Hip fracture rates and time trends in use of anti-osteoporosis medications in Denmark for the period 2005 to 2015: Missed opportunities in fracture prevention

BACKGROUND: Declining use of bisphosphonates (BP) in the United States and Europe may lead to a widening of the treatment gap for osteoporosis and an increase in fracture rates. However, a shift to non-bisphosphonates and to hospital administered i.v. BPs could lead to overestimation of the treatment gap if analyses are based exclusively on BP prescriptions. When a healthcare system successfully narrows the treatment gap by making appropriate use of anti-osteoporosis drugs, we would expect to see declining rates of osteoporotic fractures with much of the decrease being statistically attributable to medication uptake. We analysed a best-case scenario where all use of BPs, denosumab, raloxifene and PTH analogues - including the oncology area - was contrasted with the trend in hip fracture rates. This scenario also considered users of raloxifene and teriparatide as covered by osteoporosis drugs though the primary RCT for raloxifene showed no risk reduction in nonvertebral fractures and the RCT for teriparatide risk reductions for non-vertebral fractures but not hip fracture specifically. Sensitivity analyses were also done.

METHODS: We used aggregate statistics on hip fracture events and total use of the above medications estimating the number of persons potentially covered. The reduction in hip fracture rates attributable to treatment was estimated using the absolute risk reduction (ARR) found in real-world users of oral alendronate in Denmark with the ARR in the FIT primary prevention arm as an alternative scenario.

RESULTS: A plateau in use of osteoporosis medications occurred in 2014. Between 2005 and 2015, hip fracture rates declined by 30%. However, only up to 20% of the observed reduction in hip fracture rates was statistically attributable to treatment even in a best-case scenario. Sensitivity analyses where raloxifene and teriparatide were excluded did not impact on this finding.

DISCUSSION: Anti-osteoporosis treatment in Denmark reached a plateau in 2014 even in a best-case scenario where all dispensations were assumed to be for osteoporosis. Future studies may be able to distinguish between the oncology area and the osteoporosis indication as well as provide a delineation of age and gender demographics among users of hospital administered osteoporosis medications. About 80% of the decline in hip fracture rates appears to be due to factors other than osteoporosis medication. The plateau in use of osteoporosis treatment at a level that is too low to make a meaningful impact on societal fracture burden is problematic given the predicted increased age-specific hip fracture rates.