Bone strength and microarchitecture remained stronger at 24 months after treatment with denosumab compared to risedronate, in a study of 110 adults using glucocorticoids.
Patients using glucocorticoids are at increased risk for vertebral and nonvertebral fractures at both the start of treatment or as treatment continues, wrote Piet Geusens, MD, of Maastricht University, the Netherlands, and colleagues.
Dr. Piet Geusens
Imaging data collected via high-resolution peripheral quantitative computed tomography (HR-pQCT) allow for the assessment of bone microarchitecture and strength, but specific data comparing the impact of bone treatment in patients using glucocorticoids are lacking, they said.
In a study published in the Journal of Bone and Mineral Research, the researchers identified a subset of 56 patients randomized to denosumab and 54 to risedronate patients out of a total of 590 patients who were enrolled in a phase 3 randomized, controlled trial of denosumab vs. risedronate for bone mineral density. The main results of the larger trial – presented at EULAR 2018 – showed greater increases in bone strength with denosumab over risedronate in patients receiving glucocorticoids.
In the current study, the researchers reviewed HR-pQCT scans of the distal radius and tibia at baseline, 12 months, and 24 months. Bone strength and microarchitecture were defined in terms of failure load (FL) as a primary outcome. Patients also were divided into subpopulations of those initiating glucocorticoid treatment (GC-I) and continuing treatment (GC-C).
Baseline characteristics were mainly balanced among the treatment groups within the GC-I and GC-C categories.
Among the GC-I patients, in the denosumab group, FL increased significantly from baseline to 12 months at the radius at tibia (1.8% and 1.7%, respectively) but did not change significantly in the risedronate group, which translated to a significant treatment difference between the drugs of 3.3% for radius and 2.5% for tibia.
At 24 months, the radius measure of FL was unchanged from baseline in denosumab patients but significantly decreased in risedronate patients, with a difference of –4.1%, which translated to a significant between-treatment difference at the radius of 5.6% (P < .001). Changes at the tibia were not significantly different between the groups at 24 months.
Among the GC-C patients, FL was unchanged from baseline to 12 months for both the denosumab and risedronate groups. However, FL significantly increased with denosumab (4.3%) and remained unchanged in the risedronate group.
The researchers also found significant differences between denosumab and risedronate in percentage changes in cortical bone mineral density, and less prominent changes and differences in trabecular bone mineral density.
The study findings were limited by several factors including the use of the HR-pQCT scanner, which limits the measurement of trabecular microarchitecture, and the use of only standard HR-pQCT parameters, which do not allow insight into endosteal changes, and the inability to correct for multiplicity of data, the researchers noted.
However, the results support the superiority of denosumab over risedronate for preventing FL and total bone mineral density loss at the radius and tibia in new glucocorticoid users, and for increasing FL and total bone mineral density at the radius in long-term glucocorticoid users, they said.
Denosumab therefore could be a useful therapeutic option and could inform decision-making in patients initiating GC-therapy or on long-term GC-therapy, they concluded.
The study was supported by Amgen. Dr. Geusens disclosed grants from Amgen, Celgene, Lilly, Merck, Pfizer, Roche, UCB, Fresenius, Mylan, and Sandoz, and grants and other funding from AbbVie, outside the current study.