Retrospective Study
Copyright ©The Author(s) 2023.
World J Gastrointest Surg. Jun 27, 2023; 15(6): 1138-1148
Published online Jun 27, 2023. doi: 10.4240/wjgs.v15.i6.1138
Table 1 Demographics and comorbidity of the study subjects, n (%)

Overall (N = 382)
Polyps (n = 169)
Non-polyps (n = 213)
P value
Age, yr57.0 ± 14.062.1 ± 11.753.0 ± 14.40
    19-4570 (18)11 (7)59 (28)0
    46-60150 (39)65 (38)85 (40)0.428
    61-92162 (43)93 (55)69 (32)0
Male213 (56)108 (64)105 (49)0.003
Bilestone34 (9)18 (11)16 (8)0.187
Constipation67 (18)38 (22)29 (14)0.017
Diabetes53 (14)32 (19)21 (10)0.008
Fatty liver/cirrhosis127 (33)70 (41)57 (27)0.002
FGID37 (10)9 (5)28 (13)0.007
GERD54 (14)19 (11)35 (16)0.096
Hyperlipidemia60 (16)33 (20)27 (13)0.046
Hypertension108 (28)64 (38)44 (21)0
Hyperuricemia42 (11)20 (12)22 (10)0.38
IBS49 (13)14 (8)35 (16)0.013
PU31 (8)24 (14)7 (3)0
Table 2 Small intestine bacteria overgrowth distribution between polyp & non-polyp groups
SIBO (+)
Overall (N = 382)
Polyps (n = 169)
Non-polyps (n = 213)
P value
By methane245 (64)120 (71)125 (59)0.014a
By hydrogen 90 min119 (31)70 (41)49 (23)0.000a
By combined M and H 279 (73)136 (80)143 (67)0.004a
Table 3 The peak values of methane and hydrogen in inflammatory/hyperplastic polyp, adenomatous polyp and non-polyp groups
Peak values
Polyps (n = 169)
Non-polyps (n = 213)
P value
Inflammatory/hyperplastic polyp
Adenomatous polyp
Methane208.2197.86182.520.168
Hydrogen within 90 min209.53b220.87b172.510.001a
Table 4 Performance of prediction models for colorectal polyps
Model No.
Value cutoff (ppm) for subset
N
n (polyp/non-polyp)
Mean ppm (polyp)
Mean ppm (non-polyp)
Mean ppm (P value)
Sensitivity
Specificity
Accuracy
1Methane peak value (not applied)382169/21312.8212.060.074a0.4270.5780.511
2Methane peak value (≥ 5)359160/19913.3412.660.084a0.4170.5710.502
3Methane peak value (≥ 10)245120/12515.2815.550.9050.4430.3900.416
4Hydrogen peak value (not applied)380169/21152.3445.480.091a0.4080.6040.517
5Hydrogen peak value (≥ 10)310140/17062.0555.240.090a0.3830.5900.496
6Hydrogen peak value (≥ 20)259125/13467.8566.020.7760.4000.4390.421
7Hydrogen rise value (not applied)372165/20741.9437.400.1210.3910.5820.498
8Hydrogen rise value (≥ 10)280130/15052.1249.930.4060.3800.4770.432
9Hydrogen rise value (≥ 20)217108/10960.0663.390.4790.4920.3750.433
10Hydrogen rise value (≥ 20 by 90 min)11970/4947.7450.100.9290.4600.3230.403
11Combined M peak & H peak (M ≥ 5 &/or H ≥ 10)373166/20766.1558.480.068a0.4120.6150.525
12Combined M peak & H peak (M ≥ 5 & H ≥ 10)294134/16076.4968.280.055a0.3910.6070.508
13Combined M peak & H risen (M ≥ 5 &/or H ≥ 10)370166/20454.5850.110.1660.4030.5780.499
14Combined M peak & H rise (M ≥ 5 & H ≥ 10)267124/14366.5462.500.2390.3790.5300.460
15Combined M peak & H peak (M ≥ 10 &/or H ≥ 20)17796/8186.2885.490.6740.3900.3950.392
16Combined M peak & H rise (M ≥ 10 & H ≥ 20)14984/6577.3283.170.7230.5220.3460.445
17Combined M peak & H rise (M ≥ 10 &/or H ≥ 20 by 90 min)279136/14342.2935.710.008a0.3820.7020.546
Table 5 Model performance with key parameters (area under the receiver operating characteristic curve, accuracy, sensitivity, and specificity)
Panel ID
AUC, % (95%CI)
Accuracy
Sensitivity
Specificity
a71.6 (66.5-76.7)0.6590.6660.653
b71.4 (66.3-76.5)0.6420.6630.625
c72.0 (66.9-77.1)0.6500.6690.634
d71.7 (66.4-77.0)0.6630.6790.651
e72.9 (67.3-78.4)0.6510.6770.629
f72.6 (66.9-78.4)0.6500.6830.622
g71.7 (65.7-77.7)0.6580.6730.643