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Spinal Stenosis:Surgery or Not?
Suzannah Stout, MD
April 30, 2008
Lumbar Spinal Stenosis
Narrowing of Intraspinal CanalMost Common: DJD of spine or trauma
Disc protrusion Stress loading of posterior spine (facets) Hypertrophy of facets or ligamentum flavum Osteophyte formation
Later: Spondylolisthesis
Lumbar Spinal Stenosis
Lumbar Spinal Stenosis
Less Common Causes Space-occupying lesions Post-traumatic or -surgical fibrosis Skeletal Disease (Pagets, ankylosing
spondylitis, RA) Congenital (spina bifida, achondroplasia)
Common Sx
Low Back Pain (often mild)--65%Neurogenic Claudication--94%Numbness/tingling, weakness--40-60%Worst with standing or walkingRelieved with sitting or lying downThose with narrowing found incidentally on
imaging are often asymptomatic
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
2005 Cochrane Review
31 RCTs, often with small #sLack of long-term outcomes beyond 2-3
yrsMany trials were heterogeneous: spinal
stenosis, disc nerve compression, and spondylolisthesis
Bottom line: studies inconclusive for benefit of surgery, esp. fusion
But then….
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
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
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%)
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)
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
BUT, patients don’t always……
BEHAVE !
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
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
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
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
Results: Treatment Received
Nonsurgical Treatment: Similar, but more in Rand vs Obs Cohort visited
surgeon and got injectionsSurgery:
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)
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
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
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
Surg Nonsurg
Treatment Effect
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 variablesThe reality of patient choice about surgeryOnly looked at Spinal Stenosis (not
Spondylolisthesis or other disc disease)
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
Bottom Line
Little risk of harm in surg vs nonsurg txBoth surg and nonsurg tx improved
symptom scoresThere 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
Discussion? Questions?
How can you set up a study to prevent confounding but recognize patient choice?
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
THANKS FOR LISTENING !