Table 2. Cascade Event Rates Among Screening Breast MRI vs Mammography Recipients in the 6 Months Following the Screening Test.
| Characteristics | Event rate per 100 members | Breast MRI cascade-attributable event rate per 100 members (95% CI) | |
|---|---|---|---|
| Breast MRI (n = 9208) | Mammography (n = 9208) | ||
| Mammary | |||
| All mammary cascade events | 134.1 | 95.1 | 39.0 (33.7 to 44.2) |
| Imaging tests | 18.1 | 13.1 | 5.0 (3.8 to 6.2) |
| Procedures | 22.4 | 5.1 | 17.3 (15.5 to 19.0) |
| Visits | 89.3 | 76.0 | 13.3 (9.4 to 17.2) |
| Hospitalizations | 0.38 | 0.04 | 0.34 (0.18 to 0.50) |
| New diagnoses | 3.9 | 0.9 | 3.0 (2.5 to 3.6) |
| Extramammary | |||
| All extramammary cascade events | 304.5 | 284.8 | 19.6 (8.6 to 30.7) |
| Laboratory tests | 114.9 | 111.8 | 3.2 (−2.2 to 8.5) |
| Imaging tests | 33.3 | 33.7 | −0.45 (−2.7 to 1.8) |
| Procedures | 10.3 | 9.4 | 0.97 (−0.08 to 2.0) |
| Visits | 141.0 | 125.2 | 15.8 (10.2 to 21.4) |
| Hospitalizations | 0.27 | 0.38 | −0.11 (−0.28 to 0.06) |
| New diagnoses | 4.7 | 4.4 | 0.29 (−0.53 to 1.11) |
| Othera | |||
| Pathology/cytology | 35.8 | 21.7 | 14.1 (12.3 to 15.9) |
Abbreviation: MRI, magnetic resonance imaging.
a
Since billing codes for the laboratory tests likely to follow mammary findings (ie, pathology and cytology) do not have sufficient specificity to identify breast vs other tissue sites for biopsy or cytology samples, we grouped these events as a separate category and did not include them in counts of aggregate cascade event or spending estimates.