We found high quality evidence that hormone therapy in both primary and secondary prevention conferred no protective effects for all-cause mortality , cardiovascular death , non-fatal myocardial infa rct ion , angina , or revascularisation .
There was no strong evidence of effect on risk of stroke in this group .
Our review findings provide strong evidence that treatment with hormone therapy in post-menopausal women overall , for either primary or secondary prevention of cardiovascular disease events has little if any benefit and causes an increase in the risk of stroke and venous thromboembolic events
BACKGROUND Evidence from systematic review s of observational studies suggests that hormone therapy may have beneficial effects in reducing the incidence of cardiovascular disease events in post-menopausal women , however the results of r and omised controlled trials ( RCTs ) have had mixed results .
This is an up date d version of a Cochrane review published in 2013 .
OBJECTIVES To assess the effects of hormone therapy for the prevention of cardiovascular disease in post-menopausal women , and whether there are differential effects between use in primary or secondary prevention .
Secondary aims were to undertake exploratory analyses to ( i ) assess the impact of time since menopause that treatment was commenced ( ≥ 10 years versus < 10 years ) , and where these data were not available , use age of trial participants at baseline as a proxy ( ≥ 60 years of age versus < 60 years of age ) ; and ( ii ) assess the effects of length of time on treatment .
A Prospective, Observational Study of Postmenopausal Hormone Therapy and Primary Prevention of Cardiovascular Disease
Whether to take hormone therapy is one of the most difficult medical decisions that healthy postmenopausal women face . The apparent coronary benefits ( 1 ) of hormone use are an important part of that decision . Although the data appear consistent in suggesting long-term coronary benefits , the Heart and Estrogen/progestin Replacement Study ( 2 ) showed an increased risk for coronary events during the first year of therapy in women with existing heart disease ; we also found such an elevated risk in an examination of secondary prevention in the Nurses ' Health Study ( 3 ) . More recently , a report from the Women 's Health Initiative , an ongoing r and omized clinical trial of hormone therapy for primary prevention of cardiovascular disease , suggested similar findings in healthy women ( National Institutes of Health . Press release ) . However , additional data on short-term effects of hormone use in women without previous cardiovascular disease are sparse . Many further questions also remain . Among them is the cardiovascular effect of daily doses lower than the st and ard 0.625 mg of oral conjugated estrogen . Recent studies suggest that lower doses of hormone therapy provide bone benefits ( 4 ) and , compared with higher doses , might decrease the risk for thromboembolism ( 5 ) and reduce endometrial hyperplasia ( 4 ) . However , few data are currently available on the relation between low-dose estrogen and primary prevention of heart disease and stroke . In an earlier report , we examined the relation between postmenopausal hormone therapy and primary prevention of cardiovascular disease based on 16 years of follow-up from the Nurses ' Health Study ( 6 ) . In the current analysis , we have almost 50 % more follow-up time among women taking daily doses less than 0.625 mg and more than 800 additional cases of cardiovascular disease , allowing more precise assessment of specific associations . Thus , we now report on the relation among  low-dose estrogen , short-term hormone use , and cardiovascular events in 70 533 postmenopausal women with no previous cardiovascular disease who were followed for up to 20 years . We also provide additional information on the effects of estrogen combined with progestin . Methods The Nurses ' Health Study Cohort The Nurses ' Health Study began in 1976 when 121 700 female nurses 30 to 55 years of age completed a mailed question naire about their postmenopausal hormone use and medical history , including cardiovascular disease and its risk factors . We up date information with biennial follow-up question naires . Dietary and physical activity question naires were added in 1980 . Cohort follow-up is greater than 90 % . Ascertainment of Hormone Use In 1976 , women were asked about use and duration of hormone therapy after menopause . Beginning in 1978 , we collected information on type of hormones taken , and starting in 1980 , we asked about the dose of oral conjugated estrogen . All information is up date d biennially . Identification of Cardiovascular Disease We identified first occurrences of nonfatal myocardial infa rct ion , fatal coronary disease , and fatal and nonfatal stroke between the return of the 1976 question naire and 1 June 1996 . Nurses who reported a nonfatal infa rct ion or stroke were asked for permission to review their medical records . Nonfatal myocardial infa rct ions were confirmed by hospital records if they met World Health Organization criteria ( 7 ) ( symptoms plus either elevated levels of cardiac enzymes or diagnostic electrocardiograms ) . Infa rct ions that required hospitalization and were corroborated by interview or letter but for which medical records were unobtainable were included as probable . Infa rct ions of indeterminate age discovered on routine examination were excluded . Nonfatal strokes were confirmed by review of medical records if they were characterized by a typical neurologic deficit , were rapid in onset , lasted at least 24 hours , and met the criteria of the National Survey of Stroke ( 8) . We classified strokes as ischemic ( thrombotic or embolic occlusion of a cerebral artery ) , subarachnoid hemorrhage , or intraparenchymal hemorrhage . We excluded subdural hematomas and strokes caused by infection or neoplasia . Strokes that required hospitalization and were corroborated by letter or interview but for which medical records were unavailable were included as probable . Most deaths were reported by the participants ' families . We search ed the National Death Index to identify deaths among nonrespondents to each 2-year question naire ; mortality follow-up was more than 98 % complete ( 9 ) . For all deaths possibly attributable to cardiovascular causes , we requested permission from relatives ( subject to state regulations ) to review the medical records . Deaths were considered to be due to coronary disease if medical records or autopsy findings confirmed a fatal myocardial infa rct ion . We also included coronary disease listed on the death certificate as the underlying cause without another , more plausible cause , if the nurse was known ( from hospital records , family , or other sources ) to have had coronary disease before death . In no case was the cause listed on the death certificate used as the sole criterion for coronary death . Sudden death within 1 hour of the onset of symptoms in participants with no other plausible cause of death besides coronary disease was also included . Fatal strokes were documented by autopsy or hospital records or if stroke was listed as the underlying cause on the death certificate . The category of major coronary heart disease combines nonfatal myocardial infa rct ion and coronary death ; similarly , total stroke includes nonfatal and fatal cases . The category of combined cardiovascular disease includes major coronary heart disease and stroke . Confirmed and probable cases in each category were analyzed together ( 80 % of major coronary events and 73 % of strokes were confirmed ) . In this and previous analyses ( 6 ) , results for probable cases were similar to those for confirmed cases . The investigators conducted all interviews and record review s without knowledge of participants ' hormone use status . Population for Analysis Women who reported stroke , myocardial infa rct ion , angina , coronary revascularization , or cancer ( except nonmelanoma skin cancer ) on the 1976 question naire were excluded because their disease may have caused them to alter their hormone use . Similarly , women who reported such diagnoses on a subsequent question naire were excluded from further analysis . Thus , at the start of each 2-year interval , the base population included no women reporting these diagnoses . Our own studies ( 6 , 10 ) and other studies ( 11 ) have suggested that hormone therapy may differentially affect incident and fatal strokes ; thus , we separately examined deaths due to stroke . In these analyses , we excluded women with cancer and cardiovascular disease at baseline but did not up date the exclusions because the women who develop cardiovascular disease during follow-up are those most likely to die of stroke . We classified women as postmenopausal from the time of natural menopause or hysterectomy with bilateral oophorectomy .  Women who underwent hysterectomy without bilateral oophorectomy  were considered postmenopausal when they reached the age at which natural menopause had occurred in 90 % of the cohort ( 54 years for smokers and 56 years for nonsmokers ) . In this cohort , the women 's reports of age at menopause ( 12 ) and type of menopause ( 13 ) were highly accurate . In 1976 , 21 947 postmenopausal women entered the analysis , and 48 586 women were added during follow-up as they became postmenopausal , for a total of 70 533 participants ; 808 825 person-years of follow-up were accrued from 1976 to 1996 . Statistical Analysis For each participant , person-months were allocated to hormone categories according to the 1976 data and were up date d every 2 years ( for estrogen dose , follow-up began in 1980 ) . For analyses of type of hormone therapy , we assigned the regimen reported on the 1978 question naire to women who reported hormone use in 1976 . Analyses of type of hormone therapy were limited to users of oral conjugated estrogen with or without oral medroxyprogesterone acetate  , since these were the most common hormone regimens . If no data were available on hormones in a given time period , women were assigned to a missing category for that time period . To maintain the prospect i ve nature of the study , hormone use ( including duration ) during each 2-year period was established from women 's reports at the start of the period ; thus , we probably underestimate duration of use by an average of 1 year . Follow-up for a participant ended at the first diagnosis of cardiovascular disease , death , or 1 June 1996 , whichever came first . The primary analysis is based on incidence rates for which person-months of follow-up were used as the denominator . We used relative risk as the measure of association , defined as the incidence of cardiovascular events among women in various categories of hormone use divided by the incidence among women who never used hormones . We computed age-specific rates by using 5-year categories ( 14 ) and age-adjusted relative risks by using MantelHaenszel rate ratios ( 15 ) with 95 % CIs ( 16 ) . We used pooled logistic regression  across the ten 2-year time periods to adjust simultaneously for potential confounding factors ( 17 ) . In this approach , independent blocks of person-time are pooled for regression analysis , and time-varying covariates are readily accommo date d by assigning successive blocks of person-time to the covariate values at the start of each follow-up cycle . The dependence of the incidence rates on time is modeled nonparametrically with indicator variables . Simulation studies have established the asymptotic equivalence of pooled logistic regression to Cox regression with time-dependent covariates ( 18 ) . The necessary conditions for this equivalence include relatively short time intervals and small probability of the outcome during each interval , both
We found high quality evidence that hormone therapy in both primary and secondary prevention conferred no protective effects for all-cause mortality , cardiovascular death , non-fatal myocardial infa rct ion , angina , or revascularisation .
There was no strong evidence of effect on risk of stroke in this group .
Our review findings provide strong evidence that treatment with hormone therapy in post-menopausal women overall , for either primary or secondary prevention of cardiovascular disease events has little if any benefit and causes an increase in the risk of stroke and venous thromboembolic events
BACKGROUND Evidence from systematic review s of observational studies suggests that hormone therapy may have beneficial effects in reducing the incidence of cardiovascular disease events in post-menopausal women , however the results of r and omised controlled trials ( RCTs ) have had mixed results .
This is an up date d version of a Cochrane review published in 2013 .
OBJECTIVES To assess the effects of hormone therapy for the prevention of cardiovascular disease in post-menopausal women , and whether there are differential effects between use in primary or secondary prevention .
Secondary aims were to undertake exploratory analyses to ( i ) assess the impact of time since menopause that treatment was commenced ( ≥ 10 years versus < 10 years ) , and where these data were not available , use age of trial participants at baseline as a proxy ( ≥ 60 years of age versus < 60 years of age ) ; and ( ii ) assess the effects of length of time on treatment .