Lipoprotein particle concentrations may explain the absence of coronary protection in the women's health initiative hormone trials.
OBJECTIVE
The Women's Health Initiative randomized hormone trials unexpectedly demonstrated an increase in early coronary events. In an effort to explain this finding, we examined lipoprotein particle concentrations and their interactions with hormone therapy in a case-control substudy.


RESULTS
We randomized 16 608 postmenopausal women with intact uterus to conjugated estrogens 0.625 mg with medroxyprogesterone acetate 2.5 mg daily or to placebo, and 10 739 women with prior hysterectomy to conjugated estrogens 0.625 mg daily or placebo, and measured lipoprotein subclasses by nuclear magnetic resonance spectroscopy at baseline and year 1 in 354 women with early coronary events and matched controls. Postmenopausal hormone therapy raised high-density lipoprotein cholesterol and particle concentration and reduced low-density lipoprotein cholesterol (LDL-C; all P<0.001 versus placebo). In contrast, neither unopposed estrogen nor estrogen with progestin lowered low-density lipoprotein particle concentration (LDL-P).


CONCLUSIONS
Postmenopausal hormone therapy-induced reductions in LDL-C were not paralleled by favorable effects on LDL-P. This finding may account for the absence of coronary protection conferred by estrogen in the randomized hormone trials.
Hsia
Judith
J
Department of Medicine, George Washington University, Washington, DC, USA. judith.hsia@astrazeneca.com
Otvos
James D
JD
Rossouw
Jacques E
JE
Wu
LieLing
L
Wassertheil-Smoller
Sylvia
S
Hendrix
Susan L
SL
Robinson
Jennifer G
JG
Lund
Bernedine
B
Kuller
Lewis H
LH
D000368:Aged; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D003327:Coronary Disease / Q000097:blood / Q000139:chemically induced*; D015536:Down-Regulation; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D004966:Estrogens, Conjugated (USP) / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007044:Hysterectomy; D008074:Lipoproteins / Q000097:blood*; D009682:Magnetic Resonance Spectroscopy; D017258:Medroxyprogesterone Acetate / Q000009:adverse effects*; D008875:Middle Aged; D016017:Odds Ratio; D017698:Postmenopause; D018570:Risk Assessment; D016896:Treatment Outcome; D015854:Up-Regulation; D016387:Women's Health
D015415:Biomarkers; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D004966:Estrogens, Conjugated (USP); D008074:Lipoproteins; D017258:Medroxyprogesterone Acetate