In a study published last year, Margaret Gourlay and colleagues attempted to propose strategies for screening intervals of bone mineral density (BMD) testing . Since then, the paper has been discussed in the correspondence section of the journal [2–5]. The authors analyzed data of 4957 women, 67 years of age or older, recruited in 1986 in the USA, who did not have osteoporosis at baseline, and who were followed longitudinally for up to 15 years within the Study of Osteoporotic Fractures (SOF) . For this analysis, 49% of the total study population were excluded because they either already had osteoporosis, as defined by the World Health Organization (25%)  or treatment for osteoporosis or incomplete BMD data. BMD was measured by DXA at the femoral neck and total hip.
The primary outcome was to determine the BMD testing interval in these women, defined as the estimated time for 10% of the subjects to make the transition to osteoporosis from normal bone density or osteopenia at baseline, before a hip or clinical vertebral fracture occurred and before treatment for osteoporosis was initiated. The participants were stratified into four groups according to the [i]T[/i]-score range (lowest [i]T[/i]-score at femoral neck or total hip): normal BMD ([i]T[/i]-score ≥ 1.00), mild osteopenia ([i]T[/i]-score −1.01 to −1.49), moderate osteopenia ([i]T[/i]-score −1.50 to −1.99), and advanced osteopenia ([i]T[/i]-score −2.00 to −2.49). Sixty-two percent of women with advanced, 21% with moderate, and less than 5% with mild osteopenia, and not even 1% with normal BMD made the transition to osteoporosis.
Referring to calculations with parametric cumulative incidence models, the authors conclude that osteoporosis would develop in less than 10% of older women during rescreening intervals of approximately 1 year for women with advanced osteopenia, 5 years for women with moderate osteopenia, and 15 years for women with normal bone density or mild osteopenia, and, thus, they propose such interval testing for each group.
Head of the KLIMAX Menopause and Osteoporosis Clinic, Vienna, Austria
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