Bisphosphonate Use Is Low in Patients With Metastatic Bone Disease Despite Their High Risk for Major Osteoporotic Fractures

The incidence of pathologic fractures due to metastatic bone disease (MBD) is associated with increased mortality, with lower extremity fractures associated with the shortest survival rates. Bone health can be monitored using dual-energy X-ray absorptiometry (DEXA) scans which quantifies bone mineral density (BMD), and fracture risk can be predicted using the Fracture Risk Assessment Tool (FRAX). FRAX scoring uses an algorithm to predict an individual's 10-year probabilities of hip fracture and major osteoporotic fracture (MOF). The National Osteoporosis Foundation recommends initiation of bisphosphonate (BP) therapy for fracture prevention when FRAX scores are ≥3% for hip fracture or ≥20% for MOF. In patients with MBD, the use of BPs is associated with improved pain management and reduced incidence of pathologic fractures and other skeletal-related events. This study aimed to characterize 10-year fracture risk in patients with MBD and to evaluate the use of BP therapy in these patients. A retrospective review was performed of adult patients (≥18 years) with pathologic fractures of the long bones due to MBD that were amenable to orthopaedic surgical treatment. Patients who were admitted at our site between October 2020 and March 2023 were included. Patients with primary bone cancer were excluded. FRAX scores for each participant were calculated using the online tool hosted by the University of Sheffield's Centre for Metabolic Bone Diseases. Risk assessment for MOF was conducted in accordance with the 2010 Canadian Clinical Practice Guidelines for the Diagnosis and Management of Osteoporosis, which uses FRAX score thresholds to characterize patients at low risk (20%) of MOF. Thirty-five patients, with a mean age of 68 years (SD = 11) and 60.0% being female, were included (Table 1). Overall, 14.3% (n = 5) of the patients had previously undergone a DEXA scan and 11.4% (n = 4) of the patients were diagnosed with osteoporosis. Pathologic fractures were more common in the lower extremity (hip = 68.6%; femoral shaft = 20.0%) compared to the upper extremity (humerus = 11.4%). Mean FRAX scores for the 10-year probability of hip fracture and MOF were 3.1% (SD = 2.8) and 9.9% (SD = 5.5), respectively, with 40.0% (n = 14) of the patients at moderate-to-high risk of MOF. Due to their increased risk for hip fracture (i.e., FRAX score ≥3%), initiation of BP therapy was warranted in 42.9% (n = 15) of the patients; however, of these patients, 73.3% (n = 11) were BP-naïve. Despite being at increased fracture risk, 85.7% of patients with MBD had no prior history of osteoporosis screening or diagnostic evaluation. FRAX scores identified that nearly half of the patients were eligible for first-line BP therapy; however, nearly three-quarters of these patients were untreated. This study demonstrates an important care gap for patients with MBD, and thus, emphasizes the need for coordinated multi-disciplinary care to facilitate the proactive assessment of BMD and fracture risk. Streamlining these processes may facilitate earlier initiation of BP therapy, thereby reducing pathologic fracture incidence. For any figures or tables, please contact authors directly.