The risk of second hip fracture is decreased with compliant and persistent use of bisphosphonates

BACKGROUND: Osteoporotic fractures are characterized as fractures of the hip, spine, and forearm resulting from low energy trauma. In Denmark, hip fracture is the second most prevalent fracture in persons above 50 years of age, with an estimated incidence of 5 per 1000 inhabitants in 2011. Patients experience a 19% increased mortality within the first year following hip fractures. Furthermore, studies have shown that within 10 years after first hip fracture 40% will experience another hip fracture. The risk for second hip fracture is markedly increased, initiating at a relative risk of 11.8 within the first month after fracture and does not normalise until 15 years later.
Fracture prevention programs have focused on identifying patients at risk of secondary low energy trauma fractures. The secondary prevention programs for fractures begin immediately after the first fracture, through identification of risk factors and initiate pharmaceutical treatment.
The aim of this study was to estimate the potential benefits from alendronate treatment for secondary low energy trauma fracture patients in Denmark, compared to no pharmaceutical treatment for this group of patients.
METHODS: A Markov model, previously employed by the same authors in a cost of illness study, was modified to estimate the cost-effectiveness of bisphosphonate treatment is Danish fracture patients above 50 years. The model applied an incidence-based, bottom-up approach from a societal perspective and, thus, included direct and productivity costs.
The Markov model ran for 10 years in 1 year cycles and included 10 health states (well, wrist fracture, post wrist fracture, vertebral fracture, post vertebral fracture, first hip fracture, post first hip fracture, second hip fracture, post second hip fracture and dead). Costs were discounted at 3% rate.
This model includes all Danish citizens above 50 years of age with a fracture during the study period. The model inputs have been estimated from Danish registries and published peer-reviewed literature.
The applied effectiveness measure was the number of hip fractures, based on the medical assumption that 50% of additional hip fractures may be prevented with compliant and persistent use of alendronate in five years following the initial fracture.
RESULTS:
In the no treatment arm, the average cost was EUR 16,233 and 0.32 hip fractures per woman, and in the alendronate treatment arm the average cost was EUR 13,395 and 0.17 hip fractures per woman. The incremental cost-effectiveness ratio (ICER) resulted in a cost saving of EUR 18,623 per prevented hip fracture.
In the alendronate treatment arm, the average cost and effect was EUR 5,631 and 0.16 hip fractures per man. The no treatment arm had an average cost of EUR 9,070 and 0.29 hip fractures per man. Thus the ICER resulted in a cost saving of EUR 26,421.01 per prevented hip fracture.
Both results were robust to changes in key parameters, for both deterministic and probabilistic sensitivity analyses.
CONCLUSION: Our model shows that there is a potential cost saving by treating fracture patients with alendronate in prevention of future hip fracture, which supports the arguments of benefits from fracture prevention programs for hip fractures.