Pharmaceutical Research

Direct-to-consumer drug advertising on television may have led to increased prescribing of Vioxx® and Celebrex®

The cyclooxygenase-2 (COX-2) inhibitor Vioxx® was one of the most heavily advertised prescription drugs in recent years. According to a new study, direct-to-consumer (DTC) drug advertising on television may have led to an increase in doctor's visits by osteoarthritis patients and an increase in prescriptions for Merck's Vioxx® and Pfizer's Celebrex® prior to the 2004 removal of Vioxx® from the market because of evidence it increased the risk of heart attack and stroke.

W. David Bradford, Ph.D., of the Medical University of South Carolina, and colleagues matched monthly clinical information from 57 primary care practices in 2000-2002 to monthly brand-specific drug advertising data for local and network television. The researchers estimated that a 100 percent increase in local and national Vioxx® ads would, on average, have increased the number of visits by osteoarthritis patients per month by 0.8 percent and 7.4 percent, respectively. They estimated that a 100 percent increase in DTC national advertising of Celebrex® would have led to a 2 percent increase in monthly visits. Local Celebrex® advertising did not influence office visit rates.

DTC advertising of Vioxx® increased the likelihood that patients would be prescribed both Vioxx® and Celebrex® during these office visits; however, Celebrex® ads only affected Vioxx® use. For example, a tenfold increase in local Vioxx® DTC spots would have generated about a 0.5 percent increase in the rate of Vioxx® prescribing each month. A 50 percent increase in monthly national Celebrex® ads would have led to an increase of about 0.5 percent in Vioxx® prescribing. This may have been because in 2000 Merck invested in nearly twice as many DTC ads for Vioxx® as Pfizer did for Celebrex®. Pfizer concentrated on direct-to-physician marketing of Celebrex® via office visits by pharmaceutical representatives. The study was supported in part by the Agency for Healthcare Research and Quality (HS11326).

See "How direct-to-consumer television advertising for osteoarthritis drugs affects physicians' prescribing behavior," by Dr. Bradford, Andrew N. Kleit, Ph.D., Paul J. Neitert, Ph.D., and others, in the September 2006 Health Affairs 25(5), pp. 1371-1377.

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