Clinical Health Updates

Poor evidence for antioxidants for arthritis

Clinical Question:
Are antioxidants effective in treating arthritis?

Bottom Line:
Clinical trials testing the efficacy of vitamin E in the treatment of OA and inflammatory arthritis have been methodologically weak and have produced contradictory findings. There is presently no convincing evidence that selenium, vitamin A, vitamin C or the combination product selenium ACE is effective in the treatment of any type of arthritis.

Reference:
Canter PH, Wider B, Ernst E. The antioxidant vitamins A, C, E and selenium in the treatment of arthritis: a systematic review of randomized clinical trials. Rheumatology 2007;46:1223-1233.

Study Design:
Systematic review

Synopsis:
These authors searched multiple databases for randomized trials of vitamins A, C, E and of selenium in managing arthritis. Although the team searched the reference lists of retrieved articles, they did not search for unpublished data. This latter step is important since publication bias favors active treatment more than placebo. Two authors independently evaluated articles for inclusion, and disagreements were resolved through discussion with a third member of the team. Although the quality of the included studies was assessed using a standard scale (Jadad), the authors don’t say if this, too, was done independently. The authors found 22 papers reporting data on 20 randomized trials, 11 of which studied inflammatory arthritis and 9 studied osteoarthritis. Six of the studies used a nonsteroidal anti-inflammatory drug (NSAID) as a comparator, 1 compared other antioxidants, and 1 compared fish oil. The overall quality of the studies was marginal (average = 2.9 on a 5-point scale) and only 5 studies scored at least 4 points. The authors point out that even among these higher scoring studies, other methodologic flaws existed that were not captured by the Jadad scale. Unlike many other researchers, this group properly decided against pooling the results given the poor quality of the studies and just summarized the key findings. One trial suggested that vitamin E was better than placebo but equivalent to NSAIDs in patients with inflammatory arthritis. In osteoarthritis, 2 short-term trials suggest that vitamin E was better than placebo but 2 long-term trials found it to be equivalent to placebo. Two additional trials found vitamin E and NSAIDs comparable. The remaining studies failed to show any benefit.