Black DM, Reid IR, Napoli N, et al. - The yearly infusion of Zoledronic acid (ZOL) [done for reducing fracture risk] is commonly followed by an acute-phase reaction (APR), consisting of flu-like symptoms within 3 days after infusion. Correlation of APR occurrence with drug efficacy has been analyzed herein.

• From the 3-year randomized clinical trial, Health Outcomes and Reduced Incidence with Zoledronic Acid Once Yearly-Pivotal Fracture Trial (HORIZON-PFT), data were retrieved for analysis.

• The ZOL group included 3,862 women and the placebo group included 3,852 women.

• APR occurred in 42.4% of women in the ZOL group vs 11.8% women in the placebo group.

• There was a similar difference in BMD mean change for ZOL vs placebo for women with and without an APR.

• Among ZOL women, vertebral fracture risk appeared to be 51% lower among those with APR vs those without.

• For nonvertebral and hip fracture, there appeared a similar but nonsignificant trend.