Effectiveness of antiresorptives for the prevention of nonvertebral low-trauma fractures in a population-based cohort of women

Observational studies are needed to quantify real-life effectiveness of antiresorptive therapy in the prevention of clinical fractures. Antiresorptive therapies were associated with an overall 32% reduction in low-trauma nonvertebral fracture risk among women 50 and older. Effectiveness may be lower among older women and those without risk factors.

Randomized controlled trials have shown that antiresorptive therapies reduce the risk of fracture in selected populations, but further study is needed to quantify their real-life effectiveness. The study objective was to determine the association between antiresorptive use and low-trauma nonvertebral fracture in women 50 and older.

The design was a retrospective nested case-control study (density-based sampling) within the Canadian Multicentre Osteoporosis Study. There were 5,979 eligible women with 453 cases and 1,304 matched controls.

The current use of antiresorptives was associated with a decreased risk of fracture with OR = 0.68, 95% CI: 0.52-0.91; where OR is the adjusted odds ratio and CI is the confidence interval. Subgroup analysis yielded OR = 0.61, 95% CI: 0.42-0.89 for ages 50-74; OR = 0.76, 95% CI: 0.50-1.17 for ages 75+; OR = 0.58, 95% CI: 0.40-0.83 for those with a major risk factor; and OR = 0.92; 95% CI: 0.59-1.42 for those without a major risk factor. Major risk factors were prevalent low-trauma fracture, vertebral deformity (grade 2+), and BMD T-score < or = -2.5.

Antiresorptive therapy is associated with a clinically important reduction in low-trauma nonvertebral fracture risk among community-dwelling women aged 50 and older. Antiresorptive therapy may be less effective for women 75 and older and women without major risk factors.