Time to Clinically Relevant Fracture Risk Scores in Postmenopausal Women

Abstract

Background: Clinical practice guidelines recommend use of fracture risk scores for screening and pharmacologic treatment decisions. The timing of occurrence of treatment-level (according to 2014 National Osteoporosis Foundation guidelines) or screening-level (according to 2011 US Preventive Services Task Force guidelines) fracture risk scores has not been estimated in postmenopausal women.

Methods: We conducted a retrospective competing risk analysis of new occurrence of treatment-level and screening-level fracture risk scores in postmenopausal women aged 50 years and older, prior to receipt of pharmacologic treatment and prior to first hip or clinical vertebral fracture.

Results: In 54,280 postmenopausal women aged 50 to 64 years without a bone mineral density test, the time for 10% to develop a treatment-level FRAX score could not be estimated accurately because of rare incidence of treatment-level scores. In 6096 women who had FRAX scores calculated with bone mineral density, the estimated unadjusted time to treatment-level FRAX ranged from 7.6 years (95% confidence interval [CI], 6.6-8.7) for those aged 65 to 69, to 5.1 years (95% CI, 3.5-7.5) for those aged 75 to 79 at baseline. Of 17,967 women aged 50 to 64 with a screening-level FRAX at baseline, 100 (0.6%) experienced a hip or clinical vertebral fracture by age 65 years.

Conclusions: Postmenopausal women with sub-threshold fracture risk scores at baseline were unlikely to develop a treatment-level FRAX score between ages 50 and 64 years. After age 65, the increased incidence of treatment-level fracture risk scores, osteoporosis, and major osteoporotic fracture supports more frequent consideration of FRAX and bone mineral density testing.

Trial registration: ClinicalTrials.gov NCT00000611.

Keywords: Bone density; Fractures; Menopausal; Osteoporosis/epidemiology; Risk assessment.

Figure 1. Study population for primary analyses of time to treatment-level or screening-level FRAX risk score

Of the 111,556 women who did not have a DXA bone density test, 57,276 were excluded, including those who had a past hip or clinical vertebral fracture or antifracture treatment (bisphosphonate or calcitonin) at their first study examination, or who did not have adequate data for a FRAX score calculation at two or more examinations, or one FRAX score and subsequent development of a competing risk. In the cohort of 54,280 women with adequate data for a FRAX-without-BMD score prior to censoring, two transitions were studied: transition to treatment-level FRAX score (10-year estimated risk of major osteoporotic fracture ≥20% or of hip fracture ≥3%), and transition to screening-level FRAX score (10-year estimated risk of major osteoporotic fracture ≥9.3%). By a similar exclusion process, 6096 eligible participants who had at least one bone mineral density test were identified and were studied for transition to treatment-level FRAX-with-BMD score. The 39,568 women excluded for screening-level or treatment-level FRAX scores at baseline could not participate in the main analysis, but their incidence of hip and clinical vertebral fracture was examined.