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National Collaborating Centre for Acute Care (UK). Nutrition Support for Adults: Oral Nutrition Support, Enteral Tube Feeding and Parenteral Nutrition. London: National Collaborating Centre for Acute Care (UK); 2006 Feb. (NICE Clinical Guidelines, No. 32.)

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Nutrition Support for Adults: Oral Nutrition Support, Enteral Tube Feeding and Parenteral Nutrition.

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Glossary of Terms

Amended from a glossary produced by the Patient Involvement Unit, NICE.

Absolute risk reduction (Risk difference)

The difference in event rates between two groups (one subtracted from the other) in a comparative study.


Summary of a study, which may be published alone or as an introduction to a full scientific paper.

Acute Phase Response

A group of physiologic processes occurring soon after the onset of infection, trauma, inflammatory processes, and some malignant conditions. The most prominent change is a dramatic increase of acute phase proteins, especially C-reactive protein, in the serum. Also seen are fever, increased vascular permeability, and a variety of metabolic and pathologic changes2.


A statistical procedure in which the effects of differences in composition of the populations being compared (or treatment given at the same time) have been minimised by statistical methods.

Algorithm (in guidelines)

A flow chart of the clinical decision pathway described in the guideline, where decision points are represented with boxes, linked with arrows.

Allocation concealment

The process used to prevent advance knowledge of group assignment in a RCT. The allocation process should be impervious to any influence by the individual making the allocation, by being administered by someone who is not responsible for recruiting participants.


The equipment and consumables required for enteral and parenteral nutrition.


The degree to which the results of an observation, study or review are likely to hold true in a particular clinical practice setting.

Appraisal of Guidelines, Research and Evaluation (AGREE)

An international collaboration of researchers and policy makers whose aim is to improve the quality and effectiveness of clinical practice guidelines ( The AGREE instrument, developed by the group, is designed to assess the quality of clinical guidelines.

Appraisal Committee

A standing advisory committee of the Institute. Its members are drawn from the NHS, patient/carer organisations, relevant academic disciplines and the pharmaceutical and medical devices industries.

Arm (of a clinical study)

Sub-section of individuals within a study who receive one particular intervention, for example placebo arm.

Assessment protocol

Written instructions for the conduct and analysis of the assessment of a technology.

Assessment Report

In technology appraisals, a critical review of the clinical and cost effectiveness of a health technology/technologies. It is prepared by the Assessment Group. To prepare the report, the Assessment Group carries out a review of the published literature and the submissions from manufacturers and sponsors.


Statistical relationship between two or more events, characteristics or other variables. The relationship may or may not be causal.


See ‘Clinical audit’.

Audit trail

Records of action to assess practice against standards. Also a record of actions, for example changes to a draft guideline so that reasons can be apparent to a third party.


The initial set of measurements at the beginning of a study (after run-in period where applicable), with which subsequent results are compared.


Influences on a study that can lead to invalid conclusions about a treatment or intervention. Bias in research can make a treatment look better or worse than it really is. Bias can even make it look as if the treatment works when it actually doesn’t. Bias can occur by chance or as a result of systematic errors in the design and execution of a study. Bias can occur at different stages in the research process, e.g. in the collection, analysis, interpretation, publication or review of research data.

Blinding (masking)

Keeping the study participants, caregivers, researchers and outcome assessors unaware about the interventions to which the participants have been allocated in a study

Body Mass Index

A measure of body weight relative to height used to determine whether people are underweight, at a healthy weight, over weight or obese.

Bolus/intermittent feeding

The administration of a feed through an enteral tube delivered as a single portion over a short period of time.

Capital costs

Costs of purchasing major capital assets (usually land, buildings or equipment). Capital costs represent investments at one point in time.

Care homes

This refers to residential and nursing care.

Carer (caregiver)

Someone other than a health professional who is involved in caring for a person with a medical condition.

Case-control study

Comparative observational study in which the investigator selects individuals who have experienced an event (for example, developed a disease) and others who have not (controls), and then collects data to determine previous exposure to a possible cause

Case report (or case study)

Detailed report on one patient (or case), usually covering the course of that person’s disease and their response to treatment.

Case series

Report of a number of cases of a given disease, usually covering the course of the disease and the response to treatment. There is no comparison (control) group of patients.

Classification of recommendations

A code (such as A, B, C, D) given to a guideline recommendation, indicating the strength of the evidence supporting that recommendation.

Clinical audit

A quality improvement process that seeks to improve patient care and outcomes through systematic review of care against explicit criteria and the implementation of change.

Clinical efficacy

The extent to which an intervention is active when studied under controlled research conditions.

Clinical effectiveness

The extent to which an intervention produces an overall health benefit in routine clinical practice.

Clinical impact

The effect that a guideline recommendation is likely to have on the treatment or treatment outcomes, of the target population.

Clinical question

In guideline development, this term refers to the questions about treatment and care that are formulated to guide the development of evidence-based recommendations.


A healthcare professional providing direct patient care, for example doctor, nurse or physiotherapist.


A closely grouped series of events or cases of a disease or other related health phenomena with well-defined distribution patterns, in relation to time or place or both. Alternatively, a grouped unit for randomisation.

Cochrane Library

A regularly updated electronic collection of evidence-based medicine databases, including the Cochrane Database of Systematic Reviews.

Cochrane Review

A systematic review of the evidence from randomised controlled trials relating to a particular health problem or healthcare intervention, produced by the Cochrane Collaboration. Available electronically as part of the Cochrane Library.

Cohort study

A retrospective or prospective follow-up study. Groups of individuals to be followed up are defined on the basis of presence or absence of exposure to a suspected risk factor or intervention. A cohort study can be comparative, in which case two or more groups are selected on the basis of differences in their exposure to the agent of interest.

Combined modality

Use of different treatments in combination (for example surgery, chemotherapy and radiotherapy used together).


Organisations that engage in the appraisal process but that are not asked to prepare a submission dossier, and that receive the Final Appraisal Determination (FAD) for information only, without right of appeal. These organisations are manufacturers of comparator technologies, NHS Quality Improvement Scotland; the relevant National Collaborating Centre; other related research groups and other groups where appropriate.

Comments table

Table compiled by NICE to show all the comments and responses generated as part of the consultation process.

Commercial in confidence

See ‘In confidence’


This may refer to care homes (including residential care and nursing care), domiciliary care (also known as ‘home’ care) and primary care.


Co-existence of more than one disease or an additional disease (other than that being studied or treated) in an individual.


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


The extent to which a person adheres to the health advice agreed with healthcare professionals. May also be referred to as ‘adherence’.

Conference proceedings

Compilation of papers presented at a conference.

Confidence interval

A range of values for an unknown population parameter with a stated ‘confidence’ (conventionally 95%) that it contains the true value. The interval is calculated from sample data, and generally straddles the sample estimate. The ‘confidence’ value means that if the method used to calculate the interval is repeated many times, then that proportion of intervals will actually contain the true value.


In a study, confounding occurs when the effect of an intervention on an outcome is distorted as a result of an association between the population or intervention or outcome and another factor (the ‘confounding variable’) that can influence the outcome independently of the intervention under study.

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. In the development of clinical guidelines, consensus methods may be used where there is a lack of strong research evidence on a particular topic. Expert consensus methods will aim to reach agreement between experts in a particular field.


The process that allows stakeholders and individuals to comment on initial versions of NICE guidance and other documents so their views can be taken into account when producing the final version.


An organisation that accepts an invitation to participate in the appraisal. Consultees can participate in the consultation on the draft scope, the Assessment Report and the Appraisal Consultation Document; consultee organisations representing patient/carers and professionals can nominate clinical specialists and patient experts to present their personal views to the Appraisal Committee, AND are given the opportunity to appeal against the Final Appraisal Determination (FAD).

CONSORT statement (Consolidated reporting of clinical trials)

Recommendations for improving the reporting of randomised controlled trials in journals. A flow diagram and checklist allow readers to understand the conduct of the study and assess the validity of the results.

Control group

A group of patients recruited into a study that receives no treatment, a treatment of known effect, or a placebo (dummy treatment) - in order to provide a comparison for a group receiving an experimental treatment, such as a new drug.

Controlled clinical trial (CCT)

A study testing a specific drug or other treatment involving two (or more) groups of patients with the same disease. One (the experimental group) receives the treatment that is being tested, and the other (the comparison or control group) receives an alternative treatment, a placebo (dummy treatment) or no treatment. The two groups are followed up to compare differences in outcomes to see how effective the experimental treatment was. A CCT where patients are randomly allocated to treatment and comparison groups is called a randomised controlled trial.

Cost benefit analysis

A type of economic evaluation where both costs and benefits of healthcare treatment are measured in the same monetary units. If benefits exceed costs, the evaluation would recommend providing the treatment.

Cost-consequences analysis (CCA)

A type of economic evaluation where various health outcomes are reported in addition to cost for each intervention, but there is no overall measure of health gain.

Cost-effectiveness analysis

An economic study design in which consequences of different interventions are measured using a single outcome, usually in ‘natural’ units (for example, life-years gained, deaths avoided, heart attacks avoided, cases detected). Alternative interventions are then compared in terms of cost per unit of effectiveness.

Cost-effectiveness model

An explicit mathematical framework, which is used to represent clinical decision problems and incorporate evidence from a variety of sources in order to estimate the costs and health outcomes.

Cost-utility analysis

A form of cost-effectiveness analysis in which the units of effectiveness are quality-adjusted life-years (QALYs).

Content expert

An individual with skills or knowledge relating to the subject being investigated.

Criterion (in audit)

An explicit statement that defines the appropriateness of healthcare decisions, services and outcomes, and that can be measured.

Cross-sectional study

The observation of a defined set of people at a single point in time or time period – a snapshot. (This type of study contrasts with a longitudinal study which follows a set of people over a period of time).

Decision analysis

A systematic way of reaching decisions, based on evidence from research. This evidence is translated into probabilities, and then into diagrams or decision trees which direct the clinician through a succession of possible scenarios, actions and outcomes.

Decision analytic techniques

A way of reaching decisions, based on evidence from research. This evidence is translated into probabilities, and then into diagrams or decision trees that direct the clinician through a succession of possible scenarios, actions and outcomes.

Decision problem

A clear specification of the interventions, patient populations and outcome measures and perspective adopted in an evaluation, with an explicit justification, relating these to the decision which the analysis is to inform.

Dietary advice

The provision of instructions on modifying food intake to improve nutritional intake.


Costs and perhaps benefits incurred today have a higher value than costs and benefits occurring in the future. Discounting health benefits reflects individual preference for benefits to be experienced in the present rather than the future. Discounting costs reflects individual preference for costs to be experienced in the future rather than the present.


An intervention is said to be dominated if there is an alternative intervention that is both less costly and more effective.


The prescribed amount of a drug to be taken, including the size and timing of the doses.

Double blind study

A study in which neither the subject (patient) nor the observer (investigator/clinician) is aware of which treatment or intervention the subject is receiving. The purpose of blinding is to protect against bias.


A participant who withdraws from a clinical trial before the end.


Any impairment of eating, drinking and swallowing.

Economic evaluation

Comparative analysis of alternative health strategies (interventions or programmes) in terms of both their costs and consequences.


See ‘Clinical efficacy’.

Effect (as in effect measure, treatment effect, estimate of effect, effect size)

The observed association between interventions and outcomes or a statistic to summarise the strength of the observed association.


See ‘Clinical effectiveness’.


Name for clinical procedures that are regarded as advantageous to the patient but not urgent.


Anions and cations in the blood, tissue fluids and cells e.g. sodium, potassium and chlorine.

Enteral nutrition

see enteral tube feeding

Enteral tube feeding

Nutrition support directly into the gut via a tube (the term as used in these guidelines does not include oral intake).

Epidemiological study

The study of a disease within a population, defining its incidence and prevalence and examining the roles of external influences (for example, infection, diet) and interventions


Information on which a decision or guidance is based. Evidence is obtained from a range of sources including randomised controlled trials, observational studies, expert opinion (of clinical professionals and/or patients).

Evidence table

A table summarising the results of a collection of studies which, taken together, represent the evidence supporting a particular recommendation or series of recommendations in a guideline.

Exclusion criteria (literature review)

Explicit standards used to decide which studies should be excluded from consideration as potential sources of evidence.

Exclusion criteria (clinical study)

Criteria that define who is not eligible to participate in a clinical study.

Expert consensus

See ‘Consensus methods’.

Extended dominance

If Option A is both more clinically effective than Option B and has a lower cost per unit of effect, when both are compared with a do-nothing alternative then Option A is said to have extended dominance over Option B. Option A is therefore more efficient and should be preferred, other things remaining equal.


In data analysis, predicting the value of a parameter outside the range of observed values.


An individual whose function is to promote the effective functioning of the group.

Focus group

A qualitative research technique. It is a method of group interview or discussion of between 6–12 people focused around a particular issue or topic. The method explicitly includes and uses the group interaction to generate data.

Follow up

Observation over a period of time of an individual, group or initially defined population whose appropriate characteristics have been assessed in order to observe changes in health status or health-related variables.

Gantt Chart

A project planning tool showing the timing of tasks within a project. Dates run from left to right and each task is represented by a horizontal bar, the left end of which marks the expected beginning of the task and the right end of which marks the planned completion date.

Gastrojejunostomy tube

Enteral tube inserted through the abdominal wall which passes through the stomach into the jejunum for the purpose of nutrition support.


Enteral tube inserted through the abdominal wall into the stomach for the purpose of nutrition support.


The extent to which the results of a study based on measurement in a particular patient population and/or a specific context hold true for another population and/or in a different context. In this instance, this is the degree to which the guideline recommendation is applicable across both geographical and contextual settings. For instance, guidelines that suggest substituting one form of labour for another should acknowledge that these costs might vary across the country.

Generic name

The general non-proprietary name of a drug or device.

Gold standard

A method, procedure or measurement that is widely accepted as being the best available.


How well a statistical model or distribution compares with the observed data.

Good Practice Points

Recommended good practice based on the clinical experience of the Guideline Development Group.

Grading evidence

A code given to a study or other evidence, indicating the quality and generalisability of the research. The highest grade evidence will usually be obtained from randomised controlled trials.

Grey literature

Reports that are unpublished or have limited distribution, and are not included in the common bibliographic retrieval systems.


Adverse effects of an intervention.

Health economics

The study of the allocation of scarce resources among alternative healthcare treatments. Health economists are concerned with both increasing the average level of health in the population and improving the distribution of health.

Health related quality of life

A combination of an individual’s physical, mental and social well-being; not merely the absence of disease.

Health technology

Any method used by those working in health services to promote health, prevent and treat disease, and improve rehabilitation and long-term care. Technologies in this context are not confined to new drugs or pieces of sophisticated equipment.


Or lack of homogeneity. The term is used in meta-analyses and systematic reviews when the results or estimates of effects of treatment from separate studies seem to be very different – in terms of the size of treatment effects or even to the extent that some indicate beneficial and others suggest adverse treatment effects. Such results may occur as a result of differences between studies in terms of the patient populations, outcome measures, definition of variables or duration of follow-up.

Home enteral tube feeding

The practice of enteral tube feeding in the community.

Home parenteral Nutrition

The practice of parenteral nutrition in the community.


This means that the results of studies included in a systematic review or meta-analysis are similar and there is no evidence of heterogeneity. Results are usually regarded as homogeneous when differences between studies could reasonably be expected to occur by chance.


A supposition made as a starting point for further investigation.


Introducing the use of the guidance recommendations in practice.

In confidence material

Information (for example, the findings of a research project) defined as ‘confidential’ as its public disclosure could have an impact on the commercial interests of a particular company or the academic interests of a research or professional organisation.

Inclusion criteria (literature review)

Explicit criteria used to decide which studies should be considered as potential sources of evidence.

Incremental analysis

The comparison of the costs and effects of one intervention compared with the next best alternative.

Incremental cost effectiveness ratio

The difference in the mean costs in the population of interest divided by the differences in the mean outcomes in the population of interest.


In epidemiology and related sciences, this word usually means a rating scale, for example, a set of numbers derived from a series of observations of specified variables. Examples include the various health status indices, and scoring systems for severity or stage of cancer.

Indication (specific)

The defined use of a technology as licensed by the Medicines and Healthcare products Regulatory Agency (MHRA).

Intention-to-treat analysis (ITT analysis)

An analysis of the results of a clinical study in which the data are analysed for all study participants as if they had remained in the group to which they were randomised, regardless of whether or not they remained in the study until the end, crossed over to another treatment or received an alternative intervention

Intermediate outcomes

Outcomes that are related to the outcome of interest but may be more easily assessed within the context of a clinical study: for example, blood pressure reduction is related to the risk of a stroke.

Internal validity

The degree to which the results of a study are likely to approximate the ‘truth’ for the participants recruited in a study (that is, are the results free of bias?). It refers to the integrity of the design and is a prerequisite for applicability (external validity) of a study’s findings. See ‘External validity’.


Healthcare action intended to benefit the patient, for example, drug treatment, surgical procedure, psychological therapy.


Enteral tube inserted through the abdominal wall directly into the jejunum for the purpose of nutrition support.

Length of stay

The total number of days a participant stays in hospital.


See ‘Product licence’.

Life year

A measure of health outcome which shows the number of years of remaining life expectancy.

Life-years gained

Average years of life gained per person as a result of the intervention.

Longitudinal study

A study of the same group of people at more than one point in time. (This type of study contrasts with a cross sectional study which observes a defined set of people at a single point in time).


Cavity or channel within a tube


A state of nutrition in which a deficiency of energy, protein and/or other nutrients causes measurable adverse effects on tissue/body form, composition, function or clinical outcome94 (in these guidelines we do not use the term to cover excess nutrient provision). For the purposes of this guideline we have considered that malnutrition is likely to be significant if a person has a BMI <18.5 kg/m2, or unintentional weight loss >10% within the previous 3–6 months, or a BMI<20 kg/m2 and unintentional weight loss >5% within the previous 3–6 months.

Malnutrition, at risk

has eaten little or nothing for more than 5 days and/or is likely to eat little or nothing for the next 5 days or longer

Medicines and Healthcare Products Regulatory Agency (MHRA)

The Executive Agency of the Department of Health protecting and promoting public health and patient safety by ensuring that medicines, healthcare products and medical equipment meet appropriate standards of safety, quality, performance and effectiveness, and are used safely.


Results from a collection of independent studies (investigating the same treatment) are pooled, using statistical techniques to synthesise their findings into a single estimate of a treatment effect. Where studies are not compatible e.g. because of differences in the study populations or in the outcomes measured, it may be inappropriate or even misleading to statistically pool results in this way. See also Systematic review & Heterogeneity.

Motility agent

A medication used to aid the movement of food from the stomach into the intestine.

Nasoduodenal (tube) feeding

Nutrition support provided via a tube inserted via the nose, oesophagus and stomach into the duodenum.

Nasogastric (tube) feeding

Nutrition support provided through a tube inserted through the nose via the oesophagus into the stomach.

Nasojejunal (tube) feeding

Nutrition support provided through a tube inserted through the nose via the oesophagus, stomach and duodenum into the jejunum.

NICE Technology Appraisals

Recommendations on the use of new and existing medicines and other treatments within the NHS in England and Wales, such as: medicines (for example, drugs), medical devices (for example, hearing aids and inhalers), diagnostic techniques (tests used to identify diseases), surgical procedures (for example, repair of hernias), health promotion activities (for example, patient education models for diabetes).

Non-experimental study

A study based on subjects selected on the basis of their availability, with no attempt having been made to avoid problems of bias.

Number needed to treat

The number of patients that who on average must be treated to prevent a single occurrence of the outcome of interest.

Nutrition assessment

A comprehensive evaluation to define nutrition status, including medical history, dietary history, physical examination, anthropometric measurements and laboratory data, by a health professional with skills and tanning in nutrition and nutrition support. For example dietitian, nutrition nurse.

Nutrition screening

A rapid, simple and general procedure used by nursing, medical or other staff, often at first contact with the patient, to detect those who have significant nutritional problems or significant risks of such problems, in order that clear guidelines for action can be implemented, e.g. simple dietary measures or referral for expert help94.

Nutrition support

The provision of nutrients and any necessary adjunctive therapeutic agents to patients orally and/or enterally by administration into the stomach or intestine and/or by intravenous infusion (parenterally) for the purpose of improving or maintaining a patient’s nutrition status’

Nutrition Support Team

A multidisciplinary team with dietetic, nursing, pharmacy and medical expertise to provide safe nutrition support.

Observational study

Retrospective or prospective study in which the investigator observes the natural course of events with or without control groups; for example, cohort studies and case–control studies.

Older people

People over the age of 65 years.

Operating costs

Ongoing costs of carrying out an intervention, excluding capital costs.

Oral Nutritional Supplement

A product for use in oral nutrition support given with the aim to increase nutritional intake.

Oral nutrition support

The modification of food and fluid by: fortifying food with protein, carbohydrate and/or fat plus minerals and vitamins; the provision snacks and/or oral nutritional supplements as extra nutrition to regular meals, changing meal patterns or the provision of dietary advice to patients on how to increase overall nutrition intake by the above.

Orogastric (tube) feeding

Nutrition support provided by a tube inserted through the mouth via the oesophagus into the stomach

Opportunity cost

The opportunity cost of investing in a healthcare intervention is the other healthcare programmes that are displaced by its introduction. This may be best measured by the health benefits that could have been achieved had the money been spent on the next best alternative healthcare intervention.


Measure of the possible results that may stem from exposure to a preventive or therapeutic intervention. Outcome measures may be intermediate endpoints or they can be final endpoints. See ‘Intermediate outcome’.

P value

The probability that an observed difference could have occurred by chance, assuming that there is in fact no underlying difference between the means of the observations. If the probability is less than 1 in 20, the P value is less than 0.05; a result with a P value of less than 0.05 is conventionally considered to be ‘statistically significant’.

Palliative care

Active holistic care of patients with advanced progressive illness, focusing on the management of pain and other symptoms and provision of psychological, social and spiritual support. The goal of palliative care is the achievement of the best quality of life for patients and their families.378

Parenteral nutrition

The provision of nutrition support through intravenous administration of nutrients such as amino acids, glucose, fat, electrolytes, vitamins and trace elements.


The period from admission through surgery until discharge, encompassing pre-operative and post-operative periods. Studies included in this guideline for surgical patients sometimes start or end their intervention outside this period. However, they always include nutrition support during some of the perioperative phase.

Peer review

A process where research is scrutinised by experts that have not been involved in the design or execution of the studies.

Pilot study

A small scale ‘test’ of the research instrument. For example, testing out (piloting) a new questionnaire with people who are similar to the population of the study, in order to highlight any problems or areas of concern, which can then be addressed before the full scale study begins.


An inactive and physically identical medication or procedure used as a comparator in controlled clinical trials.

Placebo effect

A beneficial (or adverse) effect produced by a placebo and not due to any property of the placebo itself.


See ‘Statistical power’.

Primary care

Healthcare delivered to patients outside hospitals. Primary care covers a range of services provided by GPs, nurses and other healthcare professionals, dentists, pharmacists and opticians.

Primary research

Study generating original data rather than analysing data from existing studies (which is called secondary research).

Product licence

An authorisation from the MHRA to market a medicinal product.


A probable course or outcome of a disease. Prognostic factors are patient or disease characteristics that influence the course. Good prognosis is associated with low rate of undesirable outcomes; poor prognosis is associated with a high rate of undesirable outcomes.

Proprietary name

The brand name given by the manufacturer to a drug or device it produces.

Prospective study

A study in which people are entered into the research and then followed up over a period of time with future events recorded as they happen. This contrasts with studies that are retrospective.

Qualitative research

Research concerned with subjective outcomes relating to social, emotional and experiential phenomena in health and social care.

Quality adjusted life years (QALYS)

An index of survival that is adjusted to account for the patient’s quality of life during this time. QALYs have the advantage of incorporating changes in both quantity (longevity/mortality) and quality (morbidity, psychological, functional, social and other factors) of life. Used to measure benefits in cost-utility analysis.

Quality of life

See ‘Health related quality of life

Quantitative research

Research that generates numerical data or data that can be converted into numbers, for example clinical trials or the national Census which counts people and households.

Quick Reference Guide (for a guideline or appraisal)

An abridged version of NICE guidance, which presents the key priorities for implementation and summarises the recommendations for the core clinical audience.

Random allocation or Randomisation

Allocation of participants in a research study to two or more alternative groups using a chance procedure, such as computer-generated random numbers. This approach is used in an attempt to ensure there is an even distribution of participants with different characteristics between groups and thus reduce sources of bias.

Randomised controlled trial

A comparative study in which participants are randomly allocated to intervention and control groups and followed up to examine differences in outcomes between the groups.

Rapid update

Review of existing guidance carried out sooner than originally planned because new data have become available.

Reference standard (or gold standard)

An agreed standard, for example for a test or treatment, against which other interventions can be compared.

Relative risk

The number of times more likely or less likely an event is to happen in one group compared with another (calculated as the risk of the event in group A/the risk of the event in group B).


The degree of agreement exhibited when a measurement is repeated under identical conditions. Reliability refers to the degree to which the results obtained by a measurement procedure can be replicated.


The brief given by the Department of Health and Welsh Assembly Government at the beginning of the guideline development process. This defines core areas of care that the guideline needs to address.

Research Ethics Committee

An independent committee that scrutinises proposals for research to ensure they are ethically acceptable.

Resource implication

The likely impact in terms of finance, workforce or other NHS resources.

Retrospective study

A retrospective study deals with the present/ past and does not involve studying future events. This contrasts with studies that are prospective.

Review of the literature

An article that summarises the evidence contained in a number of different individual studies and draws conclusions about their findings. It may or may not be systematically researched and developed.

Secondary benefits

Benefits resulting from a treatment in addition to the primary, intended outcome.

Secondary care

Care provided in hospitals.

Selection bias (also allocation bias)

A systematic bias in selecting participants for study groups, so that the groups have differences in prognosis and/or therapeutic sensitivities at baseline. Randomisation (with concealed allocation) of patients protects against this bias.

Selection criteria

Explicit standards used by guideline development groups to decide which studies should be included and excluded from consideration as potential sources of evidence.

Sensitivity analysis

A means of representing uncertainty in the results of economic evaluations. Uncertainty may arise from missing data, imprecise estimates or methodological controversy. Sensitivity analysis also allows for exploring the generalisability of results to other settings. The analysis is repeated using different assumptions to examine the effect on the results. One-way simple sensitivity analysis (univariate analysis): each parameter is varied individually in order to isolate the consequences of each parameter on the results of the study. Multi-way simple sensitivity analysis (scenario analysis): two or more parameters are varied at the same time and the overall effect on the results is evaluated. Threshold sensitivity analysis: the critical value of parameters above or below which the conclusions of the study will change are identified. Probabilistic sensitivity analysis: probability distributions are assigned to the uncertain parameters and are incorporated into evaluation models based on decision analytical techniques (for example, Monte Carlo simulation).

Service delivery guidance

Recommendations on service delivery primarily aimed at health service commissioners. Service delivery guidance focuses on the broad configuration and provision of clinical services and addresses only those interventions that are likely to have implications for the configuration of services.

Specialised nutrition support
Specificity (of a test)

The proportion of individuals classified as negative by the gold (or reference) standard, who are correctly identified by the study test.

Standard care

The situation in which a patient is given no supplementary nutrition support but still eats meals and snacks as appropriate for their clinical status and usual practice.

Standardised Parenteral Nutrition

Admixtures containing fixed formulations of nutrients, such as amino acids, glucose, fat emulsion and electrolytes in a single sterile container system. Additions of other nutrients such as vitamins and trace elements and occasionally supplemental electrolytes are required to ensure complete admixtures are administered.


Those with an interest in the use of a technology under appraisal or a guideline under development. Stakeholders include manufacturers, sponsors, healthcare professionals, and patient and carer groups.

Statistical power

The ability to demonstrate an association when one exists. Power is related to sample size; the larger the sample size, the greater the power and the lower the risk that a possible association could be missed.

Synthesis of evidence

A generic term to describe methods used for summarising (comparing and contrasting) evidence into a clinically meaningful conclusion in order to answer a defined clinical question. This can include systematic review (with or without meta-analysis), qualitative and narrative summaries.

Systematic review

Research that summarises the evidence on a clearly formulated question according to a pre-defined protocol using systematic and explicit methods to identify, select and appraise relevant studies, and to extract, collate and report their findings. It may or may not use statistical meta-analysis.

Systemic Inflammatory Response Syndrome (SIRS)

A systemic inflammatory response to at least two criteria leukocytosis, fever, tachycardia, and tachypnea.

Technical Lead

Appraisals team member who has responsibility for the technical aspects of the appraisal including liaising with the Assessment Group, scoping the appraisal, preparing drafts of consultation documents and advising the Appraisal Committee on technical aspects of the appraisal. There may be more than one Technical Lead for an appraisal.

Technology assessment

The process of evaluating the clinical, economic and other evidence relating to use of a technology in order to formulate guidance on its most efficient use.

Test-and-treat strategy

Testing all individuals presenting with suspected of having a condition, and treating only those with a particular test result.

Time horizon

The time span used in the NICE appraisal which reflects the period over which the main differences between interventions in health effects and use of healthcare resources are expected to be experienced, and taking into account the limitations of supportive evidence.

Treatment allocation

Assigning a participant to a particular arm of the trial.

Treatment options

The choices of intervention available.


A measure of the strength of an individual’s preference for a specific health state in relation to alternative health states. The utility scale assigns numerical values on a scale from 0 (death) to 1 (optimal or ‘perfect’ health). Health states can be considered worse than death and thus have a negative value.

Copyright © 2006, National Collaborating Centre for Acute Care.

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