Table 2.

Comparison of overall interobserver agreement for the assessment of HER2 between the optical microscope and digital environment, using the percent correct agreement metric, as well as category-specific percent correct agreement [95% CI].

Interobserver HER2	Percent correct
Scoring category	Optical whole slides	Digital whole slides	Difference
All	65.9 [52.4–78.9]	59.4 [46.5–72.0]	6.4 [−8.5–21.5]
0	65.6 [41.7–93.8]	49.7 [14.3–83.7]	15.9 [−20.8–54.8]
1+	37.7 [13.1–62.0]	29.4 [9.2–52.0]	8.3 [−25.3–39.7]
2+	44.0 [26.5–60.8]	36.2 [18.1–54.2]	7.8 [−18.0–33.8]
3+	66.6 [39.6–88.7]	58.4 [35.4–79.0]	8.2 [−14.0–30.5]
	Optical TMA	Digital TMA	Difference
All	71.7 [64.7–78.2]	72.3 [64.4–79.7]	−0.5 [−8.8–7.8]
0+	65.4 [50.3–78.1]	74.9 [59.3–88.0]	−9.5 [−23.5–4.1]
1+	48.6 [36.9–59.0]	45.3 [31.0–59.7]	3.3 [−12.4–18.5]
2+	38.1 [23.7–52.6]	36.4 [24.6–48.1]	1.8 [−14.5–17.3]
3+	77.7 [61.6–90.3]	79.7 [66.4–90.5]	−2.0 [−17.7–13.7]