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 .
Postmenopausal Hormone Therapy Increases Risk for Venous Thromboembolic Disease: The Heart and Estrogen/progestin Replacement Study
Venous thromboembolism , including thrombosis of the deep veins of the legs and embolism to the pulmonary arteries , is a serious and potentially fatal event . Venous thromboembolism is uncommon in the general population , occurring in about 1 to 4 per 1000 adults annually ( 1 , 2 ) . However , the risk is increased in persons with previous venous thromboembolism ( 3 ) , recent surgical procedures ( 4 , 5 ) , immobilization , fracture of a lower extremity ( 4 , 6 , 7 ) , cancer ( 4 , 6 , 7 ) , and inherited coagulation disorders ( 8 , 9 ) . Use of oral contraceptive pills increases risk for venous thromboembolism ( 1 , 2 ) . This increased risk is thought to be due to estrogen and to be dose related ( 3 , 4 ) . The biological potency of the estrogens generally used in postmenopausal hormone therapy is about one-fourth to one-fifth that of the estrogens in modern oral contraceptives . Until recently , there has been little evidence that low-dose estrogen therapy is associated with increased risk for venous thromboembolism ( 5 - 8 ) . Recent observational studies have suggested that postmenopausal hormone therapy causes a twofold to fourfold increase in risk for idiopathic deep venous thrombosis and pulmonary embolism ( 9 - 13 ) . However , these findings may be biased if women taking estrogen are more likely to be evaluated for nonspecific symptoms suggestive of venous thromboembolism . The Heart and Estrogen/progestin Replacement Study ( HERS ) was a r and omized , blinded , placebo-controlled trial of the effect of daily conjugated equine estrogen , 0.625 mg , plus medroxyprogesterone acetate , 2.5 mg , on the rate of new coronary events in 2763 postmenopausal women with established coronary heart disease ( 14 ) . One of the specified secondary outcomes of this trial was venous thromboembolism . An increased risk for venous thromboembolism among women assigned to hormone therapy was noted by the HERS Data and Safety Monitoring Board . The Board instructed the HERS investigators to inform participants and the scientific community of this risk and to institute measures to reduce risk . At a mean follow-up of 3.3 years , the HERS investigators notified participants to discontinue study medication in situations associated with increased risk for venous thromboembolism , such as surgery , hospitalization , fracture , and cancer , and published a letter noting the increased risk ( 15 ) . This report presents the full analysis of the findings . Methods Participants in HERS were postmenopausal women younger than 80 years of age who had coronary disease ( myocardial infa rct ion , coronary artery bypass surgery , percutaneous coronary revascularization , or angiographic evidence of at least 50 % narrowing of one or more major coronary arteries ) and had not had a hysterectomy . Women were excluded if their coronary event occurred within 6 months of r and omization ; they had used hormone therapy within 3 months of r and omization ; they had a history or baseline findings suggestive of venous thromboembolism , breast cancer , or endometrial cancer ; or they had uncontrolled hypertension , diabetes , or other life-threatening diseases ( 16 ) . The protocol was approved by the institutional review board at each of the 20 HERS clinical centers , and all participants provided written informed consent . Participants were r and omly assigned to take one tablet daily of conjugated equine estrogen , 0.625 mg , plus medroxyprogesterone acetate , 2.5 mg , or placebo that was identical in appearance . R and omization was stratified by clinical center and performed in blocks of 4 . To prevent unblinding of clinical center staff , HERS participants reported breast discomfort and vaginal bleeding directly to gynecology staff , who were located separately from the clinical center staff , did not communicate with clinical center personnel about breast or gynecologic problems , and did not participate in ascertainment of outcomes . Follow-up visits to the clinical centers occurred at 4-month intervals . Coronary events ( nonfatal myocardial infa rct ion and coronary death ) were the primary outcome of the trial ( 14 ) . At each visit , clinic staff asked participants if they had been told by a physician that they had a blood clot in the legs or lungs . Women were also asked whether they had been hospitalized , and records were review ed to determine whether venous thromboembolism had occurred . Women were not routinely asked about symptoms of venous thrombosis , such as lower-extremity edema . Diagnosis of deep venous thrombosis required documentation of thrombosis of the popliteal or more proximal veins of the legs by venography , impedance plethysmography , or sonography . Pulmonary embolism required documentation by a nuclear lung scan that suggested a high probability of pulmonary embolism ( segmental or larger perfusion defect with ventilation mismatch ) or by pulmonary angiography that revealed a constant intraluminal filling defect on multiple films . Suspected venous thromboembolism was adjudicated independently and without knowledge of treatment assignment by two physicians at the HERS Coordinating Center , located at the University of California , San Francisco ; disagreements were resolved by consensus . Persons who analyzed data were also blinded to participants ' treatment status . Data were collected on events that occurred during the trial that might be predictors of venous thromboembolism , including fractures , nonfatal myocardial infa rct ion , congestive heart failure , stroke , and transient ischemic attack ( 16 ) . Venous thromboembolism was classified as idiopathic in women who did not have concomitant cancer , nonfatal myocardial infa rct ion , congestive heart failure , or stroke and did not have a fracture , inpatient surgery , or hospitalization in the 3 months before the venous thromboembolic event . In the primary analysis , an unadjusted Cox proportional-hazards model for time to first event was used to compare the rate of venous thromboembolism among women assigned to  hormone therapy with the rate among women assigned to placebo . The primary analysis was intention-to-treat ; participants were categorized according to treatment assignment regardless of compliance . Participants who were lost to follow-up ( 33 women in the hormone therapy group and 36 in the placebo group ) were censored at the last date at which they were known to be alive without venous thromboembolism ; vital status was known for all women at the end of the trial . We also performed an as-treated analysis , in which inclusion in the risk sets was limited to women in both treatment groups whose average compliance with therapy during the trial ( measured by pill count ) was at least 80 % . Relative hazards were also estimated by year since r and omization ( women with events in earlier years were censored ) , and continuous trend in the log relative hazard was examined in a companion model . We repeated the main analyses separately for idiopathic and nonidiopathic venous thromboembolism . Potential risk factors for venous thromboembolism were first examined by using univariate proportional hazards models adjusted for treatment assignment . In these models , postr and omization events and medication use were represented by time-dependent indicators , which reverted to zero 90 days after fracture , surgery , or hospitalization or when therapy was discontinued . Variables associated with venous thromboembolism for which the associated P value was less than 0.2 in univariate analyses were considered for inclusion in multivariate models and retained in the model if the P value remained less than 0.2 . Statistical analyses were performed by using SAS software , version 6.12 ( SAS Institute , Inc. , Cary , North Carolina ) . Results The 20 HERS centers enrolled 2763 women between February 1993 and September 1994 ; of these , 1380 were assigned to the hormone therapy group and 1383 to the placebo group . Participants ranged in age from 44 to 79 years ( mean age [ SD ] , 67 7 years ) . At baseline , the treatment groups did not differ significantly ( Table 1 ) . Table 1 . Baseline Characteristics of HERS Participants At the end of the first year , 82 % of women in the hormone therapy group and 91 % in the placebo group reported taking study medication ; by the end of the third year , these proportions had decreased to 75 % and 81 % , respectively . Cumulative incidence curves for all venous thromboembolic events ( deep venous thrombosis and pulmonary embolism ) are shown in the Figure . During 10 985 woman-years of follow-up , 47 women experienced a  venous thromboembolic event : 34 in the hormone-treated group ( 6.2 per 1000 woman-years ) and 13 in the placebo group ( 2.3 per 1000 woman-years ) ( relative hazard , 2.7 [ 95 % CI , 1.4 to 5.0 ] [ P = 0.003 ] ; excess risk , 3.9 per 1000 woman-years [ CI , 1.4 to 6.4 per 1000 woman-years ] ; number needed to treat for harm , 256 [ CI , 157 to 692 ] ) . The relative hazard of venous thromboembolism did not differ significantly among the 20 clinical centers . Figure . Kaplan-Meier estimates of the cumulative incidence of venous thromboembolic events ( top ) , deep venous thrombosis ( middle ) , and pulmonary embolism ( bottom ) . More women in the hormone therapy group than in the placebo group experienced deep venous thrombosis ( 25 compared with 9 ; relative hazard , 2.8 [ CI , 1.3 to 6.0 ] ; P = 0.008 ) and pulmonary embolism ( 11 compared with 4 ; relative hazard , 2.8 [ CI , 0.9 to 8.7 ] ; P = 0.08 ) ( Table 2 ) . Two women , both in the hormone therapy group , died of pulmonary embolism . The relative hazard was increased for idiopathic ( relative hazard , 3.1 [ CI , 0.8 to 11.3 ] ) and nonidiopathic venous thromboembolic events ( relative hazard , 2.5 [ CI , 1.2 to 5.3 ] ) . The overall results were unchanged in an as-treated analysis that was limited to women who reported taking more than 80 % of their assigned study medication ( relative hazard , 3.2 [ CI , 1.5 to 6.9 ] ; P = 0.003 ) . Table 2 . Venous Thrombolic Events by Treatment Group and Year of R and omization Table 2 shows relative hazards for venous thromboembolism by year since r and omization . The number of episodes of pulmonary
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 .