J Clin Endocrinol Metab. 2021 Mar 30;dgab211. doi: 10.1210/clinem/dgab211.
Background: The value of serial bone mineral density (BMD) monitoring while on osteoporosis therapy is controversial.
Objective: We determined the percentage of women classified as suboptimal-responders to therapy with anti-resorptive medications according to two definitions of serial BMD change.
Design: Cohort study using administrative databases.
Setting: Single-payer government health system in Manitoba, Canada.
Patients: Post-menopausal women aged 40 years or older receiving anti-resorptive medications and having 3 sequential BMD measures. Women stopping or switching therapies were excluded.
Methods: The percentage of women whose spine or hip BMD decreased significantly during the first or second interval of monitoring by BMD was determined. Suboptimal-responder status was defined as BMD decrease during both monitoring intervals or BMD decreased from baseline to final BMD.
Results: There were 1369 women in the analytic cohort. Mean BMD monitoring intervals were 3.0(0.8) and 3.2(0.8) years respectively. In the first interval, 3.2% and 6.5% of women had a decrease in spine or hip BMD; 8.0% and 16.9% had decreases in the second monitoring interval, but only 1.4% showed repeated losses in both intervals. Considering the entire treatment interval, only 3.2% and 7.4% showed BMD loss at spine or hip.
Limitations: Results may not apply to situations of poor adherence to anti-resorptive medication or anabolic therapy use.
Interpretation: Among women highly adherent to anti-resorptive therapy for osteoporosis, a very small percentage sustained BMD losses on repeated measures. The value of multiple serial BMD monitoring to detect persistent suboptimal-responders should be questioned.