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Jacob K. Greenberg and David D. Limbrick Jr.

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Jacob K. Greenberg, Derek S. Brown, Margaret A. Olsen, and Wilson Z. Ray

OBJECTIVE

The Affordable Care Act expanded Medicaid eligibility in many states, improving access to some forms of elective healthcare in the United States. Whether this effort increased access to elective spine surgical care is unknown. This study’s objective was to evaluate the impact of Medicaid expansion under the Affordable Care Act on the volume and payer mix of elective spine surgery in the United States.

METHODS

This study evaluated elective spine surgical procedures performed from 2011 to 2016 and included in the all-payer State Inpatient Databases of 10 states that expanded Medicaid access in 2014, as well as 4 states that did not expand Medicaid access. Adult patients aged 18–64 years who underwent elective spine surgery were included. The authors used a quasi-experimental difference-in-difference design to evaluate the impact of Medicaid expansion on hospital procedure volume and payer mix, independent of time-dependent trends. Subgroup analysis was conducted that stratified results according to cervical fusion, thoracolumbar fusion, and noninstrumented surgery.

RESULTS

The authors identified 218,648 surgical procedures performed in 10 Medicaid expansion states and 118,693 procedures performed in 4 nonexpansion states. Medicaid expansion was associated with a 17% (95% CI 2%–35%, p = 0.03) increase in mean hospital spine surgical volume and a 23% (95% CI −0.3% to 52%, p = 0.054) increase in Medicaid volume. Privately insured surgical volumes did not change significantly (incidence rate ratio 1.13, 95% CI −5% to 34%, p = 0.18). The increase in Medicaid volume led to a shift in payer mix, with the proportion of Medicaid patients increasing by 6.0 percentage points (95% CI 4.1–7.0, p < 0.001) and the proportion of private payers decreasing by 6.7 percentage points (95% CI 4.5–8.8, p < 0.001). Although the magnitude of effects varied, these trends were similar across procedure subgroups.

CONCLUSIONS

Medicaid expansion under the Affordable Care Act was associated with an economically and statistically significant increase in spine surgery volume and the proportion of surgical patients with Medicaid insurance, indicating improved access to care.

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Jacob K. Greenberg, Derek S. Brown, Margaret A. Olsen, and Wilson Z. Ray

OBJECTIVE

The Affordable Care Act expanded Medicaid eligibility in many states, improving access to some forms of elective healthcare in the United States. Whether this effort increased access to elective spine surgical care is unknown. This study’s objective was to evaluate the impact of Medicaid expansion under the Affordable Care Act on the volume and payer mix of elective spine surgery in the United States.

METHODS

This study evaluated elective spine surgical procedures performed from 2011 to 2016 and included in the all-payer State Inpatient Databases of 10 states that expanded Medicaid access in 2014, as well as 4 states that did not expand Medicaid access. Adult patients aged 18–64 years who underwent elective spine surgery were included. The authors used a quasi-experimental difference-in-difference design to evaluate the impact of Medicaid expansion on hospital procedure volume and payer mix, independent of time-dependent trends. Subgroup analysis was conducted that stratified results according to cervical fusion, thoracolumbar fusion, and noninstrumented surgery.

RESULTS

The authors identified 218,648 surgical procedures performed in 10 Medicaid expansion states and 118,693 procedures performed in 4 nonexpansion states. Medicaid expansion was associated with a 17% (95% CI 2%–35%, p = 0.03) increase in mean hospital spine surgical volume and a 23% (95% CI −0.3% to 52%, p = 0.054) increase in Medicaid volume. Privately insured surgical volumes did not change significantly (incidence rate ratio 1.13, 95% CI −5% to 34%, p = 0.18). The increase in Medicaid volume led to a shift in payer mix, with the proportion of Medicaid patients increasing by 6.0 percentage points (95% CI 4.1–7.0, p < 0.001) and the proportion of private payers decreasing by 6.7 percentage points (95% CI 4.5–8.8, p < 0.001). Although the magnitude of effects varied, these trends were similar across procedure subgroups.

CONCLUSIONS

Medicaid expansion under the Affordable Care Act was associated with an economically and statistically significant increase in spine surgery volume and the proportion of surgical patients with Medicaid insurance, indicating improved access to care.

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S. Kathleen Bandt, Jacob K. Greenberg, Chester K. Yarbrough, Kenneth B. Schechtman, David D. Limbrick, and Jeffrey R. Leonard

Object

There has been an increase in civilian gun violence since the late 1980s, with a disproportionately high increase occurring within the pediatric population. To date, no definite treatment paradigm exists for the management of these patients, nor is there a full understanding of the predictors of favorable clinical outcome in this population.

Methods

The authors completed a retrospective review of all victims of intracranial gunshot injury from birth to age 18 years at a major metropolitan Level 1 trauma center (n = 48) from 2002 to 2011. The predictive values of widely accepted adult clinical and radiographic factors for poor prognosis were investigated.

Results

Eight statistically significant factors (p < 0.05) for favorable outcome were identified. These factors include single hemispheric involvement, absence of a transventricular trajectory, < 3 lobes involved, ≥ 1 reactive pupil on arrival, systolic blood pressure > 100 mm Hg on arrival, absence of deep nuclei and/or third ventricular involvement, initial ICP < 30 mm Hg when monitored, and absence of midline shift. Of these 8 factors, 5 were strong predictors of favorable clinical outcome as defined by Glasgow Outcome Scale score of 4 or 5. These predictive factors included absence of a transventricular trajectory, < 3 lobes involved, ≥ 1 reactive pupil on arrival, absence of deep nuclei and/or third ventricular involvement, and initial ICP < 30 mm Hg. These findings form the basis of the St. Louis Scale for Pediatric Gunshot Wounds to the Head, a novel metric to inform treatment decisions for pediatric patients who sustain these devastating injuries.

Conclusions

The pediatric population tends to demonstrate more favorable outcomes following intracranial gunshot injury when compared with the adult population; therefore some patients may benefit from more aggressive treatment than is considered for adults. The St. Louis Scale for Pediatric Gunshot Wounds to the Head may provide critical data toward evidence-based guidelines for clinical decision making.

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Chester K. Yarbrough, Jacob K. Greenberg, Matthew D. Smyth, Jeffrey R. Leonard, Tae Sung Park, and David D. Limbrick Jr.

Object

Historically, assessment of clinical outcomes following surgical management of Chiari malformation Type I (CM-I) has been challenging due to the lack of a validated instrument for widespread use. The Chicago Chiari Outcome Scale (CCOS) is a novel system intended to provide a less subjective evaluation of outcomes for patients with CM-I. The goal of this study was to externally validate the performance of the CCOS.

Methods

Patients undergoing surgery for CM-I between 2001 and 2012 were reviewed (n = 292). Inclusion criteria for this study were as follows: 1) patients receiving primary posterior fossa decompression; 2) at least 5.5 months of postoperative clinical follow-up; and 3) patients ≤ 18 years of age at the time of surgery. Outcomes were evaluated using the CCOS, along with a “gestalt” impression of whether patients experienced significant improvement after surgery. A subgroup of 118 consecutive patients undergoing operations between 2008 and 2010 was selected for analysis of interrater reliability (n = 73 meeting inclusion/exclusion criteria). In this subgroup, gestalt and CCOS scores were independently determined by 2 reviewers, and interrater reliability was assessed using the intraclass correlation coefficient (ICC) and kappa (κ) statistic.

Results

The median CCOS score was 14, and 67% of patients had improved gestalt scores after surgery. Overall, the CCOS was effective at identifying patients with improved outcome after surgery (area under curve = 0.951). The interrater reliability of the CCOS (ICC = 0.71) was high, although the reliability of the component scores ranged from poor to good (ICC 0.23–0.89). The functionality subscore demonstrated a low ICC and did not add to the predictive ability of the logistic regression model (likelihood ratio = 1.8, p = 0.18). When analyzing gestalt outcome, there was moderate agreement between raters (κ = 0.56).

Conclusions

In this external validation study, the CCOS was effective at identifying patients with improved outcomes and proved more reliable than the authors' gestalt impression of outcome. However, certain component subscores (functionality and nonpain symptoms) were found to be less reliable, and may benefit from further definition in score assignment. In particular, the functionality subscore does not add to the predictive ability of the CCOS, and may be unnecessary. Overall, the authors found the CCOS to be an improvement over the previously used assessment of outcome at their institution.

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Jacob K. Greenberg, Chad W. Washington, Ridhima Guniganti, Ralph G. Dacey Jr., Colin P. Derdeyn, and Gregory J. Zipfel

OBJECT

Hospital readmission is a common but controversial quality measure increasingly used to influence hospital compensation in the US. The objective of this study was to evaluate the causes for 30-day hospital readmission following aneurysmal subarachnoid hemorrhage (SAH) to determine the appropriateness of this performance metric and to identify potential avenues for improved patient care.

METHODS

The authors retrospectively reviewed the medical records of all patients who received surgical orendovas-cular treatment for aneurysmal SAH at Barnes-Jewish Hospital between 2003 and 2013. Two senior faculty identified by consensus the primary medical/surgical diagnosis associated with readmission as well as the underlying causes of rehospitalization.

RESULTS

Among 778 patients treated for aneurysmal SAH, 89 experienced a total of 97 readmission events, yielding a readmission rate of 11.4%. The median time from discharge to readmission was 9 days (interquartile range 3–17.5 days). Actual hydrocephalus or potential concern for hydrocephalus (e.g., headache) was the most frequent diagnosis (26/97, 26.8%), followed by infections (e.g., wound infection [5/97, 5.2%], urinary tract infection [3/97, 3.1%], and pneumonia [3/97, 3.1%]) and thromboembolic events (8/97, 8.2%). In most cases (75/97, 77.3%), we did not identify any treatment lapses contributing to readmission. The most common underlying causes for readmission were unavoidable development of SAH-related pathology (e.g., hydrocephalus; 36/97, 37.1%) and complications related to neurological impairment and immobility (e.g., thromboembolic event despite high-dose chemoprophylaxis; 21/97, 21.6%). The authors determined that 22/97 (22.7%) of the readmissions were likely preventable with alternative management. In these cases, insufficient outpatient medical care (for example, for hyponatremia; 16/97, 16.5%) was the most common shortcoming.

CONCLUSIONS

Most readmissions after aneurysmal SAH relate to late consequences of hemorrhage, such as hydrocephalus, or medical complications secondary to severe neurological injury. Although a minority of readmissions may potentially be avoided with closer medical follow-up in the transitional care environment, readmission after SAH is an insensitive and likely inappropriate hospital performance metric.

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Dinal Jayasekera, Justin K. Zhang, Jacob Blum, Rachel Jakes, Peng Sun, Saad Javeed, Jacob K. Greenberg, Sheng-Kwei Song, and Wilson Z. Ray

OBJECTIVE

Cervical spondylotic myelopathy (CSM) is the most common cause of chronic spinal cord injury, a significant public health problem. Diffusion tensor imaging (DTI) is a neuroimaging technique widely used to assess CNS tissue pathology and is increasingly used in CSM. However, DTI lacks the needed accuracy, precision, and recall to image pathologies of spinal cord injury as the disease progresses. Thus, the authors used diffusion basis spectrum imaging (DBSI) to delineate white matter injury more accurately in the setting of spinal cord compression. It was hypothesized that the profiles of multiple DBSI metrics can serve as imaging outcome predictors to accurately predict a patient’s response to therapy and his or her long-term prognosis. This hypothesis was tested by using DBSI metrics as input features in a support vector machine (SVM) algorithm.

METHODS

Fifty patients with CSM and 20 healthy controls were recruited to receive diffusion-weighted MRI examinations. All spinal cord white matter was identified as the region of interest (ROI). DBSI and DTI metrics were extracted from all voxels in the ROI and the median value of each patient was used in analyses. An SVM with optimized hyperparameters was trained using clinical and imaging metrics separately and collectively to predict patient outcomes. Patient outcomes were determined by calculating changes between pre- and postoperative modified Japanese Orthopaedic Association (mJOA) scale scores.

RESULTS

Accuracy, precision, recall, and F1 score were reported for each SVM iteration. The highest performance was observed when a combination of clinical and DBSI metrics was used to train an SVM. When assessing patient outcomes using mJOA scale scores, the SVM trained with clinical and DBSI metrics achieved accuracy and an area under the curve of 88.1% and 0.95, compared with 66.7% and 0.65, respectively, when clinical and DTI metrics were used together.

CONCLUSIONS

The accuracy and efficacy of the SVM incorporating clinical and DBSI metrics show promise for clinical applications in predicting patient outcomes. These results suggest that DBSI metrics, along with the clinical presentation, could serve as a surrogate in prognosticating outcomes of patients with CSM.

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Jacob K. Greenberg, Eric Milner, Chester K. Yarbrough, Kim Lipsey, Jay F. Piccirillo, Matthew D. Smyth, Tae Sung Park, and David D. Limbrick Jr.

OBJECT

Chiari malformation Type I (CM-I) is a common and often debilitating neurological disease. Efforts to improve treatment of CM-I are impeded by inconsistent and limited methods of evaluating clinical outcomes. To understand current approaches and lay a foundation for future research, the authors conducted a systematic review of the methods used in original published research articles to evaluate clinical outcomes in patients treated for CM-I.

METHODS

The authors searched PubMed, Embase, the Cumulative Index to Nursing and Allied Health Literature, ClinicalTrials.gov, and Cochrane databases to identify publications between January 2003 and August 2013 that met the following criteria: 1) reported clinical outcomes in patients treated for CM-I; 2) were original research articles; 3) included at least 10 patients or, if a comparative study, at least 5 patients per group; and 4) were restricted to patients with CM-I.

RESULTS

Among the 74 papers meeting inclusion criteria, there was wide variation in the outcome methods used. However, all approaches were broadly grouped into 3 categories: 1) “gestalt” impression of overall symptomatic improvement (n = 45 papers); 2) postoperative change in specific signs or symptoms (n = 20); or 3) results of various standardized assessment scales (n = 22). Among standardized scales, 11 general function measures were used, compared with 6 disease-specific tools. Only 3 papers used scales validated in patients with CM-I. To facilitate a uniform comparison of these heterogeneous approaches, the authors appraised articles in multiple domains defined a priori as integral to reporting clinical outcomes in CM-I. Notably, only 7 articles incorporated patient-response instruments when reporting outcome, and only 22 articles explicitly assessed quality of life.

CONCLUSIONS

The methods used to evaluate clinical outcomes in CM-I are inconsistent and frequently not comparable, complicating efforts to analyze results across studies. Development, validation, and incorporation of a small number of disease-specific patient-based instruments will improve the quality of research and care of CM-I patients.

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Jacob K. Greenberg, Michael P. Kelly, Joshua M. Landman, Justin K. Zhang, Shay Bess, Justin S. Smith, Lawrence G. Lenke, Christopher I. Shaffrey, and Keith H. Bridwell

OBJECTIVE

The Adult Symptomatic Lumbar Scoliosis–1 (ASLS-1) trial demonstrated the benefit of adult symptomatic lumbar scoliosis (ASLS) surgery. However, the extent to which individuals differ in their postoperative recovery trajectories is unknown. This study’s objective was to evaluate variability in and factors moderating recovery trajectories after ASLS surgery.

METHODS

The authors used longitudinal, multilevel models to analyze postoperative recovery trajectories following ASLS surgery. Study outcomes included the Oswestry Disability Index (ODI) score and Scoliosis Research Society–22 (SRS-22) subscore, which were measured every 3 months until 2 years postoperatively. The authors evaluated the influence of preoperative disability level, along with other potential trajectory moderators, including radiographic, comorbidity, pain/function, demographic, and surgical factors. The impact of different parameters was measured using the R2, which represented the amount of variability in ODI/SRS-22 explained by each model. The R2 ranged from 0 (no variability explained) to 1 (100% of variability explained).

RESULTS

Among 178 patients, there was substantial variability in recovery trajectories. Applying the average trajectory to each patient explained only 15% of the variability in ODI and 21% of the variability in SRS-22 subscore. Differences in preoperative disability (ODI/SRS-22) had the strongest influence on recovery trajectories, with patients having moderate disability experiencing the greatest and most rapid improvement after surgery. Reflecting this impact, accounting for the preoperative ODI/SRS-22 level explained an additional 56%–57% of variability in recovery trajectory, while differences in the rate of postoperative change explained another 7%–9%. Among the effect moderators tested, pain/function variables—such as visual analog scale back pain score—had the biggest impact, explaining 21%–25% of variability in trajectories. Radiographic parameters were the least influential, explaining only 3%–6% more variance than models with time alone. The authors identified several significant trajectory moderators in the final model, such as significant adverse events and the number of levels fused.

CONCLUSIONS

ASLS patients have highly variable postoperative recovery trajectories, although most reach steady state at 12 months. Preoperative disability was the most important influence, although other factors, such as number of levels fused, also impacted recovery.

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Christopher F. Dibble, Justin K. Zhang, Jacob K. Greenberg, Saad Javeed, Jawad M. Khalifeh, Deeptee Jain, Ian Dorward, Paul Santiago, Camilo Molina, Brenton Pennicooke, and Wilson Z. Ray

OBJECTIVE

Local and regional radiographic outcomes following minimally invasive (MI) transforaminal lumbar interbody fusion (TLIF) versus open TLIF remain unclear. The purpose of this study was to provide a comprehensive assessment of local and regional radiographic parameters following MI-TLIF and open TLIF. The authors hypothesized that open TLIF provides greater segmental and global lordosis correction than MI-TLIF.

METHODS

A single-center retrospective cohort study of consecutive patients undergoing MI- or open TLIF for grade I degenerative spondylolisthesis was performed. One-to-one nearest-neighbor propensity score matching (PSM) was used to match patients who underwent open TLIF to those who underwent MI-TLIF. Sagittal segmental radiographic measures included segmental lordosis (SL), anterior disc height (ADH), posterior disc height (PDH), foraminal height (FH), percent spondylolisthesis, and cage position. Lumbopelvic radiographic parameters included overall lumbar lordosis (LL), pelvic incidence (PI)–lumbar lordosis (PI-LL) mismatch, sacral slope (SS), and pelvic tilt (PT). Change in segmental or overall lordosis after surgery was considered "lordosing" if the change was > 0° and "kyphosing" if it was ≤ 0°. Student t-tests or Wilcoxon rank-sum tests were used to compare outcomes between MI-TLIF and open-TLIF groups.

RESULTS

A total of 267 patients were included in the study, 114 (43%) who underwent MI-TLIF and 153 (57%) who underwent open TLIF, with an average follow-up of 56.6 weeks (SD 23.5 weeks). After PSM, there were 75 patients in each group. At the latest follow-up both MI- and open-TLIF patients experienced significant improvements in assessment scores obtained with the Oswestry Disability Index (ODI) and the numeric rating scale for low-back pain (NRS-BP), without significant differences between groups (p > 0.05). Both MI- and open-TLIF patients experienced significant improvements in SL, ADH, and percent corrected spondylolisthesis compared to baseline (p < 0.001). However, the MI-TLIF group experienced significantly larger magnitudes of correction with respect to these metrics (ΔSL 4.14° ± 4.35° vs 1.15° ± 3.88°, p < 0.001; ΔADH 4.25 ± 3.68 vs 1.41 ± 3.77 mm, p < 0.001; percent corrected spondylolisthesis: −10.82% ± 6.47% vs −5.87% ± 8.32%, p < 0.001). In the MI-TLIF group, LL improved in 44% (0.3° ± 8.5°) of the cases, compared to 48% (0.9° ± 6.4°) of the cases in the open-TLIF group (p > 0.05). Stratification by operative technique (unilateral vs bilateral facetectomy) and by interbody device (static vs expandable) did not yield statistically significant differences (p > 0.05).

CONCLUSIONS

Both MI- and open-TLIF patients experienced significant improvements in patient-reported outcome (PRO) measures and local radiographic parameters, with neutral effects on regional alignment. Surprisingly, in our cohort, change in SL was significantly greater in MI-TLIF patients, perhaps reflecting the effect of operative techniques, technological innovations, and the preservation of the posterior tension band. Taking these results together, no significant overall differences in LL between groups were demonstrated, which suggests that MI-TLIF is comparable to open approaches in providing radiographic correction after surgery. These findings suggest that alignment targets can be achieved by either MI- or open-TLIF approaches, highlighting the importance of surgeon attention to these variables.