An article published in the November 2009 issue of The American Journal of Medicine, reports that researchers conducting a meta-analysis of the available data using Bayesian methods concluded that hormone replacement therapy (HRT) almost undoubtedly decreases mortality in younger postmenopausal women. For over sixty years, HRT has been in widespread use to treat menopausal estrogen deficiency. Over the years, numerous observational studies indicated that HRT use by younger postmenopausal women was linked with a significant reduction in total mortality. There was existing substantiation that routine use of HRT increases longevity in postmenopausal women. However, the 2002 publication of an important study, the Women’s Health Initiative (WHI), indicated increased risk for certain outcomes in older women, without increasing mortality. This initiated a debate regarding the potential benefits or harms of HRT.

Bayesian analysis uses prior data and updates it with new information, and then makes statistical inferences. The authors joined results from nineteen randomized trials. It included age-specific data from the WHI, with 16,000 younger postmenopausal women (average age of 55 years) monitored for 83,000 patient-years. It showed a mortality relative risk of 0.73. When data from eight observational studies were added to the analysis, the resultant relative risk was 0.72. Using Bayesian analysis to synthesize the available data, the probability of a mortality benefit in this population was 1.0. As a result, this suggests that the probability of the hypothesis that hormone therapy reduces total mortality in younger women is essentially 1.

Shelley R. Salpeter, MD writes “It is clear that these findings need to be interpreted in the light of potential benefits and harms of hormone therapy. The available evidence indicates that hormone therapy in younger postmenopausal women increases the risk of breast cancer and pulmonary embolism and reduces the risk of cardiovascular events, colon cancer, and hip fracture. The cardiovascular benefit is a result of a small absolute increase in stroke and a greater reduction in coronary heart disease events. The total mortality benefit for younger women seen in the randomized trials and observational studies indicates that the reduction in deaths from coronary heart disease, fracture, and colon cancer outweighed the increase in deaths from breast cancer, stroke and pulmonary embolism. In addition to this mortality benefit, hormone therapy in younger women provides an improvement in quality-of-life measures, at least in the first few years of treatment.”

“Bayesian Meta-analysis of Hormone Therapy and Mortality in Younger Postmenopausal Women”
Shelley R. Salpeter, MD, Ji Cheng, MSc, Lehana Thabane, PhD, Nicholas S. Buckley, and Edwin E. Salpeter, PhD (Posthumous).
The American Journal of Medicine, Volume 122, Issue 11 (November 2009)
The American Journal of Medicine

Written by Stephanie Brunner (B.A.)