Incidence and Predictors of Repeat Bone Mineral Densitometry: A Longitudinal Cohort Study

Existing guidelines for repeat screening and treatment monitoring intervals regarding the use of dual-energy x-ray absorptiometry (DXA) scans are conflicting or lacking. The Choosing Wisely campaign recommends against repeating DXA scans within 2 years of initial screening. It is unclear how frequently physicians order repeat scans and what clinical factors contribute to their use.

To estimate cumulative incidence and predictors of repeat DXA for screening or treatment monitoring in a regional health system.

Retrospective longitudinal cohort study PARTICIPANTS: A total of 5992 women aged 40-84 years who received initial DXA screening from 2006 to 2011 within a regional health system in Sacramento, CA.

Two- and five-year cumulative incidence and hazard rations (HR) of repeat DXA by initial screening result (classified into three groups: low or high risk of progression to osteoporosis, or osteoporosis) and whether women were prescribed osteoporosis drugs after initial DXA.

Among women not treated after initial DXA, 2-year cumulative incidence for low-risk, high-risk, and osteoporotic women was 8.0%, 13.8%, and 19.6%, respectively, increasing to 42.9%, 60.4%, and 57.4% by 5 years after initial screening. For treated women, median time to repeat DXA was over 3 years for all groups. Relative to women with low-risk initial DXA, high-risk initial DXA significantly predicted repeat screening for untreated women [adjusted HR 1.67 (95% CI 1.40-2.00)] but not within the treated group [HR 1.09 (95% CI 0.91-1.30)].

Repeat DXA screening was common in women both at low and high risk of progression to osteoporosis, with a substantial proportion of women receiving repeat scans within 2 years of initial screening. Conversely, only 60% of those at high-risk of progression to osteoporosis were re-screened within 5 years. Interventions are needed to help clinicians make higher-value decisions regarding repeat use of DXA scans.