The Role of Systematic Reviews. Comments

Hidalgo Ottolenghi, Ricardo

doi:10.5554/rca.v39i4.277

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Colombian Journal of Anestesiology

Print version ISSN 0120-3347

Rev. colomb. anestesiol. vol.39 no.4 Bogotá Oct./Dec. 2011

https://doi.org/10.5554/rca.v39i4.277

Carta al Editor

The Role of Systematic Reviews.
Comments

Ricardo Hidalgo Ottolenghi*

* Cardiólogo. Centro Ecuatoriano Cochrane. Decano, Facultad Ciencias de la Salud Eugenio Espejo. Universidad Tecnológica Equinoccial. Quito, Ecuador. Correspondencia: Universidad Tecnológica Equinoccial. Avda. Occidental s/n y Mariana de Jesús. Facultad de Ciencias de la Salud - UTE. Quito, Ecuador. Correo electrónico: rho@ute.edu.ec

I have reviewed with great interest the article entitled “The role of systematic reviews in evidence-based anesthesiology” (1), and I have the following remarks.

The subtitle - “Systematic reviews: useful but not always credible” - is confusing and inconsistent with the reasoning, for the following reasons:

Are we allowed to say that a tool is useful when we cannot fully trust it or when we harbor doubts about its content and structure?

How can a tool be useful if there are doubts about its veracity? There cannot be credibility without truth.

Regarding this point, I believe that what the author meant was that Systematic Reviews may be useful, but are not always consistent.

Later on in the text we read, “On the other hand, evidence from clinical trials is subject to varying degrees of credibility”.

Can we refer to EVIDENCE from clinical trials, or rather OUTCOMES of clinical trials?

Are these degrees on the SCALE OF EVIDENCE (according to their source, methodology, among others), or are these degrees of credibility?

How is it possible to refer to DEGREES OF CREDIBILITY, considering that credibility itself has a component of subjectivity, while a SCALE OF EVIDENCE must be, above all, very objective?

Based on these comments, it would be important to clarify these concepts in order to avoid misunderstandings, not only semantic but also epistemological, considering that this article is addressed to people who are just starting to delve into this subject.

REFERENCES

1. Vasiliadis, HS, Martí-Carvajal, A, Salanti, G. El papel de las revisiones sistemáticas en anestesiología basada en la evidencia. [Editorial]. Rev. Colomb. Anestesiol. 2011;39(2):163-171. DOI:10.5554/rcav39i

Replica

The Role of Systematic Reviews.
Comments

Haris S. Vasiliadis*, Arturo Martí-Carvajal**, Georgia Salanti***

* MD, PhD. Molecular Cell Biology and Regenerative Medicine, Sahlgrenska Academy, University of Gothenburg, Sweden. Correspondencia: Neokaisareia, PO Box 363, 45500, Ioannina, Greece. Correo electrónico:hvasil@cc.uoi.gr.

** MD, MSc. Universidad de Carabobo and Iberoamerican Cochrane Network, Valencia, Venezuela. Correo electrónico: arturo.marti.carvajal@gmail.com

*** PhD. Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina, Greece. Correo electrónico: gsalanti@ cc.uoi.gr

It is important for researchers and clinical practitioners to approach critically any published information; including results from Randomized Control Trials (RCT) or Systematic Reviews (SR).

RCTs are considered the most reliable source of information among primary research study designs. However, we should not accept their conclusions ‘at face value’ just because a study is presented as an RCT. Therefore, tools have been developed to evaluate the credibility of the provided information. For example, reviewers evaluate the validity of the method of randomization, the quality of allocation concealment or the effectiveness of blinding (1).

Systematic Reviews are also prone to bias associated with the quality of the included RCTs and the review process itself. For this purpose tools are available which can be used to evaluate the quality of a systematic review and include items regarding the availability of the protocol, the methodology followed, the outcomes’ processing and the presence of publication bias (AMSTAR) (2).

The term ‘evidence’ is not meant to characterize an objective and completely bias-free piece of information (1). It can be evidence of low or high credibility. Consequently, the term ‘quality of evidence’ is also widely used in the Cochrane Handbook. The evidence provided by scientific papers is, and should remain, the subject to constant critical appraisal and evaluation. Therefore, the GRADE Working Group has developed a tool for grading the quality of evidence (3). As response to the comments of Hidalgo R (4).

REFERENCES

1. Vasiliadis HS, Martí-Carvajal A, Salanti G. El papel de las revisiones sistemáticas en anestesiología basada en la evidencia. [Editorial]. Rev. Colomb. Anestesiol. 2011;39(2):163-171. DOI:10.5554/rcav39i.

2. Shea BJ, Hamela C, Wellsd GA, Bouterb LM, Kristjanssonf E, Grimshawg J, et al. AMSTAR is a reliable and valid measurement tool to assess the methodological quality of systematic reviews. J. Clin. Epidemiol 2009;62(10):1013-20.

3. Atkins D, Best D, Briss PA, Eccles M, Falck-Ytter Y, Flottorp S, et al. GRADE Working Group. Grading quality of evidence and strength of recommendations. BMJ 2004 Jun 19;328(7454):1490.

4. Hidalgo R. The Role of Systematic Reviews. Comments (Letter to Editor). Rev. Colomb. Anestesiol. 2011; 39(4): 614-5.

1. Vasiliadis, HS, Martí-Carvajal, A, Salanti, G. El papel de las revisiones sistemáticas en anestesiología basada en la evidencia. [Editorial]. Rev. colomb. anestesiol. 2011;39(2):163-171. DOI:10.5554/rcav39i. [ Links ]