multicenter observational study

How to write a paper?Multicenter observational study

PATOS 3rd Research Workshop

Outline

Time Contents

08:40-09:00 STROBE in PATOS research09:00-09:20 How can we make a title?09:20-09:40 Understanding Study Hypothesis (PECO)09:40-10:00 Break10:00-10:20 Understanding Study Background 10:20-10:40 Understanding Study Design and Setting10:40-11:00 Understanding Study Population11:00-11:20 Understanding Study Variables (Exposure, outcome, confounder)11:20-11:40 Understanding Statistical Analysis (Demographics, main analysis)11:40-12:00 Understanding Results (Demographics, main results)12:00-12:20 Understanding Discussion (Main findings, limitations)

I. STROBE in PATOS research

The PATOS Research WorkshopHow to write a paper?

Multicenter observational study

Definition of Epidemiology

Epidemiology is the study of the distribution and determinants of health-related states or events

(including disease) in specified populations, and the application of this study to the control of

diseases and other health problems

Epidemiologic study designEpidemiology study

Experimental study Observational study

Did an investigator manipulate the exposure conditions?

Ability to draw comparisons

Descriptive studyAnalytic study

Yes No

Yes No

Case-control studyCohort study Cross-sectional study

Directionality

Experimental studies

• An experiment is a set of observations conducted under controlled circumstances in which the scientist manipulates the conditions to ascertain what effect such manipulation has on the observations

(Rothman & Greenland, Modern Epidemiology 2nd ed.)

• Randomized controlled trials vs. non-randomized trials• PICO: Population, Intervention, Comparison, Outcome

Observational studies

• Large proportion of research (90% in some specialty journals)• Can be valuable, but also many disadvantages

• Two types of observational study• Descriptive (PO: Population, Outcome)

• Without a comparison group, deals with the distribution of disease • case reports, case series, qualitative studies, some cross-sectional studies (surveys)

• Analytic (PECO: Population, Exposure, Comparison, Outcome)• With comparison group, deals with determinants of disease• cohort studies, case-control studies, some cross-sectional studies

- Time, Place, Person

Analytic observational studies• Relatively free from ethical issues

• associations between measured exposures and outcomes• Main types of analytic observational studies

• Cohort• Case-control• Cross-sectional

• Critical design issue: Directionality• Forward: Observational cohort studies, Experimental studies• Backward: Case-control studies• Non-directional study: Cross-sectional studies

Main target of STROBE statement

STROBE Statement

• Guidance on how to report observational studies well • Focus on 3 main study designs: cohort, case-control, cross-sectional studies

• Published in Oct 2007: short paper and E&E (explanation and elaboration)

• Adopted by many journals• Find it on

• www.strobe-statement.org• www.equator-network.org

http://www.strobe-statement.org/

http://www.equator-network.org/

What is STROBE?

STROBE stands for an international, collaborative initiative of epidemiologists, methodologists, statisticians, researchers and journal

editors involved in the conduct and dissemination of observational studies, with the common aim of

STrengthening the Reporting of OBservational studies in Epidemiology

Vandenbroucke JP, et al. PLoS Med 4(10): e297.

Aims and use of STROBE

• Incomplete and inadequate reporting of research hampers the assessment of the strengths and weaknesses of the studies reported in the medical literature

• Readers need to know what was planned (and what was not), what was done, what was found, and what the results mean

• Recommendations on the reporting of studies that are endorsed by leading medical journals can improve the quality of reporting

https://www.strobe-statement.org/index.php?id=strobe-home

Aims and use of STROBE

• “We want to provide guidance on how to report observational research well. Our recommendations are not prescriptions for designing or conducting studies. Also, the checklist is not an instrument to evaluate the quality of observational research.”

• “Our intention is to explain how to report research well, not how research should be done.”

https://www.strobe-statement.org/index.php?id=strobe-aims

Translations of STROBE

STROBE

• Checklist with 22 items• Heading (where in paper), item No• Recommendation, divided into: Cohort study, Case-control study, Cross-

sectional study

We will discuss all items in this research workshop!

Title and Abstract

Title and Abstract (1)• (a) Indicate the study’s design with a commonly used term in the title

or the abstract• (b) Provide in the abstract an informative and balanced summary of

what was done and what was found

Introduction

Background/rationale (2)• Explain the scientific background and rationale for the investigation

being reported

Objectives (3) • State specific objectives, including any prespecified hypotheses

Methods

Study design (4) • Present key elements of study design early in the paper

Setting (5) • Describe the setting, locations, and relevant dates, including periods

of recruitment, exposure, follow-up, and data collection

Methods

Participants (6) • (a) Cohort study—Give the eligibility criteria, and the sources and

methods of selection of participants. Describe methods of follow-up

Case-control study—Give the eligibility criteria, and the sources and methods of case ascertainment and control selection. Give the rationale for the choice of cases and controls

Cross-sectional study—Give the eligibility criteria, and the sources and methods of selection of participants

Methods

Participants (6) • (b) Cohort study—For matched studies, give matching criteria and

number of exposed and unexposed

Case-control study—For matched studies, give matching criteria and the number of controls per case

Methods

Variables (7) • Clearly define all outcomes, exposures, predictors, potential

confounders, and effect modifiers. Give diagnostic criteria, if applicable

Data sources/measurement (8*) • For each variable of interest, give sources of data and details of

methods of assessment (measurement). Describe comparability of assessment methods if there is more than one group

*Give such information separately for cases and controls in case-control studies, and, if applicable, for exposed and unexposed groups in cohort and cross-sectional studies.

Methods

Bias (9) • Describe any efforts to address potential sources of bias

Study size (10) • Explain how the study size was arrived at

Quantitative variables (11) • Explain how quantitative variables were handled in the analyses. If

applicable, describe which groupings were chosen, and why

Important in observational studies!

Methods

Statistical methods (12) • (a) Describe all statistical methods, including those used to control for confounding• (b) Describe any methods used to examine subgroups and interactions• (c) Explain how missing data were addressed• (d) Cohort study—If applicable, explain how loss to follow-up was addressed

Case-control study—If applicable, explain how matching of cases and controls was addressed

Cross-sectional study—If applicable, describe analytical methods taking account of sampling strategy

• (e) Describe any sensitivity analyses

Results

Participants (13*) • (a) Report the numbers of individuals at each stage of the study—eg,

numbers potentially eligible, examined for eligibility, confirmed eligible, included in the study, completing follow-up, and analyzed

• (b) Give reasons for non-participation at each stage• (c) Consider use of a flow diagram


Results

Descriptive data (14*) • (a) Give characteristics of study participants (eg, demographic, clinical,

social) and information on exposures and potential confounders• (b) Indicate the number of participants with missing data for each

variable of interest• (c) Cohort study—Summarize follow-up time (eg, average and total

amount)


Results

Outcome data (15*) • Cohort study—Report numbers of outcome events or summary

measures over time• Case-control study—Report numbers in each exposure category, or

summary measures of exposure• Cross-sectional study—Report numbers of outcome events or

summary measures


Results

Main results (16) • (a) Give unadjusted estimates and, if applicable, confounder-adjusted estimates

and their precision (eg, 95% confidence intervals). Make clear which confounders were adjusted for and why they were included

• (b) Report category boundaries when continuous variables were categorised• (c) If relevant, consider translating estimates of relative risk into absolute risk for

a meaningful time period

Other analyses (17) • Report other analyses done—eg, analyses of subgroups and interactions, and

sensitivity analyses

Discussion

Key results (18) • Summarise key results with reference to study objectives

Limitations (19) • Discuss limitations of the study, taking into account sources of

potential bias or imprecision. Discuss both direction and magnitude of any potential bias

Discussion

Interpretation (20) • Give a cautious overall interpretation of results considering objectives,

limitations, multiplicity of analyses, results from similar studies, and other relevant evidence

Generalizability (21) • Discuss the generalizability (external validity) of the study results

Other information

Funding (22) • Give the source of funding and the role of the funders for the present

study and, if applicable, for the original study on which the present article is based

More detailed explanation

Vandenbroucke JP, von Elm E, Altman DA, et al. Strengthening the Reporting of

Observational Studies in Epidemiology (STROBE): Explanation and Elaboration.

PLoS Med 4(10): e297.

Thank you!

II. How can we make a title?



STROBE: Title and Abstract




STROBE Explanation

Title and Abstract (1)• Readers should be able to easily identify the design that was used

from the title or abstract • An explicit, commonly used term for the study design also helps

ensure correct indexing of articles in electronic databases


Example #1-3

• Title

Title

• The title may influence the impact of the article and the number of readers that it will attract

• Pre-submission phase• The title should focus, define and refine the author’s thoughts and, • as a result, should have a major impact on the writing process

• Post-publication phase• It strongly influences whether or not potential readers find the paper• It governs the accuracy of the inferences readers will draw about the paper

ICMJE recommendation

• The title provides a distilled description of the complete article• Should include information that, along with Abstract, will make

electronic retrieval of the article sensitive and specified

Title

• A title should be fully explanatory when standing alone• A title should summarize the main idea of the manuscript simply and,

if possible, with style• It should be a concise statement of the main topic and should identify

the study hypothesis (PECO) or theoretical issues and the relationship between them

• Avoid using abbreviations in a title• Avoid titles that are too long: words that carry little or no meaning

should be omitted

Making a title

• Most common pattern • RELATIONSHIP between EXPOSURE and OUTCOME in POPULATION:

STUDY DESIGN

• STUDY DESIGN for RELATIONSHIP between EXPOSURE and OUTCOME in POPULATION

• relationship: association, correlation, preventive effects…

• Some of them (study design, PECO, and relationship) are optional, but recommend to indicate study design in the title

Example #1-31st article: study design, exposure, and population- No relationship, no outcome

2nd article: outcome, exposure, and population- No study design

3rd article: outcome and exposure- No study design, no population

STROBE: Title and Abstract




STROBE Explanation

Title and Abstract (1)• The abstract provides key information that enables readers to

understand a study and decide whether to read the article• Abstracts should summarize key details of studies and should only

present information that is provided in the article• Authors present key results in a numerical form that includes

numbers of participants, estimates of associations and appropriate measures of variability and uncertainty (e.g., odds ratios with confidence intervals)


Example #2Statement of the research question

Summarize key details of methods

Presenting key results in numeric

Simple and clear conclusions

Thank you!

III. UnderstandingStudy Hypothesis (PECO)



multicenter observational study

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