1. The National Burden of Revision Spinal Fusion: A Focus on Patient Characteristics and Complications Sean S. Rajaee MS Linda E. A. Kanim MA Hyun W. Bae MD Cedars-Sinai Spine Center. Los Angeles, CA Tufts University School of Medicine. Boston, MA

2. My disclosure is in the Final Program Book and in the AAOS database. I have no potential conflicts with this presentation. The National Burden of Revision Spinal Fusion: A Focus on Patient Characteristics and Complications

3. Spinal Fusion Trends, 1998-2008 Rajaee & Bae et al, Spine 2012 Rates of spinal fusion increasing % Increase 1998-2008: Cervical: 90% Thoracic: 61% Lumbar: 141% ? Increase in Revisions

4. Reasons for Revision Fusion Persistent pain Failure to achieve osseous fusion Complications from surgical implants Progressive degeneration Image from http://orthoinfo.aaos.org /topic.cfm?topic=A00594

5. Risk Factors Older age Primary fusion of multiple levels Kim et al, Spine, 2005 Pre-surgical emotional status Trief et al, Spine, 2006 Smoking Carpenter et al, JBJS, 1996 Workers compensation status Trief et al, Spine, 2006 Systemic diseases Bendo et Al, Am J Orthop, 2002 Medication use (NSAIDS, steroids) Dimar et al, Spine, 1996 www.dnainfo.com Microsoft Office

6. Study Purpose Trends in revision fusion are lacking Mission 1. Present National trends in revision spinal fusion 2. Compare patient characteristics and complications between primary spinal fusion and revision 3. Compare the use of BMP, interbody devices, and fusion of multiple levels 4. Present the most common pre-op diagnosis for revision fusion

7. Study Design Retrospective analysis using a national administrative dataset: Nationwide Inpatient Sample (NIS)

8. Nationwide Inpatient Sample  Largest all-payer inpatient care database in the U.S.  Data from 8 million hospital stays each year, 20-percent sample of U.S. hospitals.  Produces national estimates

9. Methods: Selection of Discharges Spinal Fusion Discharges Primary (ICD9: 81.00-81.08) Revision (ICD9: 81.30-81.39)

10. Trends 2002-2009 Population Adjusted Rate

11. Trends, 2002-2009 % of all fusions that were ‘revisions’ annually

13. LOS and Charges, 2009 Mean Length of Stay (LOS)Mean Hospital Charges 4.2 Days 3.8 Days $4700

14. Surgical Factors, 2009 Table 2: Univariate analyses of surgical related factors in 2009 PrimaryRevisionUnadjusted OR Autogenous Bone Graft35.1%40.3%1.15 (1.1-1.2) BMP27.6%39.7%1.73 (1.6-1.8) Interbody Device53.5%41.7%0.55 (0.5-0.6) > 4 Levels Fused17.2%27.3%1.70 (1.6-1.8)

15. Surgical Factors, 2009

16. Adjusted OR, 2009

17. Comorbidities, Adjusted OR

18. Complications, Adjusted OR

19. Diagnosis Most common inpatient diagnosis for revision fusion was: ICD9 996.49 –“Mechanical complication of internal orthopedic device, implant, and graft” –46.4% of cervical refusions –46.7% of thoracic refusions –39.6% of lumbar refusions.

20. Conclusions: Epidemiologic Trends Revision spinal fusions have increased, but at a lower rate than primary fusions from 2002-2009

21. Conclusions: Surgical Differences Revision Fusions had significantly higher rates of BMP use (40% vs 28%) –Lad et al, Spine 2011: National BMP Use ~ 31% Fusion of four or more levels occurred at higher rates in spinal refusion cases (27.3% vs 17.2%)

22. Conclusions: Patient Differences Depression (odds ratio 1.53) Psychotic disorders (odds ratio 1.49) Tobacco use (odds ratio 1.10) Deficiency anemias (odds ratio 1.35) All were more common in refusion discharges.

23. Conclusions: Complication Differences –Dural tears (OR 1.4) –Surgical site infections (OR 2.3) –Wound dehiscence (OR 3.4) All were more common in refusion discharges.

24. Final Remarks –Given that the most common diagnosis for revisions was ‘mechanical complication of internal orthopedic device” Further research in different surgical factors is warranted (BMP, fusion multiple levels, interbody devices, etc) –Patient characteristics and co-morbidites identified should be carefully reviewed upon primary surgical evaluation –Higher rate of certain complications should further educate the community on the increased complexity of revision fusions

25. Thank You. Tufts University