Screening glossary of terms
Definitions of words and phrases used in relation to population, targeted and stratified screening programmes.
Acceptable threshold
The lowest level of performance a screening service is expected to attain.
Achievable threshold
The level of performance a screening service should aim to meet to run optimally.
Adverse effect
An unintended harmful or unwanted effect.
Benign
Non-cancerous.
Benchmark
A standard or measure used to compare performance, activity, service provision or outcomes.
Benchmarking
The process of comparing performance, activity, service provision or outcomes to identify best practice and improve outcomes.
Bias
Unreliable results from a study, caused by the way in which it was designed or carried out.
Call and recall
The process of inviting individuals for screening at regular defined intervals – ‘call’ being the first accepted invitation to screening and ‘recall’ being all subsequent invitations.
Case control study
An observational study comparing people with a condition (cases) to people without the condition but who are otherwise similar (controls).
Clinical effectiveness
The ability of an intervention to be given at the right time to the right people to improve a health outcome.
Completeness of offer
The proportion of people eligible for screening who are offered screening. This is a measure of how effectively a programme offers screening to the eligible population.
Confidence interval
A range of values that is likely to include the true value. A narrow confidence interval (CI) means a more precise estimate than a wide confidence interval. The CI is usually given as a percentage, so a CI of 95% has a 95 in 100 chance of including the true value.
Cost consequence analysis (CCA)
Analyses of costs, resource implications and relevant clinical benefits, looking at each aspect separately.
Cost-effectiveness analysis (CEA)
Evaluating the effectiveness of different treatments relative to their costs, with the aim of maximising outcomes (see below) and minimising opportunity costs (see below).
Cost-effectiveness plane
A matrix used to visually describe the differences (both positive and negative) in costs and health outcomes between 2 interventions.
Cost utility analysis
A type of cost-effectiveness analysis, estimating the cost per quality-adjusted life year (QALY), or other health outcome, of an intervention.
Coverage
The proportion of the eligible population that is screened and has a result documented within a specified timeframe (see also ‘screening round length’).
Critical appraisal
The review of a study to judge the quality of the method used and how reliable and relevant the results are.
Denominator
The part of a fraction that is below the line and that functions as the divisor of the numerator.
Decision tree
An analytical model using ‘branches’ to show a set of potential outcomes. Where branches meet (‘nodes’), different options are presented such as a choice, or a probability of an outcome.
Diagnostic
Something that identifies or confirms the presence of a disease or condition.
Discount rate
The rate used to reduce predicted future costs and health outcomes, as these are usually valued less than present costs.
Discounting
Applying a discount rate (see above) to predicted costs and health outcomes for interventions in the future. This can be used in economic evaluation of a screening programme where costs and benefits do not happen at the same point in time.
Due date
The date on which a subsequent screening appointment is due. May also be referred to as the ‘next test due date’ (NTDD).
Economic evaluation (economic appraisal)
Comparing costs and effects of alternative health interventions to help inform decisions relating to economic impact and value for money.
Economic modelling
A process to estimate the costs and effects of an intervention over time. Modelling uses a range of techniques and methods to combine evidence from different sources and simulate comparisons of interventions. It is used if data is not available from clinical trials or other primary research.
Effective timeframe
The time within which a screening test can be carried out and a result obtained. The effective timeframe for a test is usually specified by the relevant screening programme.
Eligible
The population or individual that is entitled to an offer of screening.
Evidence map
An evaluation of the volume and type of evidence available on a topic.
Evidence appraisal
Assessment of the quality and relevance of research evidence according to predetermined criteria.
Failsafe
A process to minimise the risk of anything going wrong in the screening pathway. Failsafe ensures procedures are in place to identify errors and prevent further or additional issues.
Grey literature
Research and information materials available outside traditional publishing channels such as journals or books. Grey literature may include materials such as reports, theses, official documents, working papers and evaluations.
Health economics
A branch of economics looking at the effectiveness, value and behaviours relating to providing and using healthcare.
Health inequities
Systematic, avoidable and unfair differences in health between different groups of people – for example due to differences in socioeconomic status, geography or ethnicity.
Health status index
Measurements of a variety of health outcomes and risk factors resulting in a numerical score. This can be used to calculate quality adjusted life years (QALYs).
Healthy years equivalent (HYE)
A measure of healthcare outcome looking at quality and quantity of life. The HYE is the hypothetical number of years spent in perfect health that someone believes is the equivalent to a given number of years spent in a specific state of reduced health.
Heterogeneity
Significant variability in results of a test or intervention (the opposite of homogeneity).
Homogeneity
Similarity of results of studies (the opposite of heterogeneity).
Horizon scanning
The systematic examination of information sources for early signs of emerging developments, for example in screening technologies or disease treatments.
Incidence
The number of new cases of a disease or condition within a defined population during a specific period. It is different from prevalence (see below).
Incident screen
Screening someone who has previously been adequately screened within the same screening programme.
Incidental findings
A disease or condition potentially identified by the screening test that is not the disease or condition being screened for.
Incremental analysis
Looking at additional cost related to outcome when comparing one intervention to another.
Incremental cost
The difference in costs between one intervention and another.
Incremental cost-effectiveness ratio (ICER)
A division of the difference in total (incremental) costs between 2 interventions by the difference in their outcomes, to show the extra cost per ‘unit’ of health effect.
Indirect costs
Costs (losses) to society such as lost wages, low productivity or negative impact on leisure or domestic activities.
Ineligible
People who do not meet the criteria for screening, for example due to age, sex, or having health conditions that make the screening test inappropriate for them.
Informed choice
A decision to accept or decline screening based on accessible, balanced, accurate, evidence-based information about the screening test and its potential harms, benefits and outcomes.
Interval cancer
A cancer diagnosed in the time between scheduled screening episodes.
Invasive cancer
Cancer that has spread beyond the layer of tissue in which it developed and is growing into surrounding, healthy tissues. Sometimes called infiltrating cancer.
Life years gained
The average number of years of life gained per person following an intervention.
Marginal analysis
Evaluating impact on costs and outcomes as a result of change. For example, determining the impact of increased uptake of current services.
Markov model
An analytical model used in decision analysis (particularly evaluation of healthcare interventions). The model uses defined states of health to show all possible consequences of an intervention.
Morbidity rate
The number or proportion of cases of a condition within a given timeframe (usually one year) within a defined population.
Mortality rate
The number or proportion of deaths within a given timeframe (usually one year) within a defined population.
Multi-cancer early detection (MCED) tests
Tests used to identify signs of more than one type of cancer at a time by looking for DNA or proteins shed from cancer cells. Some tests only show if cancer is likely, and further diagnostic tests are needed.
Net monetary benefit
The value of the intervention in monetary terms when a willingness to pay (see below) threshold for a unit of benefit is known.
Negative predictive value
The proportion of people with a negative test result who do not have the disease or condition tested for (a true negative result). A higher negative predictive value means a more sensitive test (see ‘sensitivity’).
Non-invasive
An early stage cancer that has remained localised and confined to the layer of tissue from which it first developed and has not spread (metastasized) to surrounding tissue or other parts of the body. Also known as in situ cancer (including ductal carcinoma in situ) or non-invasive cancer.
Non-attenders
Eligible people who do not take up the offer of screening following invitation.
Numerator
The part of a fraction that is above the line and signifies the number to be divided by the denominator.
Opportunity cost
What is lost or missed as a consequence of adopting a new intervention.
Outcome
The result and value of an intervention, for example numbers of early-stage disease detection and treatment.
Patient and public voice (PPV)
A person who represents patients and the public using health services. The PPV provides a lay perspective, focusing on patient and carer issues.
PICO
A PICO (population, intervention, comparison and outcome) framework is a model for structuring clinical or health-related questions. It divides the question into 4 parts – the population, the intervention(s), the comparators and the outcomes. Variations of this framework exist for use with questions with additional factors, such as different types of studies.
Population screening
A nationally delivered proactive screening programme for a group of people identified from the whole population, and defined demographically such as by age or sex.
Positive predictive value
The proportion of people with a positive test result who do have the disease or condition tested for (a true positive result). A lower positive predictive value means a less specific test (see ‘specificity’).
Prevalence
The number or proportion of people in a population with a disease or condition at a point in time or over a period, including both new and existing cases. It is different from incidence (see above).
Prevalent screen
The first time someone attends for screening and is adequately screened.
Quality assurance (QA)
A set of activities aimed at supporting screening providers to ensure they meet and adhere to screening programme standards and protocols. QA also monitors and advises on problems within a screening service.
Real world evidence
Evidence gained from data collected outside of clinical trials.
Register
A collated list of people who are either eligible or ineligible for a specific screening programme.
Screening
Using a test or examination to identify apparently healthy people who have an increased chance of a disease or condition.
Screening pathway
The ‘route’ taken by an eligible person from being invited to screening through to obtaining a screening result and onward referral if appropriate. The steps within a screening pathway will vary from programme to programme.
Screening round length
A defined amount of time between routine screening invitations.
Self-referral
A person who refers themselves for screening, for example if they no longer receive routine invitations (due to their age) but are still eligible.
Sensitivity
The ability of a screening test to correctly identify true positive results (the test result is positive, and the person has the condition).
Sensitivity analysis
A model used to test an economic evaluation. It looks at how target variables may be affected to changes in other variables. Sometimes known as a ‘what-if’ analysis.
Short-term recall
An invitation to attend screening again before the end of the routine screening interval.
Specificity
The ability of a screening test to correctly identify true negative results (the test result is negative, and the person does not have the condition).
Statistical power
The probability of identifying a true effect (if one exists) and obtaining a statistically significant result. The statistical power of a study relies on having enough people in it.
Suspended
Eligible people on the screening register who are not invited for screening – for example because they are under care due to previous screening results, are ill, or are temporarily absent from the country.
Systematic review
A summary of evidence on a review question, using defined and explicit methods to identify, select and examine relevant studies, and analyse and report their findings.
Targeted screening
A proactive screening programme for a group of people identified as being at elevated or above average risk of a specific condition. Reasons for higher risk include genetic variants, lifestyle factors, or having other health conditions.
Test accuracy
Any measure which relates to the correctness of the screening test result, such as the test sensitivity (see above), specificity (see above) or positive predictive value (see above).
Time preference
A valuation placed on receiving an intervention at an earlier rather than a later date. See also ‘discount rate’ and ‘discounting’.
True negative
A screening negative result that correctly indicates the person screened does not have the condition screened for.
True positive
A screen positive result that correctly indicates the person screened has the condition screened for.
Uptake
The proportion of the eligible population offered screening who have a result documented.
Willingness to pay
Establishing the maximum amount someone is willing to pay for a specific benefit (for example, the cost of a screening test).