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.

Ljótsson et al. BMC Gastroenterology 2011 11:110   doi:10.1186/1471-230X-11-110

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