Even though glucosamine and chondroitin are unlikely to provide clinically meaningful relief for most patients with knee OA, those with more advanced disease may nevetheless experience a benefit. A multicenter, double-blind, placebo- and celecoxib-controlled glucosamine/chondroitin arthritis intervention trial of over 1500 patients with knee OA showed that while the supplements had no significant overall effect on pain reduction, the subgroup of patients with moderate
to severe knee pain experienced significant relief with a combination of glucosamine and chondroitin compared
with a placebo.18 However, this finding was the result of an exploratory analysis and not a primary outcome of the study, so it may be subject to a type 1 error.