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Surgical Treatment of Spinal Stenosis with and without Degenerative Spondylolisthesis: Cost-Effectiveness after 2 Years

Anna N.A. Tosteson, ScD; Jon D. Lurie, MD, MS; Tor D. Tosteson, ScD; Jonathan S. Skinner, PhD; Harry Herkowitz, MD; Todd Albert, MD; Scott D. Boden, MD; Keith Bridwell, MD, PhD; Michael Longley, MD; Gunnar B. Andersson, MD, PhD; Emily A. Blood, MS; Margaret R. Grove, MS; James N. Weinstein, DO, MS, SPORT Investigators
[+] Article and Author Information

For a list of the SPORT (Spine Patient Outcomes Research Trial) investigators, see the Appendix.


From Dartmouth Medical School, Hanover, New Hampshire; William Beaumont Hospital, Royal Oak, Michigan; Rothman Institute at Thomas Jefferson University, Philadelphia, Pennsylvania; Emory University, Atlanta, Georgia; Washington University School of Medicine, St. Louis, Missouri; The Nebraska Foundation for Spinal Research, Omaha, Nebraska; and Rush University Medical Center, Chicago, Illinois.


Acknowledgment: The authors thank Catherine C. Lindsay, SM, for extensive work in the development of the cost weights utilized in this analysis; Tamara S. Morgan for creation of the patient diaries and assistance in preparing this manuscript; and Loretta Pearson for editorial assistance.

Grant Support: By the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) (U01-AR45444); Office of Research on Women's Health, National Institutes of Health; and the National Institute of Occupational Safety and Health, Centers for Disease Control and Prevention. The Multidisciplinary Clinical Research Center in Musculoskeletal Diseases is funded by NIAMS (P60-AR048094). Dr. Lurie is supported by a Research Career Award from NIAMS (K23 AR 048138).

Potential Financial Conflicts of Interest:Consultancies: T. Albert (DePuy Spine), S.D. Boden (Medtronic), K. Bridwell (DePuy, Medtronic). Grants received: M. Longley (Medtronic), J.N. Weinstein (National Institutes of Health). Patents pending: T. Albert (screw device for possible use in fusion operations). Royalties: S.D. Boden (Osteotech).

Reproducible Research Statement:Study protocol: Available upon request (e-mail, SPORT@dartmouth.edu). Statistical code and data set: Not available.

Requests for Single Reprints: Anna N.A. Tosteson, ScD, Multidisciplinary Clinical Research Center in Musculoskeletal Diseases, HB7505, Dartmouth Medical School, One Medical Center Drive, Lebanon, NH 03756.

Current Author Addresses: Drs. A.N.A. Tosteson, Lurie, T.D. Tosteson, and Weinstein; Ms. Blood; and Ms. Grove: Dartmouth-Hitchcock Medical Center, One Medical Center Drive, Lebanon, NH 03756.

Dr. Skinner: Dartmouth College, 317 Rockefeller Hall, Hanover, NH 03755.

Dr. Herkowitz: William Beaumont Hospital, 3535 West 13 Mile Road Royal Oak, MI 48073.

Dr. Albert: Rothman Institute at Thomas Jefferson University, 952 Chestnut Street, Philadelphia, PA 19107.

Dr. Boden: Emory University, Emory Orthopaedics and Spine Center, 59 Executive Park South, Suite 3000, Atlanta, GA 30329.

Dr Bridwell: Washington University, Suite 11300 West Pavilion, One Barnes-Jewish Hospital Plaza, St. Louis, MO 63110.

Dr. Longley: Nebraska Spine Surgeons, 11819 Miracle Hills Drive, Suite 102, Omaha, NE 68154-4438.

Dr. Andersson: Rush-Presbyterian-St. Luke's Medical Center, 1653 West Congress Parkway, Chicago, IL 60612-3833.

Author Contributions: Conception and design: A.N.A. Tosteson, T.D. Tosteson, T. Albert, S.D. Boden, K. Bridwell, J.N. Weinstein.

Analysis and interpretation of the data: A.N.A. Tosteson, J.D. Lurie, T.D. Tosteson, J.S. Skinner, S.D. Boden, E.A. Blood, M.R. Grove, J.N. Weinstein.

Drafting of the article: A.N.A. Tosteson, J.D. Lurie, E.A. Blood, J.N. Weinstein.

Critical revision of the article for important intellectual content: A.N.A. Tosteson, J.D. Lurie, J.S. Skinner, H. Herkowitz, T. Albert, S.D. Boden, K. Bridwell, M. Longley, G.B. Andersson, E.A. Blood, J.N. Weinstein.

Final approval of the article: A.N.A. Tosteson, J.D. Lurie, T.D. Tosteson, J.S. Skinner, H. Herkowitz, T. Albert, M. Longley, G.B. Andersson, E.A. Blood, J.N. Weinstein.

Provision of study materials or patients: J.D. Lurie, J.S. Skinner, T. Albert, S.D. Boden, M. Longley, G.B. Andersson, J.N. Weinstein.

Statistical expertise: A.N.A. Tosteson, T.D. Tosteson, E.A. Blood, J.N. Weinstein.

Obtaining of funding: A.N.A. Tosteson, J.N. Weinstein.

Administrative, technical, or logistic support: J.N. Weinstein.

Collection and assembly of data: J.N. Weinstein.


Ann Intern Med. 2008;149(12):845-853. doi:10.7326/0003-4819-149-12-200812160-00003
Text Size: A A A

Background: The SPORT (Spine Patient Outcomes Research Trial) reported favorable surgery outcomes over 2 years among patients with stenosis with and without degenerative spondylolisthesis, but the economic value of these surgeries is uncertain.

Objective: To assess the short-term cost-effectiveness of spine surgery relative to nonoperative care for stenosis alone and for stenosis with spondylolisthesis.

Design: Prospective cohort study.

Data Sources: Resource utilization, productivity, and EuroQol EQ-5D score measured at 6 weeks and at 3, 6, 12, and 24 months after treatment among SPORT participants.

Target Population: Patients with image-confirmed spinal stenosis, with and without degenerative spondylolisthesis.

Time Horizon: 2 years.

Perspective: Societal.

Intervention: Nonoperative care or surgery (primarily decompressive laminectomy for stenosis and decompressive laminectomy with fusion for stenosis associated with degenerative spondylolisthesis).

Outcome Measures: Cost per quality-adjusted life-year (QALY) gained.

Results of Base-Case Analysis: Among 634 patients with stenosis, 394 (62%) had surgery, most often decompressive laminectomy (320 of 394 [81%]). Stenosis surgeries improved health to a greater extent than nonoperative care (QALY gain, 0.17 [95% CI, 0.12 to 0.22]) at a cost of $77 600 (CI, $49 600 to $120 000) per QALY gained. Among 601 patients with degenerative spondylolisthesis, 368 (61%) had surgery, most including fusion (344 of 368 [93%]) and most with instrumentation (269 of 344 [78%]). Degenerative spondylolisthesis surgeries significantly improved health versus nonoperative care (QALY gain, 0.23 [CI, 0.19 to 0.27]), at a cost of $115 600 (CI, $90 800 to $144 900) per QALY gained.

Result of Sensitivity Analysis: Surgery cost markedly affected the value of surgery.

Limitation: The study used self-reported utilization data, 2-year time horizon, and as-treated analysis to address treatment nonadherence among randomly assigned participants.

Conclusion: The economic value of spinal stenosis surgery at 2 years compares favorably with many health interventions. Degenerative spondylolisthesis surgery is not highly cost-effective over 2 years but could show value over a longer time horizon.

Figures

Grahic Jump Location
Figure 1.
Adjusted mean EuroQol EQ-5D health state values and 95% CIs over time, by treatment received.

Top. Spinal stenosis group. Bottom. Degenerative spondylolisthesis with spinal stenosis group.

Grahic Jump Location
Grahic Jump Location
Figure 2.
Cost-effectiveness acceptability curves, by disease group and analytic assumption.

The primary analysis used total costs based on Medicare payment amounts and the EuroQol EQ-5D to estimate QALYs. The SF-6D analyses estimated QALYs based on this form. Higher surgery costs were based on 70% of the amount billed to Medicare. DS = degenerative spondylolisthesis; QALY = quality-adjusted life-year; SF-6D = Short Form-6D; SpS = spinal stenosis.

Grahic Jump Location

Tables

References

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Comments

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SPORT study/cost effectiveness analysis
Posted on January 14, 2009
Dominic J. Balestra
VA New England Healthcare System
Conflict of Interest: None Declared

I really appreciated this article estimating the cost effectiveness of back surgury. As a retired General Internist who has treated many patients with back pain at the WRJct VA over many years in both acute and chronic settings ("walk-in" clinic; emergency room; scheduled GMC), and who has some familiarity with Richard Deyo's seminal work on back pain, several questions come to mind.

1. You mention that most patients were symptomatic for at least 6-7 months prior to study in "Multidiscinplinary Spine Clinics." Did each study site allow direct scheduled appointments, unscheduled "walk-in" evaluations, or emergency room evaluations(i.e., direct access) to Spine Clinic? Asked differently, did each Spine Clinic only accept referrrals from PCPs, or Emergency Room Professionals prior to Spine Clinic evaluation and what was the mean time from initial symptom onset to initial Spine Clinic evaluation and treatment entry (disease duration)? The reason for this interest is to determine if "referral status" vs "Spine Clinic status" is the better measure of surgical efficacy at 2 years, and to determine if an increased "delay to surgury" is a predictor of surgical efficacy by allowing operation to only the most durably symtomatic pain sufferers? Is there a pain duration that might represent an inflection point in the surgical efficicay vs time-to-treatment curve?

2. Your thoroughness in detailing medical costs is very impressive. Yet the largest single ticket item, and the only truly "discriminating" cost among the four treatment arms in Table 2 is "Surgery." As a General Internist, I would be particularly interested in a breakdown of "Surgical cost" into "hospital charges-Medicare re-imbursable", "hospital charges-negotiated reduction", "hospital charges-patient copay", "hospital charges -patient balance billed", and "physician charges." Asked differently, how well do Medicare payment schedules (Part A plus Part B), reflect private insurer costs plus patient costs (total costs) and surgical cost- effectiveness? Is surgical cost effectiveness in younger, Medicare ineligable patients, better, worse, similar?

References

1. Anna N.A. Tosteson, Jon D. Lurie, Tor D. Tosteson, et al. For the SPORT Investigators Surgical Treatment of Spinal Stenosis with and without Degenerative Spondylolisthesis: Cost-Effectiveness after 2 Years Ann Intern Med 2008; 149: 845-853

Conflict of Interest:

None declared

Cost-Effectiveness of Spinal Stenosis Surgery
Posted on January 15, 2009
Neil H Shusterman
Research Pharmaceutical Services
Conflict of Interest: None Declared

TO THE EDITOR: We read with interest the article by Tosteson and colleagues (1) regarding the cost-effectiveness of surgical treatment of spinal stenosis with or without degenerative spondylolisthesis. However, we note that the health economic conclusions of the article may be more favorable than suggested by the authors based on a need to adjust the frame of reference to American dollars and adjust for inflation. This is because the authors refer to a paper by Laupacis et al (2) as a guide to determining whether a health intervention is considered "costly" or not. Two factors need to be kept in mind about this reference.

First, the Laupacis et al guidelines for interpreting health economic data were calculated in Canadian dollars at a time when the American dollar was stronger. Second, the Laupacis et al guidelines were based on the Canadian dollar in 1990, 14 years before the year used to standardize the health costs by Tosteson et al (2004). Inflation over that time period means that the value of a dollar in 2004 was not the same as in 1990. Laupacis et al suggest that interventions over CAN $100,000 per quality-adjusted life year (QALY) gained provide "weak evidence for adoption", i.e. are "costly". Based on the exchange rate in mid-1990 this would equate to U.S. $85,771 at that time (3). Adjusting for inflation in the United States between mid-1990 and mid-2004 increases this to U.S. $123,964 (4). Based on this standard, both of the interventions studied by Tosteson et al (spinal stenosis surgery and spondylolisthesis surgery) could be considered cost-effective after converting to U.S. dollars and accounting for inflation.

References

1. Tosteson ANA, Lurie JD, Tosteson TD, Skinner JS, Herkowitz H, Albert T, et al. Surgical treatment of spinal stenosis with and without degenerative spondylolisthesis: cost-effectiveness after 2 years. Ann Intern Med. 2008;149:845-853.

2. Laupacis A, Feeny D, Detsky AS, Tugwell PX. How attractive does a new technology have to be to warrant adoption and utilization? Tentative guidelines from using clinical and economic evaluations. Can Med Assoc J. 1992;146:473-481.

3. FX converter: currency converter for 164 currencies. Accessed at http://www.oanda.com/convert/classic on 11 January 2009.

4. CPI inflation calculator. U.S. Bureau of Labor Statistics. Accessed at http://data.bls.gov/cgi- bin/print.pl/data/inflation_calculator.htm on 11 January 2009.

Conflict of Interest:

None declared

IN RESPONSE:
Posted on February 4, 2009
Anna N. A. Tosteson
The Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth College
Conflict of Interest: None Declared

We thank Drs. Shusterman and Erder, for their comments which highlight both the challenge inherent in utilizing any single threshold as a benchmark for ascribing value to health care interventions and the pitfalls in adjusting for inflation and converting between currencies. If one first inflates from mid-1990 to mid-2004 Canadian Dollars (an adjustment of 1.319 (1)), then the "costly" $100,000 threshold (2) becomes $131,900. Converting between 2004 Canadian and US Dollars (1.322 Canadian Dollars per US Dollar as of July 1, 2004 (3)), one achieves a value of $131,900/1.322=$ 99,773 or approximately $100,000 in 2004 US Dollars.

To overcome relying on a single benchmark, we showed results for the most important sensitivity analyses using a cost-effectiveness acceptability curve, which graphed the proportion of times the cost per QALY gained achieved willingness-to-pay thresholds ranging from $20,000 to $300,000 (4). Such graphical presentations should be helpful to those skeptical about the use of any particular cost-effectiveness benchmark. This methodology was also useful for demonstrating the marked impact that higher surgery costs have on surgery's value- an issue raised by Dr. Balestra's comment. Our costing approach utilized national standardized Medicare payment amounts as a proxy for actual resource tilization. Thus, the surgery costs in our analysis were lower than what many private insurers pay. When surgery's cost was based on 70% of the amount hospitals billed to Medicare (a higher amount that what Medicare actually pays), in only a small minority of samples did the cost per QALY gained for surgery fall below $100,000.

The role that our costing approach had on comparisons between instrumented and non-instrumented fusion surgery warrants comment. Our report of no difference in cost between fusion types is largely an artifact of our costing approach, because Medicare payment amounts are minimally different for these surgical alternatives. While it is notable that no statistically significant health outcome differences were observed over 2-years between fusions types, further follow-up of SPORT participants using several approaches to costing will be important for understanding the long-term value of surgery.

Although the SPORT protocol specified a minimum symptom duration of 12 weeks, we are aware of no referral restrictions in place at participating centers. Prior treatments received by SPORT observational cohort participants have been described (5), and may be indicative of varied referral pathways. Our study was not designed to address the optimal symptom duration prior to surgery.

References

(1) Inflation Calculator from Bank of Canada accessed at: http://www.bankofcanada.ca/en/rates/inflation_calc.html, February 3, 2009.

(2) Laupacis A, Feeny D, Detsky AS, Tugwell PX. How attractive does a new technology have to be to warrant adoption and utilization? Tentative guidelines from using clinical and economic evaluations. Can Med Assoc J. 1992;146:473-481.

(3) Canada / U.S. Foreign Exchange Rate from St Louis Federal Reserve accessed at: http://research.stlouisfed.org/fred2/data/EXCAUS.txt, February 3, 2009.

(4) Tosteson ANA, Lurie JD, Tosteson TD, Skinner JS, Herkowitz H, Albert T, et al. Surgical treatment of spinal stenosis with and without degenerative spondylolisthesis: cost-effectiveness after 2 years. Ann Intern Med. 2008;149:845-853.

(5) Cummins J, Lurie JD, Tosteson TD, Hanscom B, Abdu WA, Birkmeyer NJO, Herkowitz H, Weinstein J. Descriptive epidemiology and prior healthcare utilization of patients in the Spine Patient Outcomes Research trial's (SPORT) three observational cohorts- Disc herniation, spinal stenosis and degenerative spondylolisthesis. Spine 2006;31:806-814.

Conflict of Interest:

None declared

Surgery for spinal stenosis
Posted on February 8, 2009
Clive L Sinoff
No Affiliation
Conflict of Interest: None Declared

The favorable conclusions drawn by the authors of this randomized controlled study should be viewed in a more sceptical light. The graph showing a clinical benefit at 2 years had the vertical axis amputated, thus expanding the apparent improvement. The real improvement was very modest even for degenerative spondylolisthesis (QALY gain 0.23). Further, at 2 years 26% of patients in the control arm were on opiates, compared to 73% of those following surgery.

The opposite conclusion is more likely: Opiates as used (details and intensity not described) provided a slight improvement and that surgically treated patients had an even greater need for pain control. In fact, much greater reductions in pain are commonly achieved with opiate treatment of adequate dose and there is little in this study to suggest surgery is effective.

I do commend the authors in undertaking a randomized study since the number of proven surgical procedures is regrettably few.

References

1. Anna N.A. Tosteson, Jon D. Lurie, Tor D. Tosteson, Jonathan S. Skinner, Harry Herkowitz, Todd Albert, Scott D. Boden, Keith Bridwell, Michael Longley, Gunnar B. Andersson, Emily A. Blood, Margaret R. Grove, James N. Weinstein for the SPORT Investigators Surgical Treatment of Spinal Stenosis with and without Degenerative Spondylolisthesis: Cost-Effectiveness after 2 Years Ann Intern Med 2008; 149: 845-853

Conflict of Interest:

None declared

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