Jacques E. Rossouw

Background and Aims: The association of fatty acids with coronary heart disease (CHD) has been examined, mainly through dietary measurements, and has generated inconsistent results due to measurement error. Large observational studies and randomized controlled trials have shown that plasma phospholipid fatty acids (PL-FA), especially those less likely to be endogenously synthesized, are good biomarkers of dietary fatty acids. Thus, PL-FA profiles may better predict CHD risk with less measurement error. Methods: We performed a matched case-control study of 2428 postmenopausal women nested in the Women’s Health Initiative Observational Study. Plasma PL-FA were measured using gas chromatography and expressed as molar percentage (moL %). Multivariable conditional logistic regression was used to calculate odds ratios (95% CIs) for CHD associated with 1 moL % change in PL-FA. Results: Higher plasma PL long-chain saturated fatty acids (SFA) were associated with increased CHD risk, while higher n-3 polyunsaturated fatty acids (PUFA) were associated with decreased risk. No significant associations were observed for very-long-chain SFA, monounsaturated fatty acids (MUFA), PUFA n-6 or trans fatty acids (TFA). Substituting 1 moL % PUFA n-6 or TFA with an equivalent proportion of PUFA n-3 were associated with lower CHD risk. Conclusions: Higher plasma PL long-chain SFA and lower PUFA n-3 were associated with increased CHD risk. A change in diet by limiting foods that are associated with plasma PL long-chain SFA and TFA while enhancing foods high in PUFA n-3 may be beneficial in CHD among postmenopausal women.

Standard analyses of data from case-control studies that are nested in a large cohort ignore information available for cohort members not sampled for the sub-study. This paper reviews several methods designed to increase estimation efficiency by using more of the data, treating the case-control sample as a two or three phase stratified sample. When applied to a study of coronary heart disease among women in the hormone trials of the Women’s Health Initiative, modest but increasing gains in precision of regression coefficients were observed depending on the amount of cohort information used in the analysis. The gains were particularly evident for pseudo- or maximum likelihood estimates whose validity depends on the assumed model being correct. Larger standard errors were obtained for coefficients estimated by inverse probability weighted methods that are more robust to model misspecification. Such misspecification may have been responsible for an important difference in one key regression coefficient estimated using the weighted compared with the more efficient methods.

We re-evaluate the Women's Health Initiative findings and their implications for clinical practice. Menopausal hormone therapy (HT) was effective for relief of vasomotor symptoms, and the risk of coronary heart disease (CHD) tended to be reduced in women close to menopause compared with the increased risk in women more distant from menopause. In recently menopausal women, short-term absolute risks of stroke and venous thromboembolism were small. Estrogen plus progestin therapy, but not estrogen therapy, increased the risk of breast cancer with a suggestion of greater risk when initiated close to the menopause. Menopausal HT increased the risk of CHD in women more than 20 years distant from menopause, particularly in women with vasomotor symptoms. It remains unknown whether the suggestive benefit for CHD in younger women will translate into benefits or harms if menopausal HT is continued into older ages. Based on Women's Health Initiative data, the use of menopausal HT for fewer than 5 years is a reasonable option for the relief of moderate to severe vasomotor symptoms. The risks seen with estrogen plus progestin therapy suggest careful periodic reassessment of the ongoing therapy needs for women taking estrogen plus progestin therapy. The more favorable profile of estrogen therapy allows for individualized management with respect to duration of use when symptoms persist. For both estrogen therapy and estrogen plus progestin therapy, the baseline risk profile of the individual woman needs to be taken into account. Menopausal HT is not suitable for long-term prevention of CHD given risks of stroke, venous thromboembolism, and breast cancer (for estrogen plus progestin therapy) found in both clinical trials and in observational studies.

Background—: Menopausal hormone therapy (MHT) increases the risk of coronary heart disease (CHD) in older women with elevated low-density lipoprotein (LDLC) levels. The endogenous estrogen receptor antagonist 27-hydroxycholesterol (27OHC) is correlated with LDLC levels and may block the beneficial effects of estrogen on the cardiovascular system. Methods and Results—: We conducted a nested case-control study in the Women's Health Initiative trials of 350 CHD cases and 813 matched controls to explore potential mediation by 27OHC of the dependence of the CHD risk elevation with MHT on LDLC. Baseline levels of 27OHC were not associated with CHD risk when LDLC was included in the multivariable models. The odds ratio for CHD associated with increased LDLC was 1.15 (95% confidence interval, 1.08–1.23) and was unchanged at 1.14 (95% confidence interval, 1.07–1.22) when 27OHC was added to the model. Baseline 27OHC did not interact with MHT on CHD risk ( P =0.81). In contrast, LDLC levels modified the effect of MHT on CHD risk ( P for interaction=0.02), and adding 27OHC did not affect this result. With the use of log scales, the effect of MHT on CHD increased linearly with increasing level of baseline LDLC, with a transition from no risk to increased risk at ≈3.36 mmol/L (130 mg/dL). Conclusions—: This study found that 27OHC does not independently increase the risk of CHD, does not modify the increased risk of CHD resulting from MHT, and does not mediate the interaction of LDLC with MHT. Measuring blood lipids may aid in counseling individual women about initiating MHT and cardiovascular risk mitigation. Clinical Trial Registration—: URL: http://www.clinicaltrials.gov . Unique identifier: NCT00000611.

Background and Purpose—: To test whether changes in plasma tissue factor pathway inhibitor (TFPI) levels or activated protein C resistance (normalized activated protein C resistance ratio [nAPCsr]) modify the increased risk of ischemic stroke due to postmenopausal hormone therapy. Methods—: Nested case–control study of 455 cases of ischemic stroke and 565 matched control subjects in the Women's Health Initiative trials of postmenopausal hormone therapy. Results—: Baseline free TFPI was associated with ischemic stroke risk (OR per SD increase, 1.17; 95% CI, 1.01–1.37; P =0.039), but baseline nAPCsr was not (OR per SD increase, 0.89; 95% CI, 0.75–1.05; P =0.15). Baseline TFPI levels and nAPCsr did not modify the effect of postmenopausal hormone therapy on ischemic stroke. Treatment-induced mean changes of −28% in free TFPI and +65% in nAPCsr did not change the risk of ischemic stroke (interaction P =0.452 and 0.971, respectively). In subgroup analyses, baseline nAPCsr was inversely associated with lacunar strokes (OR per SD increase, 0.74; 95% CI, 0.57–0.96; P =0.025) and baseline free TFPI interacted with treatment to increase large vessel atherosclerotic strokes ( P =0.008). Conclusions—: Procoagulant changes in TFPI or nAPCsr do not modify the increased ischemic stroke risk due to postmenopausal hormone therapy. Clinical Trial Registration—: URL: www.clinicaltrials.gov . Unique identifier: NCT 00000611.

Objective—: To test whether estrogen receptor polymorphisms modify the effects of postmenopausal hormone therapy on biomarkers and on risk of coronary heart disease events, stroke, or venous thromboembolism. Methods and Results—: The design was a nested case-control study in the Women's Health Initiative trials of postmenopausal hormone therapy. The study included all cases in the first 4 years: 359 cases of coronary heart disease, 248 of stroke, and 217 of venous thromboembolism. Six estrogen receptor-α polymorphisms and 1 estrogen receptor-β polymorphism were genotyped; 8 biomarkers known to be affected by hormone therapy were measured at baseline and 1 year after randomization. The polymorphisms were not associated with risk of vascular events and did not modify the increased risks of coronary heart disease, stroke, or venous thromboembolism due to hormone therapy. However, a reduced response of plasmin-antiplasmin to hormone therapy was noted for estrogen receptor-1 IVS1 (intron number 1)-354 (interaction P P =0.014) and estrogen receptor-1 IVS1-1415 (interaction P P =0.014). Conclusion—: Estrogen receptor polymorphisms reduce the effect of postmenopausal hormone therapy on plasmin-antiplasmin, a marker of coagulation and fibrinolysis. However, screening for estrogen receptor polymorphisms to identify women at less risk of adverse cardiovascular outcomes is not likely to be useful in making decisions about hormone therapy treatment.

The Women's Health Initiative (WHI) trials of postmenopausal hormone therapy (HT) tested whether the use of estrogen alone or combined with progestin would reduce the risk of coronary heart disease (CHD) in predominantly healthy postmenopausal women. The trial of conjugated equine estrogens plus medroxyprogesterone acetate in women with an intact uterus was stopped early because of an increase in cardiovascular events (CHD, stroke, and venous thromboembolism [VTE]) and in breast cancer.¹ The parallel trial of conjugated equine estrogens alone in hysterectomized women was also stopped early because of increased strokes and lack of benefit for CHD.² After publication of these findings, current recommendations state that HT should not be started or continued for the prevention of CHD.³