In association with

  • Bristol, North Somerset and South Gloucestershire Integrated Care Board
  • West of England Academic Health Science NetworkWest
  • National Institute for Health Research



Prevention refers to measures taken by an individual or a society to prevent disease happening or its consequences. In general, prevention includes a wide range of interventions, aimed at reducing risks to health. These are grouped into three categories:

  1. Primary prevention: refers to strategies used to prevent a disease happening in the first place. An example may be salt reduction to prevent an individual becoming hypertensive. Medication can be used in primary prevention such as the use of blood lowering or cholesterol lowering drugs to lower the risk of a stroke or heart attack.
  2. Secondary prevention: refers to strategies used in those with an existing disease which prevent recurrence, or significant morbidity. For example, in someone who has a heart attack cholesterol lowering drugs are used to lower the risk of subsequent heart attack and death.
  3. Tertiary prevention: refers to the prevention of long term chronic disease progression, physical deterioration and attendant suffering. For example, removing allergens which may aggravate asthmatic patients; screening for eye, renal, eye, and foot problems among diabetics to reduce the risks of complications.


The prospect of survival and recovery from a disease as anticipated from the usual course of that disease, or indicated by special features of the case.

Prognostic cohort study

This was in the CEBM glossary without anything against it

PsycINFO (Psychology Abstracts)

The PsycINFO (Psychology Abstracts) database provides extensive international coverage of literature on psychology and allied fields. PsycINFO covers psychological practice and research as well as the related clinical, social and biological disciplines. This includes information on drug and behavioural therapy, treatment of disease, drug addiction, developmental psychology, and educational psychology, as well as the psychological aspects of such areas as linguistics, social processes, pharmacology, physiology, nursing, education, anthropology, business and law. Covers the years 1806 to present and is updated weekly.

Publication bias

A bias in a systematic review caused by incompleteness of the search, such as omitting non-English language sources, or unpublished trials (inconclusive trials are less likely to be published than conclusive ones, but are not necessarily less valid).


Qualitative research is used to explore and understand people’s beliefs, experiences, attitudes, behaviour and interactions. It generates non- numerical data, e.g. a patient’s description of their pain rather than a measure of pain. In health care, qualitative techniques have been commonly used in research documenting the experience of chronic illness and in studies about the functioning of organisations. Qualitative research techniques such as focus groups and in-depth interviews have been used in one-off projects commissioned by guideline development groups to find out more about the views and experiences of patients and carers.

Qualitative approach

Qualitative research or methodology does not try to quantify anything or use statistical methods – it’s not about counting, but about words and their meaning.

It provides information about the “human” side of an issue –  behaviours, beliefs, opinions, emotions, and relationships of individuals. The most common method used to generate data in qualitative research is an interview which may be structured, semi-structured or unstructured. Focus groups and case studies are other examples.


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

Quantitative approach

A quantitative approach is more logical and data-led and provides a measure of what people think from a statistical and numerical point of view. It is used to quantify the problem by way of generating numerical data or data that can be transformed into useable statistics.

Quasi-experimental Evaluation

A quasi-experiment is an observational study in which the subjects to be observed are not randomly assigned to different groups in order to measure outcomes, as in a randomized experiment, but grouped according to a characteristic that they already possess

Randomized controlled trial (RCT)

An epidemiological experiment in which subjects in a population are randomly allocated into groups, usually called study and control groups, to receive or not receive an experimental preventive or therapeutic procedure, manoeuvre or intervention. The results are assessed by rigorous comparison of rates of disease, death, recovery or other appropriate outcomes in the study and control groups.

Relative risk (RR) (or risk ratio)

The ratio of the risk of an event in the experimental group compared to that of the control group (RR=EER / CER). Not to be confused with relative risk reduction (see below).