Effect of Abaloparatide on Bone Mineral Density and Fracture Incidence in a Subset of Younger Postmenopausal Women with Osteoporosis at High Risk for Fracture.

Purpose: Current treatment guidelines recommend treatment for postmenopausal women with a T score <2.5 regardless of age. This subgroup analysis evaluated the efficacy and safety of abaloparatide in younger postmenopausal women considered to be at high risk for fracture.

Methods: Subgroup analysis of women in the Abaloparatide Comparator Trial in Vertebral Endpoints (ACTIVE) trial who were <65 years old and met modified utilization management criteria (baseline T score ≤-2.5 [any site] and ≥1 prevalent vertebral and/or ≥1 prior clinical fracture within 5 years of randomization).

Findings: A total of 296 women (age range, 49-64 years) were included. Significant increases in bone mineral density from baseline were observed for abaloparatide versus placebo at all 3 sites at 6 months (p < 0.01 for total hip and femoral neck; p < 0.0001 for lumbar spine), 12 months (p < 0.0001 at all 3 sites), and 18 months (p < 0.0001 at all 3 sites). Fracture rates were numerically lower for abaloparatide versus placebo, consistent with the overall trial results, although the differences were not statistically significant. The number needed to treat to prevent 1 additional vertebral fracture after 18 months of treatment versus placebo was 18 for abaloparatide and 21 for teriparatide. The number needed to treat had nonsignificant trends toward lower values with abaloparatide versus teriparatide for nonvertebral fractures (23 vs 40) and clinical fractures (16 vs 73) and similar for major osteoporotic fractures (24 vs 27). The safety profile was consistent with the overall ACTIVE population.

Implications: Findings of this subgroup (post hoc) analysis are consistent with the overall ACTIVE population. Abaloparatide appears to be effective and well tolerated in this subgroup of younger postmenopausal women. ClinicalTrials.gov identifier: NCT01343004.