Assessment of spinal stability in spine metastases is challenging and is mostly done by relying on clinical experience, in the absence of validated guidelines or an established predetermined set of risk factors. The Spinal Instability Neoplastic Score (SINS) provides clinicians with a tool to assess tumor-related spine instability.
A total of 110 patients were included in this retrospective study. Time to event was calculated as the difference between start of radiotherapy and date of occurrence of an adverse event or last follow-up, with death being considered a competing event. A competing risk analysis was performed to estimate the effect of the SINS on the cumulative incidence of the occurrence of an adverse event.
Sixteen patients (15%) experienced an adverse event during follow-up. The cumulative incidence for the occurrence of an adverse event at 6 and 12 months was 11.8% (95% confidence interval 5.1%-24.0%) and 14.5% (95% confidence interval 6.9%-22.2%), respectively. Competing risk analysis showed that the final SINS classification was not significantly associated with the cumulative incidence of an adverse event within the studied population.
The clinical applicability of the SINS as a tool to assess spinal instability seems limited.