Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT)

This study is a 24 week, placebo-controlled, parallel, double-blind, five-arm trial. The randomized treatment assignment will be stratified by participating study center and baseline pain score (mild, moderate to severe). In order to establish that the study is able to detect significant treatment effects for glucosamine, chondroitin sulfate and the combination of the two, celecoxib, already established to be effective, will also be compared to placebo. Patients will receive a rescue analgesic medication, acetaminophen, which they will be allowed to take for severe pain throughout the trial but not within 24 hours prior to a study visit.

The visits include a screening visit (Visit 1.0), randomization visit (Visit 2.0), and follow-up visits at 4 weeks (Visit 3.0), 8 weeks (Visit 4.0), and 16 weeks (Visit 5.0) and a completion visit at 24 weeks (Visit 6.0) after randomization or at any time patients discontinue the study drug or withdraw from the study. All patients require an X-ray to document the presence of their disease and all patients must have clinical and X-ray evidence of OA. X-rays are read at the individual sites and then forwarded to a central radiology center for confirmatory readings.

Patient evaluations consist of; 1) the Western Ontario and MacMaster (WOMAC) osteoarthritis index, 2) patient and investigator global evaluations of disease status and response to study medication, 3) evaluation of the index knee for swelling and tenderness, 4) SF-36, 5) the Health Assessment Questionnaire (HAQ), 6) Beck Depression Inventory (BDI), 7) clinical evaluation for adverse reactions and 8) reconciliation of study medications and rescue analgesia use.

The percentage of treatment responders is the primary outcome measure. A patient will be classified as a treatment responder if there is a 20% reduction from baseline to the end of follow-up in the WOMAC pain subscale.

Following the method by which the sample size target was derived, the analysis to address the primary hypotheses will involve 3 primary comparisons 1) glucosamine vs. placebo, 2) chondroitin vs. placebo, and 3) glucosamine + chondroitin vs. placebo. A side comparison will also be done between celecoxib and placebo. Each comparison will be done using Fisher's Exact Test, with a two-sided alpha of 0.0125.