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Spinal Stenosis: Surgical vs. Medical Treatment


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  • 1. Spinal Stenosis: Surgery or Not? Suzannah Stout, MD April 30, 2008
  • 2. Lumbar Spinal Stenosis Narrowing of Intraspinal Canal Most Common: DJD of spine or trauma  Disc protrusion  Stress loading of posterior spine (facets)  Hypertrophy of facets or ligamentum flavum  Osteophyte formation Later: Spondylolisthesis
  • 3. Lumbar Spinal Stenosis
  • 4. Lumbar Spinal Stenosis Less Common Causes  Space-occupying lesions  Post-traumatic or -surgical fibrosis  Skeletal Disease (Pagets, ankylosing spondylitis, RA)  Congenital (spina bifida, achondroplasia)
  • 5. Common Sx Low Back Pain (often mild)--65% Neurogenic Claudication--94% Numbness/tingling, weakness--40-60% Worst with standing or walking Relieved with sitting or lying down Those with narrowing found incidentally on imaging are often asymptomatic
  • 6. Traditional Treatment  Physical Therapy (regimens not well studied)  Corticosteriod Injections (also not well studied)  Indications for surgery not fully agreed upon  Most common reason for back surgery in >65yo
  • 7. 2005 Cochrane Review 31 RCTs, often with small #s Lack of long-term outcomes beyond 2-3 yrs Many trials were heterogeneous: spinal stenosis, disc nerve compression, and spondylolisthesis Bottom line: studies inconclusive for benefit of surgery, esp. fusion
  • 8. But then….
  • 9. Study Objective Analyze the relative efficacy of surgical vs. nonsurgical treatment for spinal stenosis without degenerative spondylolisthesis based on patient self reported pain, function, and disability scales
  • 10. Methods  13 US medical centers  Included:  patients with neurogenic claudication or radicular leg sx >12 weeks  confirmatory imaging  Previous PT (68%), epidural injections (56%), NSAIDS or opioids OK  Excluded:  Spondylolisthesis  Lumbar instability
  • 11. Methods: Interventions Non-surgical Therapy: “usual care” but not standardized  PT  Home exercise instruction  NSAIDS Surgery: posterior decompressive laminectomy  A small amount also received instrumented or noninstrumented fusion (5%)
  • 12. Methods: Outcome Measures  Primary  Bodily pain and physical function scores on SF-36 Survey and modified Oswestry Disability Index  Secondary  Pt-reported improvement satisfaction with sx and care  Bothersomeness of stenosis and back pain via several standardized scales  F/U at 6w, 3m, 6m, 1yr, and 2yrs  Treatment Effect = (mean in score SURG) - (mean in score NON-SURG)
  • 13. Methods: Two Cohorts Randomized Cohort  289 patients enrolled  138 assigned to surgery arm  151 assigned to nonsurgical treatment Observational Cohort  365 patients enrolled  219 chose surgery  146 chose nonsurgical treatment
  • 14. BUT, patients don’t always…… BEHAVE !
  • 15. Methods: Unintended Crossover Randomized Cohort  138 assigned to surgery --> only 67% had surg by 2yrs  151 assigned to NON-surg tx --> 43% had surg by 2yrs Observational Cohort  219 chose surgery--> 96% had undergone surg by 2yrs  146 chose NON-surg tx --> 22% had surg by 2yrs
  • 16. Methods: Statistical Analysis Almost like 3 studies: Randomized, Observational, and Combined Demographics/Baseline data: Rand vs Obs cohorts, Surg vs Nonsurg Intention-to-Treat: analyzed randomized cohort  Needed 185/group to detect a 10-point difference in 100-point scale  Time: from enrollment
  • 17. Methods: Statistical Analysis As-Treated Analysis:  Time  Surgery: time starts at date of treatment  Nonsurgical: changes from baseline (even if eventually chose Surg) included here  Randomized and Observational Cohorts analyzed separately and combined  Predictors of Treatment Received in Randomized Cohort
  • 18. Results: Patients At Baseline  Rand Cohort vs Obs Cohort  All very similar demographically, sx severity, and level of stenosis  Observational Cohort: More nerve-root tension and less lateral recess stenosis  Randomized Cohort: Two Randomized Groups (Surg vs Nonsurg)  All categories very similar  Combined Cohorts: Surg vs Nonsurg  Surg: younger, more working, more reported disability, more with “pain worsening”, more severe stenosis
  • 19. Results: Treatment Received Nonsurgical Treatment:  Similar, but more in Rand vs Obs Cohort visited surgeon and got injections Surgery:  Looked at # levels decompressed, OR time, blood loss, post-op mortality, complications  Complications: dural tear (9%), wound infection (2%), transfusion (7%)  Reoperation by 2yrs in 8% (<1/2 for stenosis)  6 Deaths (vs. 7 in Nonsurg group)
  • 20. Results: Treatment Effects Intention to Treat (Randomized Cohort):  Lost power from crossover  Only statistical significance: more change in surgery group (8 points) in bodily pain score at 2yrs  No statistically significant change in Surg vs Nonsurg groups: physical function or disability index  At early times (6w, 3mo) physical function treatment effect went down
  • 21. Results: Treatment Effects As-Treated Analysis  Rand vs Obs Cohorts:  Change in scores from baseline were statistically similar in the two groups  Global Hypothesis Test  Rand vs Obs Cohorts: Surg vs Nonsurg  Favored surgery in 3 main primary outcomes in both groups over all time periods  Statistically Similar-->Combined Cohorts
  • 22. Results: Treatment Effects As-Treated Analysis  Combined Cohorts: Surg vs Nonsurg  Peak change from baseline was 6months  Bodily Pain: treatment effect of surgery was 17-point difference at 6mo, 14-points at 2yr  Physical Function: 16 points at 6mo, 11 points at 2yr  Disability Index: 14 points at 6mo, 11 points at 2yr  Secondary Outcomes: pt-reported “satisfied with symptoms” and “major improvement”  Improvement from baseline in Nonsurg group too
  • 23. Surg Nonsurg Treatment Effect
  • 24. Study Strengths Randomized and Observational Cohorts were statistically similar at baseline  Allowed for data to be combined to study both cohorts together  As-treated analysis adjusted for many confounding variables The reality of patient choice about surgery Only looked at Spinal Stenosis (not Spondylolisthesis or other disc disease)
  • 25. Study Limitations  Randomization  Surgery vs Nonsurgical Treatment: never blind  Self-reported symptoms (less after 6mo?)  Unintended Crossover  Limited intention-to-treat analysis  Combining Cohorts: eliminating benefit of randomization  Those who ultimately chose surgery were different at baseline  No standard of nonsurgical treatment
  • 26. Bottom Line Little risk of harm in surg vs nonsurg tx Both surg and nonsurg tx improved symptom scores There is improvement in patient-perceived pain, function, disability, and satisfaction* (*although, these patients were worse off from the start) Advice to patients: still try noninvasive tx first, but may be helped by surgery
  • 27. Discussion? Questions? How can you set up a study to prevent confounding but recognize patient choice?
  • 28. References **Weinstein, JN et al. Surgical versus Nonsurgical Therapy for Lumbar Spinal Stenosis. N Engl J Med 2008;358:794- 810** Gibson, JN, Waddell, G. Surgery for degenerative lumbar spondylosis. Cochrane Database Syst Rev 2005: CD001352