P2-17-06: Patterns of Bone Density Evaluation in a Community Population Treated with Aromatase Inhibitors.
Authors: Ligibel JA , O'Malley AJ , Fisher M , Daniel GW , Winer EP , Keating NL 
Published: June 2012

Aromatase inhibitors (AIs) lead to an increased risk of bone loss and fracture. Fracture rates in adjuvant AI studies have ranged from 2.3% to 11%, with higher rates seen in studies with longer duration of AI therapy and longer follow up. The American Society of Clinical Oncology recommends baseline bone density testing upon initiation of AI therapy and repeat testing every 1–2 years while on therapy. There are few data regarding the incorporation of these guidelines into clinical practice. We sought to evaluate patterns of bone density testing in a community-based cohort of breast cancer patients treated with AIs.

Methods: We obtained encounter and pharmacy data from the HealthCore Integrated Research Database, a fully integrated commercial payer dataset including patients enrolled in WellPoint insurance plans. We identified 9138 women aged ≥50 years who had at least 2 diagnosis codes for breast cancer between 2001 and 2007 (followed through 2008), and who filled at least 1 prescription for an AI. We identified bone density testing using encounter data and used logistic regression to assess patient demographic and clinical characteristics associated with baseline bone density testing (any test from 6 months before through 6 months after the first prescription for AI). Among 2038 women who continued AI therapy for ≥2 years, we used logistic regression to assess factors associated with receipt of any bone density during the 2-year period.

Results: Overall, 41.6% of women underwent baseline bone density testing. Rates of bone density testing increased over time, from 26.6% in 2002 to 44.7% in 2008 (adjusted odds ratio [AOR] for 2008 vs. 2002=2.02, 95% confidence interval [CI]=1.53−2.68). Older women were less likely to undergo baseline bone density testing (AOR for women age ≥69 vs. 51–59=0.64, 95% CI=0.56−0.72). Women taking proton pump inhibitors, which have been linked to bone density loss, were also less likely to undergo baseline bone density testing (AOR=0.86, 95% CI=0.73−1.00). Women living in areas of lower education (p&lt;.001), and areas with a higher proportion of blacks (p=.02) or Hispanics (p&lt;.001), as well as women previously treated with tamoxifen (p=.02), were all also less likely to undergo baseline bone density. Women receiving bisphosphonates in the year before initiation of an AI were more likely to undergo baseline bone density (AOR=1.33, 95% CI=1.16−1.51).

Among women on AIs for at least 2 years, 59.9% of women underwent a bone density within 2 years of starting treatment. In adjusted analyses, earlier year of AI initiation (p&lt;.001), living in areas with lower education levels (p&lt;.001), and having been previously treated with tamoxifen (p&lt;.001) were all associated with a decreased likelihood of undergoing bone density testing.

Conclusions: Despite the increased risk of fracture in women treated with AIs and guidelines recommending regular bone density evaluation, 58.4% of women starting an AI and 40.1% of women on long-term therapy did not undergo bone density evaluation in this community-based population. Older women, who might be especially vulnerable to bone loss and fracture, were less likely to undergo baseline bone density evaluation. More attention is needed to ensure that preventable fractures are avoided in patients taking AIs.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-17-06.