STROBE_checklist_cross-sectional

STROBE Statement—Checklist of items that should be included in reports of cross-sectional studies

Title and abstract

Item No 1

Recommendation

(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 Objectives Methods Study design Setting Participants Variables Data sources/ measurement Bias Study size

Quantitative variables Statistical methods

9 10 11 12 2 3 4 5 6 7 8*

Explain the scientific background and rationale for the investigation being reported State specific objectives, including any prespecified hypotheses Present key elements of study design early in the paper

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

(a) Give the eligibility criteria, and the sources and methods of selection of participants

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

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

Describe any efforts to address potential sources of bias Explain how the study size was arrived at

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

(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) If applicable, describe analytical methods taking account of sampling strategy (e) Describe any sensitivity analyses Results Participants

13*

(a) 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

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

Descriptive data

14*

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

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

Outcome data Main results

15* 16

Report numbers of outcome events or summary measures

(a) 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

(b) Report category boundaries when continuous variables were categorized (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

1

Discussion Key results Limitations Interpretation Generalisability Other information Funding

18 19 20 21 22

Summarise key results with reference to study objectives

Discuss limitations of the study, taking into account sources of potential bias or imprecision. Discuss both direction and magnitude of any potential bias

Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of analyses, results from similar studies, and other relevant evidence Discuss the generalisability (external validity) of the study results

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

*Give information separately for exposed and unexposed groups.

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.

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