CALLY index and bone mineral density as risk factors for adjacent vertebral fracture after balloon kyphoplasty for treatment of osteoporotic vertebral compression fracture: a retrospective analysis.

BACKGROUND

Adjacent vertebral re-fracture following percutaneous balloon kyphoplasty (BKP) is a common complication. The C-reactive protein-albumin-lymphocyte (CALLY) index serves as a metric to assess inflammation levels, immune status, and nutritional status. Studies have shown that the CALLY index is closely associated with various musculoskeletal disorders. The purpose of this study was to investigate the relationship between the CALLY index and the incidence of adjacent vertebral re-fracture after BKP.

OBJECTIVE

To investigate the correlation between the CALLY index and the risk of subsequent adjacent vertebral fracture following BKP in patients with osteoporotic vertebral compression fracture (OVCF).

METHODS

A retrospective analysis was conducted on 376 OVCF patients who underwent BKP. Based on the occurrence of subsequent vertebral fractures, patients were categorized into a no fracture group and a re-fracture group. Patient demographics and clinical data, including age, gender, Body Mass Index (BMI), bone cement leakage, smoking history, history of diabetes, history of hypertension, and Bone Mineral Density (BMD), were obtained. The CALLY index was calculated using the formula: Albumin (g/L) × Lymphocyte count (10⁹/L) ÷ C-reactive protein (mg/L). BMD was determined using dual-energy x-ray absorptiometry. Receiver Operating Characteristic (ROC) curve analysis was employed to evaluate the investigational value of the CALLY index for vertebral re-fracture. Univariate and multivariate logistic regression analyses were used to identify risk factors associated with vertebral re-fracture after BKP.

RESULTS

The re-fracture rate at a minimum follow-up of 12 months post-BKP was 15.7%. In the univariate logistic regression analysis, significant differences were observed between the re-fracture and no fracture groups regarding age, Cobb angle correction, vertebral height restoration ratio, intradiscal cement leakage, BMD, and the CALLY index. In the multivariate logistic regression analysis, both BMD (OR 0.948; 95% CI 0.843, 0.955; p = 0.009) and the CALLY index (OR 0.957; 95% CI 0.879, 0.946; p = 0.011) remained independent predictors for vertebral re-fracture. The Area Under the Curve (AUC) values for assessing adjacent vertebral re-fracture were 0.783 for BMD and 0.814 for the CALLY index.

CONCLUSION

The CALLY index is an independent risk factor for new-onset VCFs following BKP. This suggests that the CALLY index may serve as a potential indicator for assessing the risk of re-fracture in patients following BKP.