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. 2009 Apr;106(15):262-8.
doi: 10.3238/arztebl.2009.0262. Epub 2009 Apr 10.

Types of study in medical research: part 3 of a series on evaluation of scientific publications

Bernd Röhrig  1 , Jean-Baptist du Prel, Daniel Wachtlin, Maria Blettner
Affiliations

Types of study in medical research: part 3 of a series on evaluation of scientific publications

Bernd Röhrig et al. Dtsch Arztebl Int. 2009 Apr.

Abstract

Background: The choice of study type is an important aspect of the design of medical studies. The study design and consequent study type are major determinants of a study's scientific quality and clinical value.

Methods: This article describes the structured classification of studies into two types, primary and secondary, as well as a further subclassification of studies of primary type. This is done on the basis of a selective literature search concerning study types in medical research, in addition to the authors' own experience.

Results: Three main areas of medical research can be distinguished by study type: basic (experimental), clinical, and epidemiological research. Furthermore, clinical and epidemiological studies can be further subclassified as either interventional or noninterventional.

Conclusions: The study type that can best answer the particular research question at hand must be determined not only on a purely scientific basis, but also in view of the available financial resources, staffing, and practical feasibility (organization, medical prerequisites, number of patients, etc.).

Keywords: basic research; clinical research; epidemiology; literature search; study type.

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Figures

Figure 1
Figure 1
Classification of different study types *1, sometimes known as experimental research; *2, analogous term: interventional; *3, analogous term: noninterventional or nonexperimental This scheme is intended to classify the study types as clearly as possible. In the interests of clarity, we have excluded clinical epidemiology — a subject which borders on both clinical and epidemiological research (3). The study types in this area can be found under clinical research and epidemiology.
Figure 2
Figure 2
Graphical depiction of a prospective cohort study (simplest case [2a]) and a retrospective case control study (2b)
See this image and copyright information in PMC

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