Glossary

Abstract

This is a short structured or unstructured summary of a published research paper. The abstract appears in healthcare databases and at the start of a published paper.

Allocation Concealment

Occurs when the person enrolling a participant into a clinical trial is unaware whether the next participant will be enrolled into the intervention or control group.

Applicability

Related to whether a particular treatment or form of care that demonstrated an overall effect in a study can be expected to provide the same effect for an individual or group in a specific clinical or population setting.

ARR or Absolute Risk Reduction

The absolute amount by which the intervention reduces the risk (of death for example).

Article reviews

Such as those produced by the ACP Journal Club: enhanced abstracts of chosen articles are written, including commentary on the applicability of the study to clinical practice.

Bias

Deviation of a measurement from the ‘true’ value leading to either an over or under-estimation of the treatment effect. Bias may originate from different sources: allocation of patients, measurement, interpretation, publication and review of data.

Blinding

Technique to reduce bias as far as possible. May be either single or double blinding. Single Blinding: prevents patients in a clinical study from knowing which treatment group they have been assigned to. Double blinding: neither the patient nor the investigator knows which treatment is planned.

Boolean Operators

Are specific words used to combine keywords to improve the chances of finding relevant information. The most commonly used Boolean Operators are AND, OR and NOT.

Case-control study

A study which involves identifying patients who have the outcome of interest (cases) and control patients who do not, and looking back to see if they had the same exposure of interest.

Case reports/case series

A report on a series of patients with an outcome of interest. No control group is involved.

Chance

The absence of any cause of events that can be predicted, understood or controlled. The unknown and unpredictable element in happenings that seem to have no assignable cause.

Citation

Provides all the information that is needed to find the research paper when the full text is not available online. A citation is made up of the title, the author and the source details.

Citation database

A searchable collection of evidence and information that is organised / indexed to allow for optimal retrieval. Examples include PsyInfo, Embase, and Medline.

Cohort Study

Involves two matched groups (cohorts) of patients, one that received the exposure of interest and one that did not, and following these patients forward for the outcome of interest. Alternatively, the cohorts are defined at a point of time in the past and information is collected on subsequent outcomes.

Comparator

Treatment, prognostic indicator or test that is compared with the treatment, indicator or test of interest in a clinical trial.

Concept Topic or idea

In research studies concepts usually have a higher-level meaning.

CI or Confidence Interval

An interval within which the population parameter (the ‘true’ value) is expected to lie with a given degree of certainty (e.g. 95%). If the confidence interval crosses zero we cannot be confident that this range of values includes the true value and there is likely to be no statistically significant effect.

Confounding

The distortion of the true effect of treatment (or a risk factor) by other factors that vary between the study and control groups (e.g. baseline differences in age, sex or lifestyle).

Cost-benefit Analysis

Assesses whether the cost of an intervention is worth the benefit by measuring both in the same units; usually monetary units.

Cross-sectional study

The observation of a defined population at a single point in time or time interval. Exposure and outcome are determined simultaneously.

Evidence-Based Medicine Reviews

This Ovid database combines secondary sources of evidence from the ACP Journal Club, the Cochrane Library and MEDLINE.

Evidence Summaries

Provide a critical appraisal synthesis for a specific research article or evidence on a specific topic, so that practitioners can easily determine validity and reliability.

External Validity

The degree to which the results of a clinical study can be applied to clinical practice in a specific setting.

Experimental studies

Studies in which subjects are allocated to two or more groups to receive an intervention, exposure or test and then followed up under carefully controlled conditions.

Generalisability

The ability to reliably apply the results of a study to other populations, based on the characteristics of the subjects, size of the sample, the setting and trustworthiness of the study.

Grey Literature

A comprehensive search (especially if preparing a systematic review, or where little is known about a topic) should also include the unpublished or ‘grey’ literature that exists on the search question. Sources include conference proceedings, reports, and unpublished theses.

Hypothesis

Study question phrased in a way that allows it to be tested or refuted.

Incidence

The proportion of new cases of the target disorder in the population at risk during a specific time interval.

Indexing

The process by which the keywords of a research article is added to the thesaurus or index of a databases

Intention-to-Treat Analysis

A method of analysis for randomised controlled trials in which all patients randomly assigned to one of the treatments are analysed together, regardless of whether or not they completed or received that treatment, in order to preserve randomisation.

Internal validity

Relates to the quality of the study design in terms of the methods of a study: where bias is reduced as far as possible, where instruments are reliable and safeguards have been put in place to ensure trustworthiness.

Intervention

An action introduced in an attempt to change patient, community or organisational outcomes. This may involve a therapeutic procedure, a pharmaceutical agent, a dietary supplement, a model of care, a screening tool or the use of patient educational materials.

Keywords

Single words or phrases that define a topic, subject area or concept. Keywords become the search terms developed in the process of a search strategy.

Level of Evidence

A hierarchy of study designs according to their internal validity, or degree to which they are not susceptible to bias.

MeSH

The Medical Subject Headings, a controlled vocabulary of keywords that may be used in PubMed or Cochrane.

Meta-analysis

The results from several studies, identified in a systematic review, are combined and summarised quantitatively.

Meta-synthesis

Integrates results from a number of different but inter-related qualitative studies. The intention is interpretation rather than aggregation.

Natural language

Otherwise called “free text”, is the style used in an Ovid Basic search. The computer will search for exactly what is typed into the search box; questions, phrase etc.

NNT or Number Needed to Treat

The number of patients with a particular condition who must receive a treatment in order to prevent the occurrence of one adverse outcome.

NNH or Number Needed to Harm

The number of patients with a particular condition who, if they received the experimental treatment, would result in the occurrence of one adverse outcome.

Observational studies

These studies investigate and record ‘exposures’ to specific factors and observe outcomes. Observational studies may be more appropriate when experimental studies are not ethical.

OR or Odds Ratio

Ratio of the odds (those with the outcome divided by those without it) in the treatment group to the corresponding odds in the control group.

p-value

The probability that any particular outcome would have arisen by chance.

Power

The sample size used in a study is partly determined on the need to have sufficient statistical power (strength) to make inferences about a population from the sample.

Preappraised evidence

Resources that have undergone a filtering process to include only research of higher quality and that are regularly updated so that the evidence is current.

Qualitative Studies

Qualitative studies do not have ‘measurable’ outcomes in the same way that scientific or quantitative studies do. They usually explore the ‘quality’ of an experience – for example a patient’s experience of a hospital stay, or a new model of care. They can provide a valuable additional dimension to a research project, stand alone as ‘evidence’ of the patient perspective, or used to generate a hypothesis.

Quantitative study

A study that measures variables such as time, treatment and weight and expresses the relationship among the variables using statistics.

Randomisation

A method similar to that of ‘tossing a coin’ to assign patients to treatment groups; for example to the treatment group or control (placebo) group.

RCT or Randomised Controlled Trial

Studies that introduce a treatment (such as a drug) or exposure (such as a form of care) to examine the effect on real patients. The patients are then followed up under carefully controlled conditions. These studies are often known as Experimental (or Intervention) studies. RCTs use specific methods to reduce the likelihood of bias in order to produce evidence of cause and effect such as randomisation and blinding.

Reference management tools

Sometimes known as “Bibliographic Management software” is designed to store the references and then enable these to be easily cited in written work. Examples include EndNote and RefWorks.

Reference Test

A method, procedure or measurement that is widely regarded or accepted as being the best available (also known as the gold standard).

RRR or Relative Risk Reduction

The proportional reduction in rates of bad outcomes between experimental and control participants in a trial.

RR or Relative Risk/Risk Ratio

The risk of the outcome in the treatment group relative to that in the control group.

Reliability

Relates to the trustworthiness of the results.

Scope notes

Scope notes are written by the database producer, and provide information of when terms were first indexed and how they are defined and applied.

Search strategy

The planned and structured organisation of terms used to search a database.

Secondary Research

An academic review of primary research studies to gain new insights on a specific topic.

Selection Bias

Error due to systematic differences in characteristics between those who are selected for study and those who are not. Bias invalidates conclusions and generalisations that might otherwise be drawn from such studies.

Sensitivity

Proportion of people with the target disorder who have a positive test result. Often used to describe the effectiveness of a diagnostic or screening test.

Specificity

Proportion of people without the target disorder who have a negative test result. Often used to describe the effectiveness of a diagnostic or screening test.

Subject Headings

Categories to which terms are indexed in the thesaurus of the database.

Summaries

Integrate the best available evidence from the lower layers of the evidence hierarchy pyramid to develop practice guidelines or clinical pathways based on a full range of evidence (for example, those in BMJ Clinical Evidence).

Synonyms

These are alternative terms meaning the same thing e.g. venous thrombosis, deep vein thrombosis etc.

Synopses

Pre-appraised evidence resources that have undergone a filtering process to include only those of high quality, and updated regularly so that they are current. Synopses provide succinct descriptions of selected individual studies or systematic reviews in the form of value-added abstracts by clinical experts.

Synopses of Studies

Synopses of a study provides a succinct description of a selected high quality study that can inform clinical practice. Brief commentary by clinical experts is provided in the form of methodological critique and comment on the clinical applicability of the study findings.

Synopses of Synthesis

Synopses of synthesis provides a succinct description of selected systematic reviews in the form of value-added “abstracts” and methodological commentary by clinical experts. Such information may provide sufficient information to support change in clinical practice. Examples can be found in the Database of Abstracts of Reviews of Effects (DARE) in the Cochrane Library.

Syntheses

See systematic review.

Systems

A process by which the individual patient’s characteristics are automatically linked to the current best evidence that matches his or her specific circumstances and the clinician is provided with key aspects of management (sometimes known as Clinical Decision Support systems).

Systematic review

A summary of scientific studies that use explicit methods to perform a comprehensive literature search and critical appraisal, and that uses appropriate statistical techniques to obtain a reliable overview.

Topic reviews

Reviews of studies on one topic or area of interest, selected by means of strict inclusion criteria, analysed and presented as detailed structured reports of the findings. Systematic reviews are a good example of topic reviews

Thesaurus

Standardised list of words that groups synonyms and related concepts as well as describing the relationship between terms. A thesaurus is referred to in many ways such as controlled vocabulary, index term, in Medline the thesaurus is known as Medical Subject Headings (MeSH).

Truncation

Allows the computer to search for multiple forms of a word using a symbol such as * or $. For example music* finds musical, musician, musicality etc.

Validity

The degree to which the conclusions drawn from a study are reasonable in terms of the method, the sample and the study population.

Wildcards

A wildcard is a symbol used to stand for a character or letter within or at the end of a word. It allows searching for spelling variations or plurals. Symbols used as wildcards and the rules for their use may differ between databases, websites, and search engines.