Screening with mammography v usual care to prevent breast cancer mortality at mean 14 years follow up*
| Age groups | Number of trials† | RRR (95% CrI) | NNS (CrI) |
|---|---|---|---|
| *CrI = credible interval; NNS = number needed to screen. Other abbreviations defined in glossary. | |||
| †The meta-analysis excluded the trial rated as poor quality. | |||
| All ages (39–74 y) | 7 | 16% (9 to 23) | 1224 (665 to 2564) |
| <50 years | 7 | 15% (1 to 27) | 1792 (674 to 10 540) |
| ≥50 years | 7 | 22% (13 to 30) | 838 (494 to 1676) |