Guest post from:
Zoher Ghogawala, MD; Chairman, Department of Neurosurgery, Lahey Hospital and Medical Center; Associate Professor of Neurosurgery, Tufts University School of Medicine, Burlington, MA (top left)
John Ratliff, MD; Co-Director, Division of Spine and Peripheral Nerve Surgery, Department of Neurosurgery Stanford University Medical Center, Stanford, CA (top right)
Praveen Mummaneni, MD; Co-director UCSF’s Spine Center; Vice-chairman, Department of Neurosurgery, University of California San Francisco Medical Center, San Francisco, CA (bottom left)
James Dziura, MPH, PhD; Associate Professor in the Department of Emergency Medicine at Yale School of Medicine; Deputy Director, Yale Center for Analytical Sciences, New Haven, CT (bottom right)
The aging of the U.S. population means there is exponential growth in patients suffering pain and disability from degenerative spine problems. One of these, symptomatic lumbar spinal stenosis, is the most common diagnoses for which lumbar spinal surgery is performed in the United States. While we understand the radiographic and clinical manifestations of this condition, there are many challenges in its management, which include:
- Radiographic features that do not necessarily correspond with actual clinical symptoms; and
- Natural history that waxes and wanes over time in many patients making it sometimes difficult to know when to recommend surgery.
The significant variation in the utilization of surgery for lumbar spinal stenosis, underscores the importance of developing a better evidence base to support the development of standardized treatment guidelines.1 The recently published randomized clinical trial (RCT) — “Surgery versus nonsurgical treatment of lumbar spinal stenosis: A randomized trial” by Delitto et al. (Ann Intern Med. 2015;162:465-473) — provides high quality data but misses the opportunity to clarify how these data are best interpreted. As a result, the conclusions are open to misrepresentation by multiple stakeholders.
The authors intended to address whether surgery versus six weeks of physical therapy would have different treatment effects using the validated SF-36 physical function outcome at a two-year endpoint. The major flaw in the trial is a 57 percent crossover from the physical therapy to the surgical arm, which precludes the ability to answer the original study question and limits the ability to draw meaningful conclusions from an intention to treat analysis. The authors used complex statistical tactics (complier average causal effect and inverse probability weighted analyses) to manage the confounding effects of this high crossover. This is a reasonable approach and the authors concluded that the treatment effects in both arms were not different. This is a misleading conclusion. Given expected non adherence in these situations, a much larger trial would be required to compare patients treated with nonsurgical care only to surgical care.2 The trial is effectively a surgery versus physical therapy with a possible delayed surgery trial. The distinction is important for patients, physicians, and payers.
Few would debate the role of additional conservative treatments for patients with stenosis who are surgical candidates. However, to state that surgery is equivalent to six weeks of physical therapy is simply an incorrect assessment of the data. The authors do not report an as treated analysis as the Spine Patient Outcomes Research Trial (SPORT) investigators did when they presented results of their RCT, which had crossovers of 43 percent from nonsurgical to surgical therapy and 33 percent from surgery to nonsurgical treatment. Using an as treated analysis, they demonstrated a significant benefit associated with surgery versus nonsurgical management.3
Looking at the 82 patients in the physical therapy arm of this trial, 56 (68 percent) ultimately underwent surgery and 13 were lost to follow-up or unable to participate, leaving only 13 patients with follow-up in this arm. Therefore, for accurate interpretation of these data, it would be imperative for spinal surgeons and patients alike to have access to the following information:
- Whether compliance with six weeks of physical therapy was associated with a reduction in the crossover rate;
- Baseline characteristics of the crossover patients; and
- An as treated analysis of the data.
This information may help surgeons determine when in the natural history of symptomatic lumbar stenosis to recommend surgical intervention or not. This trial does not, however, provide high level evidence on the comparative effectiveness of surgery versus physical therapy for lumbar spinal stenosis. It does point out that to elevate clinical practice, we need:
- To focus more clinical trial development on questions that can be answered; and
- Trials to be carefully designed, correctly analyzed, and reported.
References
1. Weinstein JN, Lurie JD, Olson PR, Bronner KK, Fisher ES. United States’ trends and regional variations in lumbar spine surgery: 1992-2003. Spine 2006; 31(23): 2707-14.
2. McCormick PC. The Spine Patient Outcomes Research Trial results for lumbar disc herniation: a critical review. Journal of neurosurgery Spine 2007; 6(6): 513-20.
3. Weinstein JN, Tosteson TD, Lurie JD, et al. Surgical versus nonsurgical therapy for lumbar spinal stenosis. The New England journal of medicine 2008; 358(8): 794-810.
