Meta-analysis is a means of quantitatively combining the results of several research studies to provide an ‘average’ estimate of the treatment effect.
Methodological Research
This is research to improve the methods used in research.
Model Non-Commercial Agreement
Model Non-Commercial Agreement
Model agreement for clinical research studies. This is the standard template for the UK.
The person designated by the sponsor to perform site visits and conduct the monitoring process.
Medical Research Information Service
Methicillin-resistant Staphylococcus aureus
Multi-centre study
A study conducted to a single protocol but carried out at more than one site and by more than one investigator.


National Institute for health and Clinical Excellence
Decides which drugs are accepted into NHS treatment.
National Institute for Health Research
Established by the Department of Health (DH) for England in 2006 to provide the framework through which the DH manage and maintain the research, research staff and infrastructure of the NHS in England as a virtual national research facility.
National Research Ethics Service
Umbrella organisation responsible for all Research Ethics Committees across the UK.
National Cardiac Arrest Audit
NCAA risk prediction model
Used to predict outcomes following in-hospital cardiac arrest attended by a hospital-based resuscitation.
Children aged less than 28 days.
National Health Service
NHS Number
Unique number assigned by the NHS as a numeric ten digit code to each NHS patient.
National Institute for health and Clinical Excellence
National Institute for Health Research
National Institute for Health Research Health Services and Delivery Research Programme
National Institute for Health Research Health Technology Assessment Programme
Non-invasive ventilation
National Research Ethics Service
Numerator data
The upper part of a fraction, e.g. the number of people who have developed a disease of interest.


Obstetric Anaesthetist’s Association
Online Data Validation
Online Data Validation
Where data are validated at the point of entry.
Open label trials
In an open label trial, participants and their doctors know which treatment (or treatment strategy) they are receiving.
Open trial
This refers to a trial which is still recruiting or following up participants. It may also refer to a trial where the participant knows which treatment (or treatment strategy) they are receiving, i.e. they are not blinded (see blinding). This is usually called an ‘open label’ trial.
Outcomes are measures of health, e.g. response to treatment, occurrence or recurrence of disease, a measure of well-being.


Patient and Public Involvement
Patient and public involvement in the planning, management and dissemination of research.
Patient identifiable data
Patient identifiable data, such as NHS Number, are confidential.
Patient Information Sheet
An information leaflet given to those who have been invited to participate in a research study. The sheet is designed to provide the potential participants sufficient information to allow the person to make an informed decision.
Paediatric Cerebral Performance Category
Pulseless electrical activity
Patient Information Sheet
A placebo is a dummy treatment that is designed to be harmless and to have no effect. It looks, smells and tastes like the treatment being tested, so that trial participants do not know if they are taking the dummy treatment or the treatment itself.
Patient and Public Involvement
Principal Investigator
The lead person at a single site designated as taking responsibility within the research team for the conduct of the study.
A protocol is the plan for a research study. Protocols need to be approved by an ethics committee before the study begins to recruit participants.  They provide information on the question being addressed by the study, the eligibility criteria, and the visit schedule for trial participants.
Protein C Worldwide Evaluation in Severe Sepsis


Quality of Life
Quality of Life
As well as measuring the physical effects of a treatment (e.g. changes to blood pressure), many trials now try to assess the impact of treatments on people’s quality of life.


Research and Development
Randomisation means that a computer will decide which treatment or treatment strategy a trial participant will receive. This ensures that each participant has the same chance of receiving the treatments or strategies being compared. Randomisation ensures that the groups of people being compared in a trial are as similar as possible to start with except for the treatment they receive. This in turn ensures that any differences between these groups are only due to the treatments being compared.
Royal College of Anaesthetists
Royal College of Gynaecologists
Research Design Service
Research Ethics Committee
Research and Development
Name of the department in the hospital who gives local permission to conduct projects.
Research Design Service
Organisation with a number of experts who can help write the protocol/documents for NIHR grant applications.
Research Ethics Committee
A REC is a committee made up of healthcare professionals and lay people which reviews funded studies in order to ensure that they are ethically conducted. Study participants cannot be approached about joining a clinical study until it has been approved by an ethics committee.
Return of spontaneous circulation


Scope of data collection
Cases where data should be collected; e.g. the NCAA scope for data collection is 'All individuals (excluding neonates) receiving chest compression(s) and/or defibrillation and attended by the hospital-based resuscitation team (or equivalent) in response to the 2222 call'.
Standard Deviation
Source Data Verification
Side effects
Side effects are undesired effects that are related to a treatment.
Systemic inflammatory response syndrome
NHS organisation in which study activities and assessment are performed.
Site Specific Assessment
As assessment performed to establish suitability of a Principal Investigator and a site for the conduct of the research.
Site Specific Information
Local detail to inform a Site Specific Assessment.
Standardised Mortality Ratio
Standard Operating Procedure
Source Data Verification
A check of the original data record, such as lab reports, patient medical notes etc. against data entered onto the Case Report Forms or database.
Sequential probability ratio test
Site Specific Assessment
Site Specific Information
Standard Deviation
A measure of the spread of the data around the mean.
Standard Operating Procedure
Detailed written instructions designed to achieve uniformity of the performance of a specific function.
Standardised Mortality Ratio
Looking at acute hospital mortality, the observed number of deaths is divided by the predicted number of deaths (as calculated by a risk prediction model) for a group of critical care unit admissions, to give a mortality ratio.
Steering Group
A group of experts which help to steer the direction of a project or study.
Stratified analyses
Analyses comparing the same variable between subgroups of a population.
Suspected Unexpected Serious Adverse Reaction
Suspected Unexpected Serious Adverse Reaction
An unexpected reaction to the drug therapy.
Systematic review
Systematic reviews collate evidence from all the research studies relevant to a particular research question, using explicit and systematic methods in order to minimise bias. Therefore, they provide an objective and reliable way of reviewing evidence.


Team visit
A visit to a patient made by the hospital-based resuscitation team (or equivalent).
Trial Master File
Trend lines
Show the trend in a measure over time often trended by quarter, six month period or year.
Trial arm
Trial arm refers to one of the groups to which trial participants are assigned to in a randomised controlled trial.  The group of people receiving the current standard of care are usually referred to as the control arm.
Trial Master File
File with essential documentation held by the Chief Investigator/Sponsor organisation.
Trial phases
Clinical trials are conducted in phases: Phase I: aims to test safety and usually involves a small number of people; Phase II: aims to evaluate effectiveness and usually involves a larger number of people; Phase III: aims to compare two or more treatments or treatment strategies and monitor side effects. Results from these trials allow treatment recommendations to be made and drugs licensed; Phase IV: are post-marketing studies and collect further information on use of treatments in clinical practice.
Trial Steering Committee
A Trial Steering Committee usually oversees the conduct of a clinical trial and comprises investigators as well as independent members.
Trauma Injury Severity Score
Trial Steering Committee


UK Clinical Research Collaboration
Unit mortality
Mortality at discharge from a critical care unit.


Ventilated admissions
Admissions receiving advanced respiratory support on at least one calendar day in a critical care unit.
Ventricular fibrillation
Ventricular fibrillation is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly.
Ventricular tachycardia
A type of tachycardia, or a rapid heartbeat, that starts in the bottom chambers of the heart, called the ventricles.
Ventricular fibrillation
Vancomycin Resistant Enterococcus
Ventricular tachycardia

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