Evaluating the Evidence Behind the Surgical Treatment of Lumbar Stenosis

1. Evaluating the Evidence Behind the Surgical Treatment of Lumbar Stenosis Joseph Beshay, MD Assistant Professor of Neurological Surgery University of Texas Southwestern

2. Lumbar Stenosis • Narrowing of the Spinal canal with encroachment on the neural structures by surrounding bone or soft tissue. • Typical presentation: Radicular symptoms or neurogenic claudication. • Back pain common but not a result of lumbar stenosis per se. • May be asymptomatic • Most common reason for lumbar surgery in adults over 65 Deyo et al. Spine 1993

3. Lumbar Stenosis

4. Lumbar Stenosis • Treatment • Surgical: Laminectomy / laminotomy / foraminotomy/ Open vs MIS technique, Interspinous process device, Extension limiting device, Interspinous decompression, “chimney” laminectomy…… • Non-Surgical: Epidural steroids, Physical therapy, NSAIDS, Narcotic analgesics, spinal manipulation, back exercises…..

5. Lumbar Stenosis • In any given week I see at least one patient with ‘lumbar stenosis’ and at least one patient with ‘LOW BACK PAIN’ • Preconceived ideas……….

6. Lumbar Stenosis Thank you for seeing me today, Doctor If you can’t help me, I thank you anyways I won’t take up much of your time I baked you this pie… If you can help with my leg pains, I would be thankful

7. Back Pain

8. Back Pain Hey! Refill my Lortab Hey! Fix my back pain. Fill out this stack of disability forms I want to be able to go bowling again! Don’t you tell me to lose weight!

9. Lumbar StenosisThe Evidence • Treatment • Where is the data? • Paucity of head to head randomized trials • Many small non-randomized observational type studies. • Most randomized studies are small • Two large studies • Maine Lumbar Spine Study • SPORT (Spine patients outcomes research trial) lumbar stenosis arm.

10. Lumbar StenosisMain Lumbar Spine Study • Observational Study • Surgical vs Non-Surgical treatment determined by Surgeon and Patient • 148 patients enrolled between 1990-1992 • Excluded patients with prior lumbar surgery, cauda equina, fractures, infections, malignancies…etc. • Reported results at 1, 4 and 10 years Atlas et al. Spine 2005

11. Lumbar StenosisMain Lumbar Spine Study • 97 patients available for follow-up • Surgical group had more severe baseline symptoms and worse functional status • Leg pain relief and back related functional status favored surgery • Low back pain relief similar between both groups Atlas et al. Spine 2005

12. Lumbar StenosisMain Lumbar Spine Study Atlas et al. Spine 2005

13. Lumbar StenosisMain Lumbar Spine Study Atlas et al. Spine 2005

14. SPORT - Background • The Spine Patient Outcomes Research Trial (SPORT) was designed to assess the relative efficacy and cost-effectiveness of surgical and non-surgical approaches to the treatment of common conditions associated with low back and leg pain. • Three arms studying lumbar HNP, Stenosis and degenerative spondylolisthesis • 13 medical centers in 11 States • Randomized as well as observational cohorts Weinstein et al. NEJM 2008

15. SPORT – Lumbar Stenosis • Inclusion Criteria • Neurogenic claudication or radicular symptoms for at least 12 weeks • Cross sectional imaging confirming dx • Surgical Candidate • Exclusion Criteria • Spondylolisthesis (studied separately) • Instability (4mm translation or 10 degree angulation) • Most patients had received some form of non-surgical tx for their symptoms prior to enrollment (PT 68%, ESI 56%, Chiropractor 28%, NSAIDs 55%, Opioids 27%). Weinstein et al. NEJM 2008

16. SPORT – Lumbar Stenosis • After verifying eligibility, patients were allowed to enroll in the randomized or observational cohort. (Observational group avoids ‘enrollment bias’) • To aid in decision making, patients shown “evidence-based videotapes” with “standardized information” regarding surgical and non-surgical treatments. Weinstein et al. NEJM 2008

17. SPORT – Interventions • Surgical: “Standard posterior decompressive laminectomy.” • Non-Surgical: • “Usual care” • “….at least active physical therapy, education or counseling with home exercise instruction, and the administration of non-steroidal antiinflammatory drugs, if tolerated. Weinstein et al. NEJM 2008

18. SPORT – Outcome measures • Outcomes of bodily pain and disability • SF-36, Modified Oswestry Disability Index, other patient indices including overall satisfaction, pain, “Leg pain bothersomeness scale” • Follow-up at 6 weeks, 3 months, 6 months, 1 year and 2 years. • Effect of treatment was defined as the difference in the mean change from baseline between surgical and non-surgical groups. Weinstein et al. NEJM 2008

19. SPORT – Patients So far so good…..

20. SPORT – PatientsWhat really happened.. • Randomized Cohort • Surgical arm: At two years 67% had undergone surgery • Non-Surgical arm: At two years 43% of patients had crossed over and had surgery. • ~55% of the randomized patients had surgery. • ~40% of the randomized pt’s crossed over • Observational Cohort • Surgical arm: At two years 96% had undergone surgery • Non Surgical arm: 22% crossed over to surgery • ~66% of observational patients had surgery Weinstein et al. NEJM 2008

21. SPORT – PatientsWhat really happened.. • Bottom line: • Lots of crossover – the Achilles heal of studies comparing surgery to non-surgical tx. • Investigators maintained good follow-up • Interesting findings • Pt’s in observational cohort had more ‘signs of nerve root tension’ • Exhibited a stronger treatment preference • Group undergoing surgery tended to be younger, more likely to be working, had more pain and lower level of function. Also exhibited ‘more severe’ stenosis on imaging. Weinstein et al. NEJM 2008

22. SPORT – PatientsWhat really happened.. • Non surgical treatment • Similar between observational and randomized cohorts • More patients in the randomized group reported visits to a surgeon (45% vs 32%). Also more use of ‘injections’ (52% vs 39%) - ? An attempt to keep them in their randomized group? • More observational patients used ‘other’ medications such as gabapentin Weinstein et al. NEJM 2008

23. SPORT – PatientsWhat really happened.. • Surgical Treatment • Similar between both groups • Instrumentation in 6% of patients • 9% durotomy rate • 8% re-operation rate at 2 years with <50% for recurrent stenosis • No mortality directly attributable to surgery Weinstein et al. NEJM 2008

24. SPORT – PatientsWhat really happened.. • Crossover largely ‘predictable’ • Pts who crossed over to surgery had more severe symptoms and self-rated disability • Pts who crossed over to non-surgical tx had less bothersome sx’s and favored non-surgery at baseline. • Observational cohort very similar to randomized group though. Weinstein et al. NEJM 2008

25. SPORT How They Analyzed the Data • Randomized group: • Surgery vs no surgery with ‘intent to treat’ analysis • Surgery vs no surgery with ‘as treated’ analysis • Observation group: • Surgery vs no surgery • Looked at primary outcomes of bodily pain, physical function and mean ODI. • Secondary outcome data

26. SPORT What they found Randomized Group Weinstein et al. NEJM 2008 Weinstein et al. NEJM 2008

27. SPORT What they found Observational Group Weinstein et al. NEJM 2008

28. Weinstein et al. NEJM 2008

29. Statistical Analysis • In RCT’s not all patients adhere to protocol they were assigned to. • Non compliance • Crossover • Lost to follow-up / drop-out • This makes your data set imperfect and more difficult to analyze. • Per protocol analysis – Deviate from protocol and you’re out • Intent to treat analysis – As randomized, so analyzed • As treated analysis – Analyze based on tx not randomization

30. Statistical AnalysisOrigin of Randomization • R.A. Fisher in 1923 studied the effects of different fertilizers on potato yields. • Some fields (or even parts of a field) are more fertile than others though. • Decided to apply the fertilizer to small plots. • Randomly assign fertilizers to plots/rows. • Randomization destroys any connection between soil fertility and treatment.

31. Statistical AnalysisRandomization • Any difference between groups that arises after randomization should be due to consequences of the randomized treatment assignment • Adjusting the analysis of treatment effect by post-randomization group differences could introduce bias

32. Statistical AnalysisIntention to Treat Analysis • Includes all randomized patients in the groups to which they were randomly assigned, regardless of their adherence with the entry criteria, regardless of the treatment they actually received, and regardless of subsequent withdrawal from treatment or deviation from the protocol (Lloyd) Fisher et al., 1990

33. Statistical AnalysisIntention to Treat Analysis What happens when the crossover is great and there is, in fact, a difference between the two treatments?

34. Statistical AnalysisIntention to Treat Analysis LARD Laparoscopic AntroplastyvsRestricted Diet • 1000 patients • Inclusion criteria • Obese - BMI >40 • Surgical Candidate • Exclusion criteria • Prior surgical intervention • Psychiatric issues • Randomized to Bariatric surgery or diet only Beshay et al. Bogus Journal 2010

35. Statistical AnalysisIntention to Treat Analysis LARD Laparoscopic Antroplasty vs Restricted Diet • 1000 patients • 500 randomized to surgery • 500 randomized to diet • At the end of the study • 350 surgical patients underwent surgery • 250 diet patients underwent surgery Beshay et al. Bogus Journal 2010

36. Statistical AnalysisIntent to Treat Analysis LARD Laparoscopic Antroplasty vs Restricted Diet • In this study 60% of surgical patients experienced a significant drop in BMI while 30% of diet patients experienced a similar drop 1000 patients AT IT 500 patients 300 x 0.6 + 200 x 0.3= 240 240/500= 48% 500 patients 250 x 0.6 + 250 x 0.3 = 45% 550 pt’s 330 lost weight 60% 450 pt’s 135 lost weight 30% 500 randomized to surgery 200 patients 250 patients 500 randomized to diet Intent to treat analysis with large crossover favors the null hypothesis.

37. SPORT – Lumbar StenosisConclusions • Lumbar stenosis is common among elderly patients and is the number one cause of lumbar surgery in those older than 65. • When treating neurogenic claudication or radicular symptoms, patients will improve with operative or non-operative strategies • There is significantly more improvement with surgical intervention • Surgical intervention in this group of patients was safe • Beware of Intent to Treat Analysis in studies in which there was a large amount of crossover. • Don’t underestimate the value of observational groups.

38. Surgical Treatment of Lumbar Stenosis • ‘Standard’ open laminectomy/medial facetectomy/foraminotomy – unilateral or bilateral

39. Surgical Treatment of Lumbar Stenosis • Minimally invasive approach • Goal is to achieve same results with little muscle disruption • Utilize a tubular retractor • Incision off the midline • Muscle splitting technique

40. Surgical Treatment of Lumbar Stenosis • Minimally invasive approach

41. Surgical Treatment of Lumbar Stenosis • Minimally invasive approach

42. Surgical Treatment of Lumbar Stenosis • Minimally invasive approach

43. Surgical Treatment of Lumbar Stenosis

44. Surgical Treatment of Lumbar Stenosis

45. Surgical Treatment of Lumbar Stenosis Papavero et al. 2009

46. Surgical Treatment of Lumbar Stenosis Papavero et al. 2009

47. Surgical Treatment of Lumbar Stenosis • Are minimally invasive techniques better? • In experienced hands same results as open surgery • Less hospital stay – modest • Less post op narcotics • Less muscle disruption as assessed by CK and follow-up MRI • ? Less post op instability ? – Maybe..

48. Surgical Treatment of Lumbar Stenosis • What about interspinous process spacers?

49. Surgical Treatment of Lumbar Stenosis • What about interspinous process spacers?

50. Surgical Treatment of Lumbar Stenosis • What about interspinous process spacers? • Do they work? Yes, in selected patients. Kuchta et al. Eur Spine J 2009