Table 4.

Comparisons Between Different Methods of Ki-67 Measurement^a

Comparison Pair	Pearson Correlation Coefficient	Closeness of Match: No. (%) of Cases Within ±0.2xKi-67 Index	No. of Grade-Discordant Cases	κ
Manual counting vs manual counting
Observer 1 (DP) vs observer 2 (Ob 2) (case level)	0.976	10/20 (50)	4	1
Observer 1 (DP) vs observer 1 (Ob 1) (case level)	0.977	12/20 (60)	4	0.63
Observer 1 (Ob 1) vs observer 2 (Ob 2) (case level)	0.952	10/20 (50)	0	0.63
Manual counting vs DIA
Observer 2 (Ob 2) vs HALO (Ob 2) (hotspot level)	0.971	11/20 (55)	2	0.81
Observer 2 (Ob 2) vs HALO (DP) (case level)	0.949	7/20 (35)	2	0.81
Observer 2 (Ob 2) vs QuantCenter (DP) (case level)	0.978	10/20 (50)	2	0.81
Observer 1 (Ob 1) vs HALO (Ob 2) (case level)	0.902	7/20 (35)	2	0.81
Observer 1 (Ob 1) vs HALO (DP) (case level)	0.881	7/20 (35)	4	0.81
Observer 1 (Ob 1) vs QuantCenter (DP) (case level)	0.946	8/20 (40)	4	0.81
Observer 1 (DP) vs HALO (Ob 2) (case level)	0.942	9/20 (45)	2	0.63
Observer 1 (DP) vs HALO (DP) (hotspot level)	0.922	9/20 (45)	2	0.63
Observer 1 (DP) vs QuantCenter (DP) (hotspot level)	0.976	13/20 (65)	2	0.63
DIA vs DIA
QuantCenter (DP) vs HALO (DP) (hotspot level)	0.953	10/20 (50)	2	0.81
QuantCenter (DP) vs HALO (Ob 2) (case level)	0.969	9/20 (45)	0	1
HALO (DP) vs HALO (Ob 2) (case level)	0.980	6/20 (30)	2	0.81

DIA, digital image analysis; DP, digital image analysis pathologist; Ob, observer.

^aThe comparison pairs are grouped under three headings. For each method, the name/label in the leftmost column indicates the observer or software device performing the count followed by the person choosing the hotspot in parentheses. The grade-discordant cases column enumerates the number of cases that fall under different World Health Organization grades (G1/G2/G3) for each comparison, and κ indicates the Cohen’s κ statistic value for the pair.