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Clinical Study Types - for Librarians

Observational Studies

Observational Studies is a broad area.  It is one of the two categories that clinical studies are often divided into:  Observational studies or Interventional studies.

Observational study types include Cohort, Case-Control and Cross-Sectional studies (among others).  Observational studies are sometimes called Epidemiological studies.  

In PubMed, the study types listed above are categorized as Epidemiologic Studies.

While there is a MeSH term for Observational Study, if you are searching for observationals studies we recommend you use the MeSH term for 'Epidemiologic Studies' instead. There are over 2.6 million articles tagged with the MeSH term 'Epidemiological Studies;' but only about 100,000 articles tagged with the MeSH term 'Observational Study.' 'Observational Studies' was introduced in 2014 and MEDLINE does not retrospectively tag articles, which is one probably reason why there are comparatively few articles tagged wtih this MeSH term. 


 
Recommended:  to find "Observational Studies" in PubMed, search both MeSH terms:

("Epidemiologic Studies"[Mesh] OR "Observational Study" [Publication Type])

You will want to add keywords to the above search string; this may be a good start.   See box to the left for a modifiable search string.

Definitions

Mesh database definition for Observational Studies:

Observational Study [Publication Type]
A work that reports on the results of a clinical study in which participants may receive diagnostic, therapeutic, or other types of interventions, but the investigator does not assign participants to specific interventions (as in an interventional study). Year introduced: 2014

MeSH database definition for Epidemiologic Studies:

Epidemiologic Studies
Studies designed to examine associations, commonly, hypothesized causal relations. They are usually concerned with identifying or measuring the effects of risk factors or exposures. The common types of analytic study are CASE-CONTROL STUDIES; COHORT STUDIES; and CROSS-SECTIONAL STUDIES.  Year introduced: 1998

Where This MeSH Term Can Be Found in the MeSH 'Tree'

Below are the MeSH trees for both terms.

 

'Publication Type' or 'As Topic' - Which to Choose?

Using PubMed's "Observational Studies"

PubMed splits Observational Studies into two areas:  As Topic and Publication Type.  Which to use?  If you're doing a systematic review, use [publication type].  Basically, "Publication Type"  means it's an article about the results of a trial.  "As Topic" means it's about the general topic of trials: maybe how to recruit patients, or how to conduct a specific aspect of a trial.  Here are the official MeSH defiitions:

Observational Studies as Topic: Works about clinical studies in which participants may receive diagnostic, therapeutic, or other types of interventions, but the investigator does not assign participants to specific interventions (as in an interventional study).  Year introduced: 2014

Observational Study [Publication Type]: A work that reports on the results of a clinical study in which participants may receive diagnostic, therapeutic, or other types of interventions, but the investigator does not assign participants to specific interventions (as in an interventional study).Year introduced: 2014

 

Examples of articles that were tagged with each MeSH term:

Publication Type: (these are probably the types of articles you want)

  • Pregnancy Outcomes in COVID-19: A Prospective Cohort Study in Singapore.
  • Pulmonary edema following shoulder arthroscopy under general anesthesia with nerve block: An observational study.

As Topic: (you probably don't want these articles returned in your search results)

  • Emerging Challenges and Opportunities in Infectious Disease Epidemiology.
  • COSMOS-E: Guidance on conducting systematic reviews and meta-analyses of observational studies of etiology.