Fourteen studies involving 699 participants (although the authors state 644) were included in the review. Four randomised controlled trials (n=162), one matched control/crossover trial (n=12), one lagged intervention (n=24) and 8 uncontrolled studies (n=501) were included.
Uncontrolled studies. There was a significant reduction in overall IBS symptoms reported in the 4 studies that assessed this outcome, and specific reductions were noted in another study for abdominal pain, bloating and stool consistency. The percentage of participants who improved in the 5 studies that assessed this outcome ranged from 27 to 95%. The improvement in quality of life was statistically significant in 3 studies. Statistically significant changes in psychiatric symptoms were reported in 3 studies, in terms of reduced anxiety and depression, decreased somatisation and fewer psychological symptoms.
Controlled studies.
Statistically significant reductions in IBS symptoms were reported in 5 studies. However, it was unclear whether these were calculated from baseline, or whether these were differences between the intervention and control groups. The percentage of participants improved in the 3 studies that reported this outcome ranged from 52 to 87%. Positive changes in quality of life were reported in 2 studies. Statistically significant reductions in anxiety and/or depression were noted in 2 studies, along with decreased somatisation and psychological distress.
Ten of the 14 studies did not report on post-intervention longer term follow-up data. General improvements were noted in the other 4 studies, where follow-up ranged from 3 to 18 months Additional results on the mechanisms of action were reported.