Rev Saúde Pública 2010;44(3)Comments

Monica MaltaI

STROBE initiative: guidelines onreporting observational studies

Leticia Oliveira CardosoII
Francisco Inacio BastosIII
Monica Maria Ferreira
MagnaniniIV
Cosme Marcelo Furtado Passos
da SilvaII

ABSTRACTReporting of observational studies is often inadequate, hampering theassessment of their strengths and weaknesses and, consequently, thegeneralization of study results. The initiative named Strengthening theReporting of Observational Studies in Epidemiology (STROBE) developed
a checklist of 22 items, the STROBE Statement, with recommendations about
what should be included in a more accurate and complete description ofobservational studies. Between June and December 2008, a group of Brazilian
researchers was dedicated to the translation and adaptation of the STROBE
Statement into Portuguese. The present study aimed to show the translation
into Portuguese, introduce the discussion on the context of use, the potential
and limitations of the STROBE initiative.
DESCRIPTORS: Observational Studies. Epidemiologic Studies.
Statistical Methods and Procedures. Health Research Evaluation.
Checklist. Translations.

Clinical trials and observational studies in the context of modern
biomedical researchI

Departamento de Ciências Sociais. Escola
Nacional de Saúde Pública Sérgio Arouca(ENSP). Fundação Oswaldo Cruz (Fiocruz).
Rio de Janeiro, RJ, Brasil

II

Departamento de Epidemiologia e Métodos
Quantitativos em Saúde. ENSP. Fiocruz. Riode Janeiro, RJ, Brasil

III

Laboratório de Informação em Saúde.
Instituto de Comunicação e InformaçãoCientífica e Tecnológica em Saúde. Fiocruz.
Rio de Janeiro, RJ, BrasilIV

Instituto de Estudos em Saúde Coletiva.
Universidade Federal do Rio de Janeiro. Riode Janeiro, RJ, Brasil

Correspondence:
Monica Malta
Escola Nacional de Saúde Pública Sérgio
Arouca, Fiocruz
R. Leopoldo Bulhões, 1480, sala 905
Manguinhos
21041-210 Rio de Janeiro, RJ, Brasil
E-mail: mmalta@jhsph.edu
Received: 1/26/2010
Approved: 3/3/2010
Article available from www.scielo.br/rsp

Randomized clinical trials have been described as the gold standard forbiomedical research as they show high internal validity and, consequently,
greater accuracy in the efficacy and effectiveness evaluation of several therapeutic and preventive health practices.4
However, public health studies have frequently dealt with problems where
this study design is not adequate and/or ethical, or, yet, for which the translation of randomized controlled trial findings into concrete intervention and/or
treatment conditions faces great difficulties due to the lack of external validityof findings obtained in a clinical trial context. According to Victora et al,26
randomized clinical trials frequently represent an inadequate choice to assess
the performance and impact of large scale interventions, especially in contextsof heterogeneity, whether they are social, economic and/or geographic in nature.
In addition, there are operational aspects that can hinder or even preclude theimplementation of clinical trials: individuals may not want to be randomized
for a given intervention group, randomized selection may not be possible or
ethically acceptable in the research context, or, yet, only participants with certain
characteristics might accept to be selected.31 In view of the impossibility or
inadequacy of implementation of randomized clinical trials, whether due toethical or operational questions, observational studies appear as a more feasible
solution and, in cohort studies, are relevant alternatives to evaluate the impact
of interventions throughout time.22
Observational studies are more adequate to evaluate rare or late side effects
associated with certain treatments and they often provide a more accurate
indication of what can be achieved in routine clinical practice, once they take2

advantage of a given situation and observe its results,
which can be context-dependent.17 A clear example
that clinical trials are unable to find rare and/or lateside effects is the need to develop Phase IV (postcommercialization) clinical trials of new drugs and/or
new therapies. The recent recall of drugs approved in
all pre-clinical and clinical stages of research, approvedby regulatory organizations such as the Food and Drug
Administration (FDA) in the United States, clearly
documents clinical trial limitations and the necessityof a continuous pharmacovigilance.12
The adverse effects of non-steroidal anti-inflammatory
drugs on cardiovascular morbi-mortality has been
documented in studies with large sample sizes and longterm follow-up. Until then, these side effects had been
imperceptible in the context of clinical trials and even ofpharmacovigilance, involving a small number of cases
and/or having a relatively short follow-up period.10
Previous data emphasize the importance of observational studies. Quite frequently, randomized clinical
trials cannot be conducted due to ethical, politicalor infrastructure aspects, such as in studies that
evaluate interventions effectiveness that have favorable empirical evidence on their behalf, even if only
based on observational studies, especially evident
for vulnerable populations. This is the case of harm
reduction programs targeting injecting drug users, apublic health approach that had never been evaluatedusing randomized clinical trials, based on empirically
based evidences exclusively derived from observational studies where this intervention may prevent
new infections by different blood-borne and/or sexualtransmitted pathogens.
A second limitation to the performance of this typeof studies includes their associated costs and the timenecessary to obtain meaningful results. Observational
studies are less expensive and enable data analysis ina shorter period of time, a vital aspect towards timely
public policy design, particularly in low- and middleincome countries and in emergency situations, As an
example, a study aimed at evaluating the association
between cholesterol levels in the diet and subsequentcoronary disease could be considered.
A third issue refers to the fact that observational
study samples are frequently more representative of
the intervention target population than randomized
clinical trials, which tend to be performed in specificenvironments, such as referral hospitals, dealing withpatients who can adhere to very restrictive treatment
and follow-up protocols. Finally, many studies thatare idealized to be randomized clinical trials become,in practice, very close to observational studies, when
protocols are not followed, when patients are lost toa

STROBE Initiative

Malta M et alfollow-up, and when there are missing data, among
other problems.
Presentation of observational study results inbiomedical research
The description and presentation of study findings must
be organized in a clear way, since the study reliability
depends on a critical evaluation, made by editors, thescientific community and readers, about the study
strengths and weaknesses associated with its design,
performance and analysis. A clear and coherent description is also necessary to enable judgment of whether
and how study results should be incorporated into majorinterventions and/or public policies.26,27
However, many epidemiological studies (observationaland experimental) published in scientific journals do
not show essential information, described in a clear andadequate way.23,28-30,32
A systematic review performed in 2008 tried to evaluate
the quality of confounding reporting in observational
studies,11 identifying that a small number of publishedstudies adequately describe the role of potential
confounding variables in their results.
Trying to identify the lack of clarity in epidemiologicalstudy description, a group of European and American
researchers developed a strategy aiming to show items
that should be described in the report of randomized
clinical trials – the Consolidated Standards of Reporting
Trials (CONSORT) strategy.a The CONSORT comprisesa checklist of 22 items, which should be described whensuch studies are reported. This initiative has alreadybeen adopted by more than 300 scientific journals andits use has been associated with a better report of thosestudies and has been regularly reviewed since its firstpublication in 1996.2,6In the last 15 years, a dozen checklists have beendeveloped, aiming to improve the reporting quality ofseveral study designs. In addition to the CONSORT, theQuality of Reporting of Meta-Analyses (QUORUM)
initiative,15 the Meta-Analysis of Observational Studies
in Epidemiology (MOOSE)21 and the Standards for
Reporting of Diagnostic Accuracy (STARD) are available in the specialized literature.3
Following this trend, a group of researchers developed
the Strengthening the Reporting of Observational
Studies in Epidemiology (STROBE) initiative, which
includes recommendations to improve the quality ofobservational study reporting.30
The STROBE Initiative
The items comprising STROBE are associated withinformation that should be present in the title, abstract,

CONSORT Statement 2010. [cited 2010 Apr 12] Available from: http://www.consort-statement.org/consort-statement/

3

Rev Saúde Pública 2010;44(3)background, methodology, results and discussion ofscientific papers describing observational studies. A
total of 18 items are common to cohort, case-control
and cross-sectional studies and four items are specificfor each one of the three study designs. The STROBE
Initiative provides a model that can be followed byauthors of observational studies and aims to contributetowards a more adequate report of these studies and,
consequently, facilitating a critical reading of these publications by editors, reviewers and readers in general.30
The STROBE Initiative was originally published in
English. Subsequently, independent research groups
from several countries translated the observation
checklist and the basic principles of this initiative into
other languages, aiming to promote the principles thatshould guide the report of observational studies to anever wider public.1,8,9,16,20,28,29
The present study shows the first Portuguese versionof the STROBE Initiative basic principles, which wasdeveloped in partnership between researchers from theFundação Oswaldo Cruz (Oswaldo Cruz Foundation)at the Universidade Federal do Rio de Janeiro (Rio deJaneiro Federal University) and the researchers whodeveloped this initiative.
Objective and Use of the STROBE Initiative
The checklist and documents describing the STROBE
Initiative were developed in a collaborative processthat included researchers working with epidemiology,
statistics and research methodology, in addition to theeditors of several scientific journals. The purpose of
the STROBE Initiative is to provide recommendations on how to report observational studies in a more
adequate way. One must remember, however, that theserecommendations are not prescriptions for designingor conducting studies. In addition, although clarity indescription is a prerequisite for the assessment, thechecklist should not be used as an instrument to assess
observational study quality.30
The international literature comprises articles where
the reasons to include different checklist items, themethodology used and the examples considered asadequate descriptions of items involved in this checklist are explained in detail.24,25 The STROBE Initiative
recommends the use of the checklist combined with
explanatory articles on its different items.bTranslation of the STROBE Initiative into
Portuguese
In 2008, one of the authors of the present study(MM), together with the researcher responsible forb

the international STROBE Initiative (Mathias Egger),established a partnership to translate this document into
Portuguese. The team responsible for the STROBE
Initiative authorized the Brazilian group to developa Portuguese version of the checklist on which the
STROBE Initiative is based.
The initial translation was independently performed by
two authors of the present article (MM & LC). Afterreaching a consensus on the final translation, this text
was sent to the researchers who had not been involvedin the translation process (FIB, MMFM, CMFPS),
who reviewed it. Finally, all authors met to obtain a
final version of the text, aiming to develop a checklist
comprising the most commonly used terms in studies
and publications in the epidemiology of observational
studies.c The items included in the checklist are widely
discussed by the authors of the STROBE Initiative(webannex).c
Recent developments of the STROBE Initiative:
strengths and weaknesses
The STROBE Initiative has raised a growing debate
in the scientific literature. According to some authors,
the initiative has been viewed as an important strategy
which, in the near future, may be associated with the
improvement in the report of observational studies.5,11,20
However, other authors see the Initiative with reservation. Editors are reticent, since the STROBE Initiative
seeks to formalize the description of studies performed
in a research field as heterogeneous as epidemiology,
particularly when dealing with observational studies.
According to them, such initiative could jeopardize theperformance and description of unique and creative
studies.7 Some researchers believe that the STROBE
Initiative is important for this field of knowledge, but
it must be seen as an initiative under permanent review,
since this kind of strategy represents a consensus of a
specific group, in a given moment.18-20
According to MacMahon & Weiss,14 these checklists
can be useful for a researcher in the beginning of his/her career, for whom this type of organization canfacilitate the report of a study carried out by them.
However, these authors state that the principles on
which these checklists are based should be observedin the beginning of the process, at the very inception of
the study, then comprising the design, conduction andanalysis of observational studies, and not exclusively at
the moment when the research is reported. In addition,authors highlight the risk that, for situations where theauthor only becomes aware of these checklists whenwriting their article, they would report what they shouldhave done, and not what they actually did.

STROBE Statement. Strengthening the reporting of observational studies in epidemiology. Strobe checklists: version 4. Berna:
University of Bern; 2007[cited 2010 Apr 12]. Available from: http://www.strobe-statement.org/index.php?id=available-checklistsc
The Portuguese versions of the checklist and the article by von Elm et al (translated by Malta M, Cardoso LO) are available as supplementar material
to this article on the internet at: www.scielo.br/rsp

4

Apart from criticisms, the STROBE Initiative can beused as another instrument to guide the developmentof observational epidemiological studies, in addition
to the possibility of being used as a bibliography forundergraduate and postgraduate students, aiming tocontribute to the qualification of new generations ofresearchers.
Authors in this study recognize that the STROBE
Initiative must be seen as an ongoing process, open
to reviews, recommendations, criticisms and new
evidence. At the moment, this initiative is limited to thethree main designs of observational studies and is in its

STROBE Initiative

Malta M et al

first version. According to the authors of the STROBE
Initiative, initiatives seeking to adapt the checklist toother designs are welcome, such as case-crossoverstudies or ecological studies, in addition to topics
associated with specific areas. The first extension of
STROBE is currently being developed for studies that
evaluate the association between diseases and genes. It
has been called the “Extension to Genetic Association
Studies (STREGA) Initiative”.13 Researchers who havean interest in developing extensions of the STROBE
Initiative can contact the coordination group throughthe initiative’s website, aiming to avoid the duplication of efforts.

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