Ability of lactulose breath test results to accurately identify colorectal polyps through the measurement of small intestine bacterial overgrowth

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
1	Methane peak value (not applied)	382	169/213	12.82	12.06	0.074a	0.427	0.578	0.511
2	Methane peak value (≥ 5)	359	160/199	13.34	12.66	0.084a	0.417	0.571	0.502
3	Methane peak value (≥ 10)	245	120/125	15.28	15.55	0.905	0.443	0.390	0.416
4	Hydrogen peak value (not applied)	380	169/211	52.34	45.48	0.091a	0.408	0.604	0.517
5	Hydrogen peak value (≥ 10)	310	140/170	62.05	55.24	0.090a	0.383	0.590	0.496
6	Hydrogen peak value (≥ 20)	259	125/134	67.85	66.02	0.776	0.400	0.439	0.421
7	Hydrogen rise value (not applied)	372	165/207	41.94	37.40	0.121	0.391	0.582	0.498
8	Hydrogen rise value (≥ 10)	280	130/150	52.12	49.93	0.406	0.380	0.477	0.432
9	Hydrogen rise value (≥ 20)	217	108/109	60.06	63.39	0.479	0.492	0.375	0.433
10	Hydrogen rise value (≥ 20 by 90 min)	119	70/49	47.74	50.10	0.929	0.460	0.323	0.403
11	Combined M peak & H peak (M ≥ 5 &/or H ≥ 10)	373	166/207	66.15	58.48	0.068a	0.412	0.615	0.525
12	Combined M peak & H peak (M ≥ 5 & H ≥ 10)	294	134/160	76.49	68.28	0.055a	0.391	0.607	0.508
13	Combined M peak & H risen (M ≥ 5 &/or H ≥ 10)	370	166/204	54.58	50.11	0.166	0.403	0.578	0.499
14	Combined M peak & H rise (M ≥ 5 & H ≥ 10)	267	124/143	66.54	62.50	0.239	0.379	0.530	0.460
15	Combined M peak & H peak (M ≥ 10 &/or H ≥ 20)	177	96/81	86.28	85.49	0.674	0.390	0.395	0.392
16	Combined M peak & H rise (M ≥ 10 & H ≥ 20)	149	84/65	77.32	83.17	0.723	0.522	0.346	0.445
17	Combined M peak & H rise (M ≥ 10 &/or H ≥ 20 by 90 min)	279	136/143	42.29	35.71	0.008a	0.382	0.702	0.546

^aP < 0.1 for difference in mean value of lactulose breath test between polyp and non-polyp groups for further assessment.

Rise values are baseline-subtracted peak values during the tests. Bold P values indicate the 7 best models in further assessment. ppm: Parts per million.