Table 3 STROBE Statement—Checklist of items that should be included in reports of cohort studies

Title and abstract

1

(a) Indicate the study’s design with a commonly used term in the title or the abstract

Yes

(b) Provide in the abstract an informative and balanced summary of what was done and what was found

Yes

 Background/ rationale

2

Explain the scientific background and rationale for the investigation being reported

Yes

 Objectives

3

State specific objectives, including any prespecified hypotheses

Yes

 Study design

4

Present key elements of study design early in the paper

Yes

 Setting

5

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

Yes

 Participants

6

(a) Give the eligibility criteria, and the sources and methods of selection of participants. Describe methods of follow-up

Yes

(b) For matched studies, give matching criteria and number of exposed and unexposed

Yes

 Variables

7

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

Yes (where applicable)

 Data sources/ measurement

8^a

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

Yes (where applicable)

 Bias

9

Describe any efforts to address potential sources of bias

Yes

 Study size

10

Explain how the study size was arrived at

Yes

 Quantitative variables

11

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

Yes

 Statistical methods

12

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

Yes

(b) Describe any methods used to examine subgroups and interactions

Yes

(c) Explain how missing data were addressed

N/A

(d) If applicable, explain how loss to follow-up was addressed

N/A

(e) Describe any sensitivity analyses

N/A

 Participants

13^a

(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

Yes

(b) Give reasons for non-participation at each stage

Yes

(c) Consider use of a flow diagram

Yes

 Descriptive data

14^a

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

Yes

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

N/A

(c) Summarise follow-up time (eg, average and total amount)

Yes

 Outcome data

15^a

Report numbers of outcome events or summary measures over time

Yes

 Main results

16

(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

Yes

(b) Report category boundaries when continuous variables were categorized

Yes

(c) If relevant, consider translating estimates of relative risk into absolute risk for a meaningful time period

N/A

 Other analyses

17

Report other analyses done—eg analyses of subgroups and interactions, and sensitivity analyses

Yes

 Key results

18

Summarise key results with reference to study objectives

Yes

 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

Yes

 Interpretation

20

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

Yes

 Generalisability

21

Discuss the generalisability (external validity) of the study results

Yes

 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

Yes