Predictive Value of Bone Turnover Markers During Discontinuation With Alendronate

Background:

Osteoporosis increases the risk of fractures. Alendronate reduces the risk of both vertebral- and hip fractures by approximately 50%. It has, however, become evident that long-term anti-resorptive may lead to serious side effects such as atypical femoral fractures or osteonecrosis of the jaw. The alendronate extension study (FLEX) showed that despite stopping treatment after five years the anti-fracture efficacy regarding non-vertebral and radiological vertebral fractures persists for an additional five years in patients with bone mineral density (BMD) T-score > -2.5 at the femoral neck, no fractures during treatment, and no previous vertebral fracture. It is therefore now clinical practice, that treatment is discontinued after five years in patients that fulfil these criteria. Based on the alendronate extension study it was assumed, that bone turnover monitored by biochemical markers would stay suppressed for years after stopping treatment, however, other studies have demonstrated that there is a great variability in the change in bone turnover markers seen after stopping treatment with alendronate in a real-life setting.

Aim:

To investigate the predictive value of markers of bone turnover on bone loss 12 months after stopping alendronate therapy.

Methods:

The study is a cohort study comprising 136 patients with osteoporosis stopping treatment with alendronate.

Perspectives:

The study will contribute with new knowledge about biochemical markers of bone turnover as predictors of bone loss after stopping treatment with alendronate. It will thus be possible to identify patients who will experience a decrease in BMD during treatment break, and for this particular group of patients treatment can be re-initiated earlier so further loss of bone will be avoided. On the other hand, the biochemical markers of bone turnover could also shed light on who can tolerate treatment break, thereby avoid long-term treatment with alendronate, which may be associated with serious side effects. Finally, the use of blood samples rather than DXA will reduce the use of X-rays.

Inclusion criteria

• Postmenopausal women (postmenopausal for at least two years)
• Men above 50 years
• Treatment for at least five years with alendronate
• BMD T-score total hip > -2.5
• BMD T-score lumbar spine (L1-L4) > -4

Exclusion criteria

• Any low-energy fracture within the previous five years during alendronate treatment (not including fingers, toes, or skull)
• Low-energy vertebral fracture at any time
• Low-energy hip fracture at any time
• Ongoing treatment with glucocorticoids
• Metabolic bone disease
• Hormone replacement therapy
• Cancer
• Other conditions affecting bone metabolism