Compliance and discontinuation of denosumab treatment in postmenopausal Japanese women with primary osteoporosis or rheumatoid arthritis and osteoporosis

Objectives: The aim of this study was to examine the discontinuation and occurrence of fracture during denosumab treatment in Japanese women with primary osteoporosis or rheumatoid arthritis (RA) with osteoporosis. Methods: This retrospective study included 143 patients with primary osteoporosis and 96 patients with RA and osteoporosis who were treated with denosumab. Treatment discontinuation, fracture occurrence, lumbar spine (L1–4) bone mineral density (LS-BMD), and bilateral total hip BMD (TH-BMD) were examined before and at 1 and 2 years after treatment commencement. Results: In the primary osteoporosis group, 32 cases dropped out and no fractures occurred from 0 to 1 year. Eighteen cases were lost to follow-up and no fractures were noted from 1 to 2 years. In the RA with osteoporosis group, 7 cases dropped out and no fracture occurred from 0 to 1 year. Twenty-one cases were lost to follow-up and 2 nonvertebral fractures were noted from 1 to 2 years. In this group, 13 cases dropped out from 1 to 2 years and 16 cases dropped out during the 2-year study period due to economic reasons. LS-BMD and TH-BMD values increased continuously for 2 years of treatment in both primary osteoporosis and RA with osteoporosis groups. Conclusions: These results suggest that during denosumab therapy, the discontinuation rate is expected to remain low during 2 years of treatment in primary osteoporotic patients. In RA patients with osteoporosis, however, the discontinuation rate may increase due to economic reasons from 1 to 2 years of therapy.