A type of observational study commonly used to look at factors associated with a disease

Source: National Library of Medicine

Statements that include recommendations intended to optimize patient care that are informed by a systematic review of evidence and assessment of the benefits and harms of clinical interventions in particular circumstances.

Source: UT Southwestern Health Sciences Digital Library and Learning Center

Clinical trials are a type of research that studies new tests and treatments and evaluates their effects on human health outcomes.

Source: World Health Organization

An observational study with 2 or more groups (cohorts) of people with similar characteristics. One group has a treatment, is exposed to a risk factor or has a particular symptom and the other group does not. The study follows their progress over time and records what happens.

Source: National Institute for Health and Care Excellence (NICE)

Epidemiological reviews describe a problem in terms of its causes, distribution, control and prevention, and can be used to help focus the review questions. For example, an epidemiological review of accidents would provide information on the most common accidents, morbidity and mortality statistics, and data on inequalities in the impact of accidents.

Source: National Institute for Health and Care Excellence (NICE)

Study regarding the observation over a period of time of a person, group or defined population to observe changes in health status or health- and social care-related variables.

Source: National Institute for Health and Care Excellence (NICE)

The broadest type of research review methods which allows for the simultaneous inclusion of experimental and non-experimental research to more fully understand a phenomenon of concern.

Source: UT Southwestern Health Sciences Digital Library and Learning Center

A summary of the evidence from several studies, with conclusions about the findings. It may or may not be systematically researched and developed.

Source: National Institute for Health and Care Excellence (NICE)

A study in which subjects are followed over time with continuous or repeated monitoring of risk factors or health outcomes, or both.

Source: British Medical Journal

A method often used in systematic reviews to combine results from several studies of the same test, treatment or other intervention to estimate the overall effect of the treatment.

Source: National Institute for Health and Care Excellence (NICE)

A non-systematic way to review published materials that provide an examination of recent or current literature on a broad and/or wide range of subjects.

Source: UT Southwestern Health Sciences Digital Library and Learning Center

Summary of findings presented as a written description rather than, for example, as a graph or table.

Source: National Institute for Health and Care Excellence (NICE)

These are trials in which participants (or groups) are allocated to receive either the intervention or a control (or comparison intervention) but the allocation is not randomised. This type of study is often called a controlled before-and-after (CBA) study.

Source: National Institute for Health and Care Excellence (NICE)

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).

Source: National Institute for Health and Care Excellence (NICE)

Clinical trials for which the hypothesis and study design are developed specifically to answer the questions faced by decision makers.

Source: Tunis et. al. (2003)

A research study in which the health or other characteristic of patients is monitored (or 'followed up') for a period of time, with events recorded as they happen. This contrasts with retrospective studies.

Source: National Institute for Health and Care Excellence (NICE)

Qualitative research explores people's beliefs, experiences, attitudes, behaviour and interactions. It asks questions about how and why, rather than how much. It generates non-numerical data, such as a person's description of their pain rather than a measure of pain. Qualitative research techniques include focus groups and in‑depth interviews.

Source: National Institute for Health and Care Excellence (NICE)

An experiment in which two or more interventions, possibly including a control intervention or no intervention, are compared by being randomly allocated to participants

Source: Cochrane.org

A type of knowledge synthesis in which components of the systematic review process are simplified or omitted to produce information in a short period time. Review team will determine scope and methods based on time available. Used on emerging issues needing timely answers.

Source: UT Southwestern Health Sciences Digital Library and Learning Center

A theory-based method for synthesising findings from a number of qualitative studies.

Source: Cochrane.org

An analysis or study planned and conducted after the dataset has already been collected. For example, routinely collected data may be analysed retrospectively to evaluate the effects of a new programme.

Source: Cochrane.org

A review type that provides a comprehensive overview to address broader review questions than traditionally more specific systematic reviews of effectiveness or qualitative evidence. Scoping reviews are a useful tool to determine the scope or coverage of a body of literature on a given topic and give clear indication of the volume of literature and studies available as well as an overview (broad or detailed) of its focus.

Source: Peters et. al. 2020

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

Source: National Institute of Health and Care Excellence (NICE)

A review type that systematically collects and evaluates information from multiple systematic reviews and meta-analyses on all clinical outcomes for which these have been performed.

Source: Papatheodorou (2019)