The search conducted in PUBMED used the following terms: (ibuprofen OR naproxen OR diclofenac OR meloxicam OR etoricoxib OR celecoxib OR mefenamic OR indometacin OR etodo- lac OR tramadol OR morphine OR codeine OR dihydro- codeine OR oxycodone OR diamorphine OR methadone OR hydromorphone OR duloxetine) AND (osteoarthritis) AND (English [lang]) AND (clinical trial [ptyp]).