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Like probably many others, we have been waiting eagerly for the results of the Long-term Evaluation of Glucosamine Sulfate (LEGS) study.1 The expectation was that this trial would shed light onto the ongoing controversy about the value of chondroitin, glucosamine and their combination in the treatment of osteoarthritis (OA) of the knee, and provide answers to several open questions. The LEGS study fully met this expectation as to the structure-modifying effect of the combination of chondroitin sulfate and glucosamine sulfate. However, what do the results of this trial tell us about the structure-modifying effect of chondroitin sulfate or glucosamine sulfate alone, or about the symptomatic effect of chondroitin sulfate, glucosamine sulfate or the combination thereof? Unfortunately, the results of the LEGS study add very little to this question as we will point out subsequently.
Symptomatic effect: The main symptomatic outcome measure in the LEGS study was changed from the use of non-steroidal anti-inflammatory drugs (NSAIDs) to self-reported pain when the authors realised that only about 20% of the patients recruited till that point in time were taking NSAIDs. The alternative primary outcome measure to assess the symptomatic effect was the maximum score of pain ‘at its worst’ recorded daily in a 7-day diary that the participants had to complete every 2 months. There are several problems with this alternative outcome measure: (1) It seems not to have been validated, that is, we have not found any relevant validation study. (2) Experiences with it are lacking, that is, we are not aware of any other trial in which this measure had been used. (3) Pain due to knee OA is activity-related (depending on the activity), that is, a patient with knee OA may not suffer from pain while walking, but may do so when descending stairs. We do not know what …
Competing interests AGH is employed by IBSA Institut Biochimique SA, a Swiss manufacturer and distributor of a chondroitin sulfate prescription drug and a glucosamine sulfate dietary supplement. Analysis of the publication of the LEGS study and the preparation of this letter were carried out on behalf of IBSA.
Provenance and peer review Not commissioned; externally peer reviewed.