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National Collaborating Centre for Nursing and Supportive Care (UK). Clinical Practice Guideline for the Assessment and Prevention of Falls in Older People. London: Royal College of Nursing (UK); 2004 Nov. (NICE Clinical Guidelines, No. 21.)

  • This publication is provided for historical reference only and the information may be out of date.

This publication is provided for historical reference only and the information may be out of date.

General glossary

Partially based on Clinical epidemiology glossary by the Evidence Based Medicine Working Group, www.ed.ualberta.ca/ebm;Information for national collaborating centres and guideline development groups (NICE 2001).

Absolute risk reduction

The difference between the observed event rates (proportions of individuals with the outcome of interest) in the two groups.


Health or other quality of life gain resulting from an intervention. See ‘health benefit’. May also refer to economic benefit.


Non-parametric simulation process that involves random re-sampling with replacement from the original data to estimate p values, standard error and confidence intervals.


May result from flaws in the design of a study or in the analysis of results and may result in either an underestimate or an overestimate of the effect.

Capital costs

Major capital assets, generally equipment, buildings and land. They represent investments at a single point in time.

Case-control study

A study in which the effects of an exposure in a group of patients, (cases) who have a particular condition, are compared with the effects of the exposure in a similar group of people who do not have the clinical condition – the latter is called the control group.

Clinical effectiveness

The extent to which an intervention – for example, a device or treatment – produces health benefits, in other words, more good than harm.

Cochrane collaboration

An international organisation in which people retrieve, appraise and review available evidence of the effect of interventions in health care. The Cochrane Database of Systematic Reviews contains regularly updated reviews on a variety of issues. The Cochrane Library contains the Central Register of Controlled Trials (CENTRAL) and a number of other databases that are regularly updated. It is available as CD-Rom or on the internet (www.cochranelibrary.com).

Cohort study

Follow-up of exposed and non-exposed groups of patients – the ‘exposure’ is either a treatment or condition – with a comparison of outcomes during the time followed-up.


Interventions/treatments etc other than the treatment under study that are applied differently to the treatment and control groups.


Co-existence of a disease or diseases in a study population in addition to the condition that is the subject of study.


The standard intervention against which the intervention under appraisal is compared. The comparator can be no intervention, for example, best supportive care.

Confidence interval

The ranges of numerical values in which we can be confident that the population value being estimated were found. Confidence intervals indicate the strength of evidence; where confidence intervals are wide they indicate less precise estimates of effects.

Cost benefit analysis

An economic analysis that expresses both costs and outcomes in monetary terms. Benefits are valued in monetary terms, using valuations of people's observed or stated preferences, for example, the willingness-to-pay approach.

Cost consequences

The amount of money that will need to be spent as a result of the implementation of the guidance.

Cost effectiveness acceptability curves

Graphs that plot the costs per extra unit of effect of an intervention on the x axis against the probability (chance) of these values being achieved on the y axis. In technology appraisals, cost effectiveness acceptability curves assist in the decision-making process.

Cost effectiveness analysis

An economic study design in which consequences of different interventions may vary but can be measured using the same clinical outcome measure. Alternative interventions are then compared in terms of cost per unit of effectiveness.

Cost effectiveness

The cost per unit of benefit of an intervention. In cost effectiveness analysis, the outcomes of different interventions are converted into health gains for which a cost can be associated.

Cost effectiveness modelling

A synthesis of inputs from various sources in order to calculate an estimate of costs and/or benefits.

Cost effectiveness plane

A graphical illustration of cost effectiveness. The horizontal axis represents the difference in effect between the intervention of interest and the comparator. The vertical axis represents the difference in cost.

Cost impact

The total cost to the person, the NHS or to society.

Cost utility analysis

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

Decision analytic model (decision tree)

A systematic 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. The main disadvantage is that they are not suited to represent multiple outcome events that recur over time.


The process of converting future pounds and future health outcomes to their present value.


The dominant intervention is the intervention with the highest effectiveness and lowest costs compared with the alternatives.

Economic evaluation

Comparative analysis of alternative courses of action in terms of both their costs and consequences.


The extent to which interventions achieve health improvements in real practice settings.


The extent to which medical interventions achieve health improvements under ideal circumstances.

Epidemiological study

A study that looks at how a disease or clinical condition is distributed across geographical areas.


Fair distribution of resources or benefits.

Extended dominance

The incremental cost effectiveness ratio for a given treatment alternative is higher than that of the next, more effective, alternative.


Factors that are external to the individual.


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

Gold standard

A reference standard for evaluation of a diagnostic test. For the purposes of a study, the gold standard test is assumed to have 100 per cent sensitivity and specificity. Choice of the gold standard must therefore be evaluated in appraising a diagnosis study.

Health professional

Includes nurses, allied health professionals and doctors.

Health related quality of life (HRQoL)

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

Health technology assessment

The process by which evidence on the clinical effectiveness and the costs and benefits of using a technology in clinical practice is systematically evaluated.

Healthy years equivalent

A measure of health-related quality of life used in cost-utility analysis. It is the hypothetical number of years spent in perfect health that could be considered equivalent to the actual number of years spent in a defined imperfect health state. It differs from a QALY because not only is it based on the individual's preferences for the duration of life, but also on the individual's preference for the states of health.

Incremental cost effectiveness ratio (ICER)

The incremental cost effectiveness ratio is obtained by dividing the cost differences between two treatments by the outcome differences.


The number of new cases of illness commencing, or of persons falling ill during a specified time period in a given population.

Incremental cost

The difference between marginal costs of alternative interventions.

Incremental analysis

The analysis of additional costs and additional clinical outcomes with different interventions.


Factors present within the individual.

Logistic regression model

A data analysis technique to derive an equation to predict the probability of an event given one or more predictor variables. This model assumes that the natural logarithm of the odds for the event (the logit) is a linear sum of weighted values of the predictor variable. The weights are derived from data using the method of maximum likelihood.

Marginal analysis

The additional costs and additional outcome that can be obtained from one additional unit of service (for example, one extra day in hospital or additional tests).


A statistical method of summarising the results from a group of similar studies.

Monte Carlo simulation

Monte Carlo simulation randomly generates values for uncertain model input variables over and over to simulate a distribution of outputs for model.

Multivariate model

A mathematical model for analysis of the relationship between two or more predictor (independent) variables and the outcome (dependent) variable.

Number needed to treat

The number of patients who need to be treated to prevent one event.

Odds ratio

Odds in favour of being exposed in subjects with the target disorder divided by the odds in favour of being exposed in control subjects (without the target disorder).

Opportunity costs

The opportunity cost of investing in a health care intervention is best measured by the health benefits (such as life-years saved, or quality-adjusted life years gained) that could have been achieved had the money been spent on the next best alternative intervention or care. It also includes lost opportunity for other health care programmes that may be displaced by the introduction of the new technology.

Predictive validity

A risk assessment tool would have high predictive validity if the predictions it makes of the risk of falling in a sample became true – that is it has both high sensitivity and specificity.


The proportion of persons with a particular disease within a given population at a given time.

Quality adjusted life expectancy

Life expectancy using quality adjusted life years rather than nominal life years.

Quality adjusted life years (QALYs)

A measure of health outcome that assigns to each time period a weight. This ranges from 0-1, corresponding to the health-related quality of life during that period, where a weight of 1 corresponds to optimal health, and a weight of 0 corresponds to a health state judged as equivalent to death. These are then aggregated across time periods.

Randomised controlled trial

A clinical trial in which the treatments are randomly assigned to subjects. The random allocation eliminates bias in the assignment of treatment to patients and establishes the basis for the statistical analysis.

Relative risk

An estimate of the magnitude of an association between exposure and disease, which also indicates the likelihood of developing the disease among persons who are exposed, relative to those who are not. It is defined as the ratio of incidence of disease in the exposed group, divided by the corresponding incidence in the non- exposed group.

Retrospective cohort study

A study in which a defined group of persons with an exposure and an appropriate comparison group who are not exposed are identified retrospectively and followed from the time of exposure to the present. The incidence – or mortality – rates for the exposed and unexposed are assessed.


Percentage of those who developed a condition who were predicted to be at risk.

Sensitivity analysis

Allows for uncertainty in 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.


Percentage of those correctly predicted not to be at risk.

Systematic review

A way of finding, assessing and using evidence from studies – usually RCTs – to obtain a reliable overview.


Anyone using the guideline.


The extent to which a variable or intervention measures what it is supposed to measure or accomplish:

  • Internal validity – of a study refers to the integrity of the design;
  • External validity – of a study refers to the appropriateness by which its results can be applied to non-study patients or populations.

Copyright © 2005, Royal College of Nursing.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means electronic,mechanical, photocopying, recording or otherwise,without prior permission of the Publishers or a licence permitting restricted copying issued by the Copyright Licensing Agency, 90 Tottenham Court Road, London W1T 4LP.This publication may not be lent, resold, hired out or otherwise disposed of by ways of trade in any form of binding or cover other than that in which it is published,without the prior consent of the Publishers.

Cover of Clinical Practice Guideline for the Assessment and Prevention of Falls in Older People
Clinical Practice Guideline for the Assessment and Prevention of Falls in Older People.
NICE Clinical Guidelines, No. 21.
National Collaborating Centre for Nursing and Supportive Care (UK).

NICE (National Institute for Health and Care Excellence)

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