Evidence of effectiveness of herbal medicinal products in the treatment of arthritis. Part 2: Rheumatoid arthritis.

Herbal medicinal products (HMPs) that interact with the mediators of inflammation are used in the treatment of rheumatoid arthritis (RA). The aim of this study was to update a previous systematic review published in 2000. We searched electronic databases (MEDLINE, EMBASE, CISCOM, AMED, CINAHL, Cochrane registers) to June 2007, unrestricted by date or language, and included randomized controlled trials that compared HMPs with inert (placebo) or active controls in patients with rheumatoid arthritis. Five reviewers contributed to data extraction. Disagreements were discussed and resolved by consensus with reference to Cochrane guidelines and advice from the Cochrane Collaboration. Twenty studies (10 identified for this review update, and 10 of the 11 studies of the original review) investigating 14 HMPs were included. Meta-analysis was restricted to data from previous seven studies with oils from borage, blackcurrant and evening primrose containing gamma linolenic acid (GLA). GLA doses equal or higher than 1400 mg/day showed benefit in the alleviation of rheumatic complaints whereas lower doses ( approximately 500 mg) were ineffective. Three studies compared products from Tripterygium wilfordii (thunder god vine) to placebos and returned favorable results but data could not be pooled because the interventions and measures differed. Serious adverse effects occurred in one study. In a follow-up study all side effects were mild to moderate and resolved after the intervention ceased, but time to resolution was variable. Two studies comparing Phytodolor NR to placebo were of limited use because some measures were poorly defined. The remaining studies, each considering differing HMPs, were assessed individually. For most HMPs used in the treatment of RA, the evidence of effectiveness was insufficient to either recommend or discourage their use. Interventions with HMPs containing GLA or Tripterygium wilfordii extract appear to produce therapeutic effects but further investigations are warranted to prove their effectiveness and safety.