Context

The Women's Health Initiative (WHI) hormone therapy (HT) trials showed protection against hip and total fractures, but a later observational report suggested loss of benefit and a rebound increased risk after cessation of HT.

Objective

The purpose of this study was to examine fractures after discontinuation of HT.

Design and setting

Two placebo-controlled randomized trials served as the study setting.

Patients

Study patients included WHI participants (N = 15,187) who continued active HT or placebo through the intervention period and who did not take HT in the postintervention period.

Interventions

Trial interventions included conjugated equine estrogen (CEE) plus medroxyprogesterone acetate (MPA) in naturally menopausal women and CEE alone in women with prior hysterectomy.

Main outcome measures

Total fractures and hip fractures through 5 years after discontinuation of HT were recorded.

Results

Hip fractures were infrequent (∼2.5 per 1000 person-years); this finding was similar between trials and in former HT and placebo groups. There was no difference in total fractures in the CEE + MPA trial for former HT vs former placebo users (28.9 per 1000 person-years and 29.9 per 1000 person-years, respectively; hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.87 to 1.09; P = 0.63); however, in the CEE-alone trial, total fractures were higher in former placebo users (36.9 per 1000 person-years) compared with the former active group (31.1 per 1000 person-years), a finding that was suggestive of a residual benefit of CEE against total fractures (HR, 0.85; 95% CI, 0.73 to 0.98; P = 0.03).

Conclusions

We found no evidence for increased fracture risk, either sustained or transient, for former HT users compared with former placebo users after stopping HT. There was residual benefit for total fractures in former HT users from the CEE-alone study.

Context

In the Women's Health Initiative trial of estrogen-plus-progestin therapy, women assigned to active treatment had fewer fractures.

Objective

To test the hypothesis that the relative risk reduction of estrogen plus progestin on fractures differs according to risk factors for fractures.

Design, setting, and participants

Randomized controlled trial (September 1993-July 2002) in which 16 608 postmenopausal women aged 50 to 79 years with an intact uterus at baseline were recruited at 40 US clinical centers and followed up for an average of 5.6 years.

Intervention

Women were randomly assigned to receive conjugated equine estrogen, 0.625 mg/d, plus medroxyprogesterone acetate, 2.5 mg/d, in 1 tablet (n = 8506) or placebo (n = 8102).

Main outcome measures

All confirmed osteoporotic fracture events that occurred from enrollment to discontinuation of the trial (July 7, 2002); bone mineral density (BMD), measured in a subset of women (n = 1024) at baseline and years 1 and 3; and a global index, developed to summarize the balance of risks and benefits to test whether the risk-benefit profile differed across tertiles of fracture risk.

Results

Seven hundred thirty-three women (8.6%) in the estrogen-plus-progestin group and 896 women (11.1%) in the placebo group experienced a fracture (hazard ratio [HR], 0.76; 95% confidence interval [CI], 0.69-0.83). The effect did not differ in women stratified by age, body mass index, smoking status, history of falls, personal and family history of fracture, total calcium intake, past use of hormone therapy, BMD, or summary fracture risk score. Total hip BMD increased 3.7% after 3 years of treatment with estrogen plus progestin compared with 0.14% in the placebo group (P<.001). The HR for the global index was similar across tertiles of the fracture risk scale (lowest fracture risk tertile, HR, 1.20; 95% CI, 0.93-1.58; middle tertile, HR, 1.23; 95% CI, 1.04-1.46; highest tertile, HR, 1.03; 95% CI, 0.88-1.24) (P for interaction =.54).

Conclusions

This study demonstrates that estrogen plus progestin increases BMD and reduces the risk of fracture in healthy postmenopausal women. The decreased risk of fracture attributed to estrogen plus progestin appeared to be present in all subgroups of women examined. When considering the effects of hormone therapy on other important disease outcomes in a global model, there was no net benefit, even in women considered to be at high risk of fracture.