A Comparison of DRG and CPT for Cost Analysis in Spine Surgery Open Access

Abstract

The prevalence of neck and back disorders in the United States is estimated to be 80% in the adult population and represents the third largest source of spending, totaling $87.6 Billion USD. The most common grouping of administrative healthcare data is by Diagnosis Related Group (DRG), but in spine surgery the array of pathologies, operations, and techniques contained in a single DRG is very heterogeneous. Current Procedure Terminology (CPT) codes focus on reimbursement for services rendered and can be more specific to describe the surgical approach and technique performed. The specificity and familiarity of the CPT coding structure for surgeons makes it an attractive option for classification in spine surgery cost analysis research. We conducted a retrospective cohort study of 5,020 surgeries over 4 years at a single institution aimed at comparing the association between total cost and either MS-DRG or our novel CPT-based surgical categorization method (CSC). The adjusted R² for a linear regression model of total cost was similar for MS-DRG and CSC (0.65 vs. 0.57) and the addition of the CSC term to the MS-DRG model had a significant increase in the R² (0.65 to 0.74). To allow for cost analysis at the surgical or provider level, the CSC method creates groups of similar surgical approaches and techniques, enabling better analysis of the drivers of variability that could predict changes in total cost. Further development of this CSC method may enable the development of surgeon-led initiatives to streamline resource utilization and maximize procedural cost savings in spine surgery. 

 

Table of Contents

Introduction    1

Background    2

Methods         5

Hypothesis and Specific Aims          5

Study Design and Study Population  5

CPT-based Surgical Categorization Method 6

Data Analysis 7

Results 9

Discussion     13

Conclusions   17

References      18

Tables And Figures   19

Figure 1: Spine Related MS-DRG Codes     19

Figure 2: Spine Related CPT Codes  20

Figure 3: CPT Categorization Method          22

Figure 4: Flowchart of Inclusion/Exclusion Process 23

Figure 5: Distribution of Total Cost  24

Figure 6: Distribution of Logarithm of Total Cost    25

Figure 7: Boxplot of DRG Category and Total Cost 26

Figure 8: Boxplot of CPT Based Surgical Categories and Total Cost          27

Table 1: Descriptive Statistics for MS-DRG Codes 28

Table 2: Frequency of CPT Codes in Dataset 29

Table 3: Descriptive Statistics for CPT Based Surgical Categories  30

Table 4: Descriptive Statistics for Cervical CPT Based Surgical Categories           31

Table 5: Descriptive Statistics for Thoracic CPT Based Surgical Categories           32

Table 6: Descriptive Statistics for Lumbar CPT Based Surgical Categories 33

Table 7: Descriptive Statistics for Fusion Operations           34

Table 8: Descriptive Statistics for Non-Fusion Operations   35

Table 9: Linear Regression Parameters of Log Total Cost vs. DRG 36

Table 10: Exponentiated Linear Regression Parameters of Log Total Cost vs. DRG          37

Table 11: Linear Regression Parameters of Log Total Cost vs. CPT Based Surgical Category       38

Table 12: Exponentiated Linear Regression Parameters of Log Total Cost vs. CPT Based Surgical Category       39

Table 13: Linear Regression Parameters of Log Total Cost vs. DRG plus CPT Based Surgical Category  40

Table 14: Exponentiated Linear Regression Parameters of Log Total Cost vs. DRG plus CPT Based Surgical Category 42

Table 15: Comparison of DRG and CPT Based Surgical Category Models 44

 

About this Master's Thesis

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School	Laney Graduate School
Department	Clinical Research
Degree	M.S.
Submission	Master's Thesis
Language	English
Research Field	Economics, Finance Health Sciences, Surgery
Keyword	Spine Surgery Current Procedural Terminology Diagnosis Related Groups Cost Analysis Cost Variability
Committee Chair / Thesis Advisor	Halkos, Michael, Emory University
Committee Members	Blumberg, Henry, Emory University Bruce, Beau, Emory University Klein, Mitchel, Emory University

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