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 anti-resorptive medications according to two definitions of serial BMD change.Cohort study using administrative databases.Single-payer government health system in Manitoba, Canada.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.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 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.Results may not apply to situations of poor adherence to anti-resorptive medication or anabolic therapy use.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.
Gregory A Kline, Suzanne N Morin, Sidney Feldman, Lisa M Lix, William D Leslie