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Types of Research Articles Part I

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This article describes some of the most common types of research articles published in medical journals. Medical journals publish many types of articles not discussed here. A comprehensive list is available from the National Library of Medicine.

Research articles can be primary or secondary. A primary research article describes the design, methods, and results of a study. A secondary research article is a review of at least two primary research articles.

Primary articles

Clinical trial report 

Definition: Study in people

Description: Clinical trials find out whether the results of basic research study can apply to people. The “gold standard” for clinical research on treatments and prevention strategies is the double-blind, randomized, controlled clinical trial. In this ideal study, participants are randomly assigned to one or more treatments or to a placebo. Also, the patients and the physicians treating them don’t know whether the patient is getting an active treatment or a placebo.

Use clinical trial reports to:

  • Find out about a rigorous assessment one or more treatments or prevention strategies
  • Track progress of research on a treatment or prevention strategy
  • Learn whether results from animal studies apply to people

Basic research report

Definition: Study of biochemical substances or biological process to find out how a particular process works 

Description: Basic research can be done in test tubes (known as in vitro research) or in laboratory animals (known as in vivo research). Studies in mice and other animals help scientists learn how people might react when they are exposed to a drug. But animals have different physiology than people. Also, studies often expose animals to much higher doses of an experimental drug than the doses that might be used in humans. So it’s not always possible to generalize results from animal studies to people. 

Use basic research reports to:

  • Learn what types of issues researchers are studying
  • Found out about promising new findings that might eventually be tested in people

Case report

Definition: Report on a single patient

Description: A typical case report describes the patient’s condition, how the physician chose to treat the patient, and the results of this treatment. A case reports often includes a review of relevant medical journal articles. Case reports often feature a patient with an unusual disease or an unusual response to treatment.

Use case reports to:

  • Learn about something rare that hasn’t been reported before and might be important for health-care providers to know

Papers that Summarize Other Papers

Systematic review

Definition: A critical assessment and evaluation of all primary studies on a given patient-related issue

Description: Although systematic reviews typically include only randomized, controlled trials, some systematic reviews include other types of studies. The authors of a systematic review use an organized method to find, bring together, and evaluate a set of study reports on a particular topic using criteria chosen in advance. A systematic review describes the findings of the research studies included in the review. 

Use systematic reviews to:

  • Assimilate comprehensive information about primary studies
  • Compare results from different primary studies
  • Find out whether findings of primary studies are consistent and can be generalized to patients who weren’t in the study


Definition: A statistical analysis of findings from at least two primary studies

Description: One purpose of a meta-analysis is to evaluate the effectiveness of a treatment by combining data from several randomized, controlled trials. The authors of a meta-analysis use statistical analysis techniques to assess the data from several primary studies (usually randomized, controlled trials). The authors gather information from the primary research reports on the inclusion criteria, sample size, characteristics of study participants, and results for each study included in their analysis.

Use meta-analyses to:

  • Understand the research more easily than by reading each of the primary study reports
  • Get a precise estimate of the effect of the treatment
  • Compare the robustness of relevant studies

Narrative (non-systematic) review 

Definition: A review of other publications (either original research or other reviews) that does not use the rigorous methods of systematic review or meta-analysis

Description: Review authors choose articles to summarize that are familiar to them or that are prominent in the field. Many journals do not have a standard format for non-systematic review articles, which can vary in length and type of information presented. The reviewers describe all of the articles and draw conclusions from them. But they don’t use statistics or other rigorous methods to find or evaluate the articles in their review.

Use narrative reviews to:

  • Get a helpful introduction to a topic
  • Obtain an overview of the literature on the topic
  • Learn about a topic that is too broad or too new for a systematic review


Trisha Greenhalgh. How to read a paper: Papers that summarise other papers (systematic reviews and meta-analyses). BMJ 1997;315:672.

Bernd Röhrig, Jean-Baptist du Prel, Daniel Wachtlin, and Maria Blettner. Types of study in medical research: part 3 of a series on evaluation of scientific publications. Deutsches Arzteblatt International. 2009;106(15):262-268. doi:10.3238/arztebl.2009.0262.

U.S. National Library of Medicine. Publication characteristics (publication types) – scope notes

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