Endocrine Abstracts

There is concern about the effects of long-term bisphosphonate use. A ‘treatment holiday’ is now considered after 5 years but there is no evidence as to the best way in which to monitor this.

Aim: To look at the effect that a ‘treatment holiday’ has on the bone turnover marker, amino-terminal propeptide (P1NP) and bone mineral density (BMD).

Methods: A retrospective case note review of 55 patients currently undergoing a bisphosphonate treatment holiday. P1NP and BMD were recorded at baseline and at intervals during the treatment holiday. The BMD was recorded as a percentage change to determine clinical significance (±3%).

Results: There were 55 subjects aged 68.9±1.7 who had received treatment with a bisphosphonate for 87.2±4.5 months prior to stopping. The P1NP when the bisphosphonate was stopped was 18.8 μg/l±1.5. There was a significant increase in P1NP at 1 year (31.1±1.8, P=0.000) but no significant change at 2 years (32.8±1.8) and 3 years (32.1±3.5). Hip BMD and Spine BMB remained clinically stable at 24 months with a percentage change at the hip of −1.1±0.5 and the spine 0.1±0.8.

11 patients has a significant (>3%) bone loss at the hip at 24 months. These patients had a rise in P1NP of 21.7±4.3 from baseline at 12 months compared to a rise of 13.9±2.2 in those with no significant bone loss. There was a significant correlation between the level of increase of P1NP at 12 months and the percentage change in BMD at total hip (r=−0.35, P=0.04).

Conclusion: After an initial rise in P1NP after stopping the bisphosphonate this then appears to remains stable for at least 3 years. On average bone mineral density remains clinically stable for at least 24 months. A greater rise in P1NP at 1 year may predict the level of bone loss at 24 months.