When news comes out about the dangers of some drug, prescriptions of the drug tend to plummet. This makes sense—doctors hear about the new evidence and they lay off the drug. But what if doctors aren't responding to the science but instead to a drop-off in promotion by drug companies? asked researchers at Stanford University. They looked at how drug companies changed their habits after the summer 2002 announcement that hormone replacement therapy did more harm than good.

What the researchers wanted to know: How did promotional expenditures for hormone therapy change after July 2002, when the Women's Health Initiative Estrogen Plus Progestin Trial was stopped because women on those two hormones had a higher risk of serious health problems?

What they did: The researchers used a database on prescriptions to find out how many prescriptions were dispensed for hormone therapy between January 2001 and December 2003. For the same three years, they looked at reports on promotional spending for those drugs—including visits to physicians and pharmacists, ads in medical journals, free samples for physicians, and direct-to-consumer advertising on television and radio and in magazines and newspapers.

What they found: Nearly half of post-menopausal women were taking hormones in the late 1990s. Those prescriptions dropped fast after the July 2002 announcement. By the end of 2003, total prescriptions had fallen 43 percent, and Prempro, the combination of estrogen and progesterone used in the study, was down 80 percent. In the quarter before the July 2002 announcement, pharmaceutical companies spent $71 million promoting hormone therapy—which works out to an average of $350 per year per doctor practicing in the United States. Like prescriptions, promotional spending dropped precipitately after the July 2002 announcement, to $45 million in the first quarter of 2003. But it rose again, up to $55 million in the last quarter of 2003.

What the study means to you: Studies have found that doctors' prescribing habits are closely related to companies' promotions. Doctors are busy, and drug company representatives who show up with scientific evidence and free samples provide an easy way to get information about drugs.

Caveats: This doesn't prove that the plunge in promotional spending—to only $220 per doctor per year—caused the drop in prescriptions. They just happened at the same time. In this case, doctors had plenty of other ways to learn the news about this drug—articles in prominent journals and all of the media attention about the end of the trial, for example. The researchers also note that after the Prempro trial ended, companies spent more money on promoting lower-dose versions of their hormone replacement therapies, even though no one knows if lower doses are safer. (They may well be safer, but no one knows.)

Find out more: An abrupt end to a major menopause study leaves women as confused as ever: www.usnews.com/health/briefs

Read the article: Majumdar, S.R., Almasi, E.A., and R.S. Stafford. "Promotion and Prescribing of Hormone Therapy After Report of Harm by the Women's Health Initiative." Journal of the American Medical Association. Oct. 27, 2004, Vol. 292, No. 16, pp. 1983–1988.

Abstract online: http://jama.ama-assn.org