Carol Wasilauskas

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.

The Relationship of Biochemical Markers of Bone Turnover to Bone Density Changes in Postmenopausal Women: Results from the Postmenopausal Estrogen/Progestin Interventions (PEPI) Trial

We assessed the associations of eight bone turnover markers (BTMs) with baseline and 1‐year percentage changes in lumbar spine and hip bone mineral density (BMD) of 293 postmenopausal women undergoing treatment with hormone replacement therapy (HRT) or placebo using squared correlation coefficients (R2). In 239 women assigned to treatment with estrogen alone or with with estrogen plus progestins (active treatment), mean percentage changes for all markers decreased significantly and remained below baseline values through 3 years of study, whereas mean percentage changes for 54 women assigned to the placebo group showed no significant change from baseline in any marker. At baseline, age and body mass index (BMI) together accounted for 16% and 25% of the variance in spine and hip BMD, respectively. The telopeptide resorption marker, cross‐linked N‐telopeptide of type I collagen (NTX), alone accounted for 12% and 8% of variance, respectively. Another telopeptide, carboxy‐terminal telopeptide of type I collagen (Crosslaps), accounted for 8% and 7% of variance, respectively. A bone‐specific alkaline phosphatase (BALP‐2) accounted for 8% of variance at the spine and 5% at the hip. No other marker accounted for more than 5% of total variance at either site; adding either baseline NTX, Crosslaps, or BAP‐2 to regressions containing age and BMI increased R2 values at the spine and hip to about 22% and 28%, respectively. In the placebo group, baseline spine BMD accounted for 4% of the variance in 1‐year spine BMD percentage change, whereas baseline values for age and BMI accounted for 1% and 0% of the variance, respectively; none of the three accounted for more than 0% of hip BMD percentage change; Crosslaps and NTX contributed 5% and 4% to the variance in 1‐year spine BMD percentage change, but other markers accounted for < 2% of variance at the spine. At the hip, another BALP (BALP‐1) accounted for 4% of variance, but no other baseline marker except NTX accounted for more than 1% of variance. In the active treatment group, baseline values for age, BMI, and spine BMD together accounted for 13% of the percentage change in spine BMD and for 4% of the BMD change at the hip. No individual or pair of baseline markers significantly enhanced these R2 values, but addition of 1‐year percentage changes in some individual markers did significantly increase it. The largest R2 value was obtained by adding the percentage change in BALP‐2, which increased the R2 in spine BMD percentage change to 20% and that at the hip to 8%. Adding baseline and change variables for all eight markers to the regression increased R2 to 28% at the spine and 12% at the hip. Restricting the set of analyses to individuals who suppressed marker activity beyond the precision error for the measurement did not improve R2s for the regressions. When baseline marker values were stratified into quartiles, only NTX and osteocalcin showed significant relationships between quartile and change in spine BMD, and these did not reach significance at the hip. When the 1‐year change in markers was stratified into quartiles, significant relationships with percentage change in spine BMD were observed only for BALP phosphatases. We conclude that BTMs are not a surrogate for BMD to identify women with low bone mass and that they offer little useful information for predicting BMD changes for individual untreated or HRT‐treated postmenopausal women.

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.