Cumulative Incidence and Factors Associated with Subsequent Vertebral Compression Fractures: A Nationwide Population-based Study

Real-world rates and risk factors for subsequent treatment with vertebroplasty or balloon kyphoplasty after initial vertebral augmentation: a retrospective cohort study

The purpose of this study was to determine the real-world incidence and predictors of additional vertebroplasty or balloon kyphoplasty after initial vertebral augmentation, as a proxy for subsequent symptomatic vertebral fracture. Of patients, 15.5% underwent subsequent vertebral augmentation. The patient's comorbidities are strongly associated with risk of subsequent treatment.

PURPOSE

To determine the real-world incidence and predictors of additional vertebroplasty or balloon kyphoplasty after initial vertebral augmentation, as a proxy for subsequent symptomatic and disabling vertebral fracture.

METHODS

We conducted a retrospective cohort study using commercial insurance claims data (Optum's de-identified Clinformatics® Data Mart Database). Adult patients who underwent subsequent treatment for vertebral fracture within 24 months of initial balloon kyphoplasty (BKP) or vertebroplasty (VP) were classified into "subsequent treatment" or "no subsequent treatment" cohorts. Survival analysis was applied to investigate the effect of risk factors on subsequent treatment.

RESULTS

Between 1 January 2008 and 30 June 2020, a total of 32,513 adult patients underwent a BKP/VP procedure following a diagnosis of vertebral compression fracture in the preceding 12 months. Five thousand thirty-five patients (15.5%) underwent a subsequent BKP/VP treatment within 2 years; 90% had a single fracture level treated. An increased hazard of subsequent treatment was associated with a number of fractures treated at initial BKP/VP (≥ 4 levels, adjusted hazard ratio (AHR) 1.68 (95% CI 1.24-2.26); steroid use, AHR 1.9 (95% CI 1.31-1.48); Elixhauser Comorbidity Index ≥ 4, AHR 1.44 (95% CI 1.17-1.77); and multiple myeloma, AHR 1.31 (95% CI 1.13-1.53)). Age < 70 years was associated with reduced hazard of subsequent treatment (AHR 0.81, 95% CI 0.74-0.89).

CONCLUSIONS

One in seven patients underwent subsequent treatment for vertebral fracture after initial vertebral augmentation. Baseline patient characteristics were associated with increased risk of subsequent fracture within 2 years, suggesting that a patient's natural history is strongly associated with risk of subsequent treatment rather than the initial surgical procedure itself.

Biomechanical CT-computed bone strength predicts the risk of subsequent vertebral fracture

Following primary fractures and percutaneous kyphoplasty (PKP), patients have a high risk of incurring a subsequent vertebral fracture (SVF). Given that SVF is a consequence of mechanical deterioration of the vertebra, we sought to examine whether vertebral strength derived from QCT-based finite element analysis (i.e., BCT) can predict the risk of SVF. Sixty-six patients who underwent PKP were categorized into two groups: control or non-SVF group (age: 70 ± 7 years; n = 40) and SVF group (age: 69 ± 8 years; n = 26). BCT was performed on L4 or L3 vertebrae to noninvasively measure vertebral strength. Vertebral strength was also estimated based upon the geometry and material properties of the vertebra. Additionally, trabecular volumetric bone mineral density (vBMD) and L1 Hounsfield unit (HU) were measured. t-Test, χ² test or Mann Whitney U test were used to compare differences in these parameters between the two groups. The predictive abilities of BCT strength and other measured parameters were evaluated using the receiver operating characteristic (ROC) analysis. Results showed no significant difference in either vBMD or L1 HU between the control and SVF groups (p > 0.05), whereas BCT-computed and estimated vertebral strength values were significantly reduced by 33 % and 24 % for the SVF group relative to the non-SVF group, respectively. ROC curve indicated that BCT strength had the largest area under the curve, compared to other parameters. These results suggest that BCT-computed vertebral strength may serve as a surrogate for assessing risk of SVF.