Table 2.

Proportional incidence of first-year interval breast cancers by type of previous negative mammography report.

	Mammography report
	Standard negative	Negative with RES
Woman-years at risk, n*	272,710	3286
OBS, n (rate)†	96 (35.3)	4 (121.7)
EXP, n	640.4	7.6
OBS:EXP ratio (95% CI)	0.15 (0.12-0.18)	0.53 (0.14-1.35)
Ratio‡ of the OBS:EXP ratios (95% CI)	1.00 (referent)	3.51 (0.94-9.29)

* Adjusted for general mortality and rounded to the whole-number value.

† Per 100,000 woman-years at risk.

‡ Adjusted for woman's age (5-year groups).

RES, recommendation for early (<24 months) rescreen; OBS:EXP ratio, observed:expected ratio or proportional incidence of interval cancers; CI, confidence interval.