Predictors Of Outcomes And Cost After Spinal Fusion Surgery And Construction Of Patient Risk ...

89 Pages·2016·2.81 MB·English

Predictors Of Outcomes And Cost After Spinal Fusion Surgery
And Construction Of Patient Risk Calculators

BY

ABDULRAHMAN AZMY ABUTALEB

THESIS

Submitted as partial fulfillment of requirements
for the degree of Master of Science in Bioengineering
in the Graduate College of the
University of Illinois at Chicago, 2016

Chicago, Illinois

Masters Committee:

David Eddington, Chair and Advisor
Alpesh Patel, Dept. of Orthopedic Surgery, Northwestern University
Wellington Hsu, Dept. of Orthopedic Surgery, Northwestern University
For my parents,
Azmy Abutaleb and Fatma Said,
for all their sacrifices

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ACKNOWLEDGMENTS

First I would like to thank Dr. Alpesh Patel for being an awesome mentor and always
[
being available for my guidance. He was not only a guide in research, but he played a major role
in my academic career and my choice of specialty. Thank You!!
I would also like to thank Dr. Wellington Hsu for reviewing several of my abstracts
submitted from this thesis and sitting on my committee. Dr. David Eddington for supporting my
thesis and allowing me to return to the university during medical school to complete my work.
Moreover, I thank him for his close friendship through the years that continued throughout and
after my graduate studies at UIC.
I also extend my thanks to Anna Pawloski and Zack Seeskin for their contributions to this
project. Anna Pawloski is a trained EDW data analyst who retrieved all of the data for this project
making this thesis possible. Zack Seeskin, the statistician wizard, who helped me with the
statistical analyses in STATA.
I would like to also thank Leigh Dziemiela, Dr. Patel's Administrative Assistant, who helped
ensure all of my deadlines were met. She played a vital role in organizing my thesis defense and I
sincerely appreciate all of her help.
Finally, I would like to thank my friends Sarmad, Nabeel, and Nour for their continued
support and motivation to complete my graduate studies. I could not have asked for more
inspiring company for my journey.

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TABLE OF CONTENTS

CHAPTER 1: CERVICAL FUSION SURGERY OUTCOMES
1.1 INTRODUCTION……….……….……….……….……….……….………...1
1.2 METHODS……….……….……….……….……….……….……….……….2
1.3 RESULTS……….……….……….……….……….……….……….………...4
1.4 DISCUSSION……….……….……….……….……….……….……….……5
1.5 FIGURES AND TABLES…………………………………………………...10

CHAPTER 2: CERVICAL FUSION SURGERY COST AND CHARGES
2.1 INTRODUCTION……….……….……….……….……….……….……….19
2.2 METHODS……….……….……….……….……….……….……….……...20
2.3 RESULTS……….……….……….……….……….……….……….…….…22
2.4 DISCUSSION……….……….……….……….……….……….…………....25
2.5 FIGURES AND TABLES………………………………………………...…29

CHAPTER 3: THORACOLUMBAR FUSION SURGERY OUTCOMES
3.1 INTRODUCTION……….……….……….……….……….……….……….39
3.2 METHODS……….……….……….……….……….……….……….……...40
3.3 RESULTS……….……….……….……….……….……….……….……….41
3.4 DISCUSSION……….……….……….……….……….……….……….…...42
3.5 FIGURES AND TABLES…………………………………………………...46

CHAPTER 4: THORACOLUMBAR FUSION SURGERY COST AND CHARGES
4.1 INTRODUCTION……….……….……….……….……….……….……….55
4.2 METHODS……….……….……….……….……….……….……….……...56
4.3 RESULTS……….……….……….……….……….……….……….…….…57
4.4 DISCUSSION……….……….……….……….……….……….……………59
4.5 FIGURES AND TABLES…………………………………………………...63

CHAPTER 5: SPINE FUSION SURGERY RELATIVE RISK CALCULATORS
5.1 INTRODUCTION…………………………………………………………...69
5.2 METHODS…………………………………………………………………..69
5.3 CALCULATOR & EXAMPLE PATIENT………………………………….72

REFERENCES……….……….……….……….……….……….………………………74

VITA……………………………………………………………………………………..79

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LIST OF TABLES

I. CHARLSON COMORBIDITY INDEX WEIGHTED VALUES……………………….10
II. PATIENT POPULATION OF CERVICAL FUSION SURGERY…………………….11
III. RATES OF COMPLICATIONS FOR CERVICAL FUSION SURGERY……………13
IV. OUTCOMES OF CERVICAL FUSION SURGERY AS A FUNCTION OF THE
CHARLSON COMORBIDITY INDEX………………………………………………………14

V. LENGTH OF STAY FOR CERVICAL FUSION SURGERY…………………………...15
VI. OPERATING ROOM TIME FOR CERVICAL FUSION SURGERY………………..16
VII. 0-30 DAY READMISSIONS FOR CERVICAL FUSION SURGERY……………….17
VIII. COMPARISON OF POST-OPERATIVE COMPLICATIONS TO NATIONAL
AVERAGES OF COMPLICATION RATES FOR CERVICAL FUSION
SURGERY…………………………………………………………………………………………...18

IX. CHARLSON COMORBIDITY INDEX WEIGHTED VALUES……………………….29
X. COMPARISON OF PATIENT POPULATION IN STUDY TO THAT OF
NATIONAL PATIENT POPULATION FOR CERIVCAL FUSION SURGERY…30

XI. COST OF CERVICAL FUSION SURGERY………………………………………………..31
XII. COST OF ANTERIOR CERVICAL FUSION SURGERY………………………………32
XIII. INCREASE IN THE COST OF CERVICAL FUSION SURGERY AS A FUNCTION
OF THE CHARLSON COMORBIDITY INDEX………………………………………….33

XIV. COST OF CERVICAL FUSION ALONE BY SRUGICAL APPROACH…………….33
XV. CHARGES FOR CERVICAL FUSION SURGERY……………………………………….34
XVI. CHARGES FOR ANTERIOR CERVICAL FUSION SURGERY……………………...35
XVII. SIGNIFICANT CONTRIBUTORS TO CHARGES FOR CERVICAL FUSION
SURGERY…………………………………………………………………………………………..36

XVIII. INCREASES IN CHARGES FOR CERVICAL FUSION SURGERY AS A
FUNCTION OF THE CHARLSON COMORBIDITY INDEX………………………...37
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XIX. TOP TEN CHARGES IN ANTERIOR CERVICAL FUSION………………………….38
LIST OF TABLES (Continued)

XX. CHARLSON COMORBIDITY INDEX WEIGHTED VALUES……………………….46
XXI. PATIENT POPULATION OF THORACOLUMBAR FUSION SURGERY……….47
XXII. OUTCOMES OF THORACOLUMBAR FUSION SURGERY AS A FUNCTION OF
THE CHARLSON COMORBIDITY INDEX……………………………………………….49

XXIII. OPERATING ROOM TIME FOR THORACOLUMBAR FUSION SURGERY…..50
XXIV. LENGTH OF STAY FOR THORACOLUMBAR FUSION SURGERY……………...51
XXV. 0-30 DAY READMISSOINS FOR THORACOLUMBAR FUSION SURGERY....52
XXVI. 31-60 DAY READMISSIONS FOR THORACOLUMBAR FUSION SURGERY.53
XXVII. COMPARISON OF POST-OPERATIVE COMPLICATIONS TO NATIONAL
AVERAGES OF COMPLICATION RATES FOR THORACOLUMBAR FUSION
SURGERY…………………………………………………………………………………………...54

XXVIII. COMPARISON OF PATIENT POPULATION IN STUDY TO THAT OF
NATIONAL PATIENT POPULATION FOR THORACOLUMBAR FUSION
SURGERY…………………………………………………………………………………………...63

XXIX. COST OF THORACOLUMBAR FUSION SURGERY…………………………………..64
XXX. COST OF THORACOLUMBAR FUSION OPERATION ALONE…………………..64
XXXI. CHARGES OF THORACOLUMBAR FUSION SURGERY……………………………65
XXXII. SIGNIFICANT CONTRIBUTORS FOR THORACOLUMBAR FUSION
SURGERY………………………………………………………………………………………...…66

XXXIII. CHARGES FOR THORACOLUMBAR FUSION SURGERY AS A FUNCTION OF
THE CHARLSON COMORBDITIY INDEX……………………………………………….67

XXXIV. TOP TEN CHARGES FOR THORACOLUMBAR FUSION SURGERY…………...68
XXXV. PATIENT DEMOGRAPHICS AND COMORBIDITIES INCLUDED IN
CALCULATOR………………………………………………………………..72

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FIGURES
I. THE INCIDENCE OF POST-OPERATIVE COMPLICATIONS OF
CERVICAL FUSION SURGERY…………………………………………..12

II. THE INCIDENCE OF POST-OPERATIVE COMPLICATIONS OF
THORACOLUMBAR FUSION SURGERY………………………………..48

III. PATIENT RISK CALCULATOR…………………………………………...73

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LIST OF ABBREVIATIONS
ACF Anterior Cervical Fusion
AIDS Acquired Immunodeficiency Syndrome
BMI Body Mass Index
BMP Bone Morphogenetic Protein
CAPF Combined Anterior Posterior Cervical Fusion Surgery
CCI Charlson Comorbidity Index
CCR Cost-to-Charges Ratio
CFS Cervical Fusion Surgery
CNS Central Nervous System
CSF Cerebrospinal Fluid
CVA Cerebrovascular Accident
DVT Deep Vein Thrombosis
EDW Electronic Data Warehouse
EEG Electroencephalogram
EKG Electrocardiogram
LOS Length Of Stay
NIS National Inpatient Sample
OR time Operating Room Time
PCF Posterior Cervical Fusion
TLFS Thoracolumbar Fusion Surgery

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SUMMARY
This study is aimed to better understand the outcomes and cost of undergoing
Spinal Fusion Surgery at a tertiary medical center. Patient demographics and
comorbidities were used to predict operating room time, length of stay, adverse
outcomes, readmission rates, cost to the hospital and charges to the patient. The two main
surgical groups analyzed were patients undergoing Cervical Fusion Surgery and
Thoracolumbar Fusion Surgery. Cervical Fusion Surgery was further categorized into
Anterior Cervical Fusion, Posterior Cervical Fusion, and Combined Anterior Posterior
Cervical Fusion Surgery.
With outcomes and cost analyzed as a function of patient demographics and
comorbidities, a Patient Risk Calculator was constructed. Utilizing the calculator
surgeons can better predict the individualized risk of surgery for their patients. Surgeons
can then form a more informed and thorough pre-operative assessment of patient
comorbidities and demographics in order to reduce patient morbidity and hospital costs.
In addition, hospitals can predict the cost of spine surgery and allocate administrative
funds in a more efficient manner. Finally, post-operative risk stratification of patients
during recovery and rehab can assist physicians in anticipating and addressing post-
operative complications.
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CHAPTER 1: CERVICAL FUSION SURGERY OUTCOMES

1.1 INTRODUCTION:

The and over the past decade surgical interventions have been on the rise.1-3
Specifically, the rate of Cervical Fusion Surgery (CFS) has increased over the years, with
an increase of 206% between 1992 and 2005 amongst Medicare beneficiaries and 26% in
the number of CFS performed nationally between 2002 and 2011.1,4
Anterior Cervical Fusion (ACF) has become the most common cervical spine
surgery, making up 83% of all CFS.4 Other approaches for CFS that make up the
remaining 17% of CFS include Posterior Cervical Fusion (PCF) and Combined Anterior
and Posterior Cervical Fusion Surgery (CAPF). However recent studies have come to
question the long-term benefits of CFS, especially in an aging patient population with
compounding comorbidities.5-11 The American Association of Neurological
Surgeons/Congress of Neurological Surgeons (AANS/CNS) and North American Spine
Society have narrowed the indications for CFS to a select few indications most
importantly cervical spondylotic radiculopathy and myelopathy after failure of medical
treatment, which are indications supported by class I/level B and class III evidence
respectively.12
Identifying the incidence and predictors of adverse events post-operatively may
help guide clinical decision-making before and after surgical interventions. Additionally,
identifying predictors of administrative outcomes such as hospital stay and readmissions
may provide additional insights into cost and resource utilization in spine surgery. The
purpose of this study is to identify clinical factors and patient comorbidities that correlate
with complications, Length Of Stay (LOS), Operating Room time (OR time), and
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