Internal and Emergency Medicine

, Volume 10, Issue 6, pp 745–747 | Cite as

When should we change our clinical practice based on the results of a clinical study? The hierarchy of evidence

  • Giorgio Costantino
  • Nicola Montano
  • Giovanni CasazzaEmail author


In the first paper of this series [ 1], we described how to perform a bibliographic search aimed at retrieving the available evidence. Once we have collected the relevant literature, and before deciding if it could be helpful in our clinical practice, we have to judge its quality. For this purpose, a framework for ranking the quality of evidence can be of help in classifying clinical studies [ 2]. The hierarchy of evidence is usually represented with a pyramid: studies are ranked according to the quality of the evidence they provide: from those with the lowest (the base of the pyramid) to those with the highest level (the apex of the pyramid) (Fig.  1). To a first approximation, this schematic representation can be considered valid for all the types of studies. Nevertheless, in this brief note we will consider three different fields of clinical research (i.e. intervention, diagnosis and prognosis) and we will show that each field has its own hierarchy of evidence that is...


Systematic Review Pyramid Clinical Question Validation Cohort Prognostic Score 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Conflict of interest

The Authors declare that they have no conflict of interest.

Statement of human and animal rights

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This article does not contain any studies with human and animals performed by any of the authors.


  1. 1.
    Costantino G, Montano N, Casazza G (2015) When should we change our clinical practice based on the results of a clinical study? Searching for evidence: PICOS and PubMed. Intern Emerg Med. doi: 10.1007/s11739-015-1225-5
  2. 2.
    Guyatt GH, Sackett DL, Sinclair JC, Hayward R, Cook DJ, Cook RJ (1995) Users’ guides to the medical literature. IX. A method for grading health care recommendations. JAMA 274:1800–1804CrossRefPubMedGoogle Scholar
  3. 3.
    Pocock S (1985) Current issues in the design and interpretation of clinical trials. BMJ 290:39–42PubMedCentralCrossRefPubMedGoogle Scholar
  4. 4.
    Colli A, Fraquelli M, Casazza G, Conte D, Nikolova D, Duca P, Thorlund K, Gluud C (2014) The architecture of diagnostic research: from bench to bedside—research guidelines using liver stiffness as an example. Hepatology 60(1):408–418. doi: 10.1002/hep.26948 CrossRefPubMedGoogle Scholar
  5. 5.
    Hemingway H, Croft P, Perel P, Hayden JA, Abrams K, Timmis A, Briggs A, Udumyan R, Moons KG, Steyerberg EW, Roberts I, Schroter S, Altman DG, Riley RD, PROGRESS Group (2013) Prognosis research strategy (PROGRESS) 1: a framework for researching clinical outcomes. BMJ 346:e5595. doi: 10.1136/bmj.e5595 PubMedCentralCrossRefPubMedGoogle Scholar

Copyright information

© SIMI 2015

Authors and Affiliations

  • Giorgio Costantino
    • 1
  • Nicola Montano
    • 1
    • 2
  • Giovanni Casazza
    • 2
    Email author
  1. 1.Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico di MilanoMilanItaly
  2. 2.Dipartimento di Scienze Biomediche e Cliniche “L. Sacco”Università degli Studi di MilanoMilanItaly

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