Question 4 d) It was reported that this study was double-blinded. Clearly explain the meaning of double-blinded. Here is the story behind the question: 4. Celebrex is the third in a family of popular prescription painkillers to be linked to a higher incidence of heart attacks. This followed the Sept. 30, 2004 removal of Vioxx from the market and the later revelation that Bextra also presents an increased health risk. Celebrex, Vioxx and Bextra all work by inhibiting a protein called COX-2 that has been linked to inflammation. Celebrex and Vioxx were both introduced in 1999 and instantly became top selling drugs for Merck and Pfizer, respectively. Pfizer, the world's largest drug maker, introduced Bextra in the United States in 2001, also to robust sales. While Merck removed Vioxx from the market, as of the end of 2004, Pfizer has been reluctant to follow suit with its COX-2 products. The company has insisted after the removal of Vioxx that its Celebrex was safe and it has continued to advertise and market the drug. One of the earlier studies involving Celebrex was reported in the September 13, 2000 issue of the Journal of the American Medical Association (Web site www.jama.com). Three anti-inflammatory drugs were tested to compare the gastrointestinal (GI) side effects. A summary of this study was given in the December 5, 2000 edition of the Orlando Sentinel under the section entitled "Quick Study: Updates on Major Health Topics." The article reports that of the nearly 8000 arthritis patients, half took celecoxib (brand name Celebrex), a pain reliever called a COX-2 inhibitor. The other half took either ibuprofen or diclofenac conventional nonsteroidal anti-inflammatory drugs (NSAIDs) commonly used for arthritis.NSAIDs can lead to gastrointestinal (GI) problems. In this study, patients taking celecoxib were less likely to get ulcers than those taking standard daily doses of the NSAIDs.