Friday, January 11, 2013
The Latest Evidence Based Recommendations for Spine Surgery
The Spine Evidence Based Medicine (EBM) Editorial Group published their sixth biannual review of recent spine surgery literature in an effort to give the spine community evidence based recommendations for practice. This group has done an exemplary job producing these reviews, and this most recent installment reviews important studies on the topics of ischemic optic neuropathy (ION), the use of local bone graft for one level fusions, the effect of duration of symptoms on outcomes for lumbar disc herniation, nonfusion surgery for thoracolumbar fractures, and post-operative radiographic predictors of outcomes for cervical myelopathy. The most important paper is a review of the American Society of Anesthesiologists’ postoperative visual loss database that identified 80 spine surgery patients who developed ION. The authors then identified 320 control patients and performed a case-control study that identified a number of risk factors for ION, including male gender, obesity, diabetes, use of the Wilson frame, duration of anesthesia, prolonged intraoperative hypotension, and multiple variables associated with high intraoperative blood loss. This valuable study could potentially affect practice by encouraging surgeons to avoid the Wilson frame unless absolutely indicated and cause anesthesiologists to be more mindful of their management of hypotension. Another important study used an RCT design to compare local bone grafting to local bone plus iliac crest bone grafting for one level instrumented fusion for degenerative spondylolisthesis. Similar to other trials on this topic, the authors showed no significant differences in fusion rates or clinical outcome scores. They did report persistent sensory changes or pain in a substantial minority of patients who had iliac crest bone graft harvested. Unfortunately, they obtained the bone graft through a separate incision, so patient blinding was not possible, which could have influenced the rate of these subjective outcomes. The group made a weak recommendation to adopt local bone grafting for one level fusion for degenerative spondylolisthesis based on this and other similar trials. The only other paper that resulted in a recommendation to impact clinical practice was the SPORT subgroup analysis that found worse surgical and nonoperative outcomes in disk herniation patients with a duration of symptoms greater than six months, though these subgroups were markedly different, and it is possible that unmeasured confounders were driving the differences in outcomes rather than duration of symptoms. Nonetheless, it does provide information we can offer patients who are considering the timing of discectomy. Unfortunately, methodological limitations precluded any recommendations for clinical practice based on the studies of postoperative radiographic predictors of outcomes in cervical myelopathy or nonfusion surgery in thoracolumbar fractures.
These biannual EBM reviews continue to be very valuable resources for the practicing spine surgeon. They provide a summary of important literature from a variety of sources—some of which are likely not on the reading list of most spine surgeons—and provide clear suggestions about how this literature should affect practice. Additionally, their findings inform the spine community about the quality of the current scientific literature and typically serve as a reminder of the need for high quality studies to address many of the clinical questions we face daily. It is surprising that in a six month period only one study was identified that resulted in a strong recommendation to change clinical practice, two studies led to a weak recommendations for change, and two studies were so limited that no change in practice could be recommended. While this review is not a comprehensive evaluation of every paper published over a six month period, the authors do strive to identify all high impact papers that could affect clinical practice in a meaningful way. It is somewhat disheartening that only three such papers could be identified. It is easy to become highly critical of the literature and give up the effort to produce high quality studies that impact practice. Hopefully these reviews will have the opposite effect and inspire the spine community to make the effort to undertake the difficult studies to answer important questions that could affect what we do on a daily basis and improve patient outcomes.
Please read the latest installment of “Evidence-Based Recommendations for Spine Surgery” in the January 1 issue and the accompanying commentaries. Will any of these studies affect how you practice? Let us know by leaving a comment on The Spine Blog.
Adam Pearson, MD, MS
Associate Web Editor