External validation of a model to predict the survival of patients presenting with a spinal epidural metastasis

Abstract

The surgical treatment of spinal metastases is evolving. The major problem is the selection of patients who may benefit from surgical treatment. One of the criteria is an expected survival of at least 3 months. A prediction model has been previously developed. The present study has been performed in order to validate externally the model and to demonstrate that this model can be generalized to other institutions and other countries than the Netherlands. Data of 356 patients from five centers in Germany, Spain, Sweden, and the Netherlands who were treated for metastatic epidural spinal cord compression were collected. Hazard ratios in the test population corresponded with those of the developmental population. However, the observed and the expected survival were different. Analysis revealed that the baseline hazard function was significantly different. This tempted us to combine the data and develop a new prediction model. Estimating iteratively, a baseline hazard was composed. An adapted prediction model is presented. External validation of a prediction model revealed a difference in expected survival, although the relative contribution of the specific hazard ratios was the same as in the developmental population. This study emphasized the need to check the baseline hazard function in external validation. A new model has been developed using an estimated baseline hazard.

Survival of women with spinal compression syndrome due to bone metastasis secondary to breast cancer

“…In this study, death occurred in 92% of cases, 9 months (95% CI [3][4][5][6][7][8][9][10][11][12][13][14] after the diagnosis of compression syndrome. A similar result was found in others studies, who reports that the overall survival of patients with compression syndrome was 9 months 15 and 12 months 16 after the development of neurological signs. Significantly, longer survival is associated with a longer interval between diagnosis of the tumor and the development of compression syndrome 12 .…”

The Oswestry Risk Index

“…The larger importance of visceral metastases compared to bony metastases in predicting survival in this study concurs with other studies. [4][5][6]28 Clearly from the above, the similar overall ability of the scoring systems to predict survival hides major differences in performance between individual items within each system. It is therefore not surprising that prediction of survival improved after combining the most predictive items (Nagelkerke's R 2 = 0.31 vs Nagelkerke's R 2 = 0.15 to 0.18 for the original systems).…”

“…8,9 However, many other studies have found the same positive correlation between general condition and survival as our study. 6,10,12,27,28 Tomita et al 2 believed that the general condition was reflective of the status of the visceral metastasis, although they did not investigate this proposed link.…”

The Dutch national guideline on metastases and hematological malignancies localized within the spine; a multidisciplinary collaboration towards timely and proactive management

“…These models have been developed and partially validated in Dutch patients and are therefore considered to be valid for use with Dutch patient populations. The Van der Linden model has already been successfully validated in the Canadian population [49] and the Bartels model has also been geographically and prospectively validated [48,61]; nevertheless, these models should be validated further for truly international use. These models were based on current clinical practice; however, new treatment options are currently being developed, and are expected to increase the survival of patients with spinal metastases.…”

“…Details of these prognostic models can be found in Table 4. The accuracy of the Tokuhashi model is reported to vary greatly [43][44][45][46][47], but the other models have been shown to permit a reliable assessment of the survival of patients with symptomatic spinal metastases, with no model being superior to the others [11,48,49].…”