Table 2.
Reporting of STROBE subitems relating to the study methods in 47 articles describing case–control studies
| STROBE subitem | No (%) of articles that reported subitem in sufficient detail | No (%) of articles that reported subitem but not in sufficient detail | No (%) of articles that did not report the subitem at all | Not applicable |
|---|---|---|---|---|
| STROBE Item 4 Study design | ||||
| 4 Present key elements of study design early in the paper | 41 (87.2) | 4 (8.5) | 2 (4.3) | 0 (0) |
| STROBE Item 5 Study setting (five subitems) | ||||
| 5.1 Describe the study setting | 42 (89.4) | 3 (6.4) | 2 (4.3) | 0 (0) |
| 5.2 Describe the study locations | 43 (91.5) | 4 (8.5) | 0 (0) | 0 (0) |
| 5.3 The period of recruitment | 39 (83) | 4 (8.5) | 4 (8.5) | 0 (0%) |
| 5.4 Describe the period of exposure | 14 (29.8) | 4 (8.5) | 22 (46.8) | 7 (14.9) |
| 5.5 Describe the period of data collection | 25 (53.2) | 6 (12.8) | 16 (34) | 0 (0) |
| STROBE Item 6 Participants (10 subitems) | ||||
| 6.1 Give the eligibility criteria for cases | 39 (83) | 5 (10.6) | 3 (6.4) | 0 (0) |
| 6.2 Give the eligibility criteria for controls | 35 (74.5) | 1 (2.1) | 11 (23.4) | 0 (0) |
| 6.3 Give the source of cases | 47 (100) | 0 (0) | 0 (0) | 0 (0) |
| 6.4 Give the source of controls | 45 (95.7) | 0 (0) | 2 (4.3) | 0 (0) |
| 6.5 Give the methods of case ascertainment | 41 (87.2) | 1 (2.1) | 5 (10.6) | 0 (0) |
| 6.6 Give the methods of control selection | 40 (85.1) | 0 (0) | 7 (14.9) | 0 (0) |
| 6.7 Give the rationale for the choice of cases | 13 (27.7) | 0 (0) | 34 (72.3) | 0 (0) |
| 6.8 Give the rationale for the choice of controls | 13 (27.7) | 0 (0) | 34 (72.3) | 0 (0) |
| 6.9 Give the matching criteria | 35 (74.5) | 3 (6.4) | 7 (14.9) | 2 (4.3) |
| 6.10 Give the number of controls per case | 37 (78.7) | 6 (12.8) | 4 (8.5) | 0 (0) |
| STROBE Item 7 Variables (three subitems) | ||||
| 7.1 Clearly define all the outcomes | 36 (76.6) | 10 (21.3) | 1 (2.1) | 0 (0) |
| 7.2 Clearly define all exposures evaluated | 36 (76.6) | 9 (19.1) | 2 (4.3) | 0 (0) |
| 7.3 Clearly define all potential confounders | 35 (74.5) | 11 (23.4) | 1 (2.1) | 0 (0) |
| STROBE item 8 Data sources/measurement (four subitems) for each variable of interest | ||||
| 8.1 Give sources of data for cases | 47 (100) | 0 (0) | 0 (0) | 0 (0) |
| 8.2 Give sources of data for controls | 45 (95.7) | 1 (2.1) | 1 (2.1) | 0 (0) |
| 8.3 Give details of methods of assessment (measurement) for cases | 26 (55.3) | 18 (38.3) | 3 (6.4) | 0 (0) |
| 8.4 Give details of methods of assessment (measurement) for controls | 36 (76.6) | 7 (14.9) | 4 (8.5) | 0 (0) |
| STROBE Item 9 Bias | ||||
| 9 Describe any efforts to address potential sources of bias | 18 (38.3) | 3 (6.4) | 26 (55.3) | 0 (0) |
| STROBE Item 10 Study size | ||||
| 10 Explain how the study size was arrived at | 2 (4.3) | 2 (4.3) | 43 (91.5) | 0 (0) |
| STROBE Item 11 Quantitative variables (three subitems) | ||||
| 11.1 Explain how quantitative variables were handled in the analyses | 33 (70.2) | 7 (14.9) | 7 (14.9) | 0 (0) |
| 11.2 Which groupings were chosen | 41 (87.2) | 4 (8.5) | 2 (4.3) | 0 (0) |
| 11.3 Why groupings were chosen | 7 (14.9) | 2 (4.3) | 38 (80.9) | 0 (0) |