Main results | STROBE Item description [5] | Item No | n (%) of adhering publications; total n = 147 |
---|---|---|---|
Title and abstract | (a) Indicate the study’s design with a commonly used term | 1a | 67 (45.6) |
(b) Provide in the abstract an informative and balanced summary | 1b | 102 (69.4) | |
Introduction | |||
Background/ rationale | Explain the scientific background and rationale for the investigation | 2 | 24 (16.3) |
Objectives | State specific objectives, including any prespecified hypotheses | 3 | 113 (76.9) |
Methods | |||
Study design | Present key elements of study design early in the paper | 4 | 61 (41.5) |
Setting | Describe the setting, locations, and relevant dates | 5 | 108 (73.5) |
Participants | (a) Cohort study—Give the eligibility criteria, and the sources and methods of selection of participants and the 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 | 6a | 9 (6.1) |
(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 | 6b | 17/40a (42.5) | |
Variables | Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. Give diagnostic criteria | 7 | 27 (18.4) |
Data sources/ measurement | 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 | 8 | 117 (79.6) |
Bias | Describe any efforts to address potential sources of bias | 9 | 2 (1.4) |
Study size | Explain how the study size was arrived at | 10 | 18 (12.2) |
Quantitative variables | Explain how quantitative variables were handled in the analyses. Describe which groupings were chosen and why | 11 | 97 (66.0) |
Statistical methods | (a) Describe all statistical methods, including those used to control for confounding | 12a | 133 (90.5) |
(b) Describe any methods used to examine subgroups and interactions | 12b | 6/40a (15.0) | |
(c) Explain how missing data were addressed | 12c | 41 (27.9) | |
(d) Cohort study—Explain how loss to follow-up was addressed Case–control study—Explain how matching of cases and controls was addressed Cross-sectional study—Describe analytical methods taking account of sampling strategy | 12d | 10/30a (33.3) | |
(e) Describe any sensitivity analyses | 12e | 34/36a (94.4) | |
Results | |||
Participants | (a) Report numbers of individuals at each stage of study | 13a | 93 (63.3) |
(b) Give reasons for non-participation at each stage | 13b | 88 (59.9) | |
(c) Consider use of a flow diagram | 13c | 61 (41.5) | |
Descriptive data | (a) Give characteristics of study participants and information on exposures and potential confounders | 14a | 79 (53.7) |
(b) Indicate number of participants with missing data for each variable of interest | 14b | 39 (26.5) | |
(c) Cohort study—Summarise follow-up time | 14c | 13/26a (50.0) | |
Outcome data | 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 | 15 | 139 (94.6) |
Main results | (a) Give unadjusted and confounder-adjusted estimates and their precision. Make clear which confounders were adjusted for and why | 16a | 37 (25.2) |
(b) Report category boundaries when continuous variables were categorised | 16b | 2/3a (66.7) | |
(c) If relevant, consider translating estimates of relative risk into absolute risk for a meaningful time period | 16c | Not evaluated | |
Other analyses | Report other analyses done | 17 | 60/63a (95.2) |
Discussion | |||
Key results | Summarise key results with reference to study objectives | 18 | 35 (23.8) |
Limitations | Discuss limitations and potential bias of the study | 19 | 5 (3.4) |
Interpretation | Give a cautious overall interpretation of results | 20 | 95 (64.6) |
Generalisability | Discuss the generalisability (external validity) of the study results | 21 | 40 (27.2) |
Other Information | |||
Funding | Give the source of funding and the role of the funders | 22 | 85 (57.8) |
Overall adherence of all analysed publications | Mean ± standard deviation | all | 45.6 ± 13.7 |
Median [interquartile range] | all | 46.2 [34.6–57.1] |