Table 1.
Checklist for rating of study quality
| 1 | Aim of the study | Evaluation of validity of self-report was clearly stated as one of the aims of the study | 3 | Main aim |
| 2 | Part of study or secondary analysis | |||
| 1 | Addressed in small part of study | |||
| 0 | No aim or not clearly stated | |||
| 2 | Sampling | The sampling frame and sampling procedures were clearly stated | 3 | All 3 items OK |
| 2 | 2 items OK | |||
| Inclusion and exclusion criteria were clear | 1 | 1 item OK | ||
| Able to account for all of the participants at each stage of the study | 0 | None OK | ||
| 3 | Sample size | The study was well powered; studies fell into four sizes according to their likelihood of good statistical power | 3 | >600 |
| 2 | 300–600 | |||
| 1 | 100–300 | |||
| 0 | <100 | |||
| 4 | Response rate | The response rate was satisfying | 3 | >85% |
| 2 | 70–85% | |||
| 1 | 50–69% | |||
| 0 | <50 | |||
| 5 | Design | The design was a | 3 | Prospective cohort or cross-sectional with controls |
| 2 | Case–control | |||
| 1 | Cohort or cross-sectional without controls | |||
| 0 | Not clearly designed | |||
| 6 | Timeline | Self-report before examination/testing | 1 | Yes |
| 0 | No | |||
| 7 | Interval | The interval between self-report and examination was clear and not too long to introduce significant changes in health status | 3 | Self-report immediately (same day) before examination/testing |
| 2 | Self-report within 6 w before examination/testing | |||
| 1 | Report before examination/testing without interval stated or interval > 6 w | |||
| 0 | Examination/testing before self-report | |||
| 8 | Blinding of examiner | Was the examining professional aware of the outcomes of self-report | 1 | Examiner was blinded to self-report |
| 0 | Examiner was not blinded to self-report or blinding not stated | |||
| 9 | Outcome assessment | Case definitions for self-report and outcome of examination/testing were explicit and relevant, and the study referred to assessment criteria to suggest it was repeatable. | 3 | Clear case definitions for participant and examiner and explicit stated criteria |
| 2 | Clear case definitions without criteria stated | |||
| 1 | Minimal case definitions | |||
| 0 | Or no criteria stated |
A total quality score was calculated to rate the quality of the study as high (16 or higher), moderate (12–15), or low (11 or lower)