Making the best use of osteoporosis agents
The assessment of osteoporosis and its management are changing, with the expectation of new fracture-risk guidelines from the World Health Organization (WHO) as well as the introduction of longer-acting bisphosphonates. Diagnosis of osteoporosis has traditionally utilized bone mineral density (BMD) measurement, but new reimbursement limits, with payments already down 50%, are leading scanners to drop their leases of dual-energy x-ray absorptiometry (DEXA) machines. In fact, further cuts in payment for such procedures are anticipated in the coming years.
On the treatment side, patients have voted for the monthly agent ibandronate (Boniva) over prior leaders alendronate (Fosamax) and risedronate (Actonel) with their weekly dosing schedules. Longer-acting versions of risedronate are appearing to recapture market share. This trend heralds the newly approved yearly infusion of zoledronic acid (Reclast). Clearly the consumer prefers convenience when it is an option. Whether this trend will carry over to IV administration of these agents is uncertain, particularly if problems in insurance reimbursement arise.
Who should be treated
As the diagnostic role of BMD measurements declines, fracture-risk assessment is likely to emerge as the best method of defining who will be treated. Combining BMD with clinical risk factors will provide long-term probabilities of fracture and allow insurers to pay for treatment at predetermined levels of absolute risk. Presently, insurers utilize T-score measurements to define when clinicians should intervene with therapy, since fracture risk nearly doubles with each standard-deviation decrease in BMD.
However, at least half of all fractures in our society occur in women whose BMD scores have not yet reached -2.5 SD because so many more women are osteopenic than are osteoporotic. Thus, other risk factors need to be assessed and combined with BMD to predict who should be treated.
The most important risk factors to be integrated into the new WHO algorithm will be age and previous fracture, since each can be an independent indicator of fivefold increments in fracture incidence. Risk of hip fracture (Figure 1) increases from 2.5% to 12.5% over 10 years when comparing 50-year-olds with 80 year-olds who have T scores of -2.5. Vertebral-fracture rates do likewise over three years in women with prior vertebral fractures.
The WHO task force that is preparing this highly anticipated risk-assessment tool has proposed additional candidate factors after literature meta-analysis. Steroid use, in doses equivalent to 5 mg prednisone, will likely be utilized along with cigarette smoking, family history of fracture, and “high” alcohol intake. These factors will be weighted and combined to aid in structuring a global-risk algorithm that will help in determining which osteopenic patient to treat and how aggressively. Predictions are that younger women with low risk will be less likely to receive a bisphosphonate, while older women with a history of fracture will be more likely to be treated, even without a BMD measurement.