A systematic review of prognostic factors predicting survival in patients with spinal bone metastases

Purpose: For the selection of treatment in patients with spinal bone metastases (SBM), survival estimation plays a crucial role to avoid over- and under-treatment. To aid clinicians in this difficult task, several prediction models have been developed, consisting of many different risk factors. The aim of this systematic review was to identify prognostic factors that are associated with survival in patients with SBM to support development of predictive models. Methods: A systematic review was performed with focus on prognostic factors associated with survival in patients with SBM. Two reviewers independently selected studies for inclusion and assessed the risk of bias. A level of evidence synthesis was performed for each prognostic factor. Inter-observer agreement for the risk of bias assessment was determined by the kappa-statistic. Results: After screening, 142 full-text articles were obtained, of which 22 met the eligibility criteria. A total of 43 different prognostic factors were investigated in the included studies, of which 17 were relevant to pre-treatment survival estimation. The prognostic factors most frequently associated with survival were the primary tumor and the performance status. The prognostic factors most frequently not associated with survival were age, gender, number and location of the SBM and the presence of a pathologic fracture. Conclusions: Prognostication for patients with SBM should be based on an accurate primary tumor classification, combined with a performance score. The benefit of adding other prognostic factors is doubtful.