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ESTRING® (estradiol) Clinical Studies

CLINICAL STUDIES

Effects on vulvar and vaginal atrophy

Two controlled studies have demonstrated the efficacy of ESTRING (estradiol vaginal ring) in the treatment of postmenopausal urogenital symptoms due to estrogen deficiency.

In a U.S. study where ESTRING was compared with conjugated estrogens vaginal cream, no difference in efficacy between the treatment groups was found with respect to improvement in the physician's global assessment of vaginal symptoms (83 percent and 82 percent of patients receiving ESTRING and cream, respectively) and in the patient's global assessment of vaginal symptoms (83 percent and 82 percent of patients receiving ESTRING and cream, respectively) after 12 weeks of treatment. In an Australian study, ESTRING was also compared with conjugated estrogens vaginal cream and no difference in the physician's assessment of improvement of vaginal mucosal atrophy (79 percent and 75 percent for ESTRING and cream, respectively) or in the patient's assessment of improvement in vaginal dryness (82 percent and 76 percent for ESTRING and cream, respectively) after 12 weeks of treatment.

In the U.S. study, symptoms of dysuria and urinary urgency improved in 74 percent and 65 percent, respectively, of patients receiving ESTRING as assessed by the patient. In the Australian study, symptoms of dysuria and urinary urgency improved in 90 percent and 71 percent, respectively, of patients receiving ESTRING as assessed by the patient.

In both studies, ESTRING and conjugated estrogens vaginal cream had a similar ability to reduce vaginal pH levels and to mature the vaginal mucosa (as measured cytologically using the maturation index and/or the maturation value) after 12 weeks of treatment. In supportive studies, ESTRING was also shown to have a similar significant treatment effect on the maturation of the urethral mucosa.

Endometrial overstimulation, as evaluated in non-hysterectomized patients participating in the U.S. study by the progestogen challenge test and pelvic sonogram, was reported for none of the 58 (0 percent) patients receiving ESTRING and 4 of the 35 patients (11 percent) receiving conjugated estrogens vaginal cream.

Of the U.S. women who completed 12 weeks of treatment, 95 percent rated product comfort for ESTRING as excellent or very good compared with 65 percent of patients receiving conjugated estrogens vaginal cream, 95 percent of ESTRING patients judged the product to be very easy or easy to use compared with 88 percent of cream patients, and 82 percent gave ESTRING an overall rating of excellent or very good compared with 58 percent for the cream.

Women's Health Initiative Studies

The WHI enrolled approximately 27,000 predominantly healthy postmenopausal women in two substudies to assess the risks and benefits of daily oral CE (0.625 mg)-alone or in combination with MPA (2.5 mg) compared to placebo in the prevention of certain chronic diseases. The primary endpoint was the incidence of coronary heart disease (CHD) (defined as nonfatal MI, silent MI and CHD death), with invasive breast cancer as the primary adverse outcome. A "global index" included the earliest occurrence of CHD, invasive breast cancer, stroke, PE, endometrial cancer (only in the CE plus MPA substudy), colorectal cancer, hip fracture, or death due to other cause. These substudies did not evaluate the effects of CE or CE plus MPA on menopausal symptoms.

WHI Estrogen-Alone Substudy

The WHI estrogen-alone substudy was stopped early because an increased risk of stroke was observed, and it was deemed that no further information would be obtained regarding the risks and benefits of estrogen-alone in predetermined primary endpoints. Results of the estrogen-alone substudy, which included 10,739 women (average 63 years of age, range 50 to 79; 75.3 percent White, 15.1 percent Black, 6.1 percent Hispanic, 3.6 percent Other), after an average follow-up of 7.1 years are presented in Table 2.

TABLE 2 - Relative and Absolute Risk Seen in the Estrogen-Alone Substudy of WHI*
EventRelative Risk CE vs. Placebo
(95% nCI)
CE
n = 5,310
Placebo
n = 5,429
Absolute Risk per 10,000 Women-Years
*
Adapted from numerous WHI publications. WHI publications can be viewed at https://www.nhlbi.nih.gov/whi/.
Nominal confidence intervals unadjusted for multiple looks and multiple comparisons.
Results are based on centrally adjudicated data for an average follow-up of 7.1 years.
§
Not included in "global index".
Results are based on an average follow-up of 6.8 years.
#
All deaths, except from breast or colorectal cancer, definite or probable CHD, PE or cerebrovascular disease.
Þ
A subset of the events was combined in a "global index" defined as the earliest occurrence of CHD events, invasive breast cancer, stroke, pulmonary embolism, endometrial cancer, colorectal cancer, hip fracture, or death due to other causes.
CHD events0.95 (0.78–1.16)5457
  Non-fatal MI0.91 (0.73–1.14)4043
  CHD death1.01 (0.71–1.43)1616
All Stroke1.33 (1.15–1.68)4533
  Ischemic stroke1.55 (1.19–2.01)3825
Deep vein thrombosis,§1.47 (1.06–2.06)2315
Pulmonary embolism1.37 (0.90–2.07)1410
Invasive breast cancer0.80 (0.62–1.04)2834
Colorectal cancer1.08 (0.75–1.55)1716
Hip fracture0.65 (0.45–0.94)1219
Vertebral fractures,§0.64 (0.44–0.93)1118
Lower arm/wrist fractures,§0.58 (0.47–0.72)3559
Total fractures,§0.71 (0.64–0.80)144197
Death due to other causes,#1.08 (0.88–1.32)5350
Overall mortality,§1.04 (0.88–1.22)7975
Global indexÞ1.02 (0.92–1.13)206201

For those outcomes included in the WHI "global index" that reached statistical significance, the absolute excess risk per 10,000 women-years in the group treated with CE-alone was 12 more strokes, while the absolute risk reduction per 10,000 women-years was 7 fewer hip fractures. The absolute excess risk of events included in the "global index" was a non-significant 5 events per 10,000 women-years. There was no difference between the groups in terms of all-cause mortality.

No overall difference for primary CHD events (nonfatal MI, silent MI and CHD death) and invasive breast cancer incidence in women receiving CE-alone compared with placebo was reported in final centrally adjudicated results from the estrogen-alone substudy, after an average follow-up of 7.1 years.

Centrally adjudicated results for stroke events from the estrogen-alone substudy, after an average follow-up of 7.1 years, reported no significant differences in distribution of stroke subtypes or severity, including fatal strokes, in women receiving CE-alone compared to placebo. Estrogen alone increased the risk for ischemic stroke, and this excess risk was present in all subgroups of women examined (see Table 2).

Timing of initiation of estrogen-alone therapy relative to the start of menopause may affect the overall risk benefit profile. The WHI estrogen-alone substudy stratified by age showed in women 50 to 59 years of age a non-significant trend toward reduced risk for CHD [hazard ratio (HR) 0.63 (95 percent CI, 0.36–1.09)] and overall mortality [HR 0.71 (95 percent CI, 0.46–1.11)].

WHI Estrogen Plus Progestin Substudy

The WHI estrogen plus progestin substudy was also stopped early. According to the predefined stopping rule, after an average follow-up of 5.6 years of treatment, the increased risk of breast cancer and cardiovascular events exceeded the specified benefits included in the "global index." The absolute excess risk of events included in the "global index" was 19 per 10,000 women-years.

For those outcomes included in the WHI "global index" that reached statistical significance after 5.6 years of follow-up, the absolute excess risks per 10,000 women-years in the group treated with CE plus MPA were 7 more CHD events, 8 more strokes, 10 more PEs, and 8 more invasive breast cancers, while the absolute risk reductions per 10,000 women-years were 6 fewer colorectal cancers and 5 fewer hip fractures.

Results of the CE plus MPA substudy, which included 16,608 women (average 63 years of age, range 50 to 79; 83.9 percent White, 6.8 percent Black, 5.4 percent Hispanic, 3.9 percent Other), are presented in Table 3. These results reflect centrally adjudicated data after an average follow-up of 5.6 years.

TABLE 3 - Relative and Absolute Risk Seen in the Estrogen Plus Progestin Substudy of WHI at an Average of 5.6 Years*,
EventRelative Risk CE/MPA vs. Placebo
(95% nCI)
CE/MPA
n = 8,506
Placebo
n = 8,102
Absolute Risk per 10,000 Women-Years
*
Adapted from numerous WHI publications. WHI publications can be viewed at https://www.nhlbi.nih.gov/whi/.
Results are based on centrally adjudicated data.
Nominal confidence intervals unadjusted for multiple looks and multiple comparisons.
§
Not included in "global index".
Includes metastatic and non-metastatic breast cancer with the exception of in situ breast cancer.
#
All deaths, except from breast or colorectal cancer, definite or probable CHD, PE or cerebrovascular disease.
Þ
A subset of the events was combined in a "global index", defined as the earliest occurrence of CHD events, invasive breast cancer, stroke, pulmonary embolism, endometrial cancer, colorectal cancer, hip fracture, or death due to other causes.
CHD events1.23 (0.99–1.53)4134
  Non-fatal MI1.28 (1.00–1.63)3125
  CHD death1.10 (0.70–1.75)88
All Stroke1.31 (1.03–1.68)3325
  Ischemic stroke1.44 (1.09–1.90)2618
Deep vein thrombosis§1.95 (1.43–2.67)2613
Pulmonary embolism2.13 (1.45–3.11)188
Invasive breast cancer1.24 (1.01–1.54)4133
Colorectal cancer0.61 (0.42–0.87)1016
Endometrial cancer§0.81 (0.48–1.36)67
Cervical cancer§1.44 (0.47–4.42)21
Hip fracture0.67 (0.47–0.96)1116
Vertebral fractures§0.65 (0.46–0.92)1117
Lower arm/wrist fractures§0.71 (0.59–0.85)4462
Total fractures0.76 (0.69–0.83)152199
Overall mortality#1.00 (0.83–1.19)5252
Global IndexÞ1.13 (1.02–1.25)184165

Timing of initiation of estrogen plus progestin therapy relative to the start of menopause may affect the overall risk benefit profile. The WHI estrogen plus progestin substudy stratified by age showed in women 50 to 59 years of age a non-significant trend toward reduced risk for overall mortality [HR 0.69 (95 percent CI, 0.44–1.07)].

Women's Health Initiative Memory Study

The WHIMS estrogen-alone ancillary study of WHI enrolled 2,947 predominantly healthy hysterectomized postmenopausal women 65 to 69 years of age (45 percent were 65 to 69 years of age, 36 percent were 70 to 74 years of age, and 19 percent were 75 years of age and older) to evaluate the effects of daily CE (0.625 mg)-alone on the incidence of probable dementia (primary outcome) compared to placebo.

After an average follow-up of 5.2 years, the relative risk of probable dementia for CE-alone versus placebo was 1.49 (95 percent CI, 0.83–2.66). The absolute risk of probable dementia for CE-alone versus placebo was 37 versus 25 cases per 10,000 women-years. Probable dementia as defined in the study included Alzheimer's disease (AD), vascular dementia (VaD) and mixed type (having features of both AD and VaD). The most common classification of probable dementia in the treatment group and the placebo group was AD. Since the ancillary study was conducted in women 65 to 79 years of age, it is unknown whether these findings apply to younger postmenopausal women. (See BOXED WARNINGS, WARNINGS, Probable Dementia, and PRECAUTIONS, Geriatric Use.)

The WHIMS ancillary study enrolled 4,532 predominantly healthy postmenopausal women 65 years of age and older (47 percent were 65 to 69 years of age, 35 percent were 70 to 74 years of age, and 18 percent were 75 years of age and older) to evaluate the effects of daily CE (0.625 mg) plus MPA (2.5 mg) on the incidence of probable dementia (primary outcome) compared to placebo.

After an average follow-up of 4 years, the relative risk of probable dementia for CE plus MPA versus placebo was 2.05 (95 percent CI, 1.21–3.48). The absolute risk of probable dementia for CE plus MPA versus placebo was 45 versus 22 cases per 10,000 women-years. Probable dementia as defined in the study included AD, VaD and mixed types (having features of both AD and VaD). The most common classification of probable dementia in the treatment group and the placebo group was AD. Since the ancillary study was conducted in women 65 to 79 years of age, it is unknown whether these findings apply to younger postmenopausal women. (See WARNINGS, Probable Dementia and PRECAUTIONS, Geriatric Use.)

When data from the two populations were pooled as planned in the WHIMS protocol, the reported overall relative risk for probable dementia was 1.76 (95 percent CI, 1.19–2.60). Differences between groups became apparent in the first year of treatment. It is unknown whether these findings apply to younger postmenopausal women. (See WARNINGS, Probable Dementia, and PRECAUTIONS, Geriatric Use.)

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