Diminishing Value from Multiple Serial Bone Densitometry in Women Receiving Antiresorptive Medication for...

The value of serial bone mineral density (BMD) monitoring while on osteoporosis therapy is controversial.

We determined the percentage of women classified as suboptimal responders to therapy with antiresorptive medications according to 2 definitions of serial BMD change.

This was a cohort study using administrative databases at a single-payer government health system in Manitoba, Canada. Participants were postmenopausal women aged 40 years or older receiving antiresorptive medications and having 3 sequential BMD measures. Women stopping or switching therapies were excluded. 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.

There were 1369 women in the analytic cohort. Mean BMD monitoring intervals were 3.0 (0.8) and 3.2 (0.8) years. 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. Results may not apply to situations of poor adherence to antiresorptive medication or anabolic therapy use.

Among women highly adherent to antiresorptive 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.