Irritable bowel syndrome symptom severity improves equally with probiotic and placebo

Table 1 Baseline demographics mean ± SD or n (%)

Characteristics	Placebo (n = 131)	Low-dose (n = 129)	High-dose (n = 131)
Age (yr)	49.4 ± 12.9	47.1 ± 13.3	47.2 ± 12.5
Gender
Male	37 (28.2)	35 (27.1)	27 (20.6)
Female	94 (71.8)	94 (72.9)	104 (79.4)
BMI (kg/m2)	24.9 ± 3.7	24.7 ± 3.7	24.5 ± 3.9
Diet
Low-carbohydrate	2 (1.5)	0 (0.0)	0 (0.0)
Vegetarian	1 (0.8)	2 (1.6)	0 (0.0)
Non-lactose	26 (19.8)	32 (24.8)	26 (19.8)
Regular	77 (58.8)	63 (48.8)	67 (51.1)
Probiotics
Daily user	24 (18.3)	25 (19.4)	18 (13.7)
Irregular user	18 (13.7)	17 (13.2)	29 (22.1)
History of using	65 (49.6)	62 (48.1)	66 (50.4)
No use	23 (17.6)	25 (19.4)	18 (13.7)
N/A	1 (0.8)	0 (0.0)	0 (0.0)
Exercise level
> 30 min 3 times a week	62 (47.3)	63 (48.8)	59 (45.0)
≤ 30 min 3 times a week	57 (43.5)	56 (43.4)	63 (48.1)
No exercise	12 (9.2)	10 (7.8)	9 (6.9)
Alcohol consumption
> 14 units/wk	1 (0.8)	0 (0.0)	0 (0.0)
≤ 14 units/wk	96 (73.3)	90 (69.8)	90 (68.7)
Non-drinker	34 (26.0)	39 (30.2)	41 (31.3)
Tobacco smoking
Current use	11 (8.4)	11 (8.5)	14 (10.7)
Never used	80 (61.1)	86 (66.7)	88 (67.2)
History of use	40 (30.5)	32 (24.8)	29 (22.1)
Drug abuse
Never used	131 (100)	129 (100)	131 (100)

Table 2 Irritable bowel syndrome symptom characteristics n (%)

	Placebo (n = 131)	Low-dose (n = 129)	High-dose (n = 131)
IBS subtype
IBS-C	25 (19.1)	20 (15.5)	20 (15.3)
IBS-D	49 (37.4)	51 (39.5)	52 (39.7)
IBS-M	56 (42.7)	58 (45.0)	58 (44.3)
IBS-U	1 (0.8)	0 (0.0)	1 (0.8)
Postinfectious IBS	9 (6.9)	4 (3.1)	7 (5.3)
Psychological comorbidities	9 (6.9)	6 (4.7)	13 (9.9)
Symptoms provoked by specific food	103 (79.8)1	116 (89.9)	120 (91.6)
Family history of intestinal disorders or diseases	95 (72.5)	97 (75.2)	92 (70.8)2

¹Two volunteers not analysed;

²One volunteer not analyzed. IBS: Irritable bowel syndrome.

Table 3 Irritable bowel syndrome symptom severity score item scores at baseline and end of intervention

Treatment		Baseline		Week 12	Change from baseline	Within-group comparison	Comparison with placebo	Comparison with low- and high-dose
	n	mean ± SD	n	mean ± SD	mean ± SD	P value	P value	P value
Severity of pain
Placebo	121	20.2 ± 20.6	118	18.5 ± 20.7	-2.2 ± 21.8	0.024	NA	0.303
Low-dose	124	24.1 ± 22.3	110	18.3 ± 18.6	-5.2 ± 24.4	0.005	0.640	NA
High-dose	122	24.3 ± 21.5	113	16.4 ± 17.8	-7.9 ± 21.8	< 0.001	0.189	NA
Number of days with pain over 10 d
Placebo	114	3.8 ± 2.8	111	2.8 ± 2.8	-1.0 ± 2.7	< 0.001	NA	0.234
Low-dose	115	4.4 ± 2.8	105	3.3 ± 2.6	-1.1 ± 2.9	< 0.001	0.470	NA
High-dose	121	4.1 ± 2.8	106	2.9 ± 2.4	-1.2 ± 2.5	< 0.001	0.634	NA
Bloating/Distension
Placebo	121	39.0 ± 28.0	118	30.7 ± 25.6	-8.3 ± 23.6	< 0.001	NA	0.669
Low-dose	122	40.5 ± 29.9	110	31.0 ± 25.7	-9.4 ± 29.6	< 0.001	0.905	NA
High-dose	122	37.1 ± 26.6	113	31.0 ± 27.3	-6.1 ± 25.8	0.002	0.535	NA
Satisfaction with bowel habits
Placebo	121	57.4 ± 22.6	118	47.3 ± 24.2	-10.3 ± 21.4	< 0.001	NA	0.964
Low-dose	124	59.4 ± 22.7	110	46.3 ± 19.8	-11.8 ± 22.4	< 0.001	0.701	NA
High-dose	122	55.0 ± 19.7	113	46.4 ± 22.6	-8.3 ± 23.3	< 0.001	0.757	NA
Interference of IBS with quality of life
Placebo	121	62.4 ± 17.0	118	48.6 ± 22.1	-13.9 ± 20.3	< 0.001	NA	0.210
Low-dose	124	60.8 ± 16.9	110	50.1 ± 19.4	-9.8 ± 16.5	< 0.001	0.133	NA
High-dose	122	59.8 ± 13.5	113	47.9 ± 16.5	-11.7 ± 13.6	< 0.001	0.509	NA

IBS: Irritable bowel syndrome.

Table 4 Change in pain score for volunteers with moderate or severe abdominal pain at baseline

Treatment	n	Baseline	Week 12	Change from baseline	Mean difference for combined active doses	P value
		mean ± SD	mean ± SD	mean ± SD	95%CI
Placebo	29	51.1 (9.3)	30.3 (22.9)	-20.8 (22.8)
Low-dose	36	53.6 (10.9)	24.4 (19.4)	-29.4 (17.9)	-9.5 (-18.8; -0.17)	0.046
High-dose	34	52.1 (10.7)	21.9 (20.6)	-31.2 (21.9)

Table 5 Change in irritable bowel syndrome-related quality of life and level of anxiety and depression (Hospital Anxiety and Depression Score)

Treatment		Baseline		Week 12	Change from baseline	Within-group comparison	Comparison with placebo	Comparison with low- and high-dose
	n	mean ± SD	n	mean ± SD	mean ± SD	P value	P value	P value
IBS-QoL
Placebo	121	66.4 ± 17.5	118	73.2 ± 19.0	7.0 ± 12.3	< 0.001	NA	0.412
Low-dose	124	63.9 ± 19.0	110	71.6 ± 19.3	7.4 ± 12.3	< 0.001	0.812	NA
High-dose	122	68.2 ± 16.5	113	76.5 ± 15.8	8.5 ± 8.8	< 0.001	0.238	NA
HADS total score
Placebo	119	9.2 ± 5.6	110	8.6 ± 6.6	-0.4 ± 4.3	0.302	NA	0.134
Low-dose	122	10.1 ± 5.7	109	9.2 ± 6.0	-1.0 ± 4.4	0.034	0.435	NA
High-dose	118	9.7 ± 5.5	109	8.2 ± 5.8	-1.5 ± 3.9	< 0.001	0.071	NA
HADS-Anxiety
Placebo	121	5.9 ± 3.5	114	5.3 ± 3.6	-0.4 ± 2.6	0.036	NA	0.246
Low-dose	122	6.1 ± 3.3	109	5.5 ± 3.1	-0.6 ± 2.7	0.011	0.726	NA
High-dose	119	6.2 ± 3.3	109	5.0 ± 3.1	-1.0 ± 2.2	< 0.001	0.099	NA
HADS-Depression
Placebo	119	3.4 ± 2.9	111	3.4 ± 3.6	0.0 ± 2.3	0.906	NA	0.162
Low-dose	124	4.0 ± 3.0	109	3.7 ± 3.4	-0.3 ± 2.2	0.258	0.376	NA
High-dose	119	3.5 ± 2.9	110	3.2 ± 3.1	-0.4 ± 2.4	0.041	0.125	NA

HADS: Hospital anxiety and depression score; IBS-QoL: Irritable bowel syndrome quality of life.

Table 6 Change in stool consistency from baseline according to Bristol stool scale¹n (%)

	n	Change to optimal from constipation or diarrhea	Change to constipation or diarrhea from optimal
Placebo	131
Week 4		18 (13.7)	15 (11.5)
Week 12		21 (16.0)	18 (13.7)
Washout		20 (15.3)	17 (13.0)
Low-dose	129
Week 4		26 (20.2)	13 (10.1)
Week 12		27 (20.9)	14 (10.9)
Washout		14 (10.9)	12 (9.3)
High-dose	131
Week 4		14 (10.7)	16 (12.2)
Week 12		18 (13.7)	20 (15.3)
Washout		14 (10.7)	18 (13.7)
Total	391	172 (44.0)	143 (36.6)

¹Bristol stool scale types 1 and 2 were classified as constipation; 3, 4, and 5 were classified as optimal stool consistency; and 6 and 7 were classified as diarrhea.