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 !