Lumbar surgery is effective 12 months after in all but 13.8% of patients—a statistic obtained, along with predictors of poor outcome, from the National Neurosurgery Quality and Outcomes Database (N2QOD), a two-year-old, nationwide, prospective, longitudinal outcomes registry that spans 43 sites.

For this study, N2QOD provided data on 12-month surgical outcomes for patients with lumbar disk herniation (n=376) and spondylolisthesis (n=247). In all patient-reported outcomes (back pain, leg pain, Oswestry Disability Index [ODI] and EQ-5D), there was aggregate improvement at three and 12 months (P<0.05). For patients who did not exhibit ODI improvement, significant predictors of worse or unchanged ODI were found at 12 months in both groups: educational level, liability claim and baseline ODI. In addition, unique predictors found for disk herniation were age, duration of symptoms and depression, and for spondylolisthesis were gender, smoking and diabetes.

“I think a lot of these predictors are consistent with factors [that] most spine surgeons would anecdotally say are likely to predict outcomes,” lead author Anthony L. Asher, MD, told Pain Medicine News.

John Ratliff, MD, who was not involved in the study, agreed, adding, “These are predictors that reflect clinical practice.”

“I think the overall endeavor here is extremely important,” said Dr. Ratliff, who is associate professor and vice chair of operations, Department of Neurosurgery, Stanford University, Stanford, Calif. “The whole concept of neurosurgeons capturing outcome metrics on their patients, following their patients using a very thorough battery of outcomes assessments, and then demonstrating in this study that they’re able to capture a high percentage of follow-up patients out in practicing neurosurgical clinics—this is extremely, extremely important. What we learn here is going to directly benefit the care we provide to patients in the future.”

Dr. Asher, who is director of N2QOD as well as co-medical director of the Neuroscience Institute, Carolinas HealthCare System, Charlotte, N.C., presented the study at the 2014 annual scientific meeting of the American Association of Neurological Surgeons (AANS), in San Francisco. “In contrast to traditional studies such as randomized clinical trials,” he said, “this registry is not time-limited; it’s not restricted just to academic or high-volume centers; and it’s not encumbered by layers of inclusion/exclusion criteria. It’s really intended to evaluate the outcomes of surgery in real-world settings, specifically for the purposes of improving the quality of care. It is, first and foremost, a quality improvement device.”

Dr. Asher added, “What is remarkable, in this particular analysis, is that we’ve observed tremendous variability in the magnitude of treatment response at the individual patient level. And our analysis of that variability—specifically, the determination of the factors that strongly influence outcomes—represents the greatest potential of this registry to advance care. That’s because understanding variability in treatment response will ultimately allow us to estimate the likelihood of patient-specific outcomes with spine surgery. That capability will open a wide new realm of possibility in personalized care.”

According to Dr. Asher, approximately 25% of patients were lost to follow-up. “Of course, data on the significant majority—75%—were captured. If we look at the largest international studies, this data collection rate compares favorably. All in all, given the challenges inherent in collecting longitudinal data, we’re doing pretty well.”

Future plans described by Dr. Asher include iteratively improving the registry, examining outcomes of patients who were evaluated for but were not offered surgery , and working with other disciplines involved in spine care to “get us to a true comparative effectiveness model.”

—George Ochoa

Drs. Asher and Ratliff reported no relevant financial conflicts of interest.