Prediction and risk factors for one year mortality in patients after surgery for pyogenic spondylodiscitis

Abstract Objective Pyogenic spondylodiscitis is a severe spinal infection often requiring surgical intervention, with notable one-year mortality rates. This study aimed to identify factors associated with 1-year mortality following instrumented surgery to guide postoperative care and surgical planning. Methods A retrospective analysis was conducted on 370 patients who underwent instrumented surgery for pyogenic spondylodiscitis (2013–2022). Univariate and multivariate logistic regression analyzed factors associated with 1-year-mortality, including age, Charlson Comorbidity Index (CCI), neurological deficits, C-reactive protein levels (CRP), type of surgery, number of spinal levels treated, complications, duration of surgery, and revision surgery. ROC analysis determined optimal cutoff values for significant factors associated with mortality. Results Out of the 370 patients included in the study, 38 (10.2%) died within one year of treatment, including 6 (1.6%) within the first 30 days. The mean follow-up period was 24 ± 3 months. Univariate analysis identified the presence of neurological deficits (OR 2.82, 95% CI 1.21–6.55, p = 0.0158), last CRP levels (OR 1.009, 95% CI 1.005–1.014, p < 0.001), and the number of spinal levels treated (OR 1.35, 95% CI 1.03–1.77, p = 0.0294) as significant factors associated with 1-year mortality. Multivariate logistic regression confirmed last CRP (OR 1.01, 95% CI 1.004–1.016, p = 0.001) and number of spinal levels treated (OR 1.345, 95% CI 1.006–1.799, p = 0.046) as independent factors associated with mortality within one year. Receiver operating characteristic (ROC) analysis identified optimal thresholds for predicting mortality: last CRP > 47 mg/L (AUC 0.767) and more than two spinal levels treated (AUC 0.638). Conclusion Elevated CRP levels(> 47 mg/L) at a median of 4 months postoperatively [IQR: 2–6], and extensive spinal surgery involving more than two levels are independent factors associated with one-year mortality. These findings highlight the importance of long-term postoperative CRP monitoring and careful surgical planning to improve outcomes in patients with pyogenic spondylodiscitis.