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.
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Negative predictive value
The proportion of people with a negative test result who do not have the disease or characteristic. It is different from specificity.
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Net benefit
The value of the benefit from a test, treatment or procedure, minus its total costs. It can be expressed in health (for example, using quality-adjusted life years) or monetary terms.
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Net health benefit
The difference between the total expected quality-adjusted life years and the health expected to be forgone elsewhere (these are the total expected costs divided by the maximum acceptable incremental cost-effectiveness ratio value).
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Net monetary benefit
The difference between the monetary value of total expected quality-adjusted life years (QALYs) and total expected costs. Total expected QALYs are calculated by multiplying expected QALYs by the maximum acceptable incremental cost-effectiveness ratio value.
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Network meta-analysis
An analysis that compares 2 or more interventions using a combination of direct evidence (from studies that directly compare the interventions of interest) and indirect evidence (from studies that do not compare the interventions of interest directly).
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NICE advice
This is a support service for pharmaceutical and healthtech companies seeking to enter the NHS market. Its aim is to help companies prepare for a NICE evaluation, or engagement with NHS payers or commissioners, by providing accurate and reliable scientific and strategic advice, education and NHS insights.
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NICE guidance
Evidence-based recommendations produced by NICE. There are 6 types of guidance:
- guidelines covering clinical topics, medicines practice, public health and social care
- diagnostics guidance
- health technology evaluations
- highly specialised technology guidance
- interventional procedures guidance
- medical technologies guidance
- technology appraisals guidance.
All guidance is developed by independent committees and is consulted on. NICE may also publish supporting documents for each piece of guidance, including advice on how to put the guidance into practice, and information on its costs, and the evidence it is based on.
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Nominal group technique
A technique used to reach agreement on a particular issue. It uses a variety of postal and direct contact techniques, with individual judgements being aggregated statistically to derive the group judgement -
Non-randomised study
A comparative study which does not involve randomisation. This can include purely observational studies, non-randomised interventional studies, and single-arm trials with external control.
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Non-reference-case analysis
An analysis that does not use the methods in the reference case.
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Notification
The process by which a notifier (usually the company for the medical technology) informs NICE about a potential technology for evaluation.
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Number needed to harm
A measure of the chance of experiencing a specified harm in a specified time because of the treatment or other intervention. Ideally, this number should be as large as possible. For example, if the number needed to harm (NNH) for drug A compared with drug B for major bleeding over 1 year is 50, on average, for every 50 people who take drug A instead of drug B for 1 year, 1 person will have major bleeding who would not have done if all 50 had got drug B. The other 49 people out of the 50 will have or not have major bleeding, just as if they had taken drug B. The NNH is 100 divided by the absolute risk increase (ARI) expressed as a percentage. For example, if the ARI is 0.1%, the NNH is 100/0.1=1,000.
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Number needed to treat
The average number of patients who need to have the treatment or other intervention for one of them to get the positive outcome in the time specified. The closer the number needed to treat (NNT) is to 1, the more effective the treatment. For example, if the NNT for drug A compared with drug B for pain relief after a tooth extraction is 4, on average, for every 4 people who get drug A instead of drug B, 1 person will have pain relief after tooth extraction who would not have done if all 4 had got drug B. The other 3 people out of the 4 will have or not have pain relief, just as if they had taken drug B. The NNT is 100 divided by the absolute risk reduction (ARR) expressed as a percentage. For example, if the ARR is 5%, the NNT is 100/5=20.