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The comments expressed by Dr Helg1 are directed at attributing the lack of symptomatic or structural benefit detected in the LEGS study for the single treatment allocations (chondroitin sulfate or glucosamine sulfate alone) to issues of study methodology.2
Dr Helg attempts to give the impression that the considered and documented change to the primary outcome was precipitate. The change of primary outcome to the maximum score of pain ‘at its worst’ reported daily for 7 days each 2 months in a participant diary with a Numerical Rating Scale (NRS) was justified in the discussion: “We had originally stated in the study registration that reduction in the use of NSAIDs would be the main symptomatic outcome measure. Our main symptomatic outcome measure was changed (and registered) to self-reported pain after recruitment of the first 200 participants demonstrated that only about 20% were using NSAIDs. Further, we felt that the specific focus of knee pain (‘at its worst’) for the daily 7-day numeric rating scale of the participant diary would be less vulnerable to a ‘floor effect’ among our study participants with mostly mild radiographic disease, and more likely to detect the ‘short episodes of more intense pain 'experienced by many people with knee OA.3 Interestingly, the mean WOMAC pain scores at baseline were low compared with the numeric rating scale scores, possibly precluding the detection of treatment benefit using this measure in a mildly symptomatic population.”
It was suggested that …
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.
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