Table 3.

Results of subgroup analyses for different covariates

Covariate	Number of studies	Standardized mean difference	LL	UL	P value within group	P value between subgroups	I2 (%)
Adherence	–	–	–	–	–	0.77	54
Reported adherencea	6	− 0.63	− 1.01	− 0.24	0.001	–	66
Adherence not reported	6	− 0.70	− 0.96	− 0.43	0.001	–	42
Age	–	–	–	–	–	0.40	54
Below medianb	6	− 0.76	− 1.09	− 0.43	0.001	–	59
Above medianb	6	− 0.56	− 0.87	− 0.25	0.001	–	52
Duration	–	–	–	–	–	0.59	50
Medianc	5	− 0.53	− 0.88	− 0.18	0.003	–	61
Above medianc	5	− 0.65	− 0.93	− 0.37	0.001	–	39
IBS subtype	–	–	–	–	–	–	–
Majority IBS-D	6	− 0.62	− 0.84	− 0.39	0.001	–	30
Outcome measure	–	–	–	–	–	0.28	13.9
IBS-SSS	6	− 0.56	− 0.85	− 0.27	0.001	–	61
Non-IBS-SSS	6	− 0.81	− 1.16	− 0.46	0.001	–	44
Risk of bias	–	–	–	–	–	–	–
Low risk of bias	9	− 0.66	− 0.92	− 0.40	0.001	–	55

IBS irritable bowel syndrome; IBS-D irritable bowel syndrome with diarrhea; IBS-SSS IBS symptom severity score; LL lower level of 95% confidence interval; UL upper level of 95% confidence interval

^aAdherence was good in all studies that reported adherence

^bMedian age was 40.9 years

^cMedian duration was 4 weeks