Question

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. (a) Explain why this is an experiment. (b) Suppose that there were exactly 8000 arthritis patients in the study and that the first half randomly selected were assigned to the Celebrex group, the next 25% randomly selected were given ibuprofen, and the remaining 25% took diclofenac. Use your calculator with a seed value of 38 to give the first five patients who were given Celebrex. (c) Suppose that only 6% of the Celebrex subjects reported ulcers, while the rates for the ibuprofen and diclofenac patients were 18% and 16%, respectively. How many Celebrex patients reported ulcers? (d) It was reported that this study was double-blinded. Clearly explain the meaning of double blinded. (e) A caveat is defined as a caution or warning. The Orlando Sentinel article listed the following two caveats for this study: (1) The study was funded by the manufacturer of Celebrex. (2) The study lasted just six months and most arthritis patients take pain relievers for longer periods of time. Comment on why these are caveats for this study.

Answer 1

The discussed study is an experiment to assess the incidence of gastrointestinal ulcers among arthritis patients using Celebrex versus other NSAIDs. It was double-blinded to prevent bias. Two caveats of the study include potential conflict of interest and a relatively short study duration.

Step-by-step explanation:

The study in question is an experiment because it involves the manipulation of variables (type of medication given to patients) and the control of other variables to determine the effect on a specific outcome (the incidence of gastrointestinal ulcers). Given that there were exactly 8000 arthritis patients in the study and that the distribution of patients to different drug groups was random, the simulation of which patients received Celebrex using a calculator with a predetermined seed value would be a mechanism to assign treatment groups in a pseudo-random fashion.

2 As the study reported that only 6% of the Celebrex subjects reported ulcers, with 4000 patients in the Celebrex group, 6% would equate to 240 patients reporting ulcers. A double-blinded study is one in which neither the participants nor the researchers know who is receiving a particular treatment, a method used to prevent bias in research results.

The caveats mentioned for this study include potential bias due to the study being funded by the manufacturer of Celebrex and the limitation of the study's duration relative to the long-term use of the drug by arthritis patients.