Age-related differences in BMD response during three years of denosumab treatment

Denosumab increases bone mineral density and reduces fracture risk in patients with osteoporosis. However, whether BMD response to denosumab differs by age, particularly during longer term treatment, remains unclear. This study investigated the association between baseline age and BMD gain during 3 years of denosumab treatment in patients with osteoporosis.

This retrospective study included patients with osteoporosis who were treated with denosumab. DXA-based BMD and bone turnover markers were followed for up to 3 years. Percent BMD gain from baseline was evaluated. The longitudinal association between baseline age and %BMD gain was assessed using multivariable linear mixed effects models for the lumbar spine and total hip. Analyses were performed in the treatment naive cohort and the overall cohort according to prior osteoporosis treatment status.

A total of 255 patients were included, of whom 110 were treatment naive. In multivariable linear mixed effects models, older baseline age was associated with smaller lumbar spine %BMD gain in the treatment naive cohort at both 1 and 3 years. Each 1 year increase in age was associated with a 0.187 percentage point lower lumbar spine %BMD gain at 1 year and a 0.293 percentage point lower gain at 3 years (1 year: β = -0.187, p = 0.006, 3 years: β = -0.293, p = 0.031). In contrast, baseline age was not significantly associated with total hip %BMD gain in the treatment naive cohort (1 year: β = -0.011, p = 0.826, 3 years: β = 0.028, p = 0.727). In the overall cohort, baseline age was not significantly associated with %BMD gain at either skeletal site.

Older baseline age was associated with a modestly smaller lumbar spine BMD gain in treatment-naive patients, whereas no statistically significant age-related association was observed at the total hip. These findings indicate a modest, site-specific association between baseline age and BMD gain in treatment-naive patients.