Baseline BMD T-score can help determine first-line therapy for women with osteoporosis
Key takeaways:
- Researchers calculated the likelihood of achieving a BMD T-score of –2.5 or higher with denosumab based on baseline BMD.
- Minimum baseline BMD T-scores for denosumab success varied based on duration of therapy.
Women with osteoporosis have at least a 50% chance of reaching their target bone mineral density at 3 years if they have a BMD T-score of at least –2.8 at the total hip or –3.1 at the lumbar spine at baseline, according to study findings.
In an analysis of data from the FREEDOM trial and its extension published in the Journal of Bone and Mineral Research, researchers calculated the minimum BMD T-score women with osteoporosis need to have at least a 50% chance of achieving a nonosteoporotic BMD T-score with denosumab (Prolia, Amgen). Felicia Cosman, MD, professor of medicine at Columbia University Vagelos College of Physicians and Surgeons, said the findings can help health care professionals determine first-line therapy for women with osteoporosis.
“For women who start with BMD levels above [–2.8 in the total hip or –3.1 in the lumbar spine], denosumab is appropriate,” Cosman told Healio. “However, for women who start with T-scores below –2.8 in the total hip or below –3.1 in the lumbar spine, optimal treatment would begin with abaloparatide (Tymlos, Radius Health), romosozumab (Evenity, Amgen) or teriparatide (Forteo, Eli Lilly). Even for those women who have higher starting BMD levels, however, for those who have a fracture history, the target BMD levels are higher.”
Data were obtained for 3,902 postmenopausal women who received denosumab during the phase 3 FREEDOM trial (mean age, 72.3 years). BMD measurements at the total hip and lumbar spine were collected through DXA scans at 1, 3, 5 and 10 years. The researchers determined the probability of achieving a BMD T-score greater than –2.5 at the total hip or at the lumbar spine at each DXA follow-up.
Odds of achieving target BMD
At baseline, 27% of women had a total hip BMD T-score of –2.5 or less. Women with a baseline total hip BMD T-score of –2.7 had a 37% chance of reaching a BMD T-score target of –2.5 at 1 year, a 71% chance of reaching their target at 3 years and a 94% chance of reaching their target at 10 years. Women with a baseline BMD T-score of –3 had a 2% likelihood of reaching their target total hip BMD T-score at 1 year, a 12% probability at 3 years and 55% odds at 10 years.
Of the participants, 81% had a lumbar spine BMD T-score –2.5 or lower at baseline. Women with a baseline lumbar spine BMD T-score of –2.7 had 67% odds of achieving a BMD T-score of –2.5 or higher at 1 year, an 86% likelihood of reaching their BMD target at 3 years and a 98% chance of achieving a BMD T-score of –2.5 at 10 years. For those with a baseline lumbar spine BMD T-score of –3, the odds of achieving a BMD T-score of –2.5 were 38% at 1 year, 59% at 3 years and 93% at 10 years.
The researchers conducted similar analyses of probability of achieving a BMD T-score greater than –2 at the total hip or lumbar spine; odds were lower than those for achieving a BMD T-score greater than –2.5.
Baseline BMD thresholds
Women needed a total hip BMD T-score of at least –2.8 to have 50% or greater odds of reaching a T-score target of –2.5 at 3 years. For lumbar spine, a minimum BMD T-score of –3.1 was needed to have 50% or greater odds of achieving a T-score target of –2.5 at 3 years. For 10 years of denosumab treatment, the minimum baseline BMD T-score required for 50% odds of reaching one’s target was –3 for total hip and –3.7 for the lumbar spine.
One of the biggest unanswered questions remains what the optimal duration of denosumab therapy is for women with osteoporosis, according to Cosman.
“This decision needs to be individualized; while not all patients should have prolonged denosumab, some will benefit from lifelong treatment,” Cosman said. “It is critical to emphasize, though, that if patients stop denosumab, they need to transition to a bisphosphonate. Zoledronic acid is the best-studied and probably most effective after denosumab discontinuation, but some patients may need a higher or more frequent dosing interval than once-yearly for the 2 years after the last denosumab injection.”
Cosman added more studies are needed to assess treatment targets and probabilities for men with osteoporosis.
For more information:
Felicia Cosman, MD, can be reached at felcosman@gmail.com.
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