Survival of patients undergoing surgery for metastatic spinal tumours and the impact of surgical site infection

Background
Patients with metastatic spinal tumours have a limited prognosis. Surgical complications which may result in prolonged hospitalisation or readmission are highly undesirable. Surgical site infection (SSI) is one such complication which can, in extreme cases, lead to death.
Aim
To assess the impact of SSI on patient survival after surgery for spinal metastases.
Methods
Demographic, operative and survival data were collected on 152 patients undergoing surgery for spinal metastases at Salford Royal NHS Foundation Trust. American Society of Anesthesiologists (ASA) grade and the Revised To kuhashi Score (RTS) were obtained as measures of health status at baseline. A semi-parametric Cox proportional hazards survival analysis was used to assess the relationships between covariates and survival.
Results
Mean age at operation was 60.5 years (standard deviation 12.9 years). Seventeen patients (11.2%) experienced SSI. At the time of last follow up, 117 patients had died. RTS score (p<0.001; hazard ratio 0.82; 95% confidence interval: 0.76-0.87) and ASA grade (p=0.022; hazard ratio 1.40; 95% confidence interval: 1.05-1.87) were significantly associated with survival, with better survival found in patients with higher RTS and lower ASA scores. Infection status was of substantive importance, with better survival in those without SSI (p=0.075). Age was not substantively related to survival (p=0.299). Overall, median survival time from operation was 262 days (95% confidence interval: 190-334 days).
Conclusions
Five-year survival in patients undergoing surgery for spinal metastases is approximately 23%. Either or both of RTS or ASA scores can be used as indicators of patient survival. There is insufficient evidence to conclude that the presence of SSI retards survival.