Changes in Nonosteoporotic Bone Density and Subsequent Fractures in Women

Osteopenia is considerably more common than osteoporosis and accounts for most of the fracture burden in women older than 50 years. It is uncertain when to initiate treatment in osteopenia. We sought to determine in women with osteopenia what effect transitioning to lower categories had on subsequent fracturing.

We surveyed 1150 women from office-based practices who had initial normal or osteopenic bone mineral densities (BMDs) and who were retested after 5.75 years. We classified categories related to baseline T scores as follows: normal (>-1.0), mild osteopenia (-1.0 to -1.49), moderate osteopenia (-1.5 to -1.99), and severe osteopenia (-2.0 to -2.49). We determined during a 9.6-year follow-up period the fracture occurrence in those who maintained their initial category status or transitioned into lower categories.

Transitioning to lower categories was not significantly different among baseline osteopenic categories but significantly more than normal baseline BMDs. Total fractures, individuals fracturing, and major fractures were significantly more, with baseline T scores of ≤-1.5 (<0.001). Although only 10.2% transitioned to osteoporosis, 90.5% of these transitions occurred with baseline T scores ≤-1.5 and accounted for significantly more fractures than baseline T scores of >-1.5.

Most subsequent fractures and transitions to osteoporosis occurred with baseline T scores ≤-1.5. Clinical risk factors need to be used to determine at what T score threshold treatment would be cost effective.