Table 3.

Continuous outcome measures

	Treatment			Waiting list			Effect size	Mixed models
	n	m	SD	n	m	SD	Cohen's d (95% CI)	Effect	B	p
GSRS-IBS
Pre	30	44.6	11.1	31	39.8	12.0		Group	4.9	.12
Post	23	31.0	10.2	27	40.9	14.5	0.77 (0.19 - 1.34)	Time	0.6	.63
FU	19	29.9	12.6					G×T	-11.7	.001
IBS-QOL
Pre	30	67.4	20.9	31	76.1	18.8		Group	-8.8	.09
Post	23	82.6	13.4	27	67.4	23.1	0.79 (0.20-1.35)	Time	-7.2	.001
FU	20	87.6	11.8					G×T	16.6	.001
VSI
Pre	30	32.5	18.0	31	27.5	16.3		Group	5.0	.22
Post	23	14.1	15.1	27	26.2	17.9	0.73 (0.14 - 1.29)	Time	-11.7	.01
FU	20	15.5	15.9					G×T	-14.6	.001
								COV	0.3	.03
Sheehan Disability Scales
Pre	30	11.9	8.1	31	8.7	6.3		Group	3.2	.08
Post	23	6.4	6.7	27	7.8	7.6	0.19 (-0.37 - 0.75)	Time	-4.4	.01
FU	20	5.2	6.6					G×T	-4.2	.002
								COV	0.1	.04

Unstandardized (B) coefficients and their p-values are given for fixed in effects in linear mixed models using all data from pre-treatment and post-treatment and all individuals (n = 61). The coefficient associated with the main effect of group denotes average score difference between the groups at the pre-treatment assessment. The coefficient associated with the effect of time denotes the average change score from pre to post-treatment across both groups. The coefficient associated with the effect of G × T (group × time) denotes the difference between groups in change score from pre- to post-treatment. COV is the effect of the pre-treatment value of GSRS-IBS, as a retained covariate in the model, on the post-treatment value. Group₀ = Treatment Group, Group₁ = Waiting List, Time₀ = Pre-treatment, and Time₁ = Post-treatment. Effect sizes are calculated as standardized mean difference (Cohen's d) at post-treatment. GSRS-IBS: Gastrointestinal symptom rating scale-IBS version. IBS-QOL: The Irritable Bowel Syndrome Quality of Life Instrument (IBS-QOL). VSI: The Visceral Sensitivity Index.