Comparable long-term retention rates and effects on bone mineral density of denosumab treatment in patients with osteoporosis with or without autoimmune inflammatory rheumatic diseases: real-life data.

Objectives: To investigate whether concomitant autoimmune inflammatory rheumatic diseases (AIIRDs) represent a risk factor for denosumab discontinuation and to explore other possible predictors.

Design: This is a real-life retrospective study conducted at our centre on consecutive patients who started treatment with denosumab from January 2014 to October 2021.

Methods: Data on patients' characteristics, denosumab prescriptions and reason for discontinuation were collected from their medical electronic records. A log-rank test was run to assess differences in the denosumab retention rate between the not AIIRD and AIIRD patients. A backward stepwise logistic regression was used to identify possible predictors of denosumab discontinuation. When available, BMD data of the lumbar spine and total hip were collected.

Results: Three hundred and sixty-three patients were included (265 not AIIRD and 98 AIIRD; median follow-up, 44 months). Sixty-nine patients discontinued denosumab at any time point (4 due to patient's decision, 3 due to medical decision, 62 were lost in follow-up). The log-rank test did not find a statistically significant difference for denosumab persistence between the two subgroups. In the binary logistic regression analysis, only older age at initiation and lower baseline serum 25-hydroxy vitamin D were confirmed as predictors for discontinuation. BMD significantly increased from baseline to the last prescription visit at both the lumbar spine and the total hip, without statistically significant differences in the not AIIRD and AIIRD patients.

Conclusion: The present data seem to suggest that AIIRDs do not represent a risk factor for denosumab discontinuation. Furthermore, the presence of AIIRDs does not seem to impair its effectiveness in terms of BMD.