Discontinuation of hormone therapy and bone mineral density: does physical activity modify that relationship?

Hormone therapy can positively impact bone mineral density after menopause. We explored bone mineral density change in postmenopausal women who discontinued hormone therapy after the Women's Health Initiative landmark 2002 trial results were published. We secondarily explored whether usual physical activity modified the results.

Postmenopausal women participating in the Buffalo OsteoPerio study with information on hip bone density, hormone therapy use, and self-reported physical activity at two time points (1997-2001; 2002-2007) were included (N = 961). Hormone therapy included three groups according to use at baseline and year 5 (non/non; current/non; current/current).

At baseline (mean age, 65.9 years; SD, 6.7 years), 480 women were not using hormone therapy, while 481 were current users. Between the baseline and 5-year visits, 336 women using hormone therapy discontinued. Baseline total hip bone density was highest in current users. After 5 years, those who continued hormone therapy exhibited no bone loss; those who discontinued exhibited the greatest loss at the total hip of -0.021 gm/cm2. Women who never used hormone therapy exhibited some loss of -0.012 gm/cm2. Usual physical activity did not appreciably impact change in bone density in any group.

This prospective observational study explored the 5-year change in bone mineral density among older postmenopausal women after the landmark 2002 hormone therapy trial findings were released. We found bone density decreased in never-users and in women who discontinued use. Bone density was maintained in current users. Although usual physical activity did not mitigate bone loss, targeted physical activity regimens should be investigated.