Bisphosphonates reduce the risk of fractures associated with osteoporosis but increase the risk of atypical subtrochanteric femur fractures. After unilateral atypical femur fracture, there is risk of contralateral fracture, but the indications for prophylactic fixation are controversial.
The purpose of this study is to use Markov modeling to determine whether contralateral prophylactic femur fracture fixation is cost-effective after a bisphosphonate-associated atypical femur fracture and, if so, what patient-related factors may influence that determination.
Markov modeling was used to determine the cost-effectiveness of contralateral prophylactic fixation after an initial atypical femur fracture. Simulated patients aged 60 to 90 years were included and separated into standard and high fracture risk cohorts. Patients with standard fracture risk were defined as those presenting with one atypical femur fracture but without symptoms or findings in the contralateral femur, whereas patients with high fracture risk were typified as those with more than one risk factor, including Asian ethnicity, prodromal pain, femoral geometry changes, or radiographic findings in the contralateral femur. Outcome probabilities and utilities were derived from studies matching to patient characteristics, and fragility fracture literature was used when atypical femur fracture data were not available. Associated costs were largely derived from Medicare 2015 reimbursement rates. Sensitivity analysis was performed on all model parameters within defined ranges.
Prophylactic fixation for a 70-year-old patient with standard risk for fracture costs USD 131,300/quality-adjusted life-year (QALY) and for high-risk patients costs USD 22,400/QALY. Sensitivity analysis revealed that prophylaxis for high-risk patients is cost-effective at USD 100,000/QALY when the cost of prophylaxis was less than USD 29,400, the probability of prophylaxis complications was less than 21%, or if the patient was younger than 89 years old. The parameters to which the model was most sensitive were the cost of prophylaxis, patient age, and probability of prophylaxis-related complications.
Prophylactic fixation of the contralateral side after unilateral atypical femur fracture is not cost-effective for standard-risk patients but is cost-effective among high-risk patients between 60 and 89 years of age with a high risk for an atypical femur fracture defined by patients with more than one risk factor such as Asian ethnicity, prodromal pain, varus proximal femur geometry, femoral bowing, or radiographic changes such as periosteal beaking and a transverse radiolucent line. However, our findings are based on several key assumptions for modeling such as the probability of fractures and complications, the costs associated for each health state, and the risks of surgical treatment. Future research should prospectively evaluate the degree of risk contributed by known radiographic and demographic parameters to guide management of the contralateral femur after a patient presents with an atypical femur fracture.
Level III, economic and decision analyses.
S. Y. Jiang, Stanford University School of Medicine, Stanford, CA, USA
D. J. Kaufman, Department of Orthopaedic Surgery, Northwestern Medicine, Chicago, IL, USA
B. Y. Chien, Harvard Combined Orthopaedic Residency Program, Boston, MA, USA
M. Longoria, R. Shachter, Department of Management Science and Engineering, Stanford University, Stanford, CA, USA
J. A. Bishop, Department of Orthopaedic Surgery, Stanford University Medical Center, Redwood City, CA, USA
S. Y. Jiang, Stanford University School of Medicine, 291 Campus Drive, Stanford, CA 94305, USA, email: firstname.lastname@example.org
One of the authors (JAB) certifies that he has received payments or benefits, during the study period, an amount of USD 10,000 to USD 100,000 from Globus Medical (Audubon, PA, USA) and less than USD 10,000 from Innomed (Savannah, GA, USA).
All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.
Each author certifies that his or her institution waived approval for the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.
This work was performed at Stanford University, Stanford, CA, USA.
Received March 09, 2018
Accepted October 08, 2018