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The Spine Blog

Friday, February 15, 2019

Do radiographic findings predict the need for fusion in degenerative spondylolisthesis?

Recent RCTs comparing decompression alone to decompression and fusion for degenerative spondylolisthesis (DS) reached somewhat contradictory conclusions, though these studies made it clear that not all DS patients need to be fused.1,2 However, it remains unclear who does need a fusion. Some studies have suggested that patients with a mobile listhesis, maintained disk height, and sagittally aligned facet joints are at increased risk for progression of listhesis following decompression without fusion, though no large study has confirmed this.3 In order to better understand if baseline radiographic findings can predict failure of decompression alone in DS, Dr. Schar and colleagues from Switzerland retrospectively reviewed a case series of 161 patients undergoing unilateral or bilateral laminotomy (midline sparing surgery) for spinal stenosis. Approximately one third of the patients had at least one level with a spondylolisthesis, and no patients underwent a fusion at the index procedure. Patients with greater than 3 mm of motion on flexion-extension radiographs were excluded. At a median four-year follow-up, 15% of patients had undergone reoperation, 72% of which were for recurrent stenosis and 28% of which were for adjacent segment stenosis. Of the 56 patients with listhesis, 18% underwent a revision surgery for recurrent stenosis. Only 4% of patients without listhesis underwent a reoperation for recurrent stenosis. Disk height and facet angle were not associated with risk of reoperation. The authors did not report patient reported outcomes (PROs).

This is a nice retrospective cohort study that demonstrated that the presence of a "stable," low-grade listhesis is a risk factor for reoperation following midline-sparing decompression. The study also failed to identify any radiographic risk factors for reoperation other than the presence of listhesis. The authors argue that an 18% reoperation rate at 4 years is acceptable and may be preferable to outcomes following fusion. However, this study lacks a fusion comparison group and really does not provide any information to guide the decision about whether or not to perform a fusion for a DS patient. The results do suggest that the reoperation rate using this technique in the absence of listhesis is very low. In order to answer the question about which DS patients benefit from fusion, a study needs to include a large number of DS patients treated decompression alone or decompression and fusion. Such a study would need to include baseline patient characteristics and radiographic studies, PROs, and reoperation rates. This would allow for subgroup analyses to be performed to compare outcomes between decompression alone and decompression and fusion for patients with different baseline characteristics and radiographic findings. More complex is determining the best decompression (i.e. midline laminectomy vs. midline-sparing laminotomy) or fusion (i.e. uninstrumented vs. instrumented vs. interbody) technique. These studies would need to include a much larger number of patients than have been assembled in prior studies in order for the subgroups to be large enough. Until such a study exists, surgeons will need to consider the available data and discuss the pros and cons of including a fusion when deciding on surgical technique with their patients. Given the technical difficulty, increased complication rate, and likely worse outcomes for a revision decompression as compared to a decompression and fusion for adjacent segment degeneration, it may make sense to fuse healthy patients who can tolerate the operation.

Please read Dr. Schar's article on this topic in the February 15 issue. Does this change your opinion about the need for fusion in DS? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

REFERENCES

1.            Forsth P, Olafsson G, Carlsson T, et al. A Randomized, Controlled Trial of Fusion Surgery for Lumbar Spinal Stenosis. The New England journal of medicine 2016;374:1413-23.

2.            Ghogawala Z, Dziura J, Butler WE, et al. Laminectomy plus Fusion versus Laminectomy Alone for Lumbar Spondylolisthesis. The New England journal of medicine 2016;374:1424-34.

3.            Blumenthal C, Curran J, Benzel EC, et al. Radiographic predictors of delayed instability following decompression without fusion for degenerative grade I lumbar spondylolisthesis. J Neurosurg Spine 2013;18:340-6.

 


Friday, February 8, 2019

Bundled payments for spinal fusion

In an effort to increase the value of surgery, the Centers for Medicare and Medicaid Services (CMS) created the Bundled Payments for Care Improvement (BPCI) program. This program has changed the traditional fee for service model to one in which hospitals and providers are paid a lump sum for the surgical care episode (generally defined from 3 days prior to surgery to 90 days after surgery) independent of the costs and events associated with the episode. The goal is to shift financial risk onto the hospitals and providers in order to motivate them to limit the cost of care while maintaining quality. This payment model has been shown to reduce the cost of care for total joint arthroplasty. In order to determine the effect of this payment model on costs and outcomes in spinal fusion, Dr. Bronson and colleagues from the Hospital for Joint Diseases in New York evaluated their experience with BPCI for non-cervical posterior spinal fusion for degenerative conditions from 2013-2014. They compared costs and outcomes for 350 patients enrolled in BPCI to a baseline cohort of 518 patients treated from 2009-2012. In both cohorts, approximately 94% of patients were classified in DRG 460 (posterior spinal fusion one to eight levels without major complication or comorbidity) with the remainder in DRB 459 (spinal fusion with major complication or comorbidity). The BPCI cohort was more likely to undergo a "complex" surgery, defined as a revision surgery, greater than 3 level fusion, or a procedure including an interbody fusion (i.e. TLIF or PLIF), as compared to the baseline group (45% vs. 23%). Most of this increase in case complexity was driven by increased use of interbody fusion (16% BPCI vs. 2% baseline). They found that the overall Medicare cost for episode was $52,655 in the BPCI cohort compared to $48,913 for the baseline cohort. They calculated that this resulted in a $1.3 million net loss for the BPCI group, despite a shorter length of stay, unchanged readmission rate, and lower rate of discharge to inpatient rehab or skilled nursing facility.

The authors have done a nice job auditing and reporting their experience with the BPCI for spinal fusion. It provides a cautionary tale to institutions considering enrollment in the program. The challenging part of interpreting this paper is that the costs are not itemized, making it impossible to determine what was driving the increased Medicare cost. They also did not perform a micro-cost analysis, so the hospital costs associated with performing the operation were not quantified. This makes it impossible to calculate the margin, which is ultimately what determines the financial viability of any surgical program. While they report a "loss" of $1.3 million, this is relative to what they would have received in Medicare payments outside of the BPCI program. If the institution made changes to reduce their costs associated with surgery (i.e. lower implant costs, lower length of stay, less imaging, lower rate of discharge to facilities, etc.), they may have actually increased their margin despite lower reimbursement by Medicare. Given that they reported increased case complexity including longer fusions and more interbody fusions, this is unlikely given that implant costs likely rose. The authors are correct in stating that a single reimbursement rate for any posterior fusion from one to eight levels regardless of revision status or use of interbody instrumentation is inappropriate. As can be seen from the high standard deviations around the Medicare costs (over 50% of the mean), this is a highly heterogeneous group. The actual hospital costs are likely much more variable given that the Medicare cost is not affected by length of stay or cost of instrumentation and includes a single payment for the inpatient stay based on the DRG. Under the current BPCI model, hospital systems are incentivized to perform the simplest, lowest cost procedure covered by the DRG on the healthiest patients they can find. This could result in the most vulnerable patients with significant comorbidities and complex spine pathology losing access to care. Hopefully this is not the goal of CMS, and future iterations of this program should do a better job of taking case complexity into account.

Please read Dr. Bronson's article on this topic in the February 15 issue. Does this change how you view the role of bundled payments in spine surgery? Let us know by leaving a comment on The Spine Blog.


Friday, February 1, 2019

Do orthopaedic spine surgeons have more complications than neurosurgeons?

​At most institutions performing spine surgery, there is a friendly rivalry between orthopaedic spine surgeons and neurosurgeons about which service has better outcomes. In an attempt to answer this provocative question, Daniel Snyder and colleagues from New York evaluated both their institutional data and the NSQIP database looking at in-hospital complications following posterior cervical decompression and fusion (PCDF). They identified over 1,200 patients at their institution who underwent PCDF from 2006-2016 and over 11,000 PCDF patients in the NSQIP database from 2007-2015. About 56% of the patients at their institution were treated by a neurosurgeon compared to 78% in the national database. The cohorts were similar in baseline characteristics including age, gender, and ASA score (though some clinically insignificant but statistically significant differences did exist). In both the institutional and NSQIP cohorts, there was a high transfusion rate for orthopaedic surgeons (14.5% vs. 9.1% institutional and 11.2% vs. 6.2% NSQIP). When all in-hospital complications including transfusion were evaluated, there was no significant difference in the institutional data (19.5% ortho vs. 22.1% neuro), but the orthopaedic surgeon group had a higher overall rate of complications in the NSQIP database (18.1% vs. 14.0%). When controlling for age, gender, and ASA score, multivariate analysis revealed that orthopaedic surgeons had a 66% increased odds of any complication compared to neurosurgeons in the NSQIP database. The authors did not perform an analysis looking at overall complication rates excluding transfusion, though a quick calculation based on their tables yielded a 5.0% rate for orthopaedists and a 13.0% rate for neurosurgeons in their institutional data base and a 6.9% rate for orthopaedists and a 7.8% rate for neurosurgeons in the NSQIP database.

While the authors pose an interesting question, the limitations of their databases and methodology make it very difficult to draw any meaningful conclusions. Patients treated by orthopaedic spine surgeons had higher transfusion rates in both cohorts, though it is unclear if this was related to variation in intra-operative blood loss, differences in magnitude of surgery, or different thresholds for transfusion. The authors inability to control for magnitude of surgery is a major potential confounder, as it is possible that orthopaedic spine surgeons tended to include more levels in their fusions which would have increased both transfusion rates and overall complication rates. The authors also should have performed an analysis of overall complications excluding transfusion as this is generally a far less serious complication compared to others they evaluated (i.e. airway complications, MI, PE, sepsis, wound infection, and death). The most significant limitation of the paper is that the outcomes evaluated are of secondary importance compared to outcomes and complications that occur after discharge from the hospital. They did not look at rates of repeat surgery, surgical site infection diagnosed after discharge (by far more common than infection diagnosed during the index hospitalization), hardware complications, post-operative neurological deficits, pseudarthrosis, or patient reported outcomes, all of which are more relevant outcomes than transfusion rate or rates of rare inpatient complications. Other than a pneumonia rate of 4.25% for neurosurgeons in the institutional cohort, all other specific complication rates were under 2.5%. The authors also did not control for diagnosis (i.e. radiculopathy vs. myelopathy), and it is well-established that myelopathy patients have higher complication rates. As an orthopaedic spine surgeon I might be accused of being defensive, but I do not think any conclusions can be drawn from this study other than that orthopaedic spine surgeons had an overall higher transfusion rate for reasons that remain unknown. On a positive note, the authors did suggest that collaboration between orthopaedic spine surgeons and neurosurgeons might improve outcomes, and everyone would agree that a healthy relationship between the two services would be helpful to patients, providers, and their entire institution.

Please read this article in the February 1 issue. Does this change how you view the association between spine surgeon specialty and outcomes? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Wed Editor


Friday, January 25, 2019

Does who you see first for back pain determine the likelihood of opioid prescription?

​The opioid epidemic has been widely studied, and many narcotic addicts had their first exposure to opioids via a prescription for pain medication. Low back pain patients are at especially high risk for opioid prescription and subsequent addiction due to prescribing patterns and the chronic nature of the problem. While patient characteristics associated with long-term narcotic use have been studied extensively, the role of the specialty of the initial provider encountered for low back pain in predicting long-term use has been less well-studied. In order to evaluate the association between initial provider specialty and likelihood of early and long-term narcotic prescription, Azad and colleagues from Stanford University analyzed almost 500,000 initial low back pain encounters in the MarketScan Commercial Claims database from 2010. All patients had an index low back pain or radiculopathy diagnosis without a prior similar diagnosis or opioid prescription in the prior 6 months. They considered these patients as opioid-naïve and presenting with acute back pain. Almost 50% had their initial encounter with a primary care physician, 18% with a specialist, 18% in an acute care setting (i.e. urgent care or the emergency department), and 17% with a non-physician provider (i.e. acupuncturist, chiropractor, physical therapist, or physician’s assistant). Overall, 40% of these patients received at least one prescription for opioids within 12 months of the initial diagnosis, and 4% received at least 6 prescriptions in that time-frame (10% of those receiving at least one prescription) and were considered long-term opioid users. Not surprisingly, those in the acute care environment were the most likely to provide an early opioid prescription within 2 weeks of diagnosis (40% acute care vs. 22% primary care). However, patients initially seen by an acute care provider were actually at somewhat decreased risk for long-term use (1% acute care vs. 2% primary care). Also not surprisingly, patients initially seen by a pain management physician were at highest risk for long-term use (7%). Patients initially seen by an acupuncturist, chiropractor, or physical therapist were the least likely to receive an opioid prescription at any point or be a long-term user.

The authors have asked an interesting question about the role of the initial low back pain provider in setting the stage for opioid use. This question differs subtly from the likelihood of prescription by provider type as it attempts to look at the role of the first contact the patient has with the healthcare system. While acute care providers are frequently criticized for overprescribing opioids for back pain, it seems as though opioids prescribed in this setting were not associated with long-term use. It is also striking that simply having an initial encounter with a non-prescribing provider (i.e. acupuncturist, chiropractor, physical therapist) seems protective against receiving an opioid prescription even though many of these patients likely encountered physicians later in their course. Like all large database studies, the ability to draw strong conclusions about causation is very limited. Many provider and patient characteristics that likely drove the decision to prescribe opioids were not captured in the database and could be strong confounders. For example, patients who were not interested in opioids or traditional medical care were probably more likely to see a non-prescribing provider initially, and this could have been the main driver of their lower risk of opioid prescription than those who sought care from a pain management provider. Additionally, the look back period was only 6 months, so some of these patients may have had a significant history of chronic back pain and/or narcotic use in the more distant past, and these patients may have been more likely to seek out different types of providers. Given the publicity about the opioid epidemic and publication of guidelines recommending against prescribing narcotics for low back pain, it would be interesting to see how patterns have changed recently compared to 2010. Avoiding the prescription of narcotics and considering alternative pain management strategies (i.e. physical therapy, chiropractic care, acupuncture) seems to be a reasonable approach to the management of acute low back pain.
Please read this article in the February 1 issue. Does this change how you consider the role of the initial provider in the treatment of acute low back pain? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

Friday, January 18, 2019

When to culture in revision spine surgery?

​The role of indolent infection in orthopaedic surgery is becoming better understood, especially in the shoulder surgery and total joint replacement literature. Many failed shoulder and joint replacement cases that present without the classic signs and symptoms of infection are found to be due to indolent infection after intra-operative cultures are obtained. The role of indolent infection in failed spine surgery is less well-defined, though there has been significant study of the role of P. acnes in disk degeneration. Given that indolent infection is a relatively common cause of failure in orthopaedic surgery on the extremities, it likely also plays a role in spine surgery. In order to better assess this, Dr. Steinhaus and colleagues at the Hospital for Special Surgery reviewed nearly 600 consecutive revision spine cases to determine which factors affected the decision to obtain intra-operative cultures and which characteristics were associated with infection. They removed the 17 cases in which infection was expected pre-operatively, which yielded 578 presumed aseptic cases. Cultures were obtained in 112 (19.4%) of these cases, and multivariate analysis demonstrated that obesity, thoracolumbar fusion, pseudarthrosis, implant failure, and the presence of instrumentation were independent predictors of cultures being obtained. Forty percent of cultured cases had positive cultures, with Staph species and P. acnes being the most common organisms. Multivariate analysis showed that male gender (OR 3.4) and pseudarthrosis (OR 4.1) predicted positive cultures, while having undergone a fusion (OR 0.3) decreased the risk of infection. Typical risk factors for infection such as obesity, diabetes, malnutrition, and smoking were not associated with positive cultures.

The authors have done a nice job looking at an issue spine surgeons frequently encounter but about which there is very little evidence to guide their decision-making. While the literature is replete with papers on risk factors for infection, very little has been published about revision cases that are presumed to be aseptic but in fact represent indolent infection. While the authors assembled a large series of nearly 600 revision cases, only 45 had positive cultures, which significantly limited their power to perform multivariate analysis looking at risk factors. It is unclear if the lack of association between traditional risk factors for infection and positive cultures found in the study was due to lack of power or because these are not risk factors for indolent infection. Given the well-established association between infection and pseudarthrosis in orthopaedic trauma surgery, many spine surgeons, including myself, routinely culture all pseudarthrosis cases. The surgeons in this series cultured 43% of the pseudarthrosis cases and 50% of the hardware failure cases, demonstrating that these diagnoses increased their rate of obtaining cultures, yet this was not a universal practice. Given the retrospective nature of the study, it is not possible to know why they obtained cultures in some of these cases but not others. The surgeons did not obtain cultures in all of the revision cases, which makes the analysis of risk factors hard to interpret due to likely selection bias. It would also be helpful to know if the surgeons were using intra-wound vancomycin powder at any point during the study as that would likely affect the infection rate and type of organisms encountered. While this paper has all of the limitations of a retrospective study, it has done a very nice job demonstrating that indolent infection is not uncommon in pseudarthrosis cases, and it is likely prudent to culture all revision cases done for this diagnosis.

Please read Dr. Steinhaus's paper on this topic in the February 1 issue. Does this change how you consider the role of intra-operative cultures in cases that are presumed to be aseptic? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor