: In osteoporosis, poor adherence to bisphosphonate (BP) therapy is common, and is associated with poor outcomes and increased treatment costs (Siris 2006; Recker 2005). Although compliance is improved with monthly vs weekly dosing (Reginster 2008), no evidence suggests cycling through BP agents offers therapeutic benefit, assessed by bone mineral density (BMD). In two randomized, open-label studies in postmenopausal women aged ≥55 years previously treated with, but suboptimally adherent to, BP therapy, subjects received denosumab (DMAb) 60 mg SC Q6M, ibandronate (IBN) 150 mg PO QM or risedronate (RIS) 150 mg PO QM for 12 months; DMAb treatment was associated with greater increases in BMD than either IBN or RIS (Recknor 2012; Roux 2012). We assessed if these differences were consistent in a subset of subjects who had BMD data recorded at baseline and month 12 stratified by prior fragility fracture. In the IBN and RIS studies, 237/767 (31%) and 280/809 (35%) subjects, respectively, had a prior fracture. There were no significant differences in baseline BMD by treatment group or prior fracture. BMD increases were greater with DMAb than IBN or RIS at all sites independent of prior fracture (Table). In subjects suboptimally adherent to an oral BP, switching to DMAb provided greater gains in BMD at all key skeletal sites measured than transitioning to either IBN or RIS. These findings suggest that the magnitude of treatment effect is not significantly influenced by classification of high risk, as defined by prior fragility fracture.
|DMAb vs IBN study||DMAb vs RIS study|
|Prior fracture||DMAb (n=399)||IBN (n=368)||Pint||DMAb (n=405)||RIS (n=404)||Pint|
|* P<0.001; † P=0.0382; ‡ P=0.0014. Pint =P-value for treatment-by-subgroup interaction|
18 May 2013 - 22 May 2013