Valery T. Miller

The Efficacy of Intensive Dietary Therapy Alone or Combined with Lovastatin in Outpatients with Hypercholesterolemia

BACKGROUND A diet low in saturated fat and cholesterol is the standard initial treatment for hypercholesterolemia. However, little quantitative information is available about the efficacy of dietary therapy in clinical practice or about the combined effects of diet and drug therapy. METHODS One hundred eleven outpatients with moderate hypercholesterolemia were treated at five lipid clinics with the National Cholesterol Education Program Step 2 diet (which is low in fat and cholesterol) and lovastatin (20 mg once daily), both alone and together. A diet high in fat and cholesterol and a placebo identical in appearance to the lovastatin were used as the respective controls. Each of the 97 patients completing the study (58 men and 39 women) underwent four consecutive nine-week periods of treatment according to a randomized, balanced design: a high-fat diet-placebo period, a low-fat diet-placebo period, a high-fat diet-lovastatin period, and a low-fat diet-lovastatin period. RESULTS The level of low-density lipoprotein (LDL) cholesterol was a mean of 5 percent (95 percent confidence interval, 3 to 7 percent) lower during the low-fat diet than during the high-fat diet (P < 0.001). With lovastatin therapy as compared with placebo, the reduction was 27 percent. Together, the low-fat diet and lovastatin led to a mean reduction of 32 percent in the level of LDL cholesterol. The level of high-density lipoprotein (HDL) cholesterol fell by 6 percent (95 percent confidence interval, 4 to 8 percent) during the low-fat diet (P < 0.001) and rose by 4 percent during treatment with lovastatin (P < 0.001). The ratio of LDL to HDL cholesterol and the level of total triglycerides were reduced by lovastatin (P < 0.001), but not by the low-fat diet. CONCLUSIONS The effects of the low-fat-low-cholesterol diet and lovastatin on lipoprotein levels were independent and additive. However, the reduction in LDL cholesterol produced by the diet was small, and its benefit was possibly offset by the accompanying reduction in the level of HDL cholesterol.

Effect of Postmenopausal Hormone Therapy on Lipoprotein(a) Concentration

BACKGROUND Postmenopausal hormone therapy has been reported to decrease levels of lipoprotein (Lp)(a) in cross-sectional studies and small or short-term longitudinal studies. We report findings from a large, prospective, placebo-controlled clinical trial that allows a broad characterization of these effects for four regimens of hormone therapy. METHODS AND RESULT The Postmenopausal Estrogen/Progestin Interventions study was a 3-year, placebo-controlled, randomized clinical trial to assess the effect of hormone regimens on cardiovascular disease risk factors in postmenopausal women 45 to 65 years of age. The active regimens were conjugated equine estrogens therapy at 0.625 mg daily, alone or in combination with each of three regimens of progestational agents: medroxyprogesterone acetate (MPA) at 2.5 mg daily (ie, continuous MPA), MPA at 10 mg days 1 to 12 (ie, cyclical MPA), and micronized progesterone at 200 mg days 1 to 12. Plasma levels of Lp(a) were measured at baseline (n = 366), 12 months (n = 354), and 36 months (n = 342). Assignment to hormone therapy resulted in a 17% to 23% average drop in Lp(a) concentrations relative to placebo (P<.0001), which was maintained across 3 years of follow-up. No significant differences were observed among the four active arms. Changes in Lp(a) associated with hormone therapy were positively correlated with changes in LDL cholesterol, total cholesterol, apolipoprotein B, and fibrinogen levels and were similar across subgroups defined by age, weight, ethnicity, and prior hormone use. CONCLUSIONS Postmenopausal estrogen therapy, with or without concomitant progestin regimens, produces consistent and sustained reductions in plasma Lp(a) concentrations.

Effects of Conjugated Equine Estrogen With and Without Three Different Progestogens on Lipoproteins, High-density Lipoprotein Subfractions, and Apolipoprotein A-i

The effects of conjugated equine estrogen and subsequent cyclical progestogen supplementation on lipoprotein and apolipoprotein A-I levels were investigated in three groups of postmenopausal women. Unopposed conjugated equine estrogen (0.625 mg) lowered total cholesterol 4-8% and low-density lipoprotein (LDL) cholesterol 12-19% below pre-treatment levels in all three groups. Levels of highdensity lipoprotein (HDL) cholesterol and apolipoprotein A-I were increased 9-13 and 9-18%, respectively, with unopposed estrogen. The increase in HDL cholesterol was mainly due to increases in the high-density lipoprotein2 (HDL2) subfraction. Addition of medroxyprogesterone acetate, norethindrone acetate, or d,l-norgestrel at doses shown previously to provide protection against endometrial hyperplasia reversed some of the beneficial estrogen effects, reducing levels of HDL cholesterol 14-17%, HDL2 cholesterol 22-37%, and apolipoprotein A-I 11-15% from those obtained cholesterol 22-37%, and apolipoprotein A-I 11-15% from those obtained with unopposed estrogen. The LDL cholesterol levels fell 12-19% with unopposed estrogen but remained 7-12% below baseline when progestogens were added. These observations demonstrate that after 3 months of treatment, all three progestogens reversed some of the favorable effects of unopposed estrogen on lipoproteins but permitted a continued modest reduction in LDL cholesterol.

Efficacy and Tolerability of Low-dose Simvastatin and Niacin, Alone and in Combination, in Patients With Combined Hyperlipidemia: A Prospective Trial.

Background: Combination lipid-lowering therapy may be desirable in patients with elevated low-density lipoprotein cholesterol, high triglycerides, and low high-density lipoprotein cholesterol. This study was conducted to determine the lipid-lowering efficacy of the combination of low-dose simvastatin and niacin in patients with combined hyperlipidemia and low high-density lipoprotein cholesterol. Methods and Results: In this multicenter, prospective, randomized trial, 180 patients with hyper cholesterolemia and hypertriglyceridernia and/or low high-density lipoprotein cholesterol were randomized to combination simvastatin (10 mg/day) and niacin (0.75 g/day) or to either drug alone for 9 weeks. The dose of niacin was doubled (from 0.75 g/day to 1.5 g/day) in both the combination and niacin arms for the remaining 8 weeks. The combination of simvastatin, 10 mg/day, and niacin, 1.5 g/day, reduced total. low-density lipoprotein, and very low-density lipoprotein cholesterol and triglycerides by 248, 29%, 45%, and 31%, respectively, while increasing high-density lipoprotein cholesterol by 31%. The addition of niacin to simvastatin did not enhance the low-density lipoprotein cholesterol-lowering effect of simvastatin; however, the combination was more effective than either monotherapy at raising high-density lipoprotein cholesterol and lowering very low-density lipoprotein cholesterol (P <.05). More patients discontinued treatment because of an adverse event in the niacin (P <.03) and combination groups (P =.06) than the simvastatin group. Conclusions: Treatment of patients with combined hyperlipidemia and/or low high-density lipoprotein with combination low-dose simvastatin and niacin resulted in large reductions in total, low-density lipoprotein, and very low-density lipoprotein cholesterol and increases in HDL cholesterol. Although the combination was well tolerated in the current trial, its safety needs to be evaluated in larger trials of longer duration.

Progestins and oral contraceptive-induced lipoprotein changes: A prospective study

In order to determine the effects on plasma lipoproteins of oral contraceptives containing progestins with varying androgenic potency, 136 healthy women were randomized into 3 groups and followed prospectively for one year while receiving either 50 mcg ethinyl estradiol and 1.0 mg ethynodiol diacetate (EED), 50 mcg ethinyl estradiol and 1.0 mg norethindrone acetate (ENA), or 50 mcg ethinyl estradiol and 0.5 mg d-1 norgestrel (ENG). Comparison was made to a self-selected group of 50 women using alternative means of contraception. Plasma cholesterol increased by 7-9% and triglycerides by 32-57% in all 3 groups (p less than 0.05). ENG use resulted in other significant lipoprotein changes including an 18% increase in low density lipoprotein cholesterol (LDL-C), a 13% fall in high density lipoprotein cholesterol (HDL-C) and a 27% decline in HDL2 cholesterol (HDL2-C) (p less than 0.05). Apoprotein A-I (Apo A-I) increased by 9% with ENA and by 11% with EED (p less than 0.05), but did not change significantly with ENG. This prospective study demonstrates that in oral contraceptive agents with identical estrogen, progestins with different androgenic potency produce major and different changes in plasma lipoproteins.

Estrogen Replacement Therapy and Coagulation: Relationship to Lipid and Lipoprotein Changes

Objective To examine the relationship of estrogen-induced changes in lipids and lipoproteins with alterations in the coagulation system. Methods Coagulation and lipid indices were measured in 31 postmenopausal women, ages 40–60 years, after a 3-month course of 0.625-mg conjugated equine estrogen. We analyzed changes in variables from baseline to 3 months using t tests for paired samples or the Wilcoxon matched-pairs signed-rank test. Results Unopposed estrogen replacement therapy produced statistically significant decreases in antithrombin-III antigen (P = .006) and activity (P = .001) and total protein S (P = .003) and a significant increase in protein C antigen (P = .017). C4b-binding protein also decreased significantly from baseline to 3 months (P < .001). Mean fibrinogen level decreased by 18.2 mg/dL, not a statistically significant change (P = .213). Estrogen produced the expected statistically significant changes in lipids and lipoproteins. Several correlations between changes in lipids and lipoproteins and coagulation indices were statistically significant. Protein C antigen and activity changes correlated directly with high-density lipoprotein cholesterol changes (r = .52, P ≤ .005; r = .38, P ≤ .05; respectively), and protein C antigen also correlated directly with increases in apoprotein A-I (r = .54, P ≤ .005). Triglyceride changes correlated directly with changes in protein C antigen (r = .36, P ≤ .05) and activity (r = .49, P ≤ .005) and inversely with C4b-binding protein (r = − .58, P ≤ .01). Apoprotein B was correlated with free protein S (r = .48, P ≤ .01). Conclusions Although several estrogen-induced changes may decrease atherosclerotic potential and hypercoagulability, others may promote coagulability. These divergent effects may be manipulated pharmacologically by other estrogen compounds or by the addition of various progestins.

A Randomized Multicenter Trial Comparing the Efficacy of Simvastatin and Fluvastatin

Background: Inhibitors of hydroxymethylglutaryl co-enzyme A reductase are widely used for the treatment of hypercholesterolemia. Physicians and third-party payers need an accurate measure of their relative potency and hypolipidemic efficacy. We have therefore compared simvastatin against fluvastatin, the newest member of this class. Methods and Results: One hundred fifty-eight hypercholesterolemic patients in seven United States lipid clinics participated in this balanced double-blind incomplete block study. After a placebo-diet run-in period, patients received treatment with active drug for three con secutive 5-week periods, with measurement of lipids in a NHLBI-CDC standardized central laboratory at the end of each period. Each patient was randomly assigned to three of the fol lowing five treatments: simvastatin 5 mg, 10 mg, and 20 mg and fluvastatin 20 mg and 40 mg. The mean percent reductions in low density lipoprotein cholesterol from baaeline were 21, 27, 32, 16, and 23 respectively. The simvastatin/fluvastatin milligram potency ratio was 6.8 (95% CI, 5.3-9.3). At the same 20 mg dosage, simvastatin produced an effect on LDL cholesterol approximately double that of fluvastatin and resulted in 46% of patients achieving their National Cholesterol Education Program low density lipoprotein cholesterol target levels, compared to 12% for fluvastatin. Conclusions. Fluvastatin at its maximal dose of 40 mg daily is approximately equivalent to simvastatin 5 mg daily. Higher doses of simvastatin are considerably more effective in the treatment of primary hypercholesterolemia.

Age at menopause in women participating in the postmenopausal estrogen/progestins interventions (PEPI) trial: An example of bias introduced by selection criteria

Our objective is to illustrate the bias introduced in assessing factors associated with age at menopause when the population sample has been selected using restricted criteria, i.e. number of years since menopause, by using a cross-sectional analysis of baseline data from a population-based randomized clinical trial. The participants were women who participated in the Postmenopausal Estrogen/Progestins Intervention (PEPI) trial, had not had a hysterectomy, were between 45 and 64 years old, and were menopausal for at least 1 but not greater than 10 years. The outcome measures were self-reported age at menopause and factors thought to be associated with it, including smoking, alcohol use, oral contraceptive use, number of pregnancies, education, income, body mass index, waist-hip ratio, thigh girth, and systolic and diastolic blood pressures. At entry, the mean age of the 601 women was 56.2 years. Mean age at menopause was 51.0 years. Chronologic (current) age was strongly correlated with age at menopause (r = 0.74, p = 0.0001). In bivariate analyses, factors associated with younger age at menopause were ever-use of cigarettes, former oral contraceptive use, and higher thigh girth; factors associated with later age at menopause were greater number of pregnancies, higher waist-hip ratio, and higher systolic blood pressure. After stratification by 5-year age intervals, these associations were no longer statistically significant. Because of restricted sampling, an artificial association was observed between chronologic age and age at time of menopause. This artifact made it difficult to distinguish between factors associated with chronologic age and those that may be independently associated with menopause. Failure to recognize this bias could lead to erroneous conclusions.

Effects of exercise and estrogen therapy on lipid profiles of postmenopausal women.

PURPOSE We compared the effects of aerobic exercise training on lipid and lipoprotein levels in 18 postmenopausal women who were (N = 8) or were not (N = 10) receiving estrogen replacement therapy (ERT). METHODS Each group was tested for lipids, diet recall and VO2max before and after a 12 wk exercise program, consisting of 30-50 min of an aerobic activity at 75-85% of VO2max, 3-4 sessions per week. RESULTS Both groups increased VO2max by 8% and neither group changed their diet. The ERT group had higher levels of triglycerides and lower levels of low density lipoprotein (LDL-C) (P < 0.01) before training. There were no mean group changes in any of the lipid variables with training. However, individual changes in LDL-C and Total Cholesterol (TC) were strongly related to baseline weight in the nonestrogen group (r = 109.91, r = -0.82) but not in ERT (r = -0.30, r = -0.51). Subsequently, all subjects were redivided into two groups based on BMI (< or = 27 or > or = 27) regardless of ERT status. TC decreased significantly (P < 0.05) in the < or = 27 BMI group. CONCLUSIONS Exercise training had little effect on the lipid profiles of the ERT and the nonestrogen groups, but body weight seems to be a modulating factor. Heavier subjects did not respond as favorably to 12 wk of exercise training as postmenopausal women with less body mass, regardless of the presence of exogenous estrogen.

Effect of hormone replacement therapy on the validity of the Friedewald equation in postmenopausal women: the postmenopausal estrogen/progestins interventions (PEPI) trial.

The Friedewald equation is often used to estimate low-density lipoprotein cholesterol (LDL-C). Hormone therapy is known to raise triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) and alter lipid contents of lipoproteins. We compared Friedewald estimated LDL-C to measured LDL-C in PEPI participants on placebo or four different hormone treatment groups. At baseline, the 0.2 coefficient for triglyceride (TG) was accurate for all five treatment groups. Among women who took >80% of their pills and whose TG was <4.5 mmol/l (400 mg/dl), LDL-C was underestimated for 69-82% of the participants in the active treatment groups, compared to 50% in the placebo group. After 3 years of therapy, the TG coefficient that offered a better fit of the Friedewald equation in the active treatment groups was 0.39 for the equation in mmol/l (0.17 for the equation in mg/dl). Using this coefficient is clearly warranted for greater accuracy in research studies.