Modeling Survival After Surgery On The Metastatic SpineAhmer Ghori MD, Dana Leonard BA, Andrew Schoenfeld MD, Ehsan Saadat MD, Mitch B Harris MD
Ahmer K Ghori MDHarvard University Orthopaedic Surgery Program
My Goal Today
Review the past and present state of managing metastatic spine.
Discuss how our model may improve the present state.
Historical: No advantage with surgery
Present: Surgery helps
Limitation: Can’t predict post op survival
Who to operate on?
Our Model
Future: Patient specific management
Evolution of spinal
instrumentation
Patient Specific
Variables
Predict survival reliably
Historic Management: Why no surgery ?
Laminectomy was the only surgical option.
No difference in laminectomy + radiation versus radiation alone with regard to: pain relief ambulation sphincter function.
Young et al 1980
Paradigm Shift
Evolution of modern spinal instrumentation.Wider decompressions
&Robust stabilization
Modern Literature
Surgery helps in managing metastatic spine
Pain.
Ambulation.
Maintain independence at end of life.Direct decompressive surgical resection in the treatment of spinal cord compression caused by metastatic cancer: a randomised trial. The Lancet. 2005;366(9486):643–648. doi:10.1016/S0140-6736(05)66954-1.
Present Limitations Choosing surgical candidates
Not a reliable process.
Existing models: Do not predict survival reliably ! Correlation with survival 20-50 %
Ragel, B. T. et al. Life Expectancy and Metastatic Spine Scoring Systems: An Academic Institutional Experience. J Spinal Disord Tech (2014). Wang M, Bünger CE, Li H, Wu C, Høy K, Niedermann B, et al. Predictive value of Tokuhashi scoring systems in spinal metastases, focusing on various primary tumor groups: Evaluation of 448 patients in the Aarhus spinal metastases database. Spine 2012;37: 573-582.
Harrington Score
Tokuhashi Score
Tomita Score
Tomita et al. Surgical strategy for spinal metastases. Spine (2001) vol. 26 (3) pp. 298-306
Modified Bauer Score
Existing scoring systems do not capture patient’s overall health state.
Ghori et al 2015
Why can’t we predict survival ?
Let’s consider a hypothetical scenario
Bauer Score: 4 Can we predict post op survival from a score of 4 alone?
Consider 2 patients
Female • Breast cancer• No visceral metastases• Solitary spine metastasis
Modified Bauer Score 4 Case 1
First patient is :
• Young• Can Ambulate• Normal
nutrition status.
Modified Bauer Score 4 Case 1
Modified Bauer Score 4: Case 2 Second patient is:
• Old.• Cannot ambulate.• Poor nutritional status.
Modified Bauer Score 4 Case 2
Both patients have a Bauer score of 4 !
Differences will affect survival
Need a model that is more specific.
Existing Models: Shortcoming
VS.
Hypothesis
Model
Quantifies patient health status
Predict post op survival reliably
Ghori et al 2015
Methods Retrospective review at four participating
institutions (BIDMC, BWH, MGH, Dartmouth).
Identify patients who had undergone spine surgery for metastatic disease between 2007 and 2013. Over 300 patients across 5 years included.
Ghori et al 2015
Variables we studied Main predictors of survival we studied
Pre-operative modified Bauer score Pre- operative ambulatory status Pre-operative serum albumin level. Pre-operative serum creatinine level. Primary tumor type. Demographics: age, sex, race. Number of comorbidities. We coined these “healthiness states”
Ghori et al 2015
Ghori et al 2015: Our Model Analyzed all permutations of these three variables. Chose combination which has best correlation with survival.
High Bauer score (3,4): 2 points
Intact ambulatory status: 1 point
Normal serum albumin level : 1 point
Ceiling score of 3.
Ghori et al 2015
Ghori et al 2015: Model
3
2
1
0
3 vs. 2 vs. 1 vs. 0P < 0.001
Ghori et al 2015 Our Model was able to explain 74% of the variation
in 1-year survival. What does that mean?
In contrast existing scoring systems : 20- 50 % correlation with survival
Ragel, B. T. et al. Life Expectancy and Metastatic Spine Scoring Systems: An Academic Institutional Experience. J Spinal Disord Tech (2014). Wang M, Bünger CE, Li H, Wu C, Høy K, Niedermann B, et al. Predictive value of Tokuhashi scoring systems in spinal metastases, focusing on various primary tumor groups: Evaluation of 448 patients in the Aarhus spinal metastases database. Spine 2012;37: 573-582.
Our Model
Practical advantage ?
Let us apply it to our two cases.
High modified Bauer score and
1. Intact ambulation2. Normal albumin
78% survival
Modified Bauer Score
(4): 59% survival
Case 1:Bauer 4
High modified Bauer score BUT
1. CANNOT ambulate2. Low albumin
32% survival
Modified Bauer Score
(4): 59% survival
Case 2:Bauer 4
Ghori et al 2015
Modified Bauer Score (4): 59%
No additional heath states: 30 %
Modified Bauer Score (4): 59%
Intact Ambulation/Normal albumin: 78 %
Ghori et al 2015
30% Vs. 78% survival: big difference !Capture patient health state Tell apart patients predict survival reliably
Our Model: Advantages Simple to apply.
Superior to existing models in predicting survival.
300 patients in our analysis: one of the largest cohorts in literature.
Our Model: Limitations
Retrospective nature of our data.
Model developed from surgical patients so may not be extrapolated to non-surgical patients.
Future Direction
Studies to validate our model by applying it to: Different databases. Prospectively studying it.
Managing Spine Metastases
Where did we come from?
Where are we going?
Historical: No benefit with Surgery
Present : Surgery – too much ? Who to operate on?
Our Model
Future approach: Improve patient selection
Operate on the RIGHT PATIENT
Evolution of spinal
instrumentation
Include Patient “Health State”
Predict survival reliably
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