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MEDLINE Indexing Online Training Course

Category V - Publication Characteristics

Clinical Trial [PT]

Clinical trials are extremely important in medicine. They are instrumental for evaluating the efficacy of a new drug, procedure, or intervention. Therefore, it is very important that indexers identify all articles reporting the results of clinical trials and label them with the Publication Type CLINICAL TRIAL (PT).

In addition to the general publication type Clinical Trial, there are several specific types of clinical trials.

  • Adaptive Clinical Trial (PT)
  • Clinical Trial, Phase I (PT)
  • Clinical Trial, Phase II (PT)
  • Clinical Trial, Phase III (PT)
  • Clinical Trial, Phase IV (PT)
  • Controlled Clinical Trial (PT)
    • Randomized Controlled Trial (PT)
      • Equivalence Trial (PT)
      • Pragmatic Clinical Trial (PT)


The terms Clinical trials, Phase I, II, III, and/or IV usually will appear somewhere in the article. If the phase of the clinical trial is not indicated in the article, the indexer is not required to do research to determine it.

The publication type CONTROLLED CLINICAL TRIAL will be used for clinical trials in which the control group is identified.

The publication type RANDOMIZED CONTROLLED TRIAL will be used for clinical trials in which patients are assigned to two or more treatment groups in a randomized fashion. The word(s) random, randomized, randomization, etc usually will appear somewhere in the article.

Randomized controlled trials are the gold standard clinical trials, and it is particularly important that indexers identify them correctly.

Last Reviewed: December 5, 2017