Does the Increase in Spine Surgery Reflect an Increase in Disease? Sohail K. Mirza, MD MPH Professor, Department of Orthopedics and Joint Professor, Department of Neurological Surgery University of Washington

X UW Tech Transfer (Synthes) X X Depuy, Surgical Dynamics, Synthes (to UW Dept. of Orthopedics) Depuy, Synthes (to Dept of Orthop) X X X X X X X X X X X X NASS Format

Disclosure I hold the University of Washington Surgical Dynamics Endowed Chair for Spine Outcomes Research (approx $90k in 2006). I receive royalties for surgical drills licensed by Synthes Spine through UW Office of Technology Transfer (approx. $16k in 2006). UW Department of Orthopedics receives spine fellowship support, research support, and endowments from Synthes Spine and Depuy Spine. I work with the spine fellows and am involved with two of the research projects supported by these funds. I prepared all the slides. Sohail K. Mirza, MD, MPH Professor, Department of Orthopedics and Sports Medicine and Department of Neurological Surgery, University of Washington Harborview Medical Center, Box Ninth Avenue Seattle, WA Tel: Fax:

no Does the increase in spine surgery reflect an increase in disease?

Search for: Show site abstracts 1,865,196 results on 5/17/2002 Back Pain 707,000,000 results on 6/ 5/ ,100,000 results on 1/15/2008

Resolution of pedicle screw litigation New posterior fixation devices New anterior fixation devices Cages Bone graft substitutes Bone morphogenetic proteins Minimally invasive spine surgery Computer-assisted surgery Artificial discs New Technologies

1.Fusion results in better pain and function outcome in patients with spondylolisthesis. 2.Fusion with instrumentation results in a higher fusion rate. 3.Instrumentation is associated with a higher complication rate. 4.Artificial disc replacement may avoid complications of fusion. New Clinical Knowledge: RCTs

Normal Degeneration

Biochemical Changes Water content Proteoglycan content Chondroitin to sulfate ratio Collagen network

Collagen Repetitive Sequence (GLY – X – Y ) X: proline Y: hydroxyproline Triple helix Tryptophan substitution?

Ala-Kokko Science 1999 JAMA 2001 Spine 2002 Col9A2: Glutamine  Tryptophan Disc disease 6/157 (vs. 0/174 controls) COL9A3: Arginine  Tryptophan Disc disease 12% (vs. 5% controls) Trp allele  3X risk for disc disease

Association with Collagen IX Tryptophan Alleles Matsui, Mirza, Eyre JBJS-B 2004

Association with Collagen IX Tryptophan Alleles

Spinal Stenosis with Spondylolisthesis

Potential Physiological Basis for Disc-associated Back Pain Initiation of a chemotactic response Vascular ingrowth Increased sensory innervation Endplate cartilage defects Inflammation

Variation

Ratio of Back Surgery Rates Deyo, Mirza CORR 2006

Weinstein, Lurie et al Spine 2006 Variation in Lumbar Fusion Rates Per 1000 Medicare Enrollees

Deyo, Mirza CORR 2006

Weinstein, Lurie et al Spine 2006 Variation in Lumbar Fusion Rates Rate Per 1000 Medicare Enrollees

LaminectomyFusion Variation in Regional Rates 8X20X Weinstein, Lurie et al Spine 2006 Variation in Lumbar Surgery Rates

Causes of Variation Lack of scientific evidence Financial Incentives and Disincentives Clinical Training and Professional Opinion New technology Weinstein, Lurie et al Spine 2006

Growth

Procedure Comparisons (2001) Deyo, Nachemson, Mirza NEJM 2004

Annual Number of Operations in U.S. Data from National Inpatient Sample, HCUP/AHRQ

Weinstein, Lurie et al Spine 2006 Inpatient Medicare Reimbursement

Rate of Lumbar Fusion30 per 100k110 per 100k Spending for Lumbar Fusion$75 million$482 million Percent Spending for Fusion14%47% Weinstein, Lurie et al Spine 2006 Inpatient Medicare Reimbursement

Deyo, Mirza et al Spine 2005

Office Visits for Back Pain Deyo, Mirza, Martin Spine 2006

National Health Interview Survey 2002 Deyo, Mirza, Martin Spine 2006

National Health Interview Survey 2002 Deyo, Mirza, Martin Spine 2006

National Health Interview Survey 2002 Deyo, Mirza, Martin Spine 2006

US Prevalence of Back Pain Deyo, Mirza, Martin Spine 2006

US Prevalence of Back Pain Deyo, Mirza, Martin Spine 2006

Potential Financial Conflicts of Interest

Favorable Results in Industry-Sponsored Research SponsorOdds Ratio95% CI Sponsor of study to 4.9 For-profit organizations to 14.4 Manufacturer of drugs to 53.2 Spinal device manufacturer to 4.5 Jacobs, Galante, Mirza, Zdeblick JBJS 2006

Favorable Results FieldIndustry-fundedIndependent Spine73%44% Hip93%37% Knee75%20%

April 8, 2002 “Surgeons have often touted procedures that ultimately proved to be disappointing.”

“Trisha Bryant assumed that the procedures her surgeon recommended were necessary and had been validated by research. I, too, made that assumption….If Trisha had explored the medical literature, however, she would have discovered that every aspect of her case – the interpretation of the MRI scan, the diagnosis of spinal instability, the rationale for fusing vertebrae, the impending discography– was controversial …” April 8, 2002

“Each approach to diagnosis and treatment is essentially a franchise, and there are too many franchises battling.” Seth Waldeman Pain Medicine, HSS April 8, 2002 “Spinal instability is routinely given as a diagnosis to these patients with chronic lower-back pain. It is a term used to justify an operation. And it is a great diagnosis, because it can’t be directly disproved.” Surgeon who performs two to three spinal fusions a week. “… within the surgical profession there’s a curious gap between rhetoric and reality.”

Conclusions Biological basis for “discogenic back pain” is not known. Rates of lumbar fusion for chronic back pain have increased without increase in prevalence of back pain. Investigator-sponsor financial conflicts are common.

Thank you.