Age at initiation of HT determines its effect on CHD
Stram DO, Liu Y, Henderson KD, et al. Age-specific effects of hormone therapy use on overall mortality and ischemic heart disease mortality among women in the California Teachers Study. Menopause 2011;18(3):253-261.
Allison MA, Manson JE. Age, hormone therapy use, coronary heart disease, and mortality [editorial]. Menopause. 2011;18(3):243-245.
The initial findings of the WHI estrogen-progestin arm suggested that menopausal HT increases the risk of CHD. Since then, however, further analyses from the WHI and other HT trials, as well as reports from the observational Nurses’ Health Study, have suggested that the timing of initiation of HT determines its effect on cardiovascular health.
In this study from the California Teachers Study (CTS), investigators explored the effect of age at initiation of HT on cardiovascular and overall mortality. The CTS is a prospective study of more than 133,000 current and retired female teachers and administrators who returned an initial questionnaire in 1995 and 1996. Participants were then followed until late 2004, or death, whichever came first. More than 71,000 participants were eligible for analysis.
Current HT users were leaner, less likely to smoke, and more likely to exercise and consume alcohol than nonusers were. The analysis was adjusted for a variety of potential cardiovascular and other confounders.
Youngest HT users had the lowest risk of death
During follow-up, 18.3% of never-users of HT died, compared with 17.9% of former users. In contrast, 6.9% of women taking HT at the time of the baseline questionnaire died during follow-up.
Overall, current HT use was associated with a reduced risk of death from CHD (hazard ratio [HR], 0.84; 95% confidence interval, 0.74–0.95). This risk reduction was most notable (HR, 0.38) in the youngest HT users (36 to 59 years old). The risk of death from CHD gradually increased with the age of current HT users, reaching a hazard ratio of approximately 0.9 in current users who were 70 years and older. However, the CHD mortality hazard ratio did not reach or exceed the referent hazard ratio (1.0) assigned to never users of HT of any age.
The overall mortality rate was lowest for the youngest HT users (HR, 0.54) and approached 1.0 in the oldest current HT users.
The associations between overall and CHD mortality were similar among users of estrogen-only and estrogen-progestin HT.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
As Allison and Manson point out in an editorial accompanying this study, the findings from the CTS are congruent with an extensive body of evidence from women and nonhuman primates. These data provide robust reassurance that HT does not increase the risk of death from CHD when it is used by recently menopausal women who have bothersome vasomotor symptoms.
Hormone therapy and dementia: Earlier use is better
Whitmer RA, Quesenberry CP, Zhou J, Yaffe K. Timing of hormone therapy and dementia: the critical window theory revisited. Ann Neurol. 2011;69(1):163–169.
Alzheimer’s disease is more common among women than men. In addition, caregivers to those who have dementia are more likely to be women. Therefore, it’s no surprise that women are especially concerned about their risk of dementia. Menopausal patients in my practice often ask whether use of HT might alter this risk.
Because vasomotor symptoms usually arise in late perimenopause or early menopause, women in observational studies (which reflect clinical practice) tend to begin HT when they are in their late 40s or early 50s. Overall, observational studies have suggested that HT is associated with a reduced risk of dementia. In contrast, the WHI clinical trial, in which the mean age of women who were randomized to HT or placebo was 63 years, found that the initiation of HT later in life increased the risk of dementia.
These observations led to the “critical window” theory regarding HT and dementia: Estrogen protects against dementia when it is taken by perimenopausal or early menopausal women, whereas it is not protective and may even accelerate cognitive decline when it is started many years after the onset of menopause.
In this recent study from the California Kaiser Permanente health maintenance organization, investigators assessed the long-term risk of dementia by timing of HT. From 1964 through 1973, menopausal “midlife” women who were 40 to 55 years old and free of dementia reported whether or not they used HT. Twenty-five to 30 years later, participants were reassessed for “late life” HT use.
Women who used HT in midlife only had the lowest prevalence of dementia, whereas those who used HT only in late life had the highest prevalence. Women who used HT at both time points had a prevalence of dementia similar to that of women who had never used HT.