Reporting the observational studies

Writing a journal article

• There is no standard or uniform style that is followed by all journals

• Each journal has its own style; but they all have their own Instructions to Authors

• Select a journal - FOLLOW THE JOURNAL’S INSTRUCTIONS TO AUTHORS

Reporting observation study

• Two guidelines – IMRaD– STROBE statement

4Grimes, DA, Schulz KF. An overview of clinical research:the lay of the land. Lancet 2002; 359; 57-61.

IMRaD / STROBE

The IMRaD Research Paper Format

• Introduction, Methods, Research [and] Discussion• A mnemonic for a common format used for

academic ['scientific'] research papers• IMRaD is simply a more 'defined' version of the "IBC"

[Introduction, Body, Conclusion] format used for all academic writing

• Considered ideal outline in early 1990s• Late 1970s, International Committee of Medical

Journal Editors (“Vancouver Group”) first published guidelines

Bradford Hills questions

• Introduction Why did you start?• Methods What did you do?• Results What did you find?

and• Discussion What does it all mean?

Introduction (including a title)

• The title is centered at the top of the first page.• Introductory section.

– Comprises one or several paragraphs which outline the research question and its significance within the topic being discussed, previous work on topic & gaps in current knowledge, making it clear what the relevance / rationale of the question and aim/objectives of the study.

– Brief and arresting – Define nature and scope of problem, but do not hide

inconvenient facts

Review of Background, 'Known Information‘*

• [*This section is not part of the 'IMRAD' mnemonic, as it is considered to be self-evident]

• What? Who? Why? How?

Methods (1)

• Describe how you gathered the information. • What events did you observe • Who did you interview? • Why did you interview these particular people? &

how you find them? • What sort of information did you collect from them?• If your paper includes interviews or surveys, here is

where you would describe their design, procedure, analysis

Methods (2)• Study design • Setting • Who is the study about?

– Participants and control subjects (in animal studies, specify genus, species)

– Inclusion & exclusion criteria • Sample size• What did you do?

– Intervention or Follow up• What did you look for? - Outcome measure

Methods (3)

• Interventions / test– If standard, give reference – If new or modified, provide details (sufficient for

reproduction by other workers) – Timing and duration of intervention – Equipment / kits / manufacturer

• Outcome– Define outcome – Parameters to assess outcome – Endpoint, cut-off values – Adverse events, if any e measures

Methods (4)

• Follow up– Frequency, method, duration (including minimum

acceptable duration) – Criteria for termination or drop-out

Per-protocol vs. intention-to-treat

• Analysis– Methods used for different parameters • – Software

Results (1)

• What did you find out from the method you had employed?

• Here's where you would include your description of the participants, main results

• Should answer all points raised in Methods• No new parameters • No miss-match between numbers in text and tables /

figures

Results (2)

• Participants – How many screened? – How many eligible? – How many recruited / excluded? – How many completed study? – Reasons for lack of completeness – Compliance with therapy / protocol All subjects should be accounted for

Results (3)

• Data presentations – Cause of incomplete data, if any (sample lost, incomplete

study) – No repetition between text and tables – No interpretation – No adjectives (most, some, often..) – Use % only if n>100 – Restrict decimal points to 1 or 2 – Provide value of p (“highly significant”, “very highly

significant” meaningles

Discussion• What do the findings presented under "Results" above

mean? Specifically, how your findings prove your thesis? • What patterns do you see in the data? • How do they correlate with what had been 'known'

about the event, and/or what you had expected to find? • Did you find what you had expected to, or were you

surprised? (Often the parts that surprised you are the most significant, and the most interesting.)

• Is further research desirable? If so, what, and how? Researchers often use this section to promote interest (and funding) for their next research project.

Limitations• Often a separate subdivision of discussion• Viewed after the fact, what would you have done

differently (if you had been able to) to obtain more objective and 'reliable' results?

• All research projects will have such "limitations": – this does not diminish the findings or disproved

with the plan and material which was used; – it simply recognizes that, had it been possible to

conduct the project differently the results could or would have been different.

Conclusion, Notes, Works Cited and Appendices

• While the IMRAD format presumes the paper's conclusion to be a subsection of the Discussion, there should be a distinct closing to the paper of several paragraphs that briefly summarize what the paper has proposed, discussed and concluded.

• Following this would be (in MLA format) possible [author] Notes, the paper's Works Cited, and possible Appendices.

STROBE • STrengthening the Reporting of OBservational

studies in Epidemiology

• Guidance on how to report observational studies well • The STROBE Statement is being endorsed by a growing

number of biomedical journals• Published in Oct 2007• 22 item checklist

Table 1.

Vandenbroucke JP, von Elm E, Altman DG, Gøtzsche PC, et al. (2007) Strengthening the Reporting of Observational Studies in Epidemiology(STROBE): Explanation and Elaboration. PLoS Med 4(10): e297. doi:10.1371/journal.pmed.0040297

http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.0040297

Recommendation Title and abstract 1 a) Indicate the study’s design with a commonly used

term in the title or the abstractb) Provide in the abstract an informative and balanced summary of what was done and what was found

Introduction Background and rationale

2 Explain the scientific background and rationale for the investigation being reported

Objectives 3 State specific objectives, including any prespecifiedhypothesis

Methods Study design 4 Present key elements of study design early in the

paper (what design, what was compared, which controls and why...etc)

Settings 5 Describe the setting, locations, and relevant dates, including periods of recruitment, exposure, follow-up, and data collection

Recommendation

Methods (cont..)

Participants

6: (a)

Cohort study - eligibility criteria, sources and methods of participant selection, follow-up methodsCase control study - eligibility criteria, sources and methods of case ascertainment and control, selection rationale for the choices of cases and controlCross-section study - eligibility criteria, sources and methods of participant selection

6: (b)

Cohort study - For matched studies, give matching criteria and number of exposed and unexposedCase control - For matched studies, give matching criteria and the number of controls per case

Variables 7 Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. Give diagnostic criteria, if applicable

Recommendation

Methods (cont..)

Data sources / measurement

8 For each variable of interest, give sources of data anddetails of methods of assessment (measurement)

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

Bias 9 Describe any efforts to address potential sources of bias(ie systematic deviation of a result from the true value) e.g.: recall bias, detection bias, interviewer bias, selection bias

Study size 10 Explain how the study size was arrived at (should be large enough to arrive at a point estimate with a reasonably narrow confidence interval)

Recommendation

Methods (cont..)

Quantitative variables

11 Explain how quantitative variables were handled in the analyses. If applicable, describe which groupings were chosen and why

Statistical methods

12 a) Describe all statistical methods, including those used to control confounding

b) Describe any methods used to examine subgroups and interactions

c) Explain how missing data were addressedd) Cohort study: if applicable, explain how loss to

follow-up was addressedCase-control: if applicable, explain how matching ofcases and controls was addressedCross-sectional: if applicable, describe analytical methods including sampling strategy

e) Describe any sensitivity analyses

Recommendation

Results

Participants 13 a) Report numbers of individuals at each stage of study -e.g., numbers potentially eligible, examined for eligibility, confirmed eligible, included in the study, completing follow-up, and analysed

b) Give reasons for non-participation at each stagec) Consider use of a flow diagram

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

Descriptive data

14 a) Give characteristics of study participants (e.g. demographic, clinical, social) and information on exposures and potential confounders

b) Indicate number of participants with missing data for each variable of interest

c) Cohort study: Summarise follow up time (e.g. average and total amount)

Separate for Case – Controls & Exposed – Unexposed

Recommendation

Results (cont)

Outcome data

15 Cohort study: Report numbers of outcome events orsummary measures over timeCase-control: Report numbers in each exposure category, or summary measures of exposureCross-sectional: Report number of outcome events or summary measuresSeparate for Case – Controls & Exposed – Unexposed

Main results 16 a) Give unadjusted estimates and, if applicable, confounder- adjusted estimates and their precision (e.g. 95%CI). 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

Recommendation

Results (cont)

Other analysis 17 Report other analyses done, e.g. analyses of subgroups and interactions, and sensitivity analyses

Discussion

Key results 18 Summarize 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

Interpretation 20 Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of analyses, results from similar studies, and other relevant evidence

Generalisability 21 Discuss the generalisability (external validity) of the study results

Funding /other information

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

Three STROBE extensions (1)

• STREGA (2009)– reporting of genetic association studies

28

Three STROBE extensions (2)

• STROBE – ME (Oct 2011)– Reporting molecular epidemiology (biomarker

studies)

29

Three STROBE extensions (3)

• STROBE abstract

- Reporting observational studies in conference abstracts (online draft)

30

More detailed explanation of strobe

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.doi:10.1371/journal.pmed.0040297

www.strobe-statement.org

Common mistakes

Introduction

• History starting from Adam • Details of previous studies • Abbreviations without full form • Details of Results and Conclusions • Intermix with Discussion

Methods and Results

• Mixed up • Errors in data (e.g., mean age 25, range 17-22) • Mismatch of data in Methods / Results /

Tables / Figures • Misinterpretation of data

Discussion

• First study in the world / India / Maharashtra… • Repeating results • Emphasizing strengths of study over its weaknesses • Inflating importance of findings • Going beyond evidence and drawing unjustified

conclusions

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