The diagnostic threshold for osteoporosis impedes fracture prevention in women at high risk for fracture: A registry-based cohort study.

The diagnostic threshold for osteoporosis, a bone mineral density (BMD) T-score ≤ -2.5, signals an increased risk for fracture. However, most fragility fractures arise among the majority of women with 'osteopenia' or 'normal' BMD. We hypothesized that a BMD T-score of -2.5, even if not intended as a treatment threshold, paradoxically may create disincentive to initiating treatment of women with osteopenia or normal BMD at high risk for fracture. From a population-based BMD registry covering the Province of Manitoba, Canada, we identified 3735 untreated women aged ≥ 50 years undergoing BMD screening in 2006-2015 found to qualify for Osteoporosis Canada guidelines-based treatment. The main outcome was prescription of an approved osteoporosis medications in the year after BMD testing ascertained from a population-based pharmacy database. We estimated adjusted odds ratios (OR, 95% confidence interval [CI]) for treatment initiation based on BMD, major fracture history (non-traumatic vertebral, hip or multiple fractures), age, and calendar year (to examine the impact of treatment guidelines published in 2010). Among these women, 50% (1853) initiated treatment: 71% with osteoporosis, 21% with osteopenia, and 5% with normal BMD with similar values in those with a prior major fracture (71%, 19%, 5%, respectively). Compared to women with osteoporosis, adjusted ORs for treatment of high risk women with osteopenia or normal BMD alone were 0.10 (95% CI 0.09-0.12) and 0.02 (95% CI 0.01-0.04), respectively, and no higher in women with a prior major fracture (OR 1.00, 95% CI 0.84-1.19) or following introduction of treatment guidelines (p = 0.294). In summary, we found evidence that the diagnostic threshold for osteoporosis may serve as a disincentive to initiation of treatment in many women at high risk for incident fracture.