Timing hypothesis (menopausal hormone therapy)

The timing hypothesis is a theory in menopausal hormone therapy that suggests the timing of hormone therapy initiation can influence its effectiveness and risks. This hypothesis is based on the observation that the effects of hormone therapy can vary depending on the time of initiation relative to menopause onset.

Background

The timing hypothesis was proposed to explain the conflicting results of the Women's Health Initiative (WHI) and the Heart and Estrogen/progestin Replacement Study (HERS). The WHI found that hormone therapy increased the risk of coronary heart disease (CHD), while the HERS found no effect. The timing hypothesis suggests that these discrepancies may be due to differences in the timing of hormone therapy initiation relative to menopause onset.

Evidence

Several studies have provided evidence supporting the timing hypothesis. For example, a reanalysis of the WHI data found that women who started hormone therapy closer to menopause had a lower risk of CHD than those who started later. Similarly, a meta-analysis of 23 randomized controlled trials found that hormone therapy initiated within 10 years of menopause onset was associated with a reduced risk of CHD and all-cause mortality.

Criticism

Despite the evidence supporting the timing hypothesis, it has been criticized for several reasons. Some argue that the evidence is not strong enough to change clinical practice, while others point out that the hypothesis does not explain all of the discrepancies between the WHI and HERS results. Furthermore, some researchers have raised concerns about the potential risks of hormone therapy, regardless of when it is initiated.

See also

• Menopause
• Hormone replacement therapy
• Women's Health Initiative
• Heart and Estrogen/progestin Replacement Study