Table 2: Quality of Evidence of Studies for Screening Mammography*.
| Study Design | Level of Evidence |
Number of Eligible Studies |
|---|---|---|
| Systematic reviews of RCTs | 1a | 0 |
| Large RCT | 1b | 2 + 6 |
| Large RCT unpublished but reported to an international scientific meeting | 1(g) | 0 |
| Small RCT | 2 | 0 |
| Small RCT unpublished but reported to an international scientific meeting | 2(g) | 0 |
| Non-RCT with contemporaneous controls | 3a | 0 |
| Non-RCT with historical controls | 3b | 0 |
| Non-RCT presented at international conference | 3(g) | 0 |
| Surveillance (database or register) | 4a | 0 |
| Case series (multisite) | 4b | 0 |
| Case series (single site) | 4c | 0 |
| Retrospective review, modeling | 4d | 0 |
| Case series presented at international conference | 4(g) | 0 |
*
RCT refers to randomized controlled trial; g, grey literature.