The NICE glossary provides brief definitions and explanations of terms used on the website. The terms describe how NICE works and how its guidance is produced.

Our glossary excludes specific clinical and medical terms. If you cannot find the term you are looking for, please email us so that we can consider adding it to the glossary.

Some definitions and examples are based on those in the HTAi consumer and patient glossary, with thanks to Health Technology Assessment International.

For terms used in social care, the Care and Support Jargon Buster from Think Local Act Personal is a useful guide to the most commonly used social care words and phrases, and what they mean.

  • Cancer service guidance

    Guidance on the way services are organised for the treatment of different types of cancer. NICE no longer produces cancer service guidance, but existing guidance is still available.
  • Care pathway

    The route a person takes through healthcare services. For example, a care pathway might show the order in which various tests are done to diagnose an illness, which treatments should be tried, and when care moves from primary to secondary care, or from hospital back into community care.
  • Carer

    Someone who looks after family, partners or friends in need of help because they are ill, frail or have a disability.
  • Case report

    An uncontrolled observational study involving an intervention and an outcome in a single patient.

  • Case series

    Reports of several patients with a given condition, usually covering the course of the condition and the response to treatment. There is no comparison (control) group of patients.

  • Case-control studies

    An observational study to find out the possible cause(s) of a disease or condition. This is done by comparing a group of patients who have the disease or condition (cases) with a group of people who do not have it (controls) but who are otherwise as similar as possible (in characteristics thought to be unrelated to the causes of the disease or condition). This means the researcher can look for aspects of their lives that differ to see if they may have caused the condition.
    For example, a group of people with lung cancer might be compared with a group of people the same age who do not have lung cancer. The researcher could compare how long both groups had been exposed to tobacco smoke. Such studies are retrospective because they look back in time from the outcome to the possible causes of a disease or condition.

  • CE mark

    The abbreviation of ‘Conformité Européene’. The CE mark is a mandatory conformity mark on medical device products placed on the single market in the European Economic Area. It allows a manufacturer to sell their products within the European market, certifying that a product has met EU consumer safety, health or environmental requirements.

  • Centre for Clinical Practice

    The centre at NICE that is responsible for guidelines on clinical topics. These are recommendations, based on the best available evidence, on the appropriate diagnosis, treatment and care of people with specific diseases and conditions. Guidelines are developed by independent guideline committees, supported by a National Collaborating Centre, or by a team at NICE.

  • Centre for Health Technology Evaluation

    The centre at NICE that is responsible for producing guidance on diagnostics, highly specialised technologies, interventional procedures and medical technologies, and technology appraisal guidance. The guidance is developed by independent committees.

  • Class (of drugs in a NICE technology appraisal)

    A group of drugs with the same or similar mechanisms of action. They may or may not have the same basic chemical structure. There may be differences between drugs in a class, such as the side effects associated with them.

  • Clinical audit

    A process for monitoring standards of clinical care to see if it is being carried out in the best way possible (known as 'best practice'). Clinical audit can be described as a systematic 'cycle'. It involves measuring care against specific criteria, taking action to improve it if necessary, and monitoring the process to sustain improvement. As the process continues, an even higher level of quality is achieved.

  • Clinical Commissioning Group Outcomes Indicator Set

    Support to enable Clinical Commissioning Groups (CCGs) and health and wellbeing partners to plan for health improvement by providing information for measuring and benchmarking outcomes of services commissioned by CCGs.

  • Clinical impact

    The effect that something is likely to have on the treatment of a particular group of people, or on the results of treating that group.

  • Clinical importance or significance

    A benefit from treatment that relates to an important outcome such as length of life, and is large enough to be important to patients and health professionals. As an example, it might include a general reduction in symptoms, less pain or improved breathing.

    Effects identified as statistically significant are not always clinically significant, because the effect is small or the outcome is not important. For example, if a treatment might lower blood pressure but there may be no evidence that this leads to an important clinical outcome, such as a lower risk of stroke or heart attack.

  • Clinical trial

    A study to determine whether a treatment is safe and effective. It is carried out with a sample of patients, usually after laboratory studies and studies with healthy volunteers have been conducted. The trial is set up to answer 1 or more questions, for example, does the treatment have any adverse side effects and, if so, how serious are they?

  • Clinician

    A healthcare professional who provides patient care. For example, a doctor, nurse, pharmacist or physiotherapist.

  • Cochrane Collaboration

    An international organisation that produces systematic reviews of the evidence from primary research relating to a particular health problem or healthcare intervention. See also Cochrane Library.

  • Cochrane Library

    A regularly updated collection of evidence-based health databases including the Cochrane Database of Systematic Reviews, which contains reviews on a variety of health topics.
  • Code list

    A list of codes (such as SNOMED-CT codes) used to define a phenotype (such as a patient characteristic, condition or clinical event).

  • Code of conduct for NICE committees

    A code of conduct developed by NICE for members of guidance committees, and other people who attend committee meetings. This code sets out the responsibilities of NICE and the committees, and the principles of transparency and confidentiality.

  • Cohort study

    See Prospective cohort study

  • Commentator

    People (commentators) invited by NICE to take part in the appraisal process and comment on the various documents produced during the process. Unlike consultees, commentators cannot appeal against the final appraisal document.

  • Commissioning

    The process used by health services and local authorities to: identify the need for local services; assess this need against the services and resources available from public, private and voluntary organisations; decide priorities; and set up contracts and service agreements to buy services. As part of the commissioning process, services are regularly evaluated.
  • Committee

    The advisory group that considers the evidence and develops the recommendations, taking into account the views of stakeholders. NICE has standing committees (which work on multiple guidelines) and topic-specific committees (which are put together for a single guideline topic). Members include practitioners and professionals (both specialists and generalists, and/or academics), care providers and commissioners, people using health and care services and/or their family members or carers, or people from communities affected by the guideline.

  • Companion diagnostic technology

    A diagnostic technology that identifies who a specific treatment is likely to help. It may also help with selecting what type of medicine and dosage someone needs.
    You may need a companion diagnostic technology to comply with the licensed indication of a pharmaceutical.

  • Company's submission

    Information supplied by the company about a drug or other treatment that is being assessed in a technology appraisal or highly specialised technology evaluation. The information includes evidence about how well the treatment works, and its value for money.

  • Comparability

    Similarity of groups in terms of characteristics likely to affect study results (such as health status or age).
  • Comparator

    The standard (for example, another intervention or usual care) against which an intervention is compared in a study. The comparator can be no intervention (for example, best supportive care).

  • Confidence interval

    A way of expressing how certain we are about the findings from a study, using statistics. It gives a range of results that is likely to include the 'true' value for the population. A wide confidence interval (CI) indicates a lack of certainty about the true effect of the test or treatment - often because a small group of patients has been studied. A narrow CI indicates a more precise estimate (for example, if a large number of patients have been studied).

    The CI is usually stated as '95% CI', which means that the range of values has a 95 in a 100 chance of including the 'true' value. For example, a study may state that 'based on our sample findings, we are 95% certain that the 'true' population blood pressure is not higher than 150 and not lower than 110'. In such a case the 95% CI would be 110 to 150.

  • Conflict of interest

    An interest that might conflict, or be perceived to conflict, with a person's duties and responsibilities during guidance development. NICE staff, contractors and committee members declare any potential interests, and do not take part in discussions in which they have a conflict of interests (for example, because they are doing consultancy work for another organisation).

  • Confounding

    In a study, confounding occurs when the effect of an intervention on an outcome is distorted because of an association between the population or intervention or outcome and another factor (the 'confounding variable' or 'confounder') that can influence the outcome independently of the intervention under investigation. For example, a study of heart disease may look at a group of people who exercise regularly and a group who do not exercise. If the ages of the people in the 2 groups are different, then any difference in heart disease rates between the 2 groups could be because of age rather than exercise. Therefore age is a confounding factor.

  • Consensus methods

    Techniques that aim to reach an agreement on a particular issue. Formal consensus methods include Delphi and nominal group techniques, and consensus development conferences. When developing NICE guidelines, consensus methods may be used when there is a lack of strong research evidence on a particular topic.

  • Consensus statement

    A statement based on the collective views of a body of experts.
  • Consistency

    The degree of similarity between the conclusions of different studies on the same topic. See also Homogeneity.

  • Constant proportional trade-off

    Proportional trade off is the proportion of life someone would trade to improve their quality of life. Constant proportional trade off assumes this stays the same regardless of how much life they have left.

  • Consultation

    The period during guidance development when stakeholders or interested members of the public can comment on draft guidance. For guidelines and technology appraisals, there is also a consultation on the draft scope.
  • Consultee

    An organisation or individual invited to comment during development of NICE guidance. Consultees can submit evidence, comment on the draft documents and appeal against a committee's final recommendations. Consultee organisations include:

    • national groups representing patients and carers
    • bodies representing healthcare professionals
    • manufacturers of the intervention being appraised.
  • Control group

    A group of people in a study who do not have the intervention or test being studied. Instead, they may have the standard intervention (sometimes called 'usual care') or a dummy intervention (placebo). The results for the control group are compared with those for a group having the intervention being tested. The aim is to check for any differences. Ideally, the people in the control group should be as similar as possible to those in the intervention group, to make it as easy as possible to detect any effects due to the intervention.

  • Controlled clinical trial

    A study testing a specific treatment by using 2 (or more) groups of patients. The experimental group has the treatment being tested. The comparison (or control) group has an alternative treatment, a dummy treatment (placebo) or no treatment. The 2 groups are compared to see how effective the experimental treatment was. If patients are randomly allocated to treatment and comparison groups, this is called a randomised controlled trial.

  • Cost effectiveness

    Value for money: how well a technology works in relation to how much it costs.

  • Cost-benefit analysis

    One of the tools used to carry out an economic evaluation. The costs and benefits are measured using the same monetary units (for example, pounds sterling) to see whether the benefits exceed the costs.
  • Cost-consequence analysis

    One of the tools used to carry out an economic evaluation. This compares the costs (such as treatment and hospital care) and the consequences (such as health outcomes) of a test or treatment with a suitable alternative. Unlike cost-benefit analysis or cost-effectiveness analysis, it does not attempt to summarise outcomes in a single measure (such as the quality-adjusted life year) or in financial terms. Instead, outcomes are shown in their natural units (some of which may be monetary) and it is left to decision-makers to determine whether, overall, the treatment is worth carrying out.
  • Cost-effectiveness analysis

    An analysis that assesses the cost of achieving a benefit by different means. The benefits are expressed in non-monetary terms related to health, such as symptom-free days, heart attacks avoided, deaths avoided or life years gained (that is, the number of years by which life is extended as a result of the intervention). Options are often compared on the cost incurred to achieve 1 outcome (for example, cost per death avoided).

  • Cost-effectiveness plane

    Represents differences in costs and health outcomes on a graph, with effectiveness on the x axis and cost on the y axis. The graph is divided into 4 ‘quadrants’. In the north east quadrant, interventions are more effective and more costly (where most interventions lie). South east is less costly and more effective, south west is less costly and less effective, and north west is more costly and less effective.

  • Cost-minimisation analysis

    One of the tools used to carry out an economic evaluation. Cost-minimisation analysis compares the costs of different interventions that provide the same benefits. If they are equally effective, only the costs are compared and the cheapest intervention will provide the best value for money. In practice, there are relatively few cost-minimisation analyses because it is rare for 2 healthcare interventions to provide exactly the same benefits.
  • Cost-utility analysis

    One of the tools used to carry out an economic evaluation. The benefits are assessed in terms of both quality and duration of life, and expressed as quality-adjusted life years (QALYs). See also Utility.

  • Covariate

    A variable used in statistical analysis other that is not an exposure or outcome. This includes confounders, effect modifiers and predictive variables.

  • Critical appraisal

    Reviewing a study to judge the quality of the method used and the reliability of the conclusions.

  • Cross-over study design

    A study comparing 2 or more treatments. Once people in the study have completed a course of 1 treatment they are switched to a different treatment. For example, for a comparison of treatments A and B, half the people would have A first followed by B. The other half would have treatment B first followed by A.

  • Cross-sectional study

    A 'snapshot' observation of a set of people at 1 time. This type of study (sometimes called a cross-sectional survey) contrasts with a longitudinal study, which follows a set of people over a period of time.

  • Culturally appropriate

    Culturally appropriate interventions take account of cultural or religious beliefs, and language and literacy skills by:

    • using community resources to improve awareness of, and increase the number of people who can get interventions
    • understanding the target community and the messages that resonate with them
    • identifying and addressing barriers to access and participation
    • developing communication strategies that are sensitive to language and information needs
    • taking account of cultural or religious practices
    • considering how closely aligned people are with their ethnic group or religion.