Number of Cases

Technical Appendix Mehrotra et al., "Evaluation of a Center of Excellence Program for Spine Surgery"

The purpose of this technical appendix is to provide detail about the methods and results that could not be included in the manuscript. The appendix includes the following tables:

Table 1: Definition of Primary Spine Surgery Categories Used in Analysis

Table 2: Classification of Primary Spine Surgeries: ICD-9-CM Procedure and Diagnosis and CPT Codes

Table 3: Patient Categories Excluded from Analytic Sample, Time Periods, and Rationale

Table 4. ICD-9-CM Diagnosis and Procedure Codes Used to Identify Patient Categories Excluded from Analytic Sample

Table 5. Cervical Simple Fusion: Number of Patients in Analytic Sample after Each Exclusion, by Designation Status, July 2007 - September 2009

Table 6: Lumbar Simple Fusion: Number of Patients in Analytic Sample after Each Exclusion, by Designation Status, July 2007 - September 2009

Table 7. Lumbar Discectomy/Decompression: Number of Patients in Analytic Sample after Each Exclusion, by Designation Status, July 2007 - September 2009

Table 8. Specifications for Identifying Complications Following Cervical Simple Fusion, Lumbar Simple Fusion, or Lumbar Discectomy/Decompression

Table 9. ICD-9-CM Procedure Codes To Be Used in Identifying Wound Complications

Table 10. ICD-9-CM Diagnosis and Procedure Codes and Time Period for Identifying Readmissions Following Cervical Simple Fusion, Lumbar Simple Fusion, or Lumbar Discectomy/Decompression

Table 11. Clinical Risk Factor Categories Used in Multivariate Models with Condition Category (CC) Numbers

Table 12. Prevalence of Medical Conditions* Among Patients With Cervical Simple Fusion, Lumbar Simple Fusion, or Lumbar Discectomy/Decompression by Designation Status

Table 13. Sensitivity Analyses: Comparison of 90 Day Medical Costs (in Dollars) Using a Different Method

1 Table 14. Number of Spine Surgeries Performed in Designated Hospitals and Other Hospitals by Type of Surgery Before Exclusions, July 2007-September 2009

2 Table 1. Definition of Primary Spine Surgery Categories Used in Analysis Spine Surgery Category Subcategories Cervical Simple Fusion with or  (Cervical simple fusion ) and not (Cervical discectomy or without Cervical discectomy or Cervical decompression) Cervical decompression  (Cervical simple fusion and Cervical discectomy and Cervical decompression)  (Cervical simple fusion and Cervical discectomy) and not (Cervical decompression)  (Cervical simple fusion and Cervical decompression) and not (Cervical discectomy) Lumbar Simple Fusion with or  (Lumbar simple fusion ) and not (Lumbar discectomy or without a Lumbar discectomy Lumbar decompression) or Lumbar decompression  (Lumbar simple fusion and Lumbar discectomy and Lumbar decompression)  (Lumbar simple fusion and Lumbar discectomy) and not (Lumbar decompression)  (Lumbar simple fusion and Lumbar decompression) and not (Lumbar discectomy) Lumbar Discectomy or Lumbar  Lumbar discectomy and not (Lumbar simple fusion or decompression without Lumbar Lumbar complex fusion or Lumbar decompression) fusion  Lumbar decompression and not (Lumbar simple fusion or Lumbar complex fusion or Lumbar discectomy)  (Lumbar discectomy and Lumbar decompression) and not (Lumbar simple fusion or Lumbar complex fusion)

3 Table 2. Classification of Primary Spine Surgeries: ICD-9-CM Procedure and Diagnosis and CPT Codes Spine Surgery ICD-9-CM Procedure ICD-9-CM Diagnosis Codes Category Codes Cervical Spine Surgery Cervical (81.02 or 81.03) AND simple fusion NOT (CERVICAL FUSION, COMPLEX) Cervical [(81.02 AND 81.03)] or complex [(81.02 or 81.03) AND fusion (81.63 or 81.64)] Cervical 80.51 (requires a One of the following diagnosis codes must be used discectomy diagnosis code in the to classify discectomy as cervical (SooHoo, next column to identify personal communication, 2010): 721.0, 721.1, as cervical) 722.0, 722.4, 722.71, 722.91, 723.0, 723.1 Cervical 03.09 (requires a One of the following diagnosis codes must be used Decompressio diagnosis code in the to classify decompression as cervical (SooHoo, n next column to identify personal communication, 2010): 721.0, 721.1, as cervical) 722.0, 722.4, 722.71, 722.91, 723.0, 723.1 Lumbar Spine Surgery Lumbar simple (81.06 or 81.07 or fusion 81.08) AND NOT (LUMBAR FUSION, COMPLEX) Lumbar [(81.06) AND (81.07 or complex 81.08)] or [(81.06 or fusion 81.07 or 81.08) AND (81.63 or 81.64)] Lumbar 80.51 (requires a One of the following diagnosis codes must be used discectomy diagnosis code in the to classify discectomy as lumbar (Weinstein et al., next column to identify 2006): 722.10, 722.73; 721.3, 722.52, 722.93; as lumbar) 721.42, 724.02; 756.11; 722.32, 724.2 Lumbar 03.09 (requires a One of the following diagnosis codes must be used decompressio diagnosis code in the to classify decompression as lumbar (Weinstein et n next column to identify al., 2006): 722.10, 722.73; 721.3, 722.52, 722.93; as lumbar) 721.42, 724.02; 756.11; 722.32, 724.2

4 Table 3: Patient Categories Excluded from Analytic Sample, Time Periods, and Rationale Rationale Exclusion Category Time Period Any refusion spine surgery during index stay  Index stay1 Refusion procedures are much less common and more heterogeneous with regard to the indication and type of procedure, making adequate control in the analysis difficult. Surgery performed on multiple levels of the spine, including  Index stay Surgeries on multiple levels of the spine are cases identified by the following pseudocode: excluded because the cost and outcomes of the ((Any Cervical=1 and Any Thoracic=1) OR procedure might differ from surgeries performed at (Any Cervical=1 and Any Lumbar=1) OR one level. (Any Thoracic=1 and Any Lumbar=1) OR (Any Cervical=1 and Any Thoracic=1 and Any Lumbar=1)) Enrollee’s address out of country: Exclude other countries  Index stay This requirement ensures all claims and costs are and US territories (GU-Guam, PR-Puerto Rico, and VI-Virgin captured. Care outside of the US might be Islands) fundamentally different. Address of the index hospital is in a state in which no  Index stay No hospitals in these states applied to the center of hospitals applied to the program: Alaska (AK), Delaware excellence program. There was concern that (DE), Mississippi (MS), Oklahoma (OK), Vermont (VT), West hospitals in these states were not actively recruited Virginia (WV), and Wyoming (WY). to participate. We therefore excluded all hospitals in these states because we did not want to mis- categorize hospitals that met the designation criteria as non-designated hospitals. Such miscategorization would bias the results to the null. Pregnancies2  Index stay Surgeries on pregnant patients are excluded because the cost and outcomes of the procedure might differ from other patients. Refusion spine surgery listed as a secondary procedure on  Index stay Patients with a refusion spine surgery listed as a index hospitalization claim secondary procedure would be likely to have different complication and readmission rates. Another primary or refusion spine surgery in prior six months  6 months before Patients with another primary or refusion spine surgery in index procedure date prior six months would be likely to have different complication and readmission rates. Repeat procedure: The CPT modifier codes, 76 (repeat  Professional claim As with refusion procedures, repeat procedures are much procedure by same physician) and 77 (repeat procedure by less common and more heterogeneous with regard to the 1 An index stay refers to the hospital stay during which the index procedure (i.e., cervical simple fusion) was performed. 2 Previous studies of outcomes and complications following spine surgery have excluded patients who are pregnant (Cook 2008; Wang, 2007; Wang 2009; AHRQ 2009). Rationale Exclusion Category Time Period another physician), indicate the procedure was repeated. for index stay indication and type of procedure, making adequate control in the analysis difficult. Spinal cord injuries, fractures of the spinal column, vertebral  6 months before Cases with these conditions were excluded to eliminate dislocations, motor vehicle and other accidents, pathologic index procedure date non-elective procedures. These are very different types of fractures, all malignant neoplasms 3 PLUS cases from a clinical perspective. These exclusions are ,  Index stay consistent with prior literature. Disc prosthesis, cervical  Index stay Disc prosthesis procedures are much less common and  Exclude these more heterogeneous with regard to the indication and type from cervical simple of procedure, making adequate control in the analysis fusion sample only difficult. Disc prosthesis, lumbar  Index stay Disc prosthesis procedures are much less common and  Exclude these more heterogeneous with regard to the indication and type from lumbar simple of procedure, making adequate control in the analysis fusion sample and difficult. lumbar discectomy and decompression sample only Use of bone morphogenetic protein (BMP)  Index stay BMP is indicated for fusion procedures, not discectomy  Exclude these and decompression procedures. from lumbar discectomy and decompression sample only Congenital disorders (spina bifida, certain congenital  6 months before Cases with these conditions were excluded to eliminate musculoskeletal deformities of spine, other congenital index procedure date non-elective procedures. These are very different types of musculoskeletal deformities, anomalies of spine)4 PLUS cases from a clinical perspective. These exclusions are  Index stay consistent with prior literature.

3 Previous studies of outcomes and complications following spine surgery have excluded traumatic spinal cord injury or vertebral fractures (Browne 2007; Cook 2007; Cook 2008; Deyo 2010; Wang, 2007; Wang 2009), and malignancies (Browne 2007; Cook 2007; Cook 2008; Deyo 2010; Wang 2007). 4 Previous studies of outcomes and complications following spine surgery have excluded congenital disorders (e.g., spina bifida) (Browne 2007). Rationale Exclusion Category Time Period Ankylosing spondylitis and other inflammatory  6 months before Cases with these conditions were excluded to eliminate spondylopathies5 index procedure date non-elective procedures. These are very different types of PLUS cases from a clinical perspective. These exclusions are  Index stay consistent with prior literature. Abscess or osteomyelitis6  6 months before Cases with these conditions were excluded to eliminate index procedure date non-elective procedures. These are very different types of ONLY cases from a clinical perspective. These exclusions are  DO NOT consistent with prior literature. INCLUDE INDEX STAY Postlaminectomy syndrome associated with a mechanical  6 months before Cases with this condition were excluded to eliminate non- complication of an internal device or graft7 index procedure date elective procedures. Clinically these are very different ONLY types of cases and these exclusions are consistent with

 DO NOT prior literature. INCLUDE INDEX STAY Hospitalizations in which patient was admitted through the  Index stay Cases with these conditions were excluded to emergency department (admit_type_code=emergency eliminate non-elective procedures. These are very department) different types of cases from a clinical perspective. These exclusions are consistent with prior literature. Hospitalizations in which patient left against medical advice  Index stay Although rare, the costs and outcomes of these (discharge_status_code =07) hospitalizations are likely very different. Place of service not inpatient hospital  Index stay These cases were excluded because acute care inpatient hospitals are the focus of this study. Not continuously enrolled from 6 months before procedure to  From 6 months This requirement ensures all claims and costs are 3 months after: Patients who die within 3 months after the before to 3 months captured. procedure were not excluded. after index procedure Primary insurance is not provided by one of the health  Index stay These patients were excluded because it might not plans .in the center of excellence initiative. be possible to capture all of their claims and costs.

5 Previous studies of outcomes and complications following spine surgery have excluded inflammatory spondyloarthropathies (Deyo 2010; Wang, 2007; Wang 2009). 7 Previous studies of outcomes and complications following spine surgery have excluded mechanical complications (Cook 2007). 6 Previous studies of outcomes and complications following spine surgery have excluded spine-related infections (Browne 2007; Cook 2007; Cook 2008; Deyo 2010). Rationale Exclusion Category Time Period Patient <18 years of age at time of index procedure  Index stay These types of spine surgeries in persons <18 years of age are rare and have different clinical indications. Age 65 years or older at time of index procedure  Index stay These patients were excluded because it might not be possible to capture all of their claims and costs due to Medicare coverage. Table 4. ICD-9-CM Diagnosis and Procedure Codes Used to Identify Patient Categories Excluded from Analytic Samples Exclusion Category and Code Type of Code

Spine Refusion 81.32 ICD-9-CM Procedure 81.33 ICD-9-CM Procedure 81.34 ICD-9-CM Procedure 81.35 ICD-9-CM Procedure 81.36 ICD-9-CM Procedure 81.37 ICD-9-CM Procedure 81.38 ICD-9-CM Procedure 81.63 ICD-9-CM Procedure 81.64 ICD-9-CM Procedure Use of bone morphogenetic protein (BMP) 84.52 ICD-9-CM Procedure Disc prosthesis, cervical 84.60 ICD-9-CM Procedure 84.61 ICD-9-CM Procedure 84.62 ICD-9-CM Procedure Disc prosthesis, lumbar 84.60 ICD-9-CM Procedure 84.64 ICD-9-CM Procedure 84.65 ICD-9-CM Procedure

Congenital Disorders 741.0x-741.9x ICD-9-CM Diagnosis 754.2 ICD-9-CM Diagnosis 756.10-756.19 ICD-9-CM Diagnosis Fractures of spinal column 805.0x ICD-9-CM Diagnosis 805.1x ICD-9-CM Diagnosis 805.2 ICD-9-CM Diagnosis 805.3 ICD-9-CM Diagnosis 805.4 ICD-9-CM Diagnosis 805.5 ICD-9-CM Diagnosis 805.6 ICD-9-CM Diagnosis 805.7 ICD-9-CM Diagnosis 805.8 ICD-9-CM Diagnosis 805.9 ICD-9-CM Diagnosis Spinal Cord Injuries 806.0x ICD-9-CM Diagnosis 806.1x ICD-9-CM Diagnosis 806.2x ICD-9-CM Diagnosis 806.3x ICD-9-CM Diagnosis 806.4 ICD-9-CM Diagnosis 806.5 ICD-9-CM Diagnosis 806.6x ICD-9-CM Diagnosis 806.7x ICD-9-CM Diagnosis 806.8 ICD-9-CM Diagnosis Exclusion Category and Code Type of Code 806.9 ICD-9-CM Diagnosis 952.0x ICD-9-CM Diagnosis 952.1x ICD-9-CM Diagnosis 952.3 ICD-9-CM Diagnosis 952.4 ICD-9-CM Diagnosis 952.5 ICD-9-CM Diagnosis 952.8 ICD-9-CM Diagnosis 952.9 ICD-9-CM Diagnosis Pathological fracture 733.1 ICD-9-CM Diagnosis 733.10 ICD-9-CM Diagnosis 733.13 ICD-9-CM Diagnosis 733.95 ICD-9-CM Diagnosis 733.8 ICD-9-CM Diagnosis 733.81 ICD-9-CM Diagnosis 733.82 ICD-9-CM Diagnosis Vertebral dislocations 839.0x ICD-9-CM Diagnosis 839.1x ICD-9-CM Diagnosis 839.2x ICD-9-CM Diagnosis 839.3x ICD-9-CM Diagnosis 839.4x ICD-9-CM Diagnosis 839.5x ICD-9-CM Diagnosis Postlaminectomy syndrome associated with a mechanical complication of an internal device or graft 722.80 ICD-9-CM Diagnosis 722.81 ICD-9-CM Diagnosis 722.82 ICD-9-CM Diagnosis 722.83 ICD-9-CM Diagnosis Abscess or Osteomyelitis 324.1 ICD-9-CM Diagnosis 324.9 ICD-9-CM Diagnosis 730.0x ICD-9-CM Diagnosis 730.1x ICD-9-CM Diagnosis 730.2x ICD-9-CM Diagnosis 730.3x ICD-9-CM Diagnosis 730.7x ICD-9-CM Diagnosis 730.8x ICD-9-CM Diagnosis 730.9x ICD-9-CM Diagnosis Ankylosing spondylitis and other inflammatory spondylopathies 720.0 ICD-9-CM Diagnosis 720.1 ICD-9-CM Diagnosis 720.2 ICD-9-CM Diagnosis 720.8x ICD-9-CM Diagnosis 720.9 ICD-9-CM Diagnosis Pregnant/Pregnancy, childbirth, puerperium V22.x ICD-9-CM Diagnosis V23.xx ICD-9-CM Diagnosis 630-676.xx ICD-9-CM Diagnosis Exclusion Category and Code Type of Code Motor Vehicle and Other Accidents E800-E848 ICD-9-CM Diagnosis Malignant neoplasms 140-172.x ICD-9-CM Diagnosis 174-239.x ICD-9-CM Diagnosis Surgery performed on multiple levels of the spine (Any Cervical=1 and Any Thoracic=1) OR (Any Cervical=1 and Any Lumbar=1) OR (Any Thoracic=1 and Any Lumbar=1) OR (Any Cervical=1 and Any Thoracic=1 and Any Lumbar=1)

Table 5. Cervical Simple Fusion: Number of Patients in Analytic Sample after Each Exclusion, by Designated Status, July 2007 - September 2009 Designated Hospitals Other Hospitals Total Sample % of % of Sample % of Size Initial Initial Size Initial Number After Sample Number Sample After Sample Exclude Exclusio Size Exclude Size Exclusio Size d n d Number Excluded n Initial sample size 17,237 100.0% 100.0% 42,462 100.0% Surgery performed on multiple levels of the spine 292 16,945 98.3% 417 98.3% 709 41,753 98.3% Any refusion spine surgery during index stay 33 16,912 98.1% 47 98.2% 80 41,673 98.1% Enrollee’s address out of country: Exclude other countries and US territories (GU- Guam, PR-Puerto Rico, and VI-Virgin Islands) 5 16,907 98.1% 4 98.1% 9 41,664 98.1% Address of the index hospital is in a state in which there were no designated hospitals: Alaska (AK), Delaware (DE), Mississippi (MS), Oklahoma (OK), Vermont (VT), West Virginia (WV), and Wyoming (WY). 116 16,791 97.4% 1,199 93.4% 1315 40,349 95.0% Pregnancies 4 16,787 97.4% 3 93.4% 7 40,342 95.0% Refusion spine surgery listed as a secondary procedure on index hospitalization claim 68 16,719 97.0% 66 93.1% 134 40,208 94.7% Another primary or refusion spine surgery in prior six months 25 16,694 96.8% 41 93.0% 66 40,142 94.5% Repeat procedure: The CPT modifier codes, 76 (repeat procedure by same physician) and 77 (repeat procedure by another physician), indicate the procedure was repeated. 93 16,601 96.3% 165 92.3% 258 39,884 93.9% Spinal cord injuries 182 16,419 95.3% 234 91.4% 416 39,468 92.9% Fractures of the spinal column 343 16,076 93.3% 392 89.8% 735 38,733 91.2% Vertebral dislocations 92 15,984 92.7% 150 89.2% 242 38,491 90.6% Motor vehicle and other accidents 2 15,982 92.7% 2 89.2% 4 38,487 90.6% Designated Hospitals Other Hospitals Total Sample % of % of Sample % of Size Initial Initial Size Initial Number After Sample Number Sample After Sample Exclude Exclusio Size Exclude Size Exclusio Size d n d Number Excluded n Pathological fractures 53 15,929 92.4% 76 88.9% 129 38,358 90.3% Disc prosthesis, cervical 39 15,890 92.2% 89 88.6% 128 38,230 90.0% Malignant neoplasms 276 15,614 90.6% 299 87.4% 575 37,655 88.7% Congenital disorders (spina bifida, certain congenital musculoskeletal deformities of spine, other congenital musculoskeletal deformities, anomalies of spine) 76 15,538 90.1% 114 86.9% 190 37,465 88.2% Ankylosing spondylitis and other inflammatory spondylopathies 11 15,527 90.1% 26 86.8% 37 37,428 88.1% Abscess or osteomyelitis 6 15,521 90.0% 4 86.8% 10 37,418 88.1% Postlaminectomy syndrome associated with a mechanical complication of an internal device or graft 1 15,520 90.0% 0 86.8% 1 37,417 88.1% Hospitalizations in which patient was admitted through the emergency department (admit_type_code=emergency department) 315 15,205 88.2% 489 84.9% 804 36,613 86.2% Hospitalizations in which patient left against medical advice (discharge_status_code =07) 5 15,200 88.2% 8 84.8% 13 36,600 86.2% Place of service not inpatient hospital 6 15,194 88.1% 14 84.8% 20 36,580 86.1% Not continuously enrolled from 6 months before procedure to 3 months after: Patients who die within 3 months after the procedure were not excluded. 967 14,227 82.5% 1,360 79.4% 2327 34,253 80.7% Primary insurance is not provided by one of the health plans .in the center of excellence initiative. 1,610 12,617 73.2% 2,674 68.8% 4284 29,969 70.6% Patient <18 years of age at time of index procedure 5 12,612 73.2% 7 68.8% 12 29,957 70.6% Designated Hospitals Other Hospitals Total Sample % of % of Sample % of Size Initial Initial Size Initial Number After Sample Number Sample After Sample Exclude Exclusio Size Exclude Size Exclusio Size d n d Number Excluded n Age 65 years or older at time of index procedure 263 12,349 71.6% 399 67.2% 662 29,295 69.0% Final sample size (after all exclusions) 12,349 71.6% 67.2% 29,295 69.0%

Table 6. Lumbar Simple Fusion: Number of Patients in Analytic Sample after Each Exclusion, by BDC Status, July 2007 - September 2009 Designated Hospitals Other Hospitals Total Sample % of % of Sample % of Size Initial Initial Size Initial Number After Sample Number Sample After Sample Exclude Exclusio Size Exclude Size Exclusio Size d n d Number Excluded n Initial sample size 18,711 100.0% 100.0% 46,929 100.0% Surgery performed on multiple levels of the spine 121 18,590 99.4% 175 99.4% 296 46,633 99.4% Any refusion spine surgery during index stay 76 18,514 98.9% 117 99.0% 193 46,440 99.0% Enrollee’s address out of country: Exclude other countries and US territories (GU- Guam, PR-Puerto Rico, and VI-Virgin Islands) 5 18,509 98.9% 9 98.9% 14 46,426 98.9% Address of the index hospital is in a state in which there were no designated hospitals: Alaska (AK), Delaware (DE), Mississippi (MS), Oklahoma (OK), Vermont (VT), West Virginia (WV), and Wyoming (WY). 102 18,407 98.4% 1,149 94.9% 1,251 45,175 96.3% Pregnancies 0 18,407 98.4% 1 94.9% 1 45,174 96.3% Refusion spine surgery listed as a secondary procedure on index hospitalization claim 130 18,277 97.7% 213 94.1% 343 44,831 95.5% Another primary or refusion spine surgery in prior six months 57 18,220 97.4% 95 93.8% 152 44,679 95.2% Repeat procedure: The CPT modifier codes, 76 (repeat procedure by same physician) and 77 (repeat procedure by another physician), indicate the procedure was repeated. 135 18,085 96.7% 325 92.6% 460 44,219 94.2% Spinal cord injuries 37 18,048 96.5% 27 92.5% 64 44,155 94.1% Fractures of the spinal column 206 17,842 95.4% 252 91.6% 458 43,697 93.1% Vertebral dislocations 15 17,827 95.3% 19 91.6% 34 43,663 93.0% Designated Hospitals Other Hospitals Total Sample % of % of Sample % of Size Initial Initial Size Initial Number After Sample Number Sample After Sample Exclude Exclusio Size Exclude Size Exclusio Size d n d Number Excluded n Motor vehicle and other accidents 1 17,826 95.3% 1 91.6% 2 43,661 93.0% Pathological fractures 116 17,710 94.7% 149 91.0% 265 43,396 92.5% Disc prosthesis, lumbar 26 17,684 94.5% 47 90.9% 73 43,323 92.3% Malignant neoplasms 276 17,408 93.0% 342 89.6% 618 42,705 91.0% Congenital disorders (spina bifida, certain congenital musculoskeletal deformities of spine, other congenital musculoskeletal deformities, anomalies of spine) 1,724 15,684 83.8% 2,369 81.3% 4,093 38,612 82.3% Ankylosing spondylitis and other inflammatory spondylopathies 13 15,671 83.8% 26 81.2% 39 38,573 82.2% Abscess or osteomyelitis 8 15,663 83.7% 13 81.1% 21 38,552 82.1% Postlaminectomy syndrome associated with a mechanical complication of an internal device or graft 3 15,660 83.7% 5 81.1% 8 38,544 82.1% Hospitalizations in which patient was admitted through the emergency department (admit_type_code=emergency department) 192 15,468 82.7% 315 80.0% 507 38,037 81.1% Hospitalizations in which patient left against medical advice (discharge_status_code =07) 3 15,465 82.7% 9 79.9% 12 38,025 81.0% Place of service not inpatient hospital 11 15,454 82.6% 16 79.9% 27 37,998 81.0% Not continuously enrolled from 6 months before procedure to 3 months after: Patients who die within 3 months after the procedure were not excluded. 1,035 14,419 77.1% 1,479 74.7% 2,514 35,484 75.6% Primary insurance is not provided by one of the health plans .in the center of excellence initiative. 2,551 11,868 63.4% 4,332 59.3% 6,883 28,601 60.9% Patient <18 years of age at time of index procedure 48 11,820 63.2% 62 59.1% 110 28,491 60.7% Designated Hospitals Other Hospitals Total Sample % of % of Sample % of Size Initial Initial Size Initial Number After Sample Number Sample After Sample Exclude Exclusio Size Exclude Size Exclusio Size d n d Number Excluded n Age 65 years or older at time of index procedure 536 11,284 60.3% 741 56.5% 1,277 27,214 58.0% Final sample size (after all exclusions) 11,284 60.3% 56.5% 27,214 58.0% Table 7. Lumbar Discectomy/Decompression: Number of Patients in Analytic Sample after Each Exclusion, by BDC Status, July 2007 - September 2009 Designated Hospitals Other Hospitals Total Sample % of % of Sample % of Size Initial Initial Size Initial Number After Sample Number Sample After Sample Exclude Exclusio Size Exclude Size Exclusio Size d n d Number Excluded n Initial sample size 20,772 100.0% 100.0% 47,508 100.0% Any refusion spine surgery during index stay 155 20,617 99.3% 237 99.1% 392 47,116 99.2% Surgery performed on multiple levels of the spine 162 20,455 98.5% 211 98.3% 373 46,743 98.4% Enrollee’s address out of country: Exclude other countries and US territories (GU- Guam, PR-Puerto Rico, and VI-Virgin Islands) 4 20,451 98.5% 11 98.3% 15 46,728 98.4% Address of the index hospital is in a state in which there were no designated hospitals: Alaska (AK), Delaware (DE), Mississippi (MS), Oklahoma (OK), Vermont (VT), West Virginia (WV), and Wyoming (WY). 166 20,285 97.7% 1,061 94.3% 1,227 45,501 95.8% Pregnancies 10 20,275 97.6% 10 94.3% 20 45,481 95.7% Refusion spine surgery listed as a secondary procedure on index hospitalization claim 4 20,271 97.6% 13 94.2% 17 45,464 95.7% Another primary or refusion spine surgery in prior six months 70 20,201 97.3% 89 93.9% 159 45,305 95.4% Repeat procedure: The CPT modifier codes, 76 (repeat procedure by same physician) and 77 (repeat procedure by another physician), indicate the procedure was repeated. 125 20,076 96.6% 258 92.9% 383 44,922 94.6% Spinal cord injuries 1 20,075 96.6% 0 92.9% 1 44,921 94.6% Fractures of the spinal column 15 20,060 96.6% 32 92.8% 47 44,874 94.5% Vertebral dislocations 13 20,047 96.5% 17 92.7% 30 44,844 94.4% Motor vehicle and other accidents 1 20,046 96.5% 1 92.7% 2 44,842 94.4% Designated Hospitals Other Hospitals Total Sample % of % of Sample % of Size Initial Initial Size Initial Number After Sample Number Sample After Sample Exclude Exclusio Size Exclude Size Exclusio Size d n d Number Excluded n Pathological fractures 10 20,036 96.5% 26 92.6% 36 44,806 94.3% Disc prosthesis, lumbar 12 20,024 96.4% 17 92.6% 29 44,777 94.3% Use of bone morphogenetic protein (BMP) 29 19,995 96.3% 27 92.5% 56 44,721 94.1% Malignant neoplasms 310 19,685 94.8% 390 91.0% 700 44,021 92.7% Congenital disorders (spina bifida, certain congenital musculoskeletal deformities of spine, other congenital musculoskeletal deformities, anomalies of spine) 119 19,566 94.2% 155 90.4% 274 43,747 92.1% Ankylosing spondylitis and other inflammatory spondylopathies 10 19,556 94.1% 23 90.4% 33 43,714 92.0% Abscess or osteomyelitis 6 19,550 94.1% 4 90.3% 10 43,704 92.0% Postlaminectomy syndrome associated with a mechanical complication of an internal device or graft 7 19,543 94.1% 5 90.3% 12 43,692 92.0% Hospitalizations in which patient was admitted through the emergency department (admit_type_code=emergency department) 1,005 18,538 89.2% 1,460 84.9% 2,465 41,227 86.8% Hospitalizations in which patient left against medical advice (discharge_status_code =07) 1 18,537 89.2% 10 84.8% 11 41,216 86.8% Place of service not inpatient hospital 9 18,528 89.2% 27 84.7% 36 41,180 86.7% Not continuously enrolled from 6 months before procedure to 3 months after: Patients who die within 3 months after the procedure were not excluded. 1,103 17,425 83.9% 1,337 79.7% 2,440 38,740 81.5% Primary insurance is not provided by one of the health plans .in the center of excellence initiative. 3,120 14,305 68.9% 4,996 61.0% 8,116 30,624 64.5% Patient <18 years of age at time of index procedure 66 14,239 68.5% 90 60.7% 156 30,468 64.1% Designated Hospitals Other Hospitals Total Sample % of % of Sample % of Size Initial Initial Size Initial Number After Sample Number Sample After Sample Exclude Exclusio Size Exclude Size Exclusio Size d n d Number Excluded n Age 65 years or older at time of index procedure 651 13,588 65.4% 906 57.3% 1,557 28,911 60.9% Final sample size (after all exclusions) 13,588 65.4% 57.3% 28,911 60.9%

Table 8. Specifications for Identifying Complications Following Cervical Simple Fusion, Lumbar Simple Fusion, or Lumbar Discectomy/Decompression

Complication ICD-9-CM Diagnosis and Procedure Codes Time Period Acute Myocardial Infarction Presence of one of the following diagnosis codes in a primary or secondary diagnosis From admission field on the record for the index hospitalization OR in a primary diagnosis field only on a date of index readmission record with an admission date that falls within the specified time period hospitalization to (see third column): 7 days after  410.xx excluding 410.x2 admission date Pneumonia Presence of one of the following diagnosis codes in a primary or secondary diagnosis From admission field on the record for the index hospitalization OR in a primary diagnosis field only on a date of index readmission record with an admission date that falls within the specified time period hospitalization to (see third column): 7 days after  480, 480.0, 480.1, 480.2, 480.3, 480.8, 480.9, 481, 482, 482.0, 482.1, 482.2, admission date 482.3, 482.30,482.31, 482.32, 482.39, 482.4, 482.40, 482.41, 482.42, 482.49, 482.81, 482.82, 482.83, 482.84, 482.89, 482.9, 483, 483.0, 483.1, 483.8, 485, 486, 487.0, 507.0 Complication ICD-9-CM Diagnosis and Procedure Codes Time Period Sepsis/Septicemia Presence of one of the following diagnosis codes in a primary or secondary diagnosis From admission field on the record for the index hospitalization or in a primary or secondary diagnosis date of index field on a readmission record with an admission date that falls within the specified time hospitalization to period (see third column): 7 days after  038, 038.0, 038.1, 038.10, 038.11, 038.12, 038.19, 038.2, 038.3, 038.4, 038.40, admission date 038.41, 038.42, 038.43, 038.44, 038.49, 038.8, 038.9, 785.52, 785.59, 790.7, 995.91, 995.92, 998.0, 998.59, 790.7, 998.59 Pulmonary Embolism Presence of one of the following diagnosis codes in a primary or secondary diagnosis From admission field on the record for the index hospitalization or in a primary or secondary diagnosis date of index field on a readmission record with an admission date that falls within the specified time hospitalization to period (see third column): 30 days after  415.1, 415.11, 415.19 admission date Death in an acute care hospital Presence of one of the following discharge status codes for the index From admission or other facility hospitalization: date of index CODE DESCRIPTION hospitalization to 20 Expired 30 days after 40 Expired at home (hospice care) admission date 41 Expired in a medical facility (e.g. hospital, SNF, ICF, free standing hospice) 42 Expired place unknown (hospice care) Complication ICD-9-CM Diagnosis and Procedure Codes Time Period Wound Complications following Restrict to cervical simple fusion. DO NOT INCLUDE WOUND COMPLICATIONS THAT From discharge Cervical Simple Fusion OCCUR DURING THE INDEX HOSPITALIZATION. date of index Presence of one of the following diagnosis codes: hospitalization to  Wound infection: 996.67, 998.3, 998.30, 998.31, 998.32, 998.33, 998.5, 998.51, 30 days after 998.59, 998.6, 998.83 admission date of index  Osteomyelitis: 730.0, 730.00, 730.1,730.10, 730.20, 730.9, 730.90 hospitalization  Arthritis-related infection: 711, 711.0, 711.00, 711.6, 711.60, 711.9, 711.90  Surgical Site Bleeding: 998.1, 998.11, 998.12, 998.13

AND at least one of the following procedure codes (see Table 2 for a complete list of codes):  Incision and Drainage: 86.22, 86.28, 86.04  77.6 (local excision of lesion or tissue of bone)  78.6 (Removal of implant from bone)]  Removal: 80.09  Arthrotomy: 80.0, 80.00, 80.1, 80.10  Procedure/diagnosis code combinations listed in a row in this table (below) labeled "Repeat Spine Surgery after Cervical Simple Fusion"  Procedures from a review of procedure codes on facility claims with a wound infection or surgical site bleeding diagnosis code within 30 days of spine surgery (see Table 9) Complication ICD-9-CM Diagnosis and Procedure Codes Time Period Wound Complications following Restrict to lumbar simple fusion or lumbar discectomy/ decompression. DO NOT From discharge Lumbar Simple Fusion or INCLUDE WOUND COMPLICATIONS THAT OCCUR DURING THE INDEX HOSPITALIZATION. date of index Lumbar Discectomy/ Presence of one of the following diagnosis codes: hospitalization to Decompression  Wound infection: 996.67, 998.3, 998.30, 998.31, 998.32, 998.33, 998.5, 998.51, 30 days after 998.59, 998.6, 998.83 admission date of index  Osteomyelitis: 730.0, 730.00, 730.1,730.10, 730.20, 730.9, 730.90 hospitalization  Arthritis-related infection: 711, 711.0, 711.00, 711.6, 711.60, 711.9, 711.90  Surgical Site Bleeding: 998.1, 998.11, 998.12, 998.13

AND at least one of the following procedure codes (see Table 2 for a complete list of codes):  Incision and Drainage: 86.22, 86.28, 86.04  77.6 (local excision of lesion or tissue of bone)  78.6 (Removal of implant from bone)  Removal: 80.09  Arthrotomy: 80.0, 80.00, 80.1, 80.10  Procedure/diagnosis codes listed in a row in this table (below) labeled "Repeat Spine Surgery after Lumbar Simple Fusion or Lumbar Discectomy/Decompression"  Procedures from a review of procedure codes on facility claims with a wound infection or surgical site bleeding diagnosis code within 30 days of spine surgery (see Table 9 below) Repeat Spine Surgery after Restrict to cervical simple fusion. From discharge Cervical Simple Fusion Presence of at least one of the following procedure codes during a readmission within date of index 90 days after admission date of index hospitalization: hospitalization to  Fusion: Presence of at least one of the following procedure codes:81.02, 81.03 90 days after admission date of  Refusion: Presence of at least one of the following procedure codes:81.32, index 81.33 hospitalization  Discectomy:  Presence of the following procedure code: 80.51 AND  Presence of one of the following diagnosis codes: 721.0, 721.1, 722.0, 722.4, 722.71, 722.91, 723.0, 723.1  Decompression  Presence of the following procedure code: 03.09 AND  Presence of one of the following diagnosis codes: 721.0, 721.1, 722.0, 722.4, 722.71, 722.91, 723.0, 723.1 Complication ICD-9-CM Diagnosis and Procedure Codes Time Period Repeat Spine Surgery after Restrict to lumbar simple fusion or lumbar discectomy/ decompression. From discharge Lumbar Simple Fusion or Presence of at least one of the following procedure codes during a readmission within date of index Lumbar Discectomy/ 90 days after admission date of index hospitalization: hospitalization to Decompression  Fusion: 81.06, 81.07, 81.08 90 days after admission date of  Refusion: 81.36, 81.37, 81.38 index  Discectomy: hospitalization  Presence of the following procedure code: 80.51 AND  Presence of one of the following diagnosis codes: 722.10, 722.73; 721.3, 722.52, 722.93; 721.42, 724.02; 756.11; 722.32, 724.2  Decompression  Presence of the following procedure code: 03.09 AND  Presence of one of the following diagnosis codes: 722.10, 722.73; 721.3, 722.52, 722.93; 721.42, 724.02; 756.11; 722.32, 724.2 Any Complication Presence of at least one of the seven complications (as defined above) Time periods for the seven complications (as defined above) *Based on information from: Yale New Haven Health Services Corporation/Center for Outcomes Research and Evaluation (YNHHSC/CORE). Form 9.1: Measure Information Form, Hospital risk-standardized complications rate following elective primary total Knee arthroplasty (THA) and/or total knee arthroplasty (TKA), Draft. July 15, 2010. Table 9. ICD-9-CM Procedure Codes To Be Used in Identifying Wound Complications ICD-9-CM Procedure Code Description Incision and Drainage 86.22 Excisional debridement of wound, infection, or burn 86.28 Nonexcisional debridement of wound, infection or burn 86.04 Other incision with drainage of skin and subcutaneous tissue Miscellaneous codes 77.6 Local excision of lesion or tissue of bone, vertebrae 78.69 Removal of implant from bone, vertebrae 80.09 Arthrotomy for removal of prosthesis, spine Arthrotomy 80.0 Arthrotomy for removal of prosthesis 80.00 Arthrotomy for removal of prosthesis, site unspecified 80.09 Arthrotomy for removal of prosthesis, spine 80.1 Arthrotomy, other 80.10 Arthrotomy, other, site unspecified 80.19 Arthrotomy, other, spine "Repeat Spine Surgery after Cervical Simple Fusion" 81.02 Other cervical fusion, anterior technique 81.03 Other cervical fusion, posterior technique 81.32 Refusion of other cervical spine, anterior technique 81.33 Refusion of other cervical spine, posterior technique 80.51 Presence of the following procedure code: 80.51 AND Presence of one of the following diagnosis codes: 721.0, 721.1, 722.0, 722.4, 722.71, 722.91, 723.0, 723.1 03.09 Presence of the following procedure code: 03.09 AND Presence of one of the following diagnosis codes: 721.0, 721.1, 722.0, 722.4, 722.71, 722.91, 723.0, 723.1 "Repeat Spine Surgery after Lumbar Simple Fusion or Lumbar Discectomy/Decompression" 81.06 Lumbar and lumbosacral fusion, anterior technique ICD-9-CM Procedure Code Description 81.07 Lumbar and lumbosacral fusion, lateral transverse process technique 81.08 Lumbar and lumbosacral fusion, posterior technique 81.36 Refusion of lumbar and lumbosacral spine, anterior technique 81.37 Refusion of lumbar and lumbosacral spine, lateral transverse process technique 81.38 Refusion of lumbar and lumbosacral spine, posterior technique 80.51 Presence of the following procedure code: 80.51 AND Presence of one of the following diagnosis codes: 722.10, 722.73; 721.3, 722.52, 722.93; 721.42, 724.02; 756.11; 722.32, 724.2 03.09 Presence of the following procedure code: 03.09 AND Presence of one of the following diagnosis codes: 722.10, 722.73; 721.3, 722.52, 722.93; 721.42, 724.02; 756.11; 722.32, 724.2 Selected from Review of Procedure Codes for Stays with a Diagnosis of Wound Infection or Surgical Site Bleeding within 30 Days of Spine Surgery 02.12 Other repair of cerebral meninges 03.02 Reopening of laminectomy site 03.09 Oth exploration & decompr spinal canal 03.39 Oth diag procs on spinal cord & spinal c 03.4 Excis/destruc lesion spinal cord/spinal 03.59 Oth repair & plastic opers on spinal cor 3.6 Lysis adhesions spinal cord & nerve root 03.8 Injec destructive agent into spinal cana 03.92 Injection of oth agent into spinal canal 3.95 Spinal blood patch 03.99 Oth opers on spinal cord & spinal canal 06.02 Reopening of wound of thyroid field 6.92 Ligation of thyroid vessels 28.0 Incis & drainage tonsil & peritonsillar 38.7 Interruption of the vena cava 38.82 Oth surg occlusion oth vessels head & ne ICD-9-CM Procedure Code Description 39.3 Suture of unspecified blood vessel 39.32 Suture of vein 39.57 Repair blood vessel w/synthetic patch gr 39.98 Control of hemorrhage,not othws specd 41.98 Other operations on bone marrow 54.12 Reopening of recent laparotomy site 54.19 Other laparotomy 54.61 Reclosure postoperative disruption abdom 54.91 Percutaneous abdominal drainage 77.19 Oth incis oth bone,except facial bones,w 77.49 Biopsy of oth bone,except facial bones 77.69 Local excis lesion/tis oth bone,except f 77.89 Oth partial ostectomy oth bone,except fa 78.09 Bone graft oth bone,except facial bones 78.59 Int fixation oth bone,except facial bone 78.69 Rem of implanted device from oth bone 80.39 Biopsy joint structure oth specd site 80.5 Excis/destruc intervertebral disc,unspec 80.51 Excision of intervertebral disc 80.89 Oth local excis/destruc lesion joint oth 81.38 Refusion of lumbar post 81.62 Fus/refus 2-3 vertebrae 81.91 Arthrocentesis 83.02 Myotomy 83.09 Other incision of soft tissue 83.14 Fasciotomy 83.19 Other division of soft tissue ICD-9-CM Procedure Code Description 83.32 Excision of lesion of muscle 83.39 Excision of lesion of other soft tissue 83.44 Other fasciectomy 83.45 Other myectomy 83.49 Other excision of soft tissue 83.65 Other suture of muscle or fascia 83.77 Muscle transfer or transplantation 83.82 Graft of muscle or fascia 83.95 Aspiration of other soft tissue 84.68 Revise disc prosth lumb 86.01 Aspiration of skin & subcutaneous tissue 86.04 Oth incis w/drainage skin & subcutaneous 86.05 Incis w/rem foreign body fr skin & subcu 86.09 Oth incision of skin & subcutaneous tis 86.22 Excisal debridement wound,infection,or b 86.28 Nonexcisal debridement wound,infection,o 86.3 Oth local excis/destruc lesion/tis skin 86.4 Radical excision of skin lesion 86.59 Closur skin & subcutaneous tis oth sites 86.66 Homograft to skin 86.7 Pedicle or flap graft,not othws specd 86.72 Advancement of pedicle graft 86.74 Attachment pedicle/flap graft to oth sit 86.89 Oth repair & reconstruction skin & subcu 93.56 Application of pressure dressing 93.57 Application of other wound dressing 96.59 Other irrigation of wound Table 10. ICD-9-CM Diagnosis and Procedure Codes and Time Period for Identifying Readmissions Following Cervical Simple Fusion, Lumbar Simple Fusion, or Lumbar Discectomy/Decompression*

Measure Element ICD-9-CM Diagnosis and Procedure Codes Time Period Denominator Patients aged 18 and older admitted to acute care inpatient hospitals for an elective, primary spine surgery. Admission date of index Patients are eligible for inclusion in the denominator if they have had one of the spine surgeries described in hospitalization from July Table 1 above 1, 2007 through September 30, 2009 Numerator: Include: From discharge date of Inclusion Any readmission to an acute care hospital within 30 days index hospitalization to 30 days after discharge date Numerator Exclude the following categories: From discharge date of Exclusion: Likely Readmissions to a different hospital on the same day that are not a discharge or transfer to index hospitalization to rehab admissions another short term hospital: 30 days after discharge **  samehosp=0 and readmit_interval_1=0 and index_discharge_status_code NE '02: date DISCHARGE/TRANSFER TO ANOTHER SHORT TERM HOSPITAL' Readmissions to a rehabilitation hospital:  PROVIDER_SPECIALTY_CODE = 'A1 SKILLED NURSING FACILITY' OR 'A3 NURSING FACILITY, OTHER' OR '25 PHYSICAL MEDICINE AND REHABILITATION' Readmissions with a principal diagnosis indicating rehabilitation:  V57.89 (Other specified rehabilitation procedure, Multiple training or therapy) or any other diagnosis that begins with a 'V' * Based on information from: Yale New Haven Health Services Corporation/Center for Outcomes Research and Evaluation (YNHHSC/CORE). Form 9.1: Measure Information Form, Hospital risk-standardized complications rate following elective primary total Knee arthroplasty (THA) and/or total knee arthroplasty (TKA), Draft. July 15, 2010. ** This exclusion was developed by the authors. Table 11. Clinical Risk Factor Categories Used in Multivariate Models with Condition Category (CC) Numbers* Clinical Risk Factor Category* Condition Category (CC)# Infection CC 1, 3-6 Metastatic Cancer and acute leukemia CC 7 Cancer CC 8-12 Diabetes and Diabetes Mellitus Complications CC 15-20, 119, 120 Protein-calorie malnutrition CC 21 Disorders of Fluid/Electrolyte/Acid-Base CC 22, 23 Rheumatoid Arthritis and Inflammatory Connective Tissue Disease CC 38 Severe hematological disorders CC 44 Dementia and senility CC 49, 50 Major psychiatric Disorders CC 54-56 Hemiplegia, paraplegia, paralysis, functional disability CC 67-69, 100-102, 177-178 Polyneuropathy CC 71 Congestive heart failure CC 80 Chronic atherosclerosis CC 83-84 Hypertension CC 89, 91 Arrhythmias CC 92, 93 Stroke CC 95, 96 Vascular or circulatory disease CC 104-106 Copd CC 108 Pneumonia CC 111-113 End-stage renal disease or dialysis CC 129**, 130 Renal failure CC 131 Decubitus ulcer or chronic skin ulcer CC 148, 149 Cellulites, local skin infection CC 152 Other injuries CC 162 Major symptoms, abnormalities CC 166 * Based on information from: Yale New Haven Health Services Corporation/Center for Outcomes Research and Evaluation (YNHHSC/CORE). Form 9.1: Measure Information Form, Hospital risk-standardized complications rate following elective primary total hip arthroplasty (THA) and/or total knee arthroplasty (TKA), Draft. July 15, 2010. # The "condition category" (CC) numbers were developed as part of the Centers for Medicare & Medicaid Services (CMS)-Hierarchical Condition Category (HCC) Model (Pope et al., 2004). Each "condition category" corresponds to a set of ICD-9-CM codes. The condition categories are defined in a "Condition Category-to-ICD-9-CM Crosswalk" which was available from the Quality Net website (www.qualitynet.org) on September 4, 2010. The crosswalk file name is 302_416_2010_ICD_9_Crosswalk.txt (exact URL not available). **The original article on the HCC model states, "CC 129, ESRD is defined by Medicare entitlement status" (Pope et al., 2004). However, because we are not analyzing Medicare claims, we were not able to assign CC 129 (End Stage Renal Disease (Medicare elig)) as originally specified. Therefore, our models contains only one indicator of ESRD, representing CC 130 (Dialysis Status).

30 Table 12. Prevalence of Clinical Risk Factorsa Among Patients Having Cervical Simple Fusion, Lumbar Simple Fusion, or Lumbar Discectomy/Decompression by Designation Status

31 Lumbar Lumbar Simple Fusion Discectomy/Decompression Designat Clinical Risk Factor ed Other Designated Other Other Hospitals Hospitals Hospitals Hospitals Hospitals N=19,710 N=9,212 N=18,477 N=11,803 N=17,535 % % % % % Infection 1.9 b 2.4 2.2 1.9 1.8 Metastatic cancer and acute leukemia 0.0 0.0 0.0 0.0 0.1 Cancer 2.4 3.0 2.7 2.8 2.3 b Diabetes and diabetes mellitus complications 11.8 12.5 13.1 11.3 12.0 Protein-calorie malnutrition 0.1 0.1 0.2 b 0.1 0.1 Disorders of fluid/electrolyte/acid-base 3.3 7.1 6.2 b 3.2 2.9 Rheumatoid arthritis and inflammatory connective tissue 2.2 3.8 3.8 2.4 2.2 disease Severe hematological disorders 0.1 0.2 0.1 b 0.1 0.1 Dementia and senility 0.7 1.2 1.5 b 1.1 1.3 Major psychiatric disorders 1.5 2.1 1.9 1.6 1.2 b Hemiplegia, paraplegia, paralysis, functional disability 2.6 1.7 1.7 2.1 1.8 Polyneuropathy 1.7 1.8 1.9 1.6 1.5 Congestive heart failure 0.8 1.3 1.2 1.0 0.9 Chronic atherosclerosis 5.2 6.5 6.5 5.7 5.5 Hypertension 36.4 42.8 43.4 35.7 37.0 b Arrhythmias 3.7 4.7 4.1 b 3.3 3.9 b Stroke 0.3 0.2 0.2 0.2 0.1 Vascular or circulatory disease 2.7 6.9 5.9 b 4.2 3.8 Chronic Obstructive Pulmonary Disease (COPD) 4.1 4.3 4.7 2.8 3.3 b Pneumonia 0.6 0.7 0.8 0.5 0.4 End-stage renal disease or dialysis 0.0 0.0 0.0 0.0 0.0 Renal failure 0.7 1.5 1.4 0.9 0.8 Decubitus ulcer or chronic skin ulcer 0.2 0.1 0.2 0.2 0.2 Cellulites, local skin infection 0.8 1.1 0.9 0.9 0.9 Other injuries 10.3 7.8 8.1 8.6 7.9 b Major symptoms, abnormalities 17.4 b 17.5 16.6 12.6 11.8 b a All clinical risk factor categories, except pneumonia, are based on primary and secondary diagnoses from the index stay and from inpatient and outpatient claims data during the six months preceding the index procedure date. The pneumonia variable is based on primary and secondary diagnoses from inpatient and outpatient claims data during the six months preceding the index procedure date, not on the index stay. b Rates in bold represent a significant difference between designated hospitals and other hospitals based on a chi-square test (P<.05).

32 Table 13. Sensitivity Analysis: Comparison of 90 day Medical Costs (in Dollars) Using a Different Method

Lumbar Cervical Simple Lumbar Simple Disectomy/ Fusion Fusion Decompression

Percentage Difference between Designated and Other Hospitals From Table 5 Total medical costs during 90 from days following admission 3.0% (0.07) 1.8% (0.29) -0.3% (0.88) Manuscript date Added to risk adjustment - 6 Modifications month baseline costs in risk 3.2% (0.09) 1.2% (0.59) 0.9% (0.62) to Model adjustment* * Because of concerns that model used in paper might not sufficiently account for differences in baseline risk, we added to the models all costs in the 6 months prior to the procedure

33 Table 14. Number of Spine Surgeries Performed in Designated Hospitals and Other Hospitals by Type of Surgery Before Exclusions, July 2007-September 2009 Unmatched Designated Hospitals Other Hospitals Hospitals Total

Included in Analytic Type of Spine Surgery Sample N % N % N % N %

Cervical simple fusion with or without a discectomy or Included 17,237 25.1 25,225 26.5 7,060 25.6 49,522 25.8 decompression

Lumbar simple fusion with or without a discectomy or Included 18,737 27.3 28,253 29.7 8,050 29.2 55,040 28.7 decompression

Lumbar discectomy or Included 20,976 30.5 27,050 28.4 7,947 28.8 55,973 29.2 decompression without fusion

Subtotal of spine surgeries 160,53 Included 56,950 82.8 80,528 84.5 23,057 83.5 83.8 included in analysis 5

Cervical complex fusion with or without a discectomy or Not included 3,206 4.7 3,782 4.0 1,038 3.8 8,026 4.2 decompression

Cervical discectomy or Not included 2,223 3.2 2,770 2.9 844 3.1 5,837 3.0 decompression without fusion

Thoracic/thoracolumbar simple fusion with or without Not included 253 0.4 268 8.7 82 0.3 603 0.3 a discectomy or decompression

Thoracic/thoracolumbar complex fusion with or Not included 1,916 2.8 2,317 75.0 915 3.3 5,148 2.7 without a discectomy or decompression

34 Unmatched Designated Hospitals Other Hospitals Hospitals Total

Included in Analytic Type of Spine Surgery Sample N % N % N % N %

Thoracic/thoracolumbar discectomy or decompression Not included 441 0.6 505 16.4 164 0.6 1,110 0.6 without fusion

Lumbar complex fusion with or without a discectomy or Not included 3,761 5.5 5,096 5.3 1,502 5.4 10,359 5.4 decompression

Total Included and 191,61 68,750 100.0 95,266 100.0 27,602 100.0 100.0 not included 8

35 References

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