Page 67 - Predicting survival in patients with spinal bone metastasesL

than one confirmed spinal metastasis and it is not unlikely that a large proportion of patients classified as having a solitary metastasis in fact have occult lesions not yet detected25. Lastly, the presence of extraspinal bone metastases was not associated with survival.
New model
A flowchart was created to guide the stratification of patients with symptomatic SBM (figure 4). Based on a maximum of three easy to obtain variables, patients are classified into one of four categories (A-D), each with a distinctly different estimated survival time. The effect of this approach is particularly striking in patients with a favorable clinical profile: by assessing two variables the median survival is split from 18.6 months (95%CI 15.1-22.1) overall, down to 4.8 months (95%CI 2.3-7.3) and up to 31.2 months (95%CI 25.2-37.3) (table 7).
Harrell’s c-statistic was almost identical when the new model was applied to an external database, indicating good reproducibility of our results. The current values of 0.71 and 0.69 indicate a good predictive value of the model and with a more accurate classification of primary cancers into one of the three clinical profiles, the value of c should rise even further.
This large data collection provides a better understanding of how risk factors interact when stratified for primary tumor. It is shown that clinical profile and performance status have a strong impact on survival in all patients with symptomatic SBM. The presence of visceral and/or brain metastases is associated with a shortened survival only in patients with a favorable clinical profile.
The model presented in this study can be used as a simple stratification tool in patients presenting with symptomatic SBM. Also, it can be used in future studies comparing efficacy of radiotherapy regimens and various types of surgical intervention, as well as studies into the effects on quality of life of different treatment modalities.
IV
PREDICTIVE MODEL
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