Risk Factors and Incidence of Unplanned Hospital Readmission After Surgery for Spinal Metastases: A Systematic Review and Meta-Analysis

Purpose No prior meta-analysis has quantified unplanned readmission after surgery for spinal metastases. This study aimed to estimate the pooled 30-day readmission incidence and to identify independently associated risk factors. Methods PubMed, Embase, Cochrane CENTRAL, Scopus, and Web of Science were systematically searched from January 2010 to March 2026. Studies reporting readmission after open surgery for spinal metastases in adults were included. Pooled incidence was estimated using Freeman-Tukey double arcsine transformation with DerSimonian-Laird random-effects modelling; restricted maximum likelihood (REML) estimation was used as sensitivity analysis. Risk factors were synthesised narratively or pooled where feasible. Quality was assessed using the Newcastle-Ottawa Scale; evidence certainty using GRADE. Results Fourteen studies (8,132 patients for incidence pooling) met inclusion criteria. Seven studies (8,132 patients) contributed to incidence pooling. The pooled 30-day readmission incidence was 16.0% (95% CI: 12.2–20.3%; I² = 93.2%). Single-centre studies (k = 5) showed 13.9% (I² = 0%), whereas database studies (k = 2) showed 20.4% (p for subgroup difference < 0.001). Prior spinal radiation was the only poolable risk factor (pooled effect 1.79; 95% CI: 1.21–2.63; k = 2). Comorbidity burden consistently increased risk across four studies (OR 1.25–2.54) with dose–response. Other significant factors included diabetes, prolonged operative time, postoperative complications, and lung primary tumour. The pooled 90-day incidence was 31.2% (95% CI: 26.9–35.6%; k = 7). Evidence certainty was very low (GRADE). Conclusions Approximately one in six patients is readmitted within 30 days of spinal metastasis surgery, a rate substantially exceeding that of general spine surgery. Comorbidity burden, prior spinal radiation, and poor functional status are the most consistently identified risk factors. These findings provide an evidence base for targeted preoperative risk stratification and structured discharge planning in this vulnerable population.