Intervals between bone mineral density testing with dual-energy X-ray absorptiometry scans in clinical practice

Intervals between dual-energy X-ray absorptiometry (DXA) scans were evaluated in a large cohort of typical clinical practice. Intensive DXA scanning (intervals < 23 months) decreased substantially, from 16.7% in 2006 to 6.7% in 2015.

Serial dual-energy X-ray absorptiometry (DXA) measurements are suggested for patients at high risk of fractures. However, little is known about how often DXA testing occurs in clinical practice.

We examined time intervals between DXA testing for monitoring purpose at two academic medical centers in the US between 2004 and 2017. The primary outcome was the presence of testing intervals < 23 months (termed "intensive DXA testing"). A generalized linear mixed model was used to evaluate the association between selected patient-level clinical factors and intensive DXA testing.

Forty-nine thousand four hundred ninety-four DXA tests from 20,200 patients were analyzed. The mean time interval between scans was 36 ± 21 months. Only 11.1% of the repeated DXA testing met the criterion for intensive testing. The percentage of intensive DXA testing dropped from 16.7% in 2006 to 6.7% in 2015 (p for trend < 0.001). After adjusting for age, gender, number of outpatient visits, and calendar year, correlates of intensive DXA testing included a baseline T-score < -2.5 at any anatomic site (OR, 4.8; 95%CI, 4.0-5.7), active use of drugs for osteoporosis (OR, 1.6; 95%CI, 1.3-1.9), and active use of glucocorticoids (OR, 1.3; 95%CI, 1.2-1.4).

The predictors of intensive DXA testing suggest that this practice is used preferentially in patients with multiple risk factors and to monitor the response to pharmacotherapy. However, intensive DXA testing has become less common in real-world clinical practice over the last decade. Further studies are required to better define the optimal use of bone mineral density testing in this vulnerable population.