Four-sample lactose hydrogen breath test for diagnosis of lactose malabsorption in irritable bowel syndrome patients with diarrhea

Table 1 Lactose malabsorption and lactose intolerance detection rates in three-dose lactose hydrogen breath test n (%)

		Lactose dose
		10 g	20 g	40 g
IBS-D	LM	25 (41.6)	52 (86.6)	56 (93.3)
	LI	11 (18.3)	28 (46.7)	51 (85)
HVs	LM	21 (35)	48 (80)	55 (91.6)
	LI	2 (3.3)	13 (21.7)	41 (68.3)

LM: Lactose malabsorption; LI: Lactose intolerance; IBS-D: Irritable bowel syndrome patients with diarrhea; HVs: Healthy volunteers.

Table 2 H₂ peak and time to H₂ peak in three-dose lactose hydrogen breath test

		Lactose dose			P value
		10 g	20 g	40 g	10 g vs 20 g	20 g vs 40 g
IBS-D	H2 peak	38.5	57	92	0.010	0.000
	(ppm)	(27.3-47.3)	(32.0-85.0)	(58.0-127.0)
	Tp	153.5 ± 32.9	151.5 ± 35.9	151.3 ± 29.6	0.702	0.613
	(min)
HVs	H2 peak	38	66	99	0.004	0.001
	(ppm)	(29.5-46)	(36.5-90.5)	(56.5-135.5)
	Tp	152.1 ± 25.2	148.1 ± 30.7	139.3 ± 30.0	0.602	0.127
	(min)

IBS-D: Irritable bowel syndrome patients with diarrhea; HVs: Healthy volunteers; Tp: Time to H₂ peak.

Table 3 Agreement of lactose malabsorption and lactose intolerance diagnosis between 4-sample lactose hydrogen breath testing and standard lactose hydrogen breath testing methods

		Standard LHBT
4SLHBT		LM				LI
IBS-D		(+)	(-)	Kappa	P value	(+)	(-)	Kappa	P value
10 g	(+)	23	0	0.931	< 0.001	10	0	0.942	< 0.001
	(-)	2	35			1	49
20 g	(+)	50	0	0.870	< 0.001	26	0	0.933	< 0.001
	(-)	2	8			2	32
40 g	(+)	55	0	0.880	< 0.001	47	0	0.839	< 0.001
	(-)	1	4			3	10
HVs
10 g	(+)	19	0	0.925	< 0.001	2	0	1.000	< 0.001
	(-)	2	39			0	58
20 g	(+)	46	0	0.902	< 0.001	12	0	0.949	< 0.001
	(-)	2	12			1	47
40 g	(+)	53	0	0.815	< 0.001	38	0	0.889	< 0.001
	(-)	2	5			3	19

LHBT: Lactose hydrogen breath test; LM: Lactose malabsorption; LI: Lactose intolerance; 4SLHBT: 4-Sample Lactose Hydrogen Breath Testing; IBS-D: Irritable bowel syndrome patients with diarrhea; HVs: Healthy volunteers.

Table 4 Sensitivity, specificity, positive predictive value, negative predictive value of 4-sample lactose hydrogen breath testing method using standard lactose hydrogen breath test method as the reference

	LHBT		Sensitivity	Specificity	PPV	NPV
IBS-D	10 g	LM	92%	100%	100%	94.6%
		LI	91%	100%	100%	98%
	20 g	LM	96%	100%	100%	80%
		LI	93%	100%	100%	94.1%
	40 g	LM	98%	100%	100%	80%
		LI	94%	100%	100%	76.9%
HVs	10 g	LM	90%	100%	100%	95.1%
		LI	100%	100%	100%	100%
	20 g	LM	96%	100%	100%	85.7%
		LI	92%	100%	100%	97.9%
	40 g	LM	96%	100%	100%	71.4%
		LI	93%	100%	100%	86.4%

LHBT: Lactose hydrogen breath test; LM: Lactose malabsorption; LI: Lactose intolerance; 4SLHBT: 4-Sample Lactose Hydrogen Breath Testing; IBS-D: Irritable bowel syndrome patients with diarrhea; HVs: Healthy volunteers; PPV: Positive predictive value; NPV: Negative predictive value.