Medical Discussions

The Spine Patient Outcomes Research Trial (SPORT) Observational Cohort.(JAMA, November 22/29, 2006) 

Posted by Dr. David Weir 

Background:-Lumbar discectomy is the most common surgical intervention for sciatic-like pain in the United States.  -The effectiveness of surgery vs. nonoperative treatment of back and leg symptoms remains controversial.

Methods:

-Prospective observational study.  Patients were evaluated at 6 weeks, 3 months, 6 months, 1 year, and 2 years of follow-up.

-Inclusion criteria- 18 years or older with intervertebral disk herniation and persistent symptoms despite some nonoperative treatment for at least 6 weeks.  Radicular pain, positive straight leg test, corresponding neurologic deficit with disk herniation on CT or MRI that corresponded to clinical symptoms.

-Exclusion criteria-  prior lumbar surgery, cauda equine syndrome, scoliosis greater than 15 degrees, segmental instability, vertebral fractures, spine infection or tumor, inflammatory spondyloarthropathy, pregnancy, unwillingness to have surgery within 6 months.

-Primary endpoints- Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) bodily pain and physical function scales and the AmericanAcademy of Orthopedic Surgeons version of the Oswestry Disability Index (ODI).

-Secondary endpoints- Self-reported improvement, work status, and satisfaction with current symptoms and care.-The study was powered to detect a 10-point difference in the SF-36 and a comparable difference in the ODI.  -743 patients enrolled, 521 chose surgery, 222 chose nonoperative care.  At 2 years 96%of the surgery arm underwent surgery and 22% of the nonoperative care group underwent surgery. Results:

-In the surgery group the adjusted change in the SF-36 score at 2 years was 42.6 for bodily pain and 43.9 for physical function.   The change in the ODI score at 2 years was -37.6.- In the nonoperative group the adjusted change in the SF-36 score at 2 years was 32.4 for bodily pain and 31.9 for physical function.  The change in the ODI score at 2 years was -24.2.-The difference between the two groups at two years (treatment effect) was 10.2 (95%CI, 5.9-14.5) for SF-36 bodily pain, 12.0 (95%CI 7.9-16.1) for SF-36 physical function, and -13.4 (95%CI -17.0 to -9.7) for ODI score.    (Higher SF-36 scores indicate less severe symptoms, a lower ODI score indicates less severe symptoms).

Discussion:Low back pain is one of the most common complaints patients have when visiting their doctor.  The SPORT trial investigators designed their trial with two cohorts, one randomized (data reported in a companion article in the same issue of JAMA) and one observational, as they anticipated a large number of cross-over in the randomization cohort.  The intention-to-treat analysis of the randomized cohort showed no difference between surgery and nonoperative treatment.  However, 40% of the patients randomized to surgery elected to not have surgery and 45% of the nonoperative arm elected to have surgery.  With such a high degree of cross-over in both arms the authors were unable to make a conclusion on the superiority of surgery or nonoperative treatment.  In the observational cohort there was a significant improvement in the surgery arm.  However, as pointed out in the editorial by Dr. Flum in the same issue, there have been multiple procedure-based observational studies that have shown improvement after surgery that subsequently failed to shown a benefit over a sham procedure.  This raises the question, how much of the surgical benefit was due to ‘procedural-placebo’ vs. the surgery alone?  Another problem with the observational cohort is the difference in base-line characteristics between the surgical and nonsurgical groups.  The patients electing to have surgery were younger, more likely to be disabled, more likely to be receiving compensation or have a claim pending, and reported worse pain and disability.Overall, both cohorts improved from baseline with surgery and nonsurgical interventions.  If we believe the results from the observational cohort, surgery results in a greater improvement in patient-reported symptoms than nonoperative management.  Given the flawed nature of the data in both the randomized and observational cohorts, it seems reasonable for patients with sciatica-like pain, confirmed by imaging, to begin with nonsurgical treatment including physical therapy, education, exercise and NSAIDS.  Patients that fail to improve with nonoperative management should consider surgery as discectomies have a low rate of complications and are frequently done as an outpatient surgery.