This two-part study will evaluate the effectiveness of etoricoxib in controlling pain in participants with osteoarthritis who are experiencing inadequate response to their current treatments. In Part 1, all participants will receive open-label etoricoxib 60 mg daily. Those participants who experience a clinically meaningful response to etoricoxib 60 mg daily within two weeks will be eligible to enter the double-blind withdrawal period (Part II). Responders entering Part 2 will be randomized in a 1:1 ratio to receive either etoricoxib 60 mg or placebo.

Inclusion Criteria:

• Clinical diagnosis of osteoarthritis of the knee or hip that requires treatment
• American Rheumatism Association (ARA) functional Class I, II or III
• Receiving a stable dose of a traditional non-steroidal anti-inflammatory drug (NSAID), a Cox-2 selective inhibitor (other than etoricoxib, e.g. celecoxib), opioid therapy or tramadol to treat their osteoarthritis-related pain for at least 2 weeks and willing to maintain treatment during baseline phase
• Moderate to severe daily pain intensity on his or her current pain regimen
• Excepting osteoarthritis, patient is judged to be in otherwise general good health based on medical history, physical examination, and routine laboratory tests
• Negative serum pregnancy test

Exclusion Criteria:

• Has not experienced at least 3 consecutive days of daily pain intensity >4 on 10-point scale
• Severe hepatic insufficiency
• Advanced renal insufficiency
• Presence of gastro-intestinal ulcer disease with active bleeding or history of the same within the past 6 months or a presence or history of inflammatory bowel disease
• History of gastric, biliary (including gastric bypass surgery), or small intestinal surgery that results in clinical malabsorption
• Receiving or will likely require treatment with ≥14 consecutive days or repeated courses of pharmacologic doses of corticosteroids
• Established ischemic heart disease, peripheral arterial disease, and/or cerebrovascular disease including a history of stroke, myocardial infarction or transient ischemic attack, and recent revascularization procedures
• Any other contraindications mentioned in the approved study drug European Union (EU) Summary of Product Characteristics (SmPC)
• Therapy with glucosamine and/or chondroitin sulfate for <6 months prior to study start.