Study designs of evaluations included in the review
Randomised and quasi-randomised trials were eligible for inclusion. None of the included studies provided enough information to ascertain if they were truly randomised.
Specific interventions included in the review
Studies using any form of TXYF, including decoction or tablet, or TXYF with the addition of other Chinese medicinal herbs (TXYF-A), were eligible for inclusion. Most of the included studies compared TXYF-A with conventional drugs. The herbal additions differed between studies. One three-arm trial compared TXYF and TXYF-A with a conventional drug. In one trial TXYF-A was given together with a conventional drug. Decoctions prepared from crude herbs were used in all the studies, and the duration of treatment ranged from 10 days to 8 weeks. The conventional drugs included oryzandum, dioctahedral smectite, cisapride, loperamide, diphenoxylatum, pinaverium bromide and nifedipinum.
Participants included in the review
Studies in patients with IBS diagnosed according to Rome I, Rome II, Manning or the Chinese National Chronic Diarrhoea Association criteria were eligible for inclusion. No details of the participants in the included studies were reported in the review.
Outcomes assessed in the review
The inclusion criteria appeared to be change in clinical measures such as abdominal pain, diarrhoea, constipation and abdominal distention. The outcome measured in the included studies was symptoms. In most studies authors defined the criteria for improvement in symptoms, while two studies used published criteria (see Other Publications of Related Interest). The symptoms were measured either immediately after treatment (near-term effectiveness), or at 3 months (short-term effectiveness) or at least 6 months (long-term effectiveness) after completion of treatment.
How were decisions on the relevance of primary studies made?
One reviewer selected potentially eligible items from the search results and two reviewers independently assessed the retrieved studies.