Oral bisphosphonate therapy provides the usual first line approach to the treatment of osteoporosis and is associated with relative reduction in fracture risk of approximately 50% at the spine, 30% at the proximal femur and up to 20% at peripheral sites. Fracture risk reduction is maintained over 5 years of treatment and there are data confirming continued efficacy of treatment for up to 10 years in individuals at high fracture risk. Prolonged bisphosphonate treatment has, however, been associated with rare but serious adverse effects including osteonecrosis of the jaw and atypical subtrochanteric femoral fractures.
Reversal of bisphosphonate treatment effect is gradual, with persisting suppression of bone turnover and maintenance of bone mineral density (BMD) for several months after cessation. It is therefore common practice to consider a pause in treatment after 5 years (3 years for IV treatment). The decision whether to pause treatment at this point is made on an individual basis, taking account of patient preference and the balance of risks and benefits. Factors increasing the individual's risk of fracture may lead to the recommendation to continue without a pause. These include advancing age, low BMD, recent fragility fracture, especially of hip or vertebrae, and use of other medication adversely affecting bone eg glucocorticoids, aromatase inhibitors or androgen deprivation therapy.
Patients who continue treatment beyond 5 years should be counselled regarding the rationale and risks of longer term treatment and given advice to minimise risk through maintenance of good dental health and prompt reporting of any symptoms of groin/thigh pain. Patients who stop bisphosphonate treatment should be evaluated to consider re-introduction if new fractures or risk factors arise, or after 2 years off treatment.