OBJECTIVE:

To evaluate the efficacy of lower doses of conjugated equine estrogens (CEE) plus medroxyprogesterone acetate (MPA) for relieving vasomotor symptoms and vaginal atrophy.

DESIGN:

A randomized, double-blind, placebo-controlled trial (the Women's Health, Osteoporosis, Progestin, Estrogen study).

SETTING:

Study centers across the United States.

PATIENT(S):

Two thousand, six hundred, seventy-three healthy, postmenopausal women with an intact uterus, including an efficacy-evaluable population (n = 241 at baseline).Intervention(s): Patients received for 1 year (13 cycles; in milligrams per day) CEE, 0.625; CEE, 0.625 and MPA, 2.5; CEE, 0.45; CEE, 0.45 and MPA, 2.5; CEE, 0.45 and MPA, 1.5; CEE, 0.3; CEE, 0.3 and MPA, 1.5; or placebo.

MAIN OUTCOME MEASURE(S):

Number and severity of hot flushes and Papanicolaou smear with vaginal maturation index (VMI) to assess vaginal atrophy.

RESULT(S):

In the efficacy-evaluable population, reduction in vasomotor symptoms was similar with CEE of 0.625 mg/d and MPA of 2.5 mg/d (the most commonly prescribed doses) and all lower combination doses. CEE of 0.625 mg/d alleviated hot flushes more effectively than the lower doses of CEE alone. VMI improved in all active treatment groups.

CONCLUSION(S):

Lower doses of CEE plus MPA relieve vasomotor symptoms and vaginal atrophy as effectively as commonly prescribed doses.