The idea behind a bisphosphonate holiday is to reduce the chance of osteonecrosis of the jaw (ONJ) and atypical femur fractures (AFF) while not compromising the risk of an osteoporotic fracture (JCEM 2019 – bisphosphonate treatment holidays)

• Bisphosphonates are the only antiresorptive medications whose effects continue after discontinuation (although the effects do slowly wane)
• Observational studies show that the risk of ONJ and AFF significantly increase after 5 years, although still rare
• Bisphosphonate holidays have some evidence that it reduces the risk of ONJ or AFF
• A NEJM study showed the risk of AFF is very low and rapidly decreases after bisphosphonate discontinuation
  • Incidence rate (per 10,000 person years) of AFF according to cumulative exposure
    • <0.25 years: 0.1
    • 0.25 to <3 years: 0.6
    • 3 to <5 years: 2.5
    • 5 to <8 years: 6.0
    • 8+ years: 13.1
  • Incidence rate (per 10,000 person years) of AFF since bisphosphonate discontinuation
    • Not yet used: 0
    • <3 months: 4.5
    • >3 to 15 months: 1.8
    • >15 to 48 months: 0.6
    • 48+ months: 0.5

A bisphosphonate holiday could be considered only if the patient is at low to moderate risk of fracture

• At high or very high risk of fractures, antiresorptive therapy should be continued because the risk of an osteoporotic fracture is far greater than the theoretical reduction in ONJ and AFF

If holiday is taken:

• The maximum recommended duration is 5 years
• Fracture risk and BMD should be re-evaluated every 2 to 4 years after discontinuation.
• Consider restarting antiresorptive therapy earlier than 5 years if significant decline in bone mineral density, fracture, or increased clinical risk for developing fracture