COMPARATIVE EFFECTIVENESS AND COST EFFECTIVENESS OF GENERIC ALENDRONATE, RISEDRONATE, DENOSUMAB AND ZOLEDRONIC ACID FOR SECONDARY PREVENTION OF FRAGILITY FRACTURES- PRELIMINARY RESULTS

Background: Osteoporosis related fractures represent a disease of the elderly. For the health care system, the fractures are important in terms of the related costs, with estimated 30% of the cost following a hip fracture constituting of long-term nursing home care. With the ageing of the population, the burden of osteoporosis related fractures is likely to increase. 

A fracture event provides an opportunity for secondary prevention, as it identifies individuals at high risk. Several pharmacological options are available for secondary fracture prevention, but there is uncertainty with regard to their relative effectiveness and cost effectiveness. The Agency for Healthcare Research and Quality (AHRQ) has pointed out the need for comprehensive pharmaco-economic evaluations in order to guide formulary decisions in this field.

Purpose: To evaluate the relative health gains and costs of secondary prevention of fractures with generic alendronate, risedronate, denosumab and zoledronic acid, compared to no treatment and relative to each other.

Method: We updated a previously published decision analytic fracture model. The model synthesizes available data on the number of fractures and related mortality and use of health care resources (pharmaceuticals, primary care, hospital care, long-term care and home based assistance). The model is set up as an individual level state transition (Markov) model and outputs include number of quality adjusted life years (QALYs) and costs. Effectiveness data were extracted from a recent systematic review, and costs were collected from publicly available sources.  We preformed analyses for women 85 years old with a previous hip fracture. In this first preliminary analysis, we assumed full compliance and lifelong treatment.

Results: Zoledronic acid was the most effective alternative, followed by denosumab, risedronate, generic alendronate and no treatment, yielding respectively 4.7661, 4.7640, 4.6715, 4.1581 and 3.8915 QALYs.  Generic alendronate had lower costs than no secondary prevention.  Zoledronic acid was more effective and less costly than both denosumab and risedronate. Compared to alendronate, zoledronic acid entails costs of $48,832 per additional QALY.

Conclusions: All options are more effective than no treatment. In terms of comparative effectiveness and cost effectiveness, our analysis indicates that zoledronic acid is the optimal strategy for secondary prevention, assuming a cost-effectiveness threshold of $50,000 per QALY gained.