Evidence strengths and limitations

Evidence strengths and limitations

There is limited published research examining rifaximin for the treatment of pouchitis. Four relevant studies were identified that have been published in full, which were of different study design, examined different indications for rifaximin and used different dosing regimens.

Isaacs et al. (2007) was the only identified randomised controlled trial (RCT) of rifaximin for the treatment of pouchitis. It was double-blind and had a suitable method of randomisation, but it is unclear if allocation was concealed. The trial was limited by its small size, with only 17 people in the intention-to-treat analysis, which meant that it lacked statistical power. The authors reported that they had planned to recruit 66 people, which would have resulted in a trial of sufficient statistical power to detect a true difference in clinical remission rates between the rifaximin and placebo groups. The trial included people with both active and chronic pouchitis but the small sample size makes subgroup analyses unreliable.

The single published RCT provides limited evidence about the effectiveness and safety of rifaximin for the treatment of acute or chronic active pouchitis.

The majority of people in the studies by Gionchetti et al. (1999) and Abdelrazeq et al. (2005) obtained remission or improvement in their pouchitis. However, these 2 small, non-comparative observational studies (n=18 and n=8, respectively) provide limited evidence about the effectiveness and safety of rifaximin in combination with ciprofloxacin for chronic refractory pouchitis.

The study by Shen et al. (2008) on the effects of open-label rifaximin maintenance treatment is limited because it was non-comparative, and because the authors reported outcomes using the modified Pouchitis Disease Activity Index (mPDAI) score, rather than the full PDAI as used by the other studies. The mPDAI includes symptomatic and endoscopic, but not histological, criteria. Moreover, the authors reported that endoscopy data were available for only 21 of the 51 participants.

Although rifaximin 200 mg daily was the dose used by majority of people, doses up to a maximum of 1800 mg daily were given. This makes it difficult to determine an optimal dose for maintenance of remission.

This relatively small, non-comparative study provides limited evidence about the effectiveness and safety of rifaximin for the maintenance of remission in people whose pouchitis responded to a 2-week course of antibiotics but relapsed without long-term treatment.

Large double-blind RCTs are needed to determine whether rifaximin is effective and safe for the treatment of acute or chronic pouchitis and pouchitis refractory to other antibiotics, or for maintenance of antibiotic-induced remission.