The NICE glossary provides brief definitions and explanations of terms and jargon used on our site. The terms describe how we work and how our guidance is produced.

Our glossary excludes specific clinical and medical terms although we intend to include these in the longer term. If you cannot find the term you are looking for, please email us so that we can consider adding it to the glossary. New terms are added regularly.

The glossary is not used for indexing the site or for navigation - for information on this, please see the NICE taxonomy.

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


Absolute risk

The likelihood of an event or outcome occurring (for example, an adverse reaction to the drug being tested) among the group being studied. Studies that compare two or more groups of people may report results in terms of the absolute risk reduction.

Absolute Risk Reduction (ARR)

A reduction in the likelihood of an event or outcome occurring as a result of a treatment or another intervention. For example, if a treatment reduces the absolute risk of death from 0.25 (25%) to 0.10 (10%), the ARR is 0.15 (15%), that is, 0.25 minus 0.10 equals 0.15.

The estimate of absolute risk reduction often comes from clinical trials. The percentage of people taking part who are receiving treatment (treatment group) and experience a specific outcome is compared with the percentage of people taking part but not receiving treatment (control group) who experience the same outcome.

Acute sector

Hospital-based healthcare services for inpatients, outpatients and people having day case treatments.

Adverse event

An unwanted outcome related to a treatment, for example a side effect from a drug, or a dangerous clot forming after surgery.


Someone who speaks on behalf of themselves or another person. In health, an advocate is usually a person who speaks on behalf of a patient, or a group of patients to help them make their wishes known.

Allied health professionals

Professionals other than doctors or nurses who are directly involved in providing healthcare. This includes physiotherapists, occupational therapists and dietitians. (All formerly known as 'professions allied to medicine' or PAMs.)


The process of looking for patterns in information to identify cause and effect or answer specific questions, such as whether a treatment works and what the risks are.

There are two types of analysis. Quantitative analysis looks for patterns in the form of numbers, such as most frequent choice of treatment option or average rating of pain during treatment. Qualitative analysis looks for patterns of meaning, feeling or beliefs. It can lead to a finding such as 'most people who support paying more for end of life therapy also believe society should give more to those with greater need.'

Appeals period

The final stage of the technology appraisal process, during which the manufacturers and organisations representing patients and carers and healthcare professionals (consultees) can appeal against the final guidance (final appraisal determination) before it is issued to the NHS. The appeals period is 15 working days.

Appeals process

Appeals process is the final part of the NICE appraisal process to ensure that the final guidance is robust, where organisations representing patients and carers, healthcare professionals and manufacturers can appeal against final advice given by the independent advisory committee on a specific medicine or treatment.


How well the results of a study or NICE evidence review can answer a clinical question or be applied to the population being considered.

Appraisal committee

An independent committee that develops NICE's guidance about using drugs or treatments in the NHS (called technology appraisal guidance). The Committee usually meets twice to discuss each drug or treatment, or group of similar drugs or treatments. The first time, the Committee produces the draft guidance (called the appraisal consultation document), based on the research findings and discussion with experts. The second time, the Committee revises the guidance after the consultation with manufacturers, healthcare professionals and patient groups, to produce a document called the final appraisal determination. The Appraisal Committee is made up of healthcare professionals and NHS managers, researchers, patients and carers, and people who work for drug companies and medical equipment manufacturers. Committee members are appointed for 3 years.

The Committee's membership is split into three branches, each with a chair and vice-chair. Each branch considers its own list of technologies and ongoing topics are not moved between the branches.

Appraisal consultation documents (ACD)

The Appraisal Committee's draft guidance about using a drug (or group of similar drugs) or treatment in the NHS (a technology appraisal). The manufacturer and organisations registered as consultees and commentators can comment on the draft guidance during a consultation period that lasts 4 weeks. The draft guidance is also posted on our website, so that anyone can read it.

Appraisal of evidence

Formal assessment of the quality of research evidence and its relevance to the clinical question or topic being considered. It is assessed according to predetermined criteria.


See Absolute Risk Reduction.

Assessment group

This term relates to: Technology appraisals

An independent group of researchers commissioned by NICE to review the evidence on a group of treatments. The assessment group includes researchers who assess the quality of studies on the treatments, and health economists who look at whether the treatments are good value for money. The Appraisal Committee bases its discussions on the assessment report produced by the assessment group.

Assessment report

This term relates to: Technology appraisals

A review of the evidence about how well a group of similar treatments work, and whether they offer value for money. The assessment report forms the basis of the Appraisal Committee's discussions. The assessment report is written by an assessment group. Assessment reports are produced for treatments being assessed using the multiple technology appraisal process, in which several similar drugs are assessed together. Organisations registered as consultees and commentators can comment on the report.


A systematic review of a practice, process or performance to establish how well it meets predetermined criteria. For example, audit may be carried out on a specific service (such as stop smoking services), to check whether it complies with laws, regulations or policies. See clinical audit.

Audit Committee

A subcommittee of NICE's board that keeps a check on NICE's finances and other aspects of the way the organisation is run.

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This page was last updated: 15 April 2011

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Selected, reliable information for health and social care in one place

Accessibility | Cymraeg | Freedom of information | Vision Impaired | Contact Us | Glossary | Data protection | Copyright | Disclaimer | Terms and conditions

Copyright 2014 National Institute for Health and Care Excellence. All rights reserved.