Discussion
This analysis found that the annual prevalence of postmenopausal HT use declined sharply in 2003 and more gradually through 2009. The proportion of women initiating HT also declined by nearly 50% from 2001 to 2003 but remained stable thereafter. In addition, it was found that the use of oral formulations, especially standard and high dose, declined, whereas the use of vaginal formulations increased from 2003 to 2009. During the past decade, prescribing of HT by FP/IM/GP physicians declined more than did prescribing by gynecologists.
Overall Prevalence and Incidence
Before the release of landmark clinical trials, postmenopausal oral HT was widely used for the prevention of coronary heart disease as well as for the relief of menopause symptoms. Prescriptions for oral HT increased in the 1990s, peaking near the year 2000. After the WHI, Hersh et al estimated that the prevalence of postmenopausal HT decreased from 42% in 2001 to 28% in 2003. The timing and relative decrease in prevalence are similar to the findings in the current report, although the rates of estimated use differ, possibly because Hersh et al estimated prevalence from the number of pharmacy claims rather than from the number of claims by individual patients. In 2005, Kim et al used a pharmacy claims database to describe oral HT prescription filling, discontinuation, and regional variation in a subset of women 55 years and older. Within 3 months of the WHI, they observed a decline from 12.5% to 9.4%. Although use declined across all regions of the United States, significant regional variations were observed. Outside the United States, Barbaglia et al evaluated self-reported use of HT among 50,918 women in Spain who participated in a breast cancer screening program. In the youngest age group of this population, use peaked in 2002 at approximately 11% and dropped to approximately 1% in 2007. The overall decrease in prevalence was attributed to a decrease in new users.
The findings from this study confirm earlier reports of a marked decrease in prescriptions for HT in the years immediately after the release of the WHI findings. These earlier reports suggested that the widespread media coverage of the WHI resulted in a faster-than-usual change in prescribing patterns of oral forms of HT. In addition, the findings suggest that the impact of the WHI has been sustained and that the incidence of women starting HT has remained low, whereas prevalence has continued to decline through 2009. Barbaglia et al reached similar conclusions about the long-term impact on prescribing in Spain. However, HT use in their population across all years was significantly lower than in this study’s population, possibly reflecting differences in practice patterns among countries or differences in the use of HT between women attending a breast cancer screening program and the general population of women in our population.
Dose and Formulation
The relative shift to lower-dose oral HT, observed by 2009 (see Figure, Supplemental Digital Content 4, http://links.lww.com/MENO/A25), seems to be aligned with current clinical guidelines that recommend prescribing the lowest effective dose consistent with treatment goals. This shift could also be caused by the fact that lower doses may be better tolerated. A relative shift to nonoral formulations was also observed (see Figure, Supplemental Digital Content 5, http://links.lww.com/MENO/A25). In their 2004 analysis, Hersh et al noted that prescriptions for vaginal formulations did not decline during their study period, although the relative prevalence of that formulation remained low. Our analysis suggests that the relative prescribing of vaginal forms of HT is increasing, especially among gynecologists. This may be due, in part, to the suggestion that nonoral formulations may offer advantages over oral, although long-term risks and benefits of nonoral formulations have not been demonstrated to the same degree as those for oral formulations.
Physician Specialty
This analysis revealed a steady decline in the proportion of women who had HT prescribed by FP/IM/GP physicians and other specialties while showing an increase in the proportion of women prescribed HT by gynecologists from 2003 to 2009. These findings are consistent with earlier reports describing physician attitudes about postmenopausal HT. Brett et al conducted a national survey in October 2003, after the publication of the initial WHI results, and found that gynecologists held stronger beliefs about the benefits of HT than internists and were more likely to support continued use of combination therapy. In addition, in a 2004 survey of fellows of the American College of Obstetricians and Gynecologists, Power et al found that nearly half of the respondents rated the WHI results as not convincing. The reasons for these differences in attitudes are not clear. It is possible that FP/IM/GP physicians may be more reluctant to use medications that could potentially increase cardiovascular risk, even if the increase in risk is low, because they routinely care for patients with cardiovascular disease. Conversely, gynecologists may be more concerned with debilitating vasomotor symptoms and genitourinary symptoms experienced by some postmenopausal women. Pharmaceutical detailing may be another factor. Although manufacturer promotional efforts overall declined significantly after the release of WHI, residual promotional spending focused on lower-dose branded HT. The data do not explain why prescribing by gynecologists has not declined as markedly as for FP/IM/GP physicians, and this may be an important area for future research.
Strengths and Limitations
This study, performed in a large national database, has many strengths, including the representation of all United States geographical regions, a large sample size, and the inclusion of many women older than 65 years. The female sample that we selected in this study has age distribution similar to that of the general female age distribution in the United States (US Census Bureau, American Community Survey, 2000-2009).
However, the findings must be interpreted in light of the following limitations. First, because prescription claims do not include the indication for use and because there was no access to medical records, the appropriateness of prescribing or the role that patients play in the decision to start or continue HT could not be determined. Second, prescription claims contain no data for medication obtained entirely through samples or purchased by the patient without using her pharmacy benefit. Third, prescription claims can confirm that a patient filled a prescription, but they cannot confirm whether and how it was used or whether they were given a prescription and did not have it filled. Finally, only women with pharmacy benefits were included; therefore, the results may not generalize to uninsured women.