Chondroitin as a Treatment for Osteoarthritis

The dietary supplement chondroitin has been selling for a long time as a treatment for joint pain due to osteoarthritis.  Recently I've even seen advertisements promoting the use of glucosamine/chondroitin (chondroitin is almost always sold in combination with glucosamine) in pets.  I suppose the theory is that if works for humans, then it should work for pets.

And yet, chondroitin hasn't actually been shown convincingly to reduce joint pain (see this blog Oct. 6, 2010).  With that as background, a new study now purports to show that high-quality pharmaceutical-grade chondroitin (not the ordinary over-the-counter stuff) actually does reduce joint pain in people suffering from knee arthritis.  In fact, chondroitin allegedly worked as well as the popular prescription nonsteroidal anti-inflammatory drug, celecoxib.

So chondroitin works, right?  Not so fast. According to the footnotes in the article, the study was sponsored (i.e. funded) by a pharmacy company that makes pharmaceutical-grade chondroitin. It's not hard to imagine that the company has a financial interest in the study's outcome.  The company even provided "editorial assistance" to the author prior to the article's publication.

Putting all that possible bias aside for a moment, the data show a minimal effect of chondroitin at best.  According to Figure 1 in the article, at six months of treatment both chondroitin and celecoxib reduced patients' reported knee pain significantly. However, patients in the placebo group (receiving neither drug) also reported a reduction in pain, by nearly the same amount. In other words, most of the patients' reported pain reduction was caused just by being enrolled in the study and thinking that they might be receiving a drug that worked.

Before I accept that chondroitin definitively reduces the knee pain of arthritis, I'd want to see this study repeated in an independent study.