Low Incidence of Jaw Osteonecrosis With Prolia, Bisphosphonate Tx

SAN FRANCISCO, CA—Treatment with Prolia (denosumab) or bisphosphonates was associated with a low incidence rate of potential osteonecrosis of the jaw among postmenopausal women with osteoporosis, according to data presented by Fei Xue, MD, Center for Observational Research, Amgen Inc, at the 2015 ACR/ARHP Annual Meeting.

Bisphosphonates, the most commonly used osteoporosis medication, have been associated with osteonecrosis of the jaw; however, no published population-based data is available on this risk in those treated with Prolia. Dr. Xue and her team set out to estimate the incidence rate of osteonecrosis of the jaw in postmenopausal women with osteoporosis using Prolia and bisphosphonates.

The prospective study included women with a diagnosis of osteoporosis or osteoporotic fracture, or who were receiving osteoporosis medications (n=2,561,119), identified using administrative data from US Medicare (May 2010 to December 2011; age ≥65 years; n=1,995,915), United Healthcare (May 2010 to March 2013; age ≥55 years; n=193,003) and national health registries from Scandinavia (Denmark, n=106,691; Norway, n=95,628; Sweden; age ≥55 years; n=169,882). Patients were followed for incidence of potential osteonecrosis of the jaw defined by ICD codes during the on-treatment period, defined as the days supplied plus 60 days, with and without a 1-year extension period.

The team found that the incidence rate per 100,000 person years of osteonecrosis of the jaw in postmenopausal women with osteoporosis was 40 (95% CI: 38–42) in the Medicare population, 27 (95% CI: 20–34) in the United Healthcare population, 37 (95% CI: 27–50) in Denmark, 17 (95% CI: 11–26) in Norway, and 25 (95% CI: 17–38) in Sweden.

In the Medicare population, classified only by the on-treatment period, the incidence rate was 70 (95% CI: 28–145) in the Prolia only cohort and 90 (95% CI: 11–328) in the Prolia plus bisphosphonates cohort. When classified by on-treatment and 1-year post-treatment period, the incidence rate was numerically lower in the Prolia only cohort, 59 (95% CI: 11–180) and the Prolia plus bisphosphonates cohort, 76 (95% CI: 30–160).

“To confirm these results, further analysis based on medically confirmed cases and adjustment for confounders will be conducted in the ongoing 10-year prospective cohort study,” Dr. Xue concluded.