Popular dietary supplements don't relieve knee pain caused by arthritis

Americans with painful osteoarthritis spend an estimated $700 million a year on glucosamine and chondroitin sulfate, hoping these dietary supplements will help their pain. The latest attempt at rigorous evaluation suggests they don't. In a large randomised trial (n = 1583), patients taking the supplements alone or in combination were no better after 24 weeks than patients taking placebo.

To measure response, researchers looked for a 20% improvement in pain as measured by the WOMAC (Western Ontario and McMaster Universities osteoarthritis) index. Response rates were 64% (203/317), 65% (208/318), 67% (211/317), and 60% (188/313) among patients taking glucosamine hydrochloride, chondroitin sulfate, both, or placebo, respectively. A fifth group of patients who took celecoxib did significantly better than the placebo group, but only by a disappointing 10% (response rate 70% (223/318); P = 0.008).

There were hints that the combined supplements might work for people with more severe pain (response rate 79% (57/72); P = 0.002). But this finding is not secure, according to a linked editorial (pp 858-60).

Many research dollars have already been spent evaluating these supplements, and the balance of evidence is now against them, at least for the treatment of pain. It's still possible that they modify the underlying disease, however. These authors are due to report on this aspect of treatment later this year.

Seasonal influenza A is resistant to adamantanes in the US

More than 90% of influenza A viruses circulating in the US are now resistant to amantadine and rimandatine, according to the latest surveillance figures. The prevalence of resistance among these viruses has jumped from 11% during the 2004-5 influenza season (October to 3) to 92% during the first half of the current influenza season (October to December 2005), prompting the US Centers for Disease Control and Prevention to urge doctors not to prescribe adamantanes for the rest …