Roel Bogie

Chapter 2

Results A total of 14 experts (7 Asian, 5 European, 1 American and 1 Australian) and 21 endoscopy fellows (10 MUMC+, 11 NTUH) participated. The LST cases comprised 50 adenomas, 18 sessile serrated adenomas/polyps and 4 early cancers. Endoscopic classification of LSTs among experts The overall IOA among experts for the endoscopic Kudo LST classification was moderate to substantial (Gwet’s AC1 coefficient: 0.62, 95% CI: 0.55 – 0.69, Table 2.1 ). Full IOA was found in 16 cases (22.2%). In 15 cases only one rater disagreed (20.8%). After recoding the endoscopic Kudo classification into 2 categories (granular vs non-granular subtype), the IOA was substantial (Gwet’s AC1 coefficient: 0.75, 95% CI: 0.66 – 0.83). Full IOA was found in 38 cases (52.8%). In 18 cases only one rater disagreed (25.0%). Agreement differed by Kudo subtypes ( Table 2.1 ). The overall mean pairwise agreement was 71.0% with the highest proportion of agreement pairs in the LST-NG-FE group ( Table 2.2 ). Notably, of all possible pairs, 10.7%were discordant pairs between LST-NG-FE and LST-NG-PD and 9.6% were discordant pairs between LST-G-H and LST-NG-FE. The highest Cohen’s kappa coefficient for the Kudo subtypes between expert raters was 0.81, while the lowest was 0.31 (median 0.61). The overall IOA for the Paris classification was substantial (Gwet’s AC1: 0.71, 95% CI: 0.65 – 0.78, mean pairwise agreement 73.8%). Full IOA was present in 20 cases (27.8%). In 15 cases only one rater disagreed (20.8%). After recoding the full Paris classification into 4 categories (0-IIa, 0-IIa+IIc, 0-IIa+Is and other), the IOA was consistent (Gwet’s AC1: 0.71, 95% CI: 0.64 – 0.78) with a mean pairwise agreement of 75.8%. None of the LSTs were categorized as Paris 0-Ip or 0-Ips subtype of lesions. The free option was used only four times (2x 0-Is and 2x 0-Is+IIa). Therapeutic plan Almost perfect agreement was found between expert raters in selecting either endoscopic treatment (EMR or ESD) or surgery as most suitable treatment (Gwet’s AC1 score: 0.94, 95% CI: 0.91 – 0.97; mean pairwise agreement: 94.2%). IOA when specifying endoscopic treatment into EMR and ESD as themost suitable treatment was moderate to substantial (Gwet’s AC1 score: 0.63, 95%CI: 0.55 – 0.70; mean pairwise agreement: 68.5%). Most discordant pairs were found between the choices EMR vs ESD as most suitable treatment (25.6%). Rater’s origin (West vs East) did not influence the agreement for endoscopic treatment vs surgery and EMR vs ESD (Gwet’s AC1 0.64 vs 0.66). Table 2.2: Overview of all observed answer pairs between all expert raters for all cases. | A total of 6552 pairs of answer were given (14 raters can make 91 unique pairs [14 x 13 x ½] for each of the 72 cases [91 x 72 = 6552]). Pairs of agreement aremarked in grey. For example: a random rater classified a case as LST-G-H while another random rater agreed 1042 times. The situation that a randomly chosen rater classified a LST as LST-G-H while another randomly chosen rater classified the LST as LST-G-NM happened 350 times, 5.3% of all 6552 observations.

LST-G-H

1042

(15.9%)

LST-G-NM LST-NG-FE LST-NG-PD

350 632

(5.3%) 999 (9.6%) 107 (1.2%) 28

(15.2%)

(1.6%) 2010 (0.4%) 701

(30.7%)

80

(10.7%) 603

(9.2%)

LST-G-H

LST-G-NM

LST-NG-FE

LST-NG-PD

26