Does the Increase in Spine Surgery Reflect an Increase in

Disease?

Sohail K. Mirza, MD MPHProfessor, Department of Orthopedics and

Joint Professor, Department of Neurological Surgery

University of Washington

X UW Tech Transfer (Synthes)

X

XDepuy, Surgical Dynamics, Synthes(to UW Dept. of Orthopedics)

Depuy, Synthes (to Dept of Orthop)

X

XX

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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 359798

325 Ninth Avenue

Seattle, WA 98104

Email: mirza@u.washington.edu Tel: 206 731 3658 Fax: 206 731 3227

no

Does the increase in spine surgery reflect an increase in disease?

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1,865,196 results on 5/17/2002

Back Pain

707,000,000 results on 6/ 5/200726,100,000 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 1999JAMA 2001 Spine 2002

Col9A2: Glutamine TryptophanDisc disease 6/157 (vs. 0/174 controls)

COL9A3: Arginine TryptophanDisc 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 2002-2003

Low-rate states High-rate statesHawaii 1.8 Montana 7.4Vermont 2.6 Oregon 7.5New Jersey 2.7 Idaho 8.4New York 2.7 Wyoming 9.2

Low-rate cities High-rate citiesTerre Haute, IN 1.6 Ft. Collins, CO 8.0Bronx, NY 1.7 Eugene, OR 8.0Honolulu, HI 1.8 Idaho Falls, ID 8.2Wilkes-Barre, PA 2.0 Slidell, LA 8.2Manhattan, NY 2.1 Amarillo, TX 8.3McAllen, TX 2.1 Newport News, VA 8.3Huntington, WV 2.2 Billings, MT 8.4Hackensack, NJ 2.2 Greeley, CO 8.6Lebanon, NH 2.3 Rapid City, SD 8.6Newark, NJ 2.3 Casper, WY 9.5East Long Island, NY 2.3 Boise, ID 9.9Paterson, NJ 2.4 Bend, OR 10.2

Overall U.S. Rate 4.5

Geographical Variations in Spine Surgery Rates(rate per 1,000 enrollees within the 2001 U.S. Medicare population)

Deyo, Mirza CORR 2006

Weinstein, Lurie et al Spine 2006

Variation in Lumbar Fusion Rates

Rate Per 1000 Medicare Enrollees

Laminectomy Fusion

Variation in

Regional Rates 8X 20X

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

Lumbar Fusions forDegenerative

DiseaseHip

ReplacementKnee

ArthroplastyNumber of procedures, 2001(listed as primary procedure) 122,316 329,900 363,536

% increase in volume 1996-2001 113% 13% 15%

Mean hospital stay, days 4.5 5.4 4.5

Median hospital stay, days 4 4 4

Mean total hospital charges, 2001 $39,900 $28,234 $25,309

Median total hospital charges $26,887 $24,017 $22,335

National Hospital Bill, 2001(mean charges times no. of hospitalizations) $4.9 Billion $9.3 Billion $9.2 Billion

Procedure Comparisons (2001)

Deyo, Nachemson, Mirza NEJM 2004

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

1992 2003Rate of Lumbar Fusion 30 per 100k 110 per 100k

Spending for Lumbar Fusion $75 million $482 million

Percent Spending for Fusion 14% 47%

Weinstein, Lurie et al Spine 2006

Inpatient Medicare Reimbursement

Deyo, Mirza et al Spine 2005

Deyo, Mirza et al Spine 2005

Deyo, Mirza et al Spine 2005

Deyo, Mirza et al Spine 2005

Deyo, Mirza et al Spine 2005

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

Sponsor Odds Ratio 95% CISponsor of study 3.6 2.6 to 4.9

For-profit organizations 5.3 2.0 to 14.4

Manufacturer of drugs 8.0 1.1 to 53.2

Spinal device manufacturer 3.3 2.4 to 4.5

Jacobs, Galante, Mirza, Zdeblick JBJS 2006

Favorable Results

Field Industry-fundedIndependent

Spine 73% 44%

Hip 93% 37%

Knee 75% 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 WaldemanPain 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.