1Park Nicollet Clinic and HealthPartners Institute, Bloomington, MN, USA
2University of Minnesota, Minneapolis, MN, USA
3University of Manitoba, Winnipeg, Canada
4McGill University, Montreal, Canada
Purpose: Our purpose was to contrast mortality associated with clinically undiagnosed prevalent vertebral fracture recognized on densitometric vertebral fracture assessment (VFA) and prior clinically diagnosed vertebral fracture.
Methods: Between 2010 and 2016, 9679 men and women (mean age [SD] 76 [6.9] years, 93% women) with central site bone density T-score ≤ −1.5 had VFA images obtained at the time of bone densitometry. Vertebrae between T4 and L4 inclusive were evaluated for prevalent vertebral fracture on these images. Participants were categorized into three mutually exclusive groups; those with no vertebral fracture on VFA and no prior clinically diagnosed vertebral fracture (n = 7983), those with a definite vertebral fracture on VFA but no vertebral fracture clinically diagnosed before the index VFA date (n = 1376), and those with a prior clinically diagnosed vertebral fracture (n = 320). We ascertained mortality after the index VFA date using Manitoba provincial vital statistics files over a mean 2.8 (SD 1.7) years. We used Cox proportional hazards models to estimate the hazard ratios (HR) and 95% confidence intervals (C.I.) of prevalent vertebral fractures with mortality adjusted for multiple covariates.
Results: Adjusted for age and sex, those with clinically undiagnosed vertebral fracture on VFA had an HR of 1.22 (95% C.I. 1.00 to 1.50) for mortality, and those with a prior clinically diagnosed vertebral fracture had an HR of 1.78 (95% C.I. 1.27 to 2.50) for mortality compared to those with no prevalent vertebral fracture. After further adjustment for comorbidity score, current smoking, and other causes of mortality, these associations were slightly attenuated (HRs 1.18 [95% C.I. 0.95 to 1.45] and of 1.70 [95% C.I. 1.21 to 2.40], respectively). Stratified by elapsed years since diagnosis, clinical vertebral fractures were associated with excess mortality for up to 10 years after their occurrence.
Conclusion: Clinically undiagnosed prevalent vertebral fracture detected on densitometric VFA images are weakly associated with subsequent mortality adjusted for age and sex, but not after accounting for other causes of mortality. Clinical vertebral fractures are associated with increased mortality for ten years after their diagnosis, even after accounting for other causes of mortality.