In the FIT Long Term Extension (FLEX) trial, ten years of alendronate (ALN) did not significantly reduce the risk of non-vertebral fractures (NVF), compared with five years of treatment.
However, continuing ALN reduced the risk of clinical, but not morphometric, vertebral fractures, regardless of baseline vertebral fracture status.
In previous studies, ALN efficacy for NVF prevention in women without prevalent vertebral fracture was limited to those with femoral neck (FN) T-score = -2.5. To determine whether the effect of long-term ALN on fracture differs by vertebral fracture status and femoral neck (FN) T-score, researchers from the University of California, San Francisco, performed a post hoc analysis using FLEX data, a randomised double-blind placebo-controlled trial among 1,099 postmenopausal women originally randomised to ALN in FIT with mean ALN use of five years. In FLEX, women were randomised to placebo (40 per cent) or ALN 5mg/d (30 per cent) or 10mg/d (30 per cent) for an additional five years. Among women without vertebral fracture at FLEX baseline (N = 720), continuation of ALN reduced NVF in women with FLEX baseline FN T-score = -2.5 (RR 0.50; 95% CI 0.26-0.96) but not with T-score > -2.5 and = -2 (RR 0.79; 95% CI 0.37-1.66) or with T-score > -2 (RR 1.41; 95% CI 0.75-2.66) (p for interaction 0.019).
Continuing alendronate for ten years instead of stopping after five years thus reduces non-vertebral fracture risk in women without prevalent vertebral fracture whose FN T-score, achieved after five years of ALN, is = -2.5, but does not reduce risk of NVF in women whose T-score is > -2.
J Bone Miner Res. 2010 Jan 8