Three factors were found to be predictive of survival in a surgical series of metastatic epidural spinal cord compression, including the type of primary tumor and a lower degree of physical disability on the SF-36 physical component score. These results were presented at the 2018 American Association of Neurological Surgeons Annual Scientific Meeting (28 April–2 May, New Orleans, USA) by Brian D Silber Award winner Anick Nater-Goulet (University of Toronto, Toronto, Canada), who is supervised by Michael Fehlings (also University of Toronto).
For this project, researchers aimed to:
- Identify preoperative predictors of survival in adults treated surgically for a single metastatic epidural spinal cord compression lesion
- Examine how these predictors relate to eight prognostic scoring systems or model
- Perform the first full external validation of these prognostic scoring systems or model in accordance to the TRIPOD (the transparent reporting of a multivariable prediction model for individual prognosis or diagnosis) guideline.
This study is the first full external validation of eight prognostic scoring systems or model conducted in accordance with the TRIPOD guidelines using prospectively collected data from patients with metastatic epidural spinal cord compression who were surgically treated. The TRIPOD guideline proposes a checklist to reduce the risk of bias when developing or validating multivariate diagnostic and prognostic models.
One hundred and forty-two surgical metastatic epidural spinal cord compression patients were enrolled in the prospective, multicentre, North American cohort study, which was sponsored by AOSpine North America and led by Fehlings. Patients were followed for at least 12 months or until death.
The investigators identified three independent preoperative clinical factors associated with longer overall survival for patients who underwent spinal decompression with or without reconstruction or stabilisation for a single metastatic epidural spinal cord compression lesion. Firstly, presence of a breast, prostate, or thyroid primary tumor. Secondly, an absence of organ metastasis. Thirdly, a lower degree of physical disability as reflected by a higher score on the SF-36v2 physical component questionnaire.
The SF-36v2 questionnaire is a generic health survey that asks 36 questions to measure functional health and well-being from the patient’s perspective, and takes five to ten minutes to complete.
Detailing why this work was undertaken, Nater-Goulet tells Spinal News International: “A recent systematic review of the literature reported that the current body of evidence exploring prognostic factors of survival in surgically treated metastatic epidural spinal cord compression patients has a moderately high risk of bias due to shortfalls in the design, conduct, analysis, and reporting of studies. Consequently, the strength of the overall body of evidence for predictors of survival in this patient population is low.” Additionally, prospectively gathered clinical data are more complete and precise than those obtained retrospectively.
Nater-Goulet comments, “We performed the first full external validation of eight current prognostic scoring systems or model in accordance with the TRIPOD guidelines, which revealed that none of these prognostic scoring systems or model were able to accurately predict survival in our surgical cohort. In fact, discrimination was possibly helpful, and calibration was overall poor. Therefore, clinicians should use these prognostic scoring systems or model with caution, especially if they are applied in a patient population different from the population in which the model was developed.”
Nater-Goulet and colleagues describes being awarded the Brian D Silber Award at AANS as “a terrific honour”, saying, “Having seen the number of exceptional abstracts presented during the session, we are convinced the decision must have been very difficult. It is thrilling to be recognised by our peers from such a well-established and outstanding association as the AANS and it is a fabulous source of motivation to pursue our goal to contribute to expanding scientific knowledge.”
Looking forward, Nater-Goulet tells Spinal News International, “There is a need to create and validate a clinical prognostic model of survival in patients with metastatic epidural spinal cord compression who undergo surgical treatment, to inform [patients] about prognosis, to assist both clinicians and patients in the process of joint clinical decision-making, and to help manage patient expectations. Although life expectancy is an important aspect to consider in patients with metastatic epidural spinal cord compression, quality-of-life is also cornerstone. Consequently, we should attempt to develop and validate clinical prognostic models of quality of life in this patient population.”