In 1992, approximately six million women were taking hormone replacement therapy (HRT) . Most of those women took HRT to relieve menopausal symptoms (i.e., hot flashes, vaginal dryness) and prevent bone loss . But some physicians were prescribing HRT to their patients because it was thought to help reduce the risk of heart disease .

But in July 2002, new evidence from two large trials—the Women’s Health Initiative (WHI) and the Heart and Estrogen/Progestin Replacement Study follow-up (HERS II)—suggested that an estrogen plus progestin regimen of HRT (combination HRT) does not protect against cardiovascular disease in postmenopausal women, and may even increase the risk of cardiovascular disease, as well as breast cancer , stroke , blood clots , and other adverse effects. Subsequent studies have confirmed these findings.

In response, new guidelines from the U.S. Preventative Task Force recommend against the routine use of HRT to treat or prevent chronic conditions. Furthermore, many health professionals are advising women to taper their doses of HRT and eventually discontinue them all together. But are women and their physicians adhering to these recommendations? How many women are still taking HRT?

A new study in the January 7, 2004 issue of the Journal of the American Medical Association revealed that the rate of HRT prescriptions has dropped drastically since July 2002, by which time the WHI and HERS II results had been published. The researchers estimate that the number of American women who receive HRT prescriptions has decreased from 91 million prescriptions in 2001 to 57 million in 2003.

About the Study

Researchers used data from two databases: the National Prescription Audit Plus (NPA) and the National Disease and Therapeutic Index (NDTI). The NPA records prescriptions that are filled at 20,000 pharmacies in the U.S. The NDTI tracks information on patient visits to 14,000 physicians every year.

From these data, the researchers tracked HRT prescriptions from January 1995 through July 2003. Assuming that women get an average of six HRT prescriptions per year (each lasting two months), the researchers estimated the number of women taking HRT by dividing the total number of prescriptions for each year by six.

The Findings

The researchers found that there were three distinct phases of HRT use:

  • 1995 to 1999 - a 57% increase in HRT prescriptions following the introduction of combination HRT
  • 1999 to June 2002 – a stabilization of HRT prescription rates as evidence began to surface about adverse effects associated with combination HRT
  • July 2002 to July 2003 - the rate of HRT prescriptions declined by 38% after findings from the WHI and HERS II trials were released

The following table summarizes the study findings:

HRT prescriptions58 million76 million90 million91 million57 million
Number of women taking HRT10 million13 million15 million15 million10 million

The declines in HRT prescriptions were most evident among the oral regimens, which were used in WHI and HERS II. Vaginal HRT formulations did not decline after July 2002. Interestingly, new prescriptions for lower-dose estrogen increased by 6% during the second half of 2002.

How Does This Affect You?

These findings suggest that widely publicized research findings can dramatically influence the behavior of doctors and their patients. The sharp decrease in HRT prescriptions after July 2002 indicates that many women and their healthcare providers have responded to the study findings and are adhering to the new recommendations. Furthermore, the increase in low-dose Premarin prescriptions may indicate that some women are tapering HRT use toward discontinuation.

These changes in clinical practice may have had a substantial effect on women’s health outcomes. Based on estimated risks of adverse events (i.e., coronary heart disease, breast cancer, stroke, and blood clots) due to HRT, the researchers estimate that the decline in HRT prescriptions resulted in 8,000 fewer adverse events in 2003, compared with 2001.

These findings shed a promising light on the future of healthcare in the U.S. Many physicians, medical schools, and hospitals are moving towards evidence-based medicine, which relies on clinical research to guide medical decisions. In this case, the WHI and HERS II results prompted swift changes in clinical practice and a media cascade that educated the public about the risks associated with HRT use.

While the findings from this study are promising, another study in the same issue of the Journal points out the difficulty of translating research findings into clinical practice. In spring 2000, the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) was stopped early because the study medication—an alpha-blocker (doxazosin)—was more risky but no more effective in treating high blood pressure than diuretics. In response to these findings, researchers saw only modest declines in doxazosin use. To enhance the impact of clinical findings on clinical practice, researchers, physicians, and the media must work together to disseminate clinical findings that could affect the health of the population.