Development and validation of a tongue image-clinical nomogram for detection of advanced colorectal adenoma

Table 1 Baseline characteristics of participants with and without advanced adenoma in the training and validation cohorts, n (%)/median (interquartile range)

Variable	Training cohort (n = 616)			Validation cohort (n = 264)			1P value
	NAA (n = 390)	AA (n = 226)	P value	NAA (n = 172)	AA (n = 92)	P value
Sex			< 0.001			0.011	1.000
Female	225 (57.7)	86 (38.1)		97 (56.4)	36 (39.1)
Male	165 (42.3)	140 (61.9)		75 (43.6)	56 (60.9)
Age (year)	54.0 (42.0-62.8)	58.0 (50.0-67.0)	< 0.001	54.5 (44.0-62.0)	60.0 (51.8-66.2)	0.001	0.796
BMI (kg/m2)	23.5 (21.2-25.6)	24.0 (22.3-25.7)	0.065	23.7 (21.2-26.3)	24.1 (22.0-26.0)	0.351	0.494
Smoking status			< 0.001			0.021	0.377
Never	329 (84.4)	147 (65.0)		136 (79.1)	60 (65.2)
Ever (former/current)	61 (15.6)	79 (35.0)		36 (20.9)	32 (34.8)
Family history of colorectal cancer			0.023			0.879	0.155
No	364 (93.3)	198 (87.6)		163 (94.8)	86 (93.5)
Yes	26 (6.7)	28 (12.4)		9 (5.2)	6 (6.5)
APCS score	2.0 (1.0-3.0)	3.0 (2.0-4.0)	< 0.001	2.0 (1.0-3.0)	3.0 (2.0-4.0)	< 0.001	0.896
M-APCS score	2.0 (1.0-3.0)	3.0 (2.0-4.0)	< 0.001	2.0 (1.0-3.0)	3.0 (2.0-4.0)	< 0.001	0.569

¹P values compare baseline characteristics between the training and validation cohorts.

P values compare advanced adenoma vs nonadvanced adenoma within each cohort. Continuous variables are presented as median (interquartile range) and were compared using the Mann-Whitney U test. Categorical variables are presented as n (%) and were compared using the χ² test or Fisher’s exact test. AA: Advanced adenoma; NAA: Nonadvanced adenoma; BMI: Body mass index; APCS: Asia-Pacific colorectal screening; M-APCS: Modified Asia-Pacific colorectal screening.

Table 2 Threshold-based classification performance in the Asia-Pacific colorectal screening score ≥ 4 subgroup using training-derived cutoffs (specificity fixed at approximately 80%)

Method	Cohort	Threshold	TP	FP	TN	FN	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	Accuracy (%)
Tongue image-clinical nomogram	Training	0.5876	54	14	54	27	66.67	79.41	79.41	66.67	72.48
	Validation	0.5876	21	7	21	15	58.33	75.00	75.00	58.33	65.62
Tongue-only model	Training	0.6344	50	15	53	31	61.73	77.94	76.92	63.10	69.13
	Validation	0.6344	23	5	23	13	63.89	82.14	82.14	63.89	71.88
APCS score	Training	5	24	16	52	57	29.63	76.47	60.00	47.71	51.01
	Validation	5	7	5	23	29	19.44	82.14	58.33	44.23	46.88
M-APCS score	Training	5	21	14	54	60	25.93	79.41	60.00	47.37	50.34
	Validation	5	9	2	26	27	25.00	92.86	81.82	49.06	54.69

Cutoffs for each method were determined in the Asia-Pacific colorectal screening score ≥ 4 training subset to achieve approximately 80% specificity and were applied unchanged to the Asia-Pacific colorectal screening score ≥ 4 validation subset. Advanced adenoma was treated as the positive class and nonadvanced adenoma as the negative class. APCS: Asia-Pacific colorectal screening; M-APCS: Modified Asia-Pacific colorectal screening; TP: True positive; FP: False positive; TN: True negative; FN: False negative; PPV: Positive predictive value; NPV: Negative predictive value.