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. 2014 Sep-Oct;34(5):415–426. doi: 10.5144/0256-4947.2014.415
Item No Recommendation
Title and abstract 1

  1. Indicate the study’s design with a commonly used term in the title or the abstract

  2. 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
 Participants 6

  1. 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

  2. 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
 Variables 7 Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. Give diagnostic criteria, if applicable
 Data sources/measurement 8a 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
 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
 Statistical methods 12

  1. Describe all statistical methods, including those used to control for confounding

  2. Describe any methods used to examine subgroups and interactions

  3. Explain how missing data were addressed

  4. 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

  5. Describe any sensitivity analyses
Results
 Participants 13*

  1. Report numbers of individuals at each stage of study—eg numbers potentially eligible, examined for eligibility, confirmed eligible, included in the study, completing follow-up, and analysed

  2. Give reasons for non-participation at each stage

  3. Consider use of a flow diagram
 Descriptive data 14a

  1. Give characteristics of study participants (eg demographic, clinical, social) and information on exposures and potential confounders

  2. Indicate number of participants with missing data for each variable of interest

  3. Cohort study - Summarise follow-up time (eg, average and total amount)
 Outcome data 15a 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
 Main results 16

  1. Give unadjusted estimates and, if applicable, confounder-adjusted estimates and their precision (eg, 95% confidence interval). Make clear which confounders were adjusted for and why they were included

  2. Report category boundaries when continuous variables were categorized

  3. 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
 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
a

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

Note: An Explanation and Elaboration article discusses each checklist item and gives methodological background and published examples of transparent reporting. The STROBE checklist is best used in conjunction with this article (freely available on the Web sites of PLoS Medicine at http://www.plosmedicine.org/, Annals of Internal Medicine at http://www.annals.org/, and Epidemiology at http://www.epidem.com/). Information on the STROBE Initiative is available at www.strobe-statement.org.