Evidence of a healthy estrogen user survivor effect.
We examined the relation between menopausal estrogen use and all-cause and cause-specific mortality in a cohort of over 49,000 women followed between 1979 and 1989 in the Breast Cancer Detection Demonstration Project (BCDDP) Follow-Up Study. We found a lower all-cause mortality rate among women who took estrogens [rate ratio (RR) = 0.7; 95% confidence interval (CI) = 0.7-0.8], particularly current users (RR = 0.3; 95% CI = 0.2-0.4), than among women who never took them. Additional analyses, however, revealed that women who had recently stopped taking estrogens had a higher all-cause mortality rate than women who had never taken them (RR = 1.4; 95% CI = 1.2-1.7). Women who had recently stopped taking estrogens also had higher mortality rates from circulatory disease (RR = 1.3; 95% CI = 1.0-1.8) and cancer (RR = 1.6; 95% CI = 1.2-2.2) than women who never took them. The most likely explanation for these results is that women stop taking estrogens when they develop symptoms of serious illness. As a consequence of this "healthy estrogen user survivor effect," nonexperimental studies are susceptible to overestimating the benefits of menopausal estrogen use, particularly current use, on mortality.
Sturgeon
S R
SR
Environmental Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892, USA.
Schairer
C
C
Brinton
L A
LA
Pearson
T
T
Hoover
R N
RN
D000368:Aged; D002318:Cardiovascular Diseases / Q000401:mortality* / Q000517:prevention & control; D002423:Cause of Death; D015331:Cohort Studies; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D008875:Middle Aged; D009369:Neoplasms / Q000401:mortality* / Q000517:prevention & control; D017698:Postmenopause; D011795:Surveys and Questionnaires; D016019:Survival Analysis; D013997:Time Factors; D014481:United States / Q000453:epidemiology