I am constantly on the look-out for good studies of alternative medicine, particularly those that yield positive findings. The trouble is that there aren’t many of those; studies tend to be either good or positive. Could this one be an exception?
The aim of this brand-new trial was to determine, if dietary supplements of glucosamine and/or chondroitin, result in reduced joint space narrowing (JSN) and pain in patients with knee osteoarthritis. It was designed as a double-blind randomised placebo-controlled clinical trial with 2-year follow-up. 605 participants, aged 45–75 years, reporting chronic knee pain and with evidence of medial tibio-femoral compartment narrowing (but retaining >2 mm medial joint space width) were randomised to once daily: glucosamine sulfate 1500 mg (n=152), chondroitin sulfate 800 mg (n=151), both of these dietary supplements (n=151) or placebo capsules (n=151). JSN (mm) over 2 years was measured from digitised knee radiographs. Maximum knee pain (0–10) was self-reported in a participant diary for 7 days every 2 months over 1 year.
The results indicate that, after adjusting for factors associated with structural disease progression (gender, body mass index (BMI), baseline structural disease severity and Heberden’s nodes), allocation to the dietary supplement combination (glucosamine–chondroitin) resulted in a statistically significant (p=0.046) reduction of 2-year JSN compared to placebo: mean difference 0.10 mm (95% CI 0.002 mm 0.20 mm); no significant structural effect for the single treatment allocations was detected. All 4 groups demonstrated reduced knee pain over the first year, but no significant between-group differences (p=0.93) were detected. 34 (6%) participants reported possibly-related adverse medical events over the 2-year follow-up period.
The authors drew the following conclusions: allocation to the glucosamine–chondroitin combination resulted in a statistically significant reduction in JSN at 2 years. While all allocation groups demonstrated reduced knee pain over the study period, none of the treatment allocation groups demonstrated significant symptomatic benefit above placebo.
This study has many strengths: it addresses a relevant research question, has a sufficiently large sample size, includes a long follow-up, and is well reported. So, it is a good study of an alternative therapy that is used by many patients. But did it really produce a positive result, i.e. findings which suggest that the tested treatments are effective? The answer seems ‘yes and no’. The combined, regular intake of both supplements caused less joint space narrowing which is a good objective sign of reduced disease activity. However, this was not paralleled by a reduction in pain that was better than that on placebo.
So, if you are a fan of glucosamine/chondroitin supplements, you will be pleased with this study, but if you are not in favour of such medications or do not have the spare cash to afford the considerable costs, you might say: I told you, they are pretty useless!