Table 1.
Interobserver agreements between pathologists using one method of rating
| Agreement of positive tumor ratio | Agreement of staining intensity | ||||
|---|---|---|---|---|---|
| Method | OCCC | Mean of standard deviations [%] (range) | Number of specimens with 10% cut-off disagreements | Fleiss’ kappa | |
| 1. Microscope | 0.682 | 12.1 (1.7–26.5) | 4 | 0.44 (P < 0.001) | |
| 2. Virtual microscopy | 0.551 | 13.7 (6.2–25.3) | 7 | 0.45 (P < 0.001) | |
| 3. Virtual microscopy with area outlining assistance | Visual estimation by the pathologists | 0.672 | 13.1 (2.3–28.3) | 6 | 0.40 (P < 0.001) |
| By computation of outlined areas | 0.694 | 12.3 (1.9–25.2) | 7 | ||
Positive tumor ratios were compared using the mean of standard deviations, overall concordance correlation coefficient (OCCC), and number of discordant ratings with respect to the 10% cutoff. Staining intensities were compared using Fleiss’ kappa test.