The Spine Blog

Friday, May 18, 2018

Type II odontoid fractures are common in the sick, elderly population, and they present a challenge to spine surgeons treating them. Multiple studies have shown high mortality rates following this injury with both surgical and non-operative treatment, with some suggesting a lower mortality associated with surgical fixation.1-3 No RCT has been performed on this topic, and it is possible that the lower mortality associated with surgery is due to selection bias. In an effort to reduce the invasiveness of C1-C2 fixation, Dr. Alhashash and colleagues in Germany developed a percutaneous transarticular fixation technique. They placed 3.5 mm transarticular screws through a percutaneous guide using biplanar fluoroscopy to assess screw location. They reported a case series of twenty elderly (average age 81) patients with multiple comorbidities (all ASA III or IV) treated with this technique. Three patients died within 3 months of surgery, with the other 17 surviving for at least one year. The fracture united in 88% of patients, with the 2 nonunion patients remaining asymptomatic. There were no infections or reoperations. The average operative time was under one hour, and average blood loss was about 40 mL.

The authors have done a nice job reporting their percutaneous technique to stabilize odontoid fractures in the elderly. This remains a controversial topic, with substantial literature support for surgical treatment. However, the vast majority of these fractures are currently treated non-operatively, with surgeons anecdotally experiencing reasonably good results with non-operative care. The current article can be viewed as a technique paper describing a novel way to stabilize these fractures. It would have been helpful if the authors reported more data about the fracture characteristics in terms of displacement, angulation, and comminution. Markedly displaced fractures can be difficult to reduce in a closed fashion, and near-anatomic reduction is necessary for this technique to be successful. They also did not report how many patients had anatomy that precluded this technique, such as an aberrant location of the vertebral arteries. Transarticular screw placement can be difficult even using an open technique, so the surgeons involved must have been technically skilled to have performed this percutaneously without any technical complications. It seems as though this is an operation that could be made easier using navigation or robotic techniques, and I’m sure more papers documenting these techniques will be forthcoming. The major question that remains is whether stabilizing these fractures decreases mortality or improves outcomes. While the observational literature suggests that this is true, a high quality RCT is necessary to prove the point.

Please read Dr. Alhashash’s paper in the June 1 issue. Is this a technique you would consider adopting? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

REFERENCES

1.            Chapman J, Smith JS, Kopjar B, et al. The AOSpine North America Geriatric Odontoid Fracture Mortality Study: a retrospective review of mortality outcomes for operative versus nonoperative treatment of 322 patients with long-term follow-up. Spine (Phila Pa 1976) 2013;38:1098-104.

2.            Pearson AM, Martin BI, Lindsey M, Mirza SK. C2 Vertebral Fractures in the Medicare Population: Incidence, Outcomes, and Costs. J Bone Joint Surg Am 2016;98:449-56.

3.            Schoenfeld AJ, Bono CM, Reichmann WM, et al. Type II Odontoid Fractures of the Cervical Spine: Do Treatment Type and Medical Comorbidities Affect Mortality in Elderly Patients? Spine (Phila Pa 1976) 2011;36:879-85.

 

Friday, May 11, 2018

Patient reported outcomes (PROs) have become widely adopted to study most medical conditions, and the spine community has been at the forefront of this effort. The Oswestry Disability Index (ODI) has been one of the most widely used spine-specific instruments since its publication in 1980. It was initially designed to evaluate patients with non-specific low back pain but has been widely adopted to study most degenerative lumbar conditions. Its suitability for conditions such as spinal stenosis has been questioned, and other measures have been designed to specifically evaluate the stenosis population (i.e. Zurich claudication questionnaire). In an effort to better understand the role of the ODI in the degenerative spondylolisthesis (DS) population, Dr. Murphy and colleagues analyzed baseline and follow-up ODI and SF-12 Physical Component Score in 154 DS patients undergoing fusion. Overall, they found a 25 point improvement in ODI and 10 point improvement in PCS, similar to prior studies in this population. The ODI items related to standing, social life, sex life, pain intensity, traveling, and walking improved the most, while items related to personal care, sleeping, sitting, and lifting improved the least. The strongest correlation between change scores on individual ODI items and the PCS score was for standing, traveling, and walking. In their multivariate regression analysis, the authors found that changes in lifting, standing, and traveling were independent predictors of change in PCS score. They found that their model including these three items was a stronger predictor of PCS change score than the overall ODI score. Based on this, they recommended that future DS studies consider using only individual ODI items rather than the composite score.

They authors have done a thorough analysis looking at how the individual ODI items change in a DS surgery population. However, their conclusion that the overall ODI should be abandoned in this population and replaced with a modified version with fewer questions oversteps the data presented. The major limitation in this study is the use of the SF-12 PCS as the “gold-standard” to which the ODI is compared. The PCS includes just 5 questions asking about moderate activities, climbing stairs, accomplishing less than one would like, activity limitation, and how much pain interferes with work. There is no reason to think that the PCS should be viewed as a gold-standard outcome measure in the DS population. Surgeons who treat DS and stenosis patients know that their major concerns are related to standing and walking limitations due to leg and back pain. Neither the ODI or SF-12 PCS is focused primarily on these problems. The ODI asks one question about standing and one about walking, answers to which were tightly correlated in the current study. Traveling and social life are secondary measures of standing and walking as these activities tend to be limited by neurogenic claudication. There is also one question about pain intensity, which seems appropriate to this population. The items on personal care, lifting, sitting, sleeping, and sex life seem less relevant to DS, and, other than sex life, tended to improve less than the other items. The SF-12 PCS does not ask any questions specific to standing and walking, and the question about work tends to be irrelevant to many DS patients who are retired. I would suggest that neither the ODI nor the SF-12 PCS score is the ideal outcome measure for DS. Many DS and stenosis patients have relatively low ODI scores as they only score high on the walking and standing items. However, the ODI has been used extensively in spine research, and abandoning it will make comparison to prior literature quite difficult. The authors suggested that some payors use an ODI threshold to determine if an individual DS patient meets indications for surgery, and this is clearly not appropriate.

Please read Dr. Murphy’s article on this topic in the June 1 issue. Does this change how you view the use of the ODI to study DS patients? Let us know by leaving a comment on The Spine Blog.


Adam Pearson, MD, MS

Associate Web Editor

Friday, May 4, 2018

Patients with degenerative spondylolisthesis (DS) frequently ask about the likelihood of progression with non-operative treatment. High quality, long-term data to answer this question in terms of patient reported and radiographic outcomes is very limited. In order to fill this void in the literature, Dr. Cushnie and colleagues from Canada performed a prospective cohort study in which they enrolled 160 DS patients who were initially treated non-operatively. About 25% of these patients underwent surgery at an average of two years into the study, and another 53 were lost to follow-up. This yielded 66 patients with at least 5 years of both radiographic and clinical follow-up. Of these patients with long-term follow-up, about 1/3 had radiographic progression of their slip by at least 5% and were categorized as the slip progression group. At baseline, those with slip progression had a greater proportion of males (42% vs. 28%) and were about 4 years younger at enrollment (63 years vs. 67 years). Neither of these differences were statistically significant. Both groups had modest improvement in SF-12 physical component score (PCS), Oswestry Disability Index (ODI), and leg pain. In the no progression group, back pain (10 point numeric rating scale) improved by 1.6 points, while the progression group only had a 0.2 point improvement. This difference was not significant. The authors concluded that patient reported outcomes improved modestly and to a similar degree in both cohorts.

The authors have done a nice job capturing the natural history of DS with both radiographic and patient reported outcomes. Like most lumbar conditions, this study found little correlation between radiographic findings in DS and symptoms. In general, slip progression did not portend a worse outcome. The authors hypothesized that the no progression group tended to have more advanced disease as baseline, and this is supported by the younger age and somewhat less severe baseline symptoms in the progression group. Clinical experience indicates that DS tends to progress to a stable state over time, at which point the disk space is collapsed and the facet joints are hypertrophied. Once this state is reached, no more progression occurs. It would have been nice if other radiographic findings like disk height and Pfirrmann grade were reported as this could help to evaluate the hypothesis that more degenerative levels tend to be stable and not progress. The study also makes it clear that improvement with nonoperative treatment is modest (i.e. about 7 points on the ODI, similar to the 8 point improvement seen in the 8 year SPORT nonoperative cohort1), and many patients who initially choose nonoperative treatment move ahead with surgery over time (25% in this study and over 40% in SPORT). This study should provide important information to patients considering treatment for DS—namely that improvement with nonoperative treatment is modest at best, though significant radiographic or clinical worsening is unlikely. As such, current symptoms rather than concern about future progression should be the driver of treatment decision making.

Please read Dr. Cushnie’s article on this topic in the May 15 issue. Does this change how you view the natural history of DS? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

REFERENCE

1.            Abdu WA, Sacks OA, Tosteson ANA, et al. Long-Term Results of Surgery Compared with Nonoperative Treatment for Lumbar Degenerative Spondylolisthesis in the Spine Patient Outcomes Research Trial (SPORT). Spine (Phila Pa 1976) 2018.

 

Saturday, April 28, 2018

The Center for Medicare and Medicaid Services (CMS) has proposed bundled payments for care episodes for common surgical procedures like total joint replacement and lumbar spinal fusion. The goal of the bundle is to shift financial risk away from CMS onto the hospital as a way to incentivize safer and more efficient care. In theory, hospitals and providers will be financially motivated to avoid costly complications, readmissions, and reoperations as paying for these events will come directly out of their reimbursement rather than being passed along to CMS. Concerns with bundled payments are related to unintended incentives that may encourage hospitals to cherry-pick the healthiest, least complex patients, game the system to make patients appear sicker than they really are, or delay care such that it occurs outside the bundled payment window. Adoption of bundled payments has occurred slowly in spine surgery, and data are just becoming available to assess its effects. Dr. Martin and colleagues provide an early glimpse into the effects of bundled payments for lumbar fusion with their article that compares fusion volumes, costs, readmission rates, and reoperation rates between hospitals participating or not participating in a bundled payment program. They compare Medicare data from 2012 (before adoption of the program) to that from 2013 (after hospitals joined the program). While hospitals enrolled in the program by January 1, 2013, they did not actually receive bundled payments until late 2013, so the data reflects the run up period to when the bundled payments began. Over 2/3 of hospitals were non-participants, 33% were in the “preparatory” program, and 5% were in the “risk-bearing” program. The risk-bearing hospitals tended to be the largest and performed the most fusions. Patient and surgical characteristics were similar across the hospital groups. From 2012 to 2013, the number of fusions performed at the non-participant hospitals decreased by 1.6%, while it increased by 3.4% at the risk-bearing hospitals. The 90-day episode of care costs were highest for the risk bearing hospitals in both 2012 and 2013, and these hospitals had the smallest decrease in costs from 2012 to 2013 (-0.4% vs. -2.9% for the nonparticipant hospitals). While the 90 day readmission rates dropped at the nonparticipant and preparatory hospitals, the readmission rate increased by 2.7% at the risk-bearing hospitals. The reoperation rate also increased significantly more at the risk-bearing hospitals (1.1%) compared to the nonparticipant hospitals (0.3%)

This study provides one of the first looks into the effect of participation in a lumbar fusion bundled payment program on outcomes such as surgical volumes, cost, readmission, and reoperation. Prior to drawing any strong conclusions, one needs to consider that these are the earliest of data that reflect conditions during the run-up to the bundled payment program rather than outcomes after the bundled payments actually began. While hospitals might have tried to adapt to the new payment model during this time frame in anticipation of the change in reimbursement, we will have to wait until later data is available from after the actual start of the bundled payments. Additionally, hospital systems will likely change care patterns after they gain experience with the bundle, so it will take time to observe the long-term effect of bundling. Nonetheless, the data presented suggest that participation in a bundled payment does not lead to safer and more efficient care in the short term. The hospitals that participated in the bundled payment program tended to be larger and busier, and it is unclear if anticipation of bundled payment had anything to do with the increase in costs, volumes, reoperations, and readmissions. It is possible that these findings are a reflection of consolidation of spine surgery at larger volume hospitals that was occurring independent of the bundled payment program. It would have been interesting to have length of stay (LOS) data to see if the increased readmission rate was related to shorter LOS driven by the bundled payment program. Please read Dr. Martin’s article on this topic in the May 15 issue. Does this change how you view the role of bundled payments for lumbar fusion? Let us know by leaving a comment on The Spine Blog.


Adam Pearson, MD, MS

Associate Web Editor

Sunday, April 22, 2018

Despite promising results in FDA studies, spine surgeons have been somewhat slow to adopt cervical disc replacement (CDR). This may in part be due to difficulty in obtaining insurance company approval for the procedure. As we gradually transition to a healthcare system focused more on quality than quantify, demonstrating the value of a procedure is going to be important in justifying its use to payors. In order to better assess the value of two level CDR, Dr. Merrill and colleagues used the 7 year data from the Medtronic Prestige two level CDR IDE trial to perform a cost-effectiveness analysis (CEA) comparing CDR to ACDF. They converted the SF-6D scores from the trial to the utility values used in CEA. Event probabilities (i.e. complications, re-operation at index or adjacent level) were also based on the trial data. Costs were calculated from average Medicare reimbursement for DRG and CPT codes associated with the two procedures, which were multiplied by 140% to reflect the higher costs to private payors. They determined that CDR resulted in a gain of 0.21 quality adjusted life years (QALYs) compared to ACDF and cost approximately an additional $18,000. This yields an incremental cost-effectiveness ratio (ICER) of about $89,000/QALY, above their willingness to pay threshold of $50,000/QALY. In their Monte Carlo simulation analysis, they found that the ICER would fall below $50,000/QALY approximately 46% of the time. Based on these results, they concluded that 2 level ACDF and CDR likely had similar cost-effectiveness.

Cost-effectiveness analysis is highly dependent on the details of the model developed by the investigators. The model used in the current study seems reasonable, though the differences in utility values are quite small. In fact, if the authors had taken into account that the ACDF group had a baseline utility 0.02 less than the CDR group, the overall utility gain advantage for CDR over 7 years would have been only about 0.07 QALYs. If this value had been used, the ICER for CDR would have been over $250,000/QALY, well above any accepted willingness to pay threshold. This quick back of the envelope calculation demonstrates how sensitive CEA is to the details of the model, especially when utility gains are small. Another issue with the IDE trials looking at CDR is the relatively high rate of index level reoperation in the ACDF groups, presumably for pseudarthrosis in most cases. Studies looking at the index level reoperation rate following ACDF in actual clinical practice have revealed a much lower reoperation rate than that reported in the IDE studies, indicating that the surgeons participating in the IDE trials may have been more aggressive in reoperating for pseudarthrosis than the average practicing spine surgeon.1 If the index level reoperation rate for ACDF was substantially lower—as it likely is in the “real world”—then CDR becomes a less cost-effective option. In the final analysis, this paper supports the conclusion that ACDF and CDR tend to have similar outcomes. While CDR may eliminate pseudarthrosis as a complication, it is rarely a problem that leads to reoperation in one or two level ACDF. CDR may offer the advantage of eliminating pseudarthrosis as a complication, but it may carry the risk of long-term mechanical failure that is not currently well-understood.

Please read Dr. Merrill’s article on this topic in the May 1 issue. Does this change how you view the cost-effectiveness of two level CDR? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

 

REFERENCE

1.            Singh K, Phillips FM, Park DK, Pelton MA, An HS, Goldberg EJ. Factors affecting reoperations after anterior cervical discectomy and fusion within and outside of a Federal Drug Administration investigational device exemption cervical disc replacement trial. Spine J 2012;12:372-8.