The Impact of Asymptomatic Human Immunodeficiency Virus-Positive Disease Status on Inpatient Complications Following Spine Surgery: A Propensity Score-Matched Analysis.

In the United States, nearly 1.2 million people > 12 years old have human immunodeficiency virus (HIV), which is associated with postoperative complications following orthopedic procedures. Little is known about how asymptomatic HIV (AHIV) patients fare postoperatively. This study compares complications after common spine surgeries between patients with and without AHIV. The Nationwide Inpatient Sample (NIS) was retrospectively reviewed from 2005-2013, identifying patients aged > 18 years who underwent 2-3-level anterior cervical discectomy and fusion (ACDF), ≥4-level thoracolumbar fusion (TLF), or 2-3-level lumbar fusion (LF). Patients with AHIV and without HIV were 1:1 propensity score-matched. Univariate analysis and multivariable binary logistic regression were performed to assess associations between HIV status and outcomes by cohort. 2-3-level ACDF (n = 594 total patients) and ≥4-level TLF (n = 86 total patients) cohorts demonstrated comparable length of stay (LOS), rates of wound-related, implant-related, medical, surgical, and overall complications between AHIV and controls. 2-3-level LF (n = 570 total patients) cohorts had comparable LOS, implant-related, medical, surgical, and overall complications. AHIV patients experienced higher postoperative respiratory complications (4.3% vs. 0.4%,). AHIV was not associated with higher risks of medical, surgical, or overall inpatient postoperative complications following most spine surgical procedures. The results suggest the postoperative course may be improved in patients with baseline control of HIV infection.

The 5-factor modified frailty index (mFI-5) is predictive of 30-day postoperative complications and readmission in patients with adult spinal deformity (ASD).

BACKGROUND: There is limited research regarding the association between the mFI-5 and postoperative complications among adult spinal deformity (ASD) patients. METHODS: Using the National Surgical Quality Improvement Project (NSQIP) database, patients with Current Procedural Terminology (CPT) codes for > 7-level fusion or < 7-level fusion with International Classification of Diseases, Ninth Revision (ICD-9) codes for ASD were identified between 2008 and 2016. Univariate analyses with post-hoc Bonferroni correction for demographics and preoperative factors were performed. Logistic regression assessed associations between mFI-5 scores and 30-day post-operative outcomes. RESULTS: 2,120 patients met criteria. Patients with an mFI-5 score of 4 or 5 were excluded, given there were<20 patients with those scores. Patients with mFI-5 scores of 1 and 2 had increased 30-day rates of pneumonia (3.5 % and 4.3 % vs 1.6 %), unplanned postoperative ventilation for > 48 h (3.1 % and 4.3 % vs 0.9 %), and UTIs (4.4 % and 7.4 % vs 2.0 %) than patients with a score of 0 (all, p < 0.05). Logistic regression revealed that compared to an mFI-5 of 0, a score of 1 was an independent predictor of 30-day reoperations (OR = 1.4; 95 % CI 1.1-18). A score of 2 was an independent predictor of overall (OR = 2.4; 95 % CI 1.4-4.1) and related (OR = 2.2; 95 % CI 1.2-4.1) 30-day readmissions. A score of 3 was not predictive of any adverse outcome. CONCLUSION: The mFI-5 score predicted complications and postoperative events in the ASD population. The mFI-5 may effectively predict 30-day readmissions. Further research is needed to identify the benefits and predictive value of mFI-5 as a risk assessment tool.

Outcomes of Patients With Parkinson Disease Undergoing Cervical Spine Surgery for Radiculopathy and Myelopathy With Minimum 2-Year Follow-up.

STUDY DESIGN: This was a retrospective cohort analysis. OBJECTIVE: To identify the impact of Parkinson disease (PD) on 2-year postoperative outcomes following cervical spine surgery (CSS). SUMMARY OF BACKGROUND DATA: (PD) patients are prone to spine malalignment and surgical interventions, yet little is known regarding outcomes of CSS among PD patients. MATERIALS AND METHODS: All patients from the Statewide Planning and Research Cooperative System with cervical radiculopathy or myelopathy who underwent CSS were included; among these, those with PD were identified. PD and non-PD patients (n=64 each) were 1:1 propensity score-matched by age, sex, race, surgical approach, and Deyo-Charlson Comorbidity Index (DCCI). Demographics, hospital-related parameters, and adverse postoperative outcomes were compared between cohorts. Logistic regression identified predictive factors for outcomes. RESULTS: Overall, patient demographics were comparable between cohorts, except that DCCI was higher in PD patients (1.28 vs. 0.67, P=0.028). PD patients had lengthier mean hospital stays than non-PD patients (6.4 vs. 4.1 d, P=0.046). PD patients also incurred comparable total hospital expenses ($69,565 vs. $57,388, P=0.248). Individual medical complication rates were comparable between cohorts; though PD patients had higher rates of postoperative altered mental status (4.7% vs. 0%, P=0.08) and acute renal failure (10.9% vs. 3.1%, P=0.084), these differences were not significant. Yet, PD patients experienced higher rates of overall medical complications (35.9% vs. 18.8%, P=0.029). PD patients had comparable rates of individual and overall surgical complications. The PD cohort underwent higher reoperation rates (15.6% vs. 7.8%, P=0.169) compared with non-PD patients, though this difference was not significant. Of note, PD was not a significant predictor of overall 2-year complications (odds ratio=1.57, P=0.268) or reoperations (odds ratio=2.03, P=0.251). CONCLUSION: Overall medical complication rates were higher in patients with PD, while individual medical complications as well as surgical complication and reoperation rates after elective CSS were similar in patients with and without PD, though PD patients required longer hospital stays. Importantly, a baseline diagnosis of PD was not significantly associated with adverse two-year medical and surgical complications. This data may improve counseling and risk-stratification for PD patients before CSS. LEVEL OF EVIDENCE: Level III.

Is the Neck Disability Index an Appropriate Measure for Changes in Physical Function After Surgery for Cervical Spondylotic Myelopathy?

BACKGROUND: The Neck Disability Index (NDI) is a 10-item questionnaire about symptoms relevant to cervical spine pathology, originally validated in the physical therapy literature. It is unclear if all of the items apply to spine surgery. The purpose of this study was to determine if improvements in the composite NDI score or specific NDI domains are appropriate measures for tracking changes in physical function after surgical intervention for cervical spondylotic myelopathy (CSM). METHODS: A retrospective cohort review of patients treated at a major academic medical center was undertaken. Baseline and postoperative standardized outcome measurement scores, including composite NDI, NDI subdomain, and SF-12 physical component score (PCS), were collected. Wilcoxon signed-rank test was used to determine whether patients exhibited improvement in each of the outcome measures included. Multiple linear regression was performed to determine whether change in NDI composite or subdomain scores predicted change in physical function after surgery for CSM-compared with the well-validated PCS score-controlling for factors such as age, sex, etc. RESULTS: Baseline data were collected on 118 patients. All outcome measures exhibited significant improvement after surgery based on the Wilcoxon signed-rank test. On linear regression, work (ß = -2.419 [-3.831, -1.006]; P = .001) and recreation (ß = -1.354 [-2.640, -0.068]; P = .039), as well as the NDI composite score (ß = -0.223 [-0.319, -0.127]; P < .001), were significant predictors of change in physical function over time. CONCLUSIONS: Although the NDI composite score did predict change in PCS over time, only 2 of the 10 NDI subdomains were found to be associated with change in physical function over time. Based on these results, the item bank and composite scoring of the NDI are inappropriate for evaluating quality of life in studies of surgically treated cervical spondylotic myelopathy patients. CLINICAL RELEVANCE: NDI may not be a valid tool in the determination of physical function changes after surgery for CSM. LEVEL OF EVIDENCE: III.

Comparing Predictors of Complications After Anterior Cervical Diskectomy and Fusion, Total Disk Arthroplasty, and Combined Anterior Cervical Diskectomy and Fusion-Total Disk Arthroplasty With a Minimum 2-Year Follow-Up.

INTRODUCTION: Outcomes after anterior cervical diskectomy and fusion (ACDF) and cervical total disk arthroplasty (TDA) are satisfactory, but related morbidity and revision surgery rates are notable. This study sought to determine complication variations among ACDF, TDA, and combined ACDF-TDA as well as predictors of postoperative complications. METHODS: Patients undergoing 1- to 2-level ACDF and/or TDA with at least a 2-year follow-up from 2009 to 2011 were identified from the Statewide Planning and Research Cooperative System database. Patient demographics, hospital-related parameters, mortality, and postoperative outcomes were compared, and their predictors were identified using multivariate logistic regression. RESULTS: A total of 16,510 and 449 individuals underwent ACDF and cervical TDA, respectively, and 201 underwent ACDF-TDA. ACDF-TDA patients had the highest rates of cardiac complications and pulmonary embolism (PE) (P ≤ 0.006), whereas TDA patients had higher individual surgical and device/implant/internal fixation complications (P ≤ 0.025). ACDF-TDA patients experienced the lowest rate of revisions. Cervical TDA increased the odds of any surgical complications (OR = 2.5, P = 0.002), overall complications (OR = 1.57, P = 0.034), and revisions (OR = 2.29, P < 0.001). Deyo index predicted any medical/surgical complications (OR = 1.43 and 1.19, respectively). Female sex was associated with increased odds of readmission (OR 1.30, P < 0.001) but was protective against medical complications (OR = 0.81, P = 0.013). DISCUSSION: Combined ACDF-TDA procedures were not associated with increases in 2-year individual or overall complications, readmissions, or revisions. LEVEL OF EVIDENCE: Level 3-Therapeutic study.

Comparison of a Posterior versus Anterior Approach for Lumbar Interbody Fusion Surgery Based on Relative Value Units.

INTRODUCTION: The current value-driven healthcare system encourages physicians to continuously optimize the value of the services they provide. Relative value units (RVUs) serve as the basis of a reimbursement model linking the concept that as the effort and value of services provided to patient's increases, physician reimbursement should increase proportionately. Spine surgery is particularly affected by these factors as there are multiple ways to achieve similar outcomes, some of which require more time, effort, and risk. Specifically, as the trend of spinal interbody fusion has increased over the past decade, the optimal approach to use-posterior versus anterior lumbar interbody fusion (PLIF vs. ALIF)-has been a source of controversy. Due to potential discrepancies in effort, one factor to consider is the correlation between RVUs and the time needed to perform a procedure. Therefore, the purpose of this study was to compare: 1) mean RVUs; 2) mean operative time; and 3) mean RVUs per unit of time between PLIF and ALIF with the utilization of a national surgical database. We also performed an individual surgeon cost benefit analysis for performing PLIF versus ALIF. MATERIALS AND METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database was utilized to identify 6,834 patients who underwent PLIF (CPT code: 22630) and 6,985 patients who underwent ALIF (CPT code: 22558) between 2008 and 2015. The mean operative times (in minutes), mean RVUs, and RVUs per minute were calculated and compared using the Student's t-tests. In addition, the reimbursement amount (in dollars) per minute, case, day, and year for an individual surgeon performing PLIF versus ALIF were also calculated and compared. A p-value of less than 0.05 was used as the threshold for statistical significance. RESULTS: Compared to ALIF cases, PLIF cases had longer mean operative times (203 vs. 212 minutes, p<0.001). However, PLIF cases were assigned lower mean RVUs than ALIF cases (22.08 vs. 23.52, p<0.001). Furthermore, PLIF had a lower mean RVU/minutes than ALIF cases (0.126 vs. 0.154, p<0.001). The reimbursement amounts calculated for PLIF versus ALIF were: $4.52 versus $5.53 per minute, $958.66 versus $1,121.95 per case, and $2,875.98 versus $3,365.86 per day. The annual cost difference was $78,380.92. CONCLUSION: The data from this study indicates a potentially greater annual compensation of nearly $80,000 for performing ALIF as opposed to PLIF due to a higher "hourly rate" for ALIF as is noted by the significantly greater RVU per minute (0.154 vs. 0.126 RVU/minutes). These results can be used by spine surgeons to design more appropriate compensation effective practices while still providing quality care.

Spinal Fusion in Parkinson's Disease Patients: A Propensity Score-Matched Analysis With Minimum 2-Year Surveillance.

STUDY DESIGN: Retrospective analysis. OBJECTIVE: To compare outcomes and complication rates between patients with and without Parkinson's disease (PD) patients undergoing surgery for adult spinal deformity (ASD). SUMMARY OF BACKGROUND DATA: There is limited literature evaluating the impact of PD on long-term outcomes after thoracolumbar fusion surgery for ASD. METHODS: Patients admitted from 2009 to 2011 with diagnoses of ASD who underwent any thoracolumbar fusion procedure with a minimum 2-year follow-up surveillance were retrospectively reviewed using New York State's Statewide Planning and Research Cooperative System. A 1:1 propensity score-match by age, Deyo score, and number of fused vertebral levels was conducted before comparing surgical outcomes of patients with ASD with and without PD. Univariate analysis compared demographics, complications, and subsequent revision. Multivariate binary stepwise logistic regression models identified independent predictors of these outcomes (covariates: age, sex, Deyo Index score, and PD diagnosis). RESULTS: A total of 576 propensity score-matched patients were identified (PD: n = 288; no-PD: n = 288), with a mean age of 69.7 years (PD) and 70.2 years (no-PD). Each cohort had comparable distributions of age, sex, race, insurance provider, Deyo score, and number of levels fused (all P > 0.05). Patients with PD incurred higher total charges across ASD surgery-related visits ($187,807 vs. $126,610, P < 0.001), yet rates of medical complications (35.8% PD vs. 34.0% no-PD, P = 0.662) and revision surgery (12.2% vs. 10.8%, P > 0.05) were comparable. Postoperative mortality rates were comparable between PD and no-PD cohorts (2.8% vs. 1.4%, P = 0.243). Logistic regression identified nine-level or higher spinal fusion as a significant predictor for an increase in total complications (odds ratio = 5.64); PD was not associated with increased odds of any adverse outcomes. CONCLUSION: Aside from higher hospital charges incurred, patients with PD experienced comparable overall complication and revision rates to a propensity score-matched patient cohort without PD from the general population undergoing thoracolumbar fusion surgery. These results can support management of concerns and postoperative expectations in this patient cohort. LEVEL OF EVIDENCE: 3.

Risk Factors for Pseudarthrosis After Surgical Site Infection of the Spine.

BACKGROUND: Pseudarthrosis following spinal fusion is a complication that frequently requires revision surgery. Reported rates of pseudarthrosis after surgical site infection (SSI) range from 30% to 85%, but few studies have identified infection as an independent risk factor for its development. The purpose of this study was to determine the incidence of clinically symptomatic pseudarthrosis in patient who developed SSI following lumbar fusion and to identify factors associated with its development. METHODS: This was a retrospective review of a prospectively collected database. Patients who underwent spinal surgery and developed SSI between January 2005 and March 2015 with a minimum 2-year follow-up were included. Patient-specific and procedural characteristics were recorded. Presence of pseudarthrosis was determined clinically by the treating surgeon and was confirmed radiographically. All those in the Pseudarthrosis group required a revision procedure after the eradication of infection. Univariate and multivariate analyses were conducted as appropriate. RESULTS: A total of 416 patients were included. Of these, 21 (5.0%) developed symptomatic pseudarthrosis following SSI. In this cohort, multivariate regression showed that age, Charlson Comorbidity Index, male sex, and surgical approach were not significant predictors of pseudarthrosis formation. However, number of levels fused was found to be the leading predictor for pseudarthrosis development (odds ratio [OR], 1.356/level, P < .001), followed by body mass index (OR, 1.083/point, P < .009) in this cohort. The number of levels fused was found to be a significant predictor of hardware removal (OR, 1.190/level, P < .001). Of the 21 pseudarthrosis cases, 85.7% found staphylococcal species, of which 27.8% exhibited methicillin-resistant Staphylococcus aureus. CONCLUSIONS: The number of spinal levels fused and body mass index are independent predictors of pseudarthrosis in patients who develop SSI after spinal fusion. LEVEL OF EVIDENCE: Level 4. CLINICAL RELEVANCE: This is the first known study to specifically identify risk factors for the development of symptomatic pseudarthrosis.

Clinical Outcomes After Four-Level Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: Anterior cervical discectomy and fusion (ACDF) demonstrates reliable improvement in neurologic symptoms associated with anterior compression of the cervical spine. There is a paucity of data on outcomes following 4-level ACDFs. The purpose of this study was to evaluate clinical outcomes for patients undergoing 4-level ACDF. METHODS: All 4-level ACDFs with at least 1-year clinical follow-up were identified. Clinical outcomes, including fusion rates, neurologic outcomes, and reoperation rates were determined. RESULTS: Retrospective review of our institutional database revealed 25 patients who underwent 4-level ACDF with at least 1-year clinical follow-up. Average age was 57.5 years (range 38.2-75.0 years); 14 (56%) were male, and average body mass index was 30.2 kg/m2 (range 19.9-43.4 kg/m2). Two (8%) required secondary cervical surgery at an average of 94.5 days postoperatively while the remaining 23 did not with an average follow-up of 19 months. Of 23 patients not requiring revision surgery, 16 (69%) patients fused by definition of less than 1 mm of spinous process motion per fused level in flexion and extension. Fifteen (65%) had at least one muscle group with one grade of weakness preoperatively. Nineteen of these patients (83%) had improved to full strength while no patients lost muscle strength. CONCLUSIONS: Review of our institution's experience demonstrated a low rate of revision cervical surgery for any reason of 8% at mean 19 months follow-up, and neurological examinations consistently improved, despite a high rate of radiographic nonunion (31%).

Utilization of Time-driven Activity-based Costing to Determine the True Cost of a Single or 2-level Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: This is a prospective case series. OBJECTIVE: To determine the actual cost of performing 1- or 2-level anterior cervical discectomy and fusion (ACDF) using actual patient data and the time-driven activity-based cost methodology. SUMMARY OF BACKGROUND DATA: As health care shifts to use value-based reimbursement, it is imperative to determine the true cost of surgical procedures. Time-driven activity-based costing determines the cost of care by determining the actual resources used in each step of the care cycle. MATERIALS AND METHODS: In total, 30 patients who underwent a 1- or 2-level ACDF by 3 surgeons at a specialty hospital were prospectively enrolled. To build an accurate process map, a research assistant accompanied the patient to every step in the care cycle including the preoperative visit, the preadmission testing, the surgery, and the postoperative visits for the first 90 days. All resources utilized and the time spent with every member of the care team was recorded. RESULTS: In total, 27 patients were analyzed. Eleven patients underwent a single-level ACDF and 16 underwent a 2-level fusion. The total cost for the episode of care was $29,299±$5048. The overwhelming cost driver was the hospital disposable costs ($13,920±$6325) which includes every item used during the hospital stay. Intraoperative personnel costs including fees for the surgeon, resident/fellow, anesthesia, nursing, surgical technician, neuromonitoring, radiology technician and orderlies, accounted for the second largest cost at $6066±$1540. The total cost excluding hospital overhead and disposables was $9071±$1939. CONCLUSIONS: Reimbursement for a bundle of care surrounding a 1- or 2-level ACDF should be no less than $29,299 to cover the true costs of the care for the entire care cycle. However, this cost may not include the true cost of all capital expenditures, and therefore may underestimate the cost.

The Outcomes of Posterior Arthrodesis for Atlantoaxial Subluxation in Down Syndrome Patients: A Meta-Analysis.

STUDY DESIGN: This is a meta-analysis. OBJECTIVE: To establish rates of (1) neurological complications, (2) bony-related complications, (3) complications delaying recovery, (4) reoperation, and (5) fatalities following posterior cervical arthrodesis in Down syndrome (DS) patients with atlantoaxial subluxation. To determine if presenting symptoms had any relationship to postoperative complications. SUMMARY OF BACKGROUND DATA: Posterior arthrodesis is commonly utilized to correct cervical instability secondary to atlantoaxial instability in DS patients. However, there has never been a global evaluation of postoperative complications associated with posterior cervical spinal arthrodesis in DS patients. METHODS: A comprehensive search of Medline/PubMed, EMBASE, and Ovid databases between January 1980 and July 2017 was utilized to identify DS patients with atlantoaxial subluxation who underwent posterior cervical arthrodesis. Data were sorted by neurological complications, complications delaying recovery, bony-related complications, reoperations, and fatalities. Patients were sorted into 2 groups based on presentation with or without neurological deficits. RESULTS: Twelve studies met inclusion criteria, including 128 DS patients. Mean age was 13.8 years (range: 6.7-32.7 y; 47.8% male). Mean follow-up was 31.7 months (range: 14.9-77 mo). All patients underwent primary posterior cervical arthrodesis with an average of 2.5 vertebrae fused. A total of 39.6% of patients had bony-related complications [95% confidence interval (CI), 31.4%-48.5%], 23.3% had neurological deficits (95% CI, 16.6%-31.6%), and 26.4% experienced complications delaying recovery (95% CI, 19.4%-34.9%). The reoperation rate was 34.9% (95% CI, 25.5%-45.6%). The mortality rate was 3.9% (95% CI, 1.5%-9.7%). Neurological complications were 4-fold (P<0.05) and reoperation was 5.5-fold (P<0.05) more likely in patients presenting with neurological deficits compared with those without. CONCLUSIONS: This study detailed global complication rates of posterior arthrodesis for DS patients, identifying bony-related complications and reoperations among the most common. Patients presenting with neurological symptoms and cervical instability have increased postoperative rates of neurological complications and reoperations than patients with instability alone. Further investigation into how postoperative complications effect patient independence is warranted.

The Impact of Comorbid Mental Health Disorders on Complications Following Adult Spinal Deformity Surgery With Minimum 2-Year Surveillance.

STUDY DESIGN: Retrospective analysis. OBJECTIVE: To compare long-term outcomes between patients with and without mental health comorbidities who are undergoing surgery for adult spinal deformity (ASD). SUMMARY OF BACKGROUND DATA: Recent literature reveals that one in three patients admitted for surgical treatment for ASD has comorbid mental health disorder. Currently, impacts of baseline mental health status on long-term outcomes following ASD surgery have not been thoroughly investigated. METHODS: Patients admitted from 2009 to 2013 with diagnoses of ASD who underwent more than or equal to 4-level thoracolumbar fusion with minimum 2-year follow-up were retrospectively reviewed using New York State's Statewide Planning and Research Cooperative System (SPARCS). Patients were stratified by fusion length (short: 4-8-level; long: ≥9 level). Patients with comorbid mental health disorder (MHD) at time of admission were selected for analysis (MHD) and compared against those without MHD (no-MHD). Univariate analysis compared demographics, complications, readmissions, and revisions between cohorts for each fusion length. Multivariate binary logistic regression models identified independent predictors of outcomes (covariates: fusion length, age, female sex, and Deyo score). RESULTS: Six thousand twenty patients (MHD: n = 1631; no-MHD: n = 4389) met inclusion criteria. Mental health diagnoses included disorders of depression (59.0%), sleep (28.0%), anxiety (24.0%), and stress (2.3%). At 2-year follow-up, MHD patients with short fusion had significantly higher complication rates (P = 0.001). MHD patients with short or long fusion also had significantly higher rates of any readmission and revision (all P ≤ 0.002). Regression modeling revealed that comorbid MHD was a significant predictor of any complication (odds ratio [OR]: 1.17, P = 0.01) and readmission (OR: 1.32, P < 0.001). MHD was the strongest predictor of any revision (OR: 1.56, P < 0.001). Long fusion most strongly predicted any complication (OR: 1.87, P < 0.001). CONCLUSION: ASD patients with comorbid depressive, sleep, anxiety, and stress disorders were more likely to experience surgical complications and revision at minimum of 2 years following spinal fusion surgery. Proper patient counseling and psychological screening/support is recommended to complement ASD treatment. LEVEL OF EVIDENCE: 3.

The Risks of Hepatitis C in Association With Cervical Spinal Surgery: Analysis of Radiculopathy and Myelopathy Patients.

STUDY DESIGN: Retrospective review. OBJECTIVE: To investigate rates of in-hospital postsurgical complications among hepatitis C-infected patients after cervical spinal surgery in comparison with uninfected patients and determine independent risk factors. SUMMARY OF BACKGROUND DATA: Studying hepatitis C virus (HCV) as a possible risk factor for cervical spine postoperative complications is prudent, given the high prevalence of cervical spondylosis and HCV in older patients. Spine literature is limited with respect to the impact of chronic HCV upon complications after surgery. MATERIALS AND METHODS: Patients who underwent cervical spine surgery for cervical radiculopathy (CR) or cervical myelopathy (CM) from 2005 to 2013 were retrospectively reviewed using the Nationwide Inpatient Sample database. Patients were divided into CR and CM groups, with comparative subgroup analysis of HCV and no-HCV patients. Univariate analysis compared demographics and complications. Binary logistic stepwise regression modeling identified any independent outcome predictors (covariates: age, sex, Deyo score, and surgical approach). RESULTS: In total, 227,310 patients (HCV: n=2542; no-HCV: n=224,764) were included. From 2005 to 2013, HCV infection prevalence among all cervical spinal fusion cases increased from 0.8% to 1.2%. HCV patients were more likely to be African American or Hispanic and have Medicare and/or Medicaid (all P<0.001). Overall complication rates among HCV patients with CR or CM increased, specifically related to device (CR: 3.1% vs. 1.9%; CM: 2.9% vs. 1.3%), hematoma/seroma (CR: 1.1% vs. 0.4%; CM: 1.8% vs. 0.8%), and sepsis (CR: 0.4% vs. 0.1%; CM: 1.1% vs. 0.5%) (all P≤0.001). Among CR and CM patients, HCV significantly predicted increased complication rates [odds ratio (OR): 1.268; OR: 1.194], hospital stay (OR: 1.738; OR: 1.861), and hospital charges (OR: 1.516; OR: 1.732; all P≤0.044). CONCLUSIONS: HCV patients undergoing cervical spinal surgery were found to have increased risks of postoperative complications and increased risk associated with surgical approach. These findings should augment preoperative risk stratification and counseling for HCV patients and their spine surgeons. LEVEL OF EVIDENCE: Level III.

Which Domains of the ODI Best Predict Change in Physical Function in Patients After Surgery for Degenerative Lumbar Spondylolisthesis?

STUDY DESIGN: A retrospective review. OBJECTIVE: The purpose of this study is to determine the differential improvement of the various individual items of the Oswestry Disability Index (ODI) and to determine their relationship to other measures of Health Related Quality of Life (HRQOL). SUMMARY OF BACKGROUND DATA: The ODI is an easily scored, common, 10-item questionnaire about symptoms relevant to lumbar spine pathology. It is not clear if all of the items can be reliably applied to spine surgery. The purpose of this study is to determine the differential improvement of the various individual items of the ODI and to determine their relationship to other measures of HRQOL. METHODS: Analysis of a prospective registry of patients treated at an academic medical center was undertaken. At baseline, standardized outcome measures including ODI and SF12 PCS were collected on all patients undergoing elective fusion surgery for degenerative spondylolisthesis. Multiple linear regressions were performed using change in SF12 PCS as the dependent variable and change in ODI components as the independent variables. RESULTS: Baseline and 1-year follow-up data were collected on 196 patients (mean age 60.4 years). There were statistically significant differences in improvement among ODI items. Surprisingly, the most improvement after surgery was noted in the standing, sex life, and social life domains. The least improvement was noted in the personal care, sleeping, and sitting domains. Linear regression for change in ODI components versus change in SF-12 PCS revealed a significant correlation (R = 0.353, P ≤ 0.001). The only retained domains in the final model were change in lifting, standing, and traveling as predictors for ΔPCS. CONCLUSION: All domains of the ODI do not improve equally after surgery for degenerative spondylolisthesis. Some of the domains that improve most (e.g., sex life) have no discernible relationship to the known pathophysiology of degenerative spondylolisthesis. Based upon these results, we conclude that the item bank and composite scoring of the ODI are inappropriate for evaluating quality of life in studies of surgically treated degenerative spondylolisthesis patients. LEVEL OF EVIDENCE: 3.

The Effect of Postoperative Spinal Infections on Patient Mortality.

STUDY DESIGN: A retrospective, matched cohort study. OBJECTIVES: This study aims to investigate the association between surgical site infection (SSI) and mortality and ascertain any factors that predict mortality in those diagnosed with SSI. SUMMARY OF BACKGROUND DATA: Despite significant efforts toward mitigation, SSI, including deep infection, remains a common complication following spine surgery, Considerable morbidity may be associated with infection, including hospital readmission, revision surgery, and delayed rehabilitation. However, it is not known whether this increase in morbidity is associated with increased mortality. METHODS: Patients from a single center requiring reoperation for SSI following elective spine surgery between 2005 and 2013 were identified in a retrospective fashion. These patients were then matched one-to-three with patients undergoing elective spine surgery without SSI. Patients were matched for age, gender, body mass index (BMI), Charlson comorbidity index, year of surgery, spine region, and approach. The Social Security Death Index was utilized to identify deceased patients and their time of death. Univariate statistics were then utilized to compare mortality rates between the two groups. In addition, the SSI cohort was evaluated for predictors of mortality following SSI. RESULTS: One-hundred ninety-five patients developed SSI at a mean of 27.4 (range: 1-467) days from the index surgery. Ninety-day, 1-year, 2-year, and 5-year mortality rates were 1.54% versus 1.03% (P = 0.70), 4.62% versus 1.2% (P = 0.006), 7.73% versus 2.25% (P = 0.001), and 15.45% versus 3.43% (P = 0.0002) for SSI versus control patients, respectively. Predictors of 2-year mortality in the SSI cohort were increased age (P = 0.02) and increased Charlson Comorbidity Index (P < 0.001). Region and approach of surgery, days to infection, and reason for elective surgery did not influence mortality. CONCLUSION: SSI results in significant morbidity in the postoperative period, with the risk of reoperation, prolonged hospitalization, and need for other invasive procedures. In addition, this study provides evidence that SSI is associated with an increased mortality following elective spine surgery. LEVEL OF EVIDENCE: 4.

Do Formal Laminectomy and Timing of Decompression for Patients With Sacral Fracture and Neurologic Deficit Affect Outcome?

OBJECTIVES: To identify whether formal sacral decompression provides improvement in outcome for patients with neurologic deficit after sacral fracture compared with patients treated with indirect decompression and whether the timing of surgical decompression influences neurologic outcome? DATA SOURCES: MEDLINE was searched via PubMed using combinations of the following search terms: "Sacral fracture," "Traumatic Sacral fracture," "Sacral fracture decompression," "Sacral fracture time to decompression," "Sacral Decompression." Only clinical studies on human subjects and in the English language were included. STUDY SELECTION: Studies that did not provide sufficient detail to confirm the nature of the sacral injury, treatment rendered, and neurologic outcome were excluded. Studies using subjects less than 18 years of age, cadavers, nonhuman subjects, or laboratory simulations were excluded. All other relevant studies were reviewed in detail. DATA EXTRACTION: All studies were assigned a level of evidence using the grading tool described by the Centre for Evidence-Based Medicine and all studies were analyzed for bias. Both cohorts in articles comparing 2 groups of patients treated differently were included in the appropriate group. Early decompression was defined as before 72 hours. DATA SYNTHESIS: The effect of decompression technique and timing of decompression surgery on partial and complete neurologic recovery was estimated using a generalized linear mixed model to implement a logistic regression with a study-level random effect. CONCLUSIONS: There was no benefit to early decompression within 72 hours and no difference between formal laminectomy and indirect decompression with respect to neurologic recovery.

The Effect of Dynamic Versus Static Plating Systems on Fusion Rates and Complications in 1-Level and/or 2-Level Anterior Cervical Discectomy and Fusion: A Systematic Review.

STUDY DESIGN: A systematic review. OBJECTIVE: To determine the effect of plate design on fusion rates in patients undergoing a 1- and 2-level anterior cervical discectomy and fusion (ACDF). METHODS: Articles published between January 1, 2002 and January 1, 2015 were systematically reviewed to determine the fusion rate of 1- and 2-level ACDFs using either a fully constrained or semiconstrained locking plate. Additional variables that were collected included the number of levels, the type of graft/cage used, the study design, the method for determining fusion, and complications. RESULTS: Fifty-two articles and 3053 patients were included. No significant difference in the fusion rate for 1- and 2-level ACDF using a fully constrained plate (96.1%) and a semiconstrained plate (95.29%) was identified (P=0.84). No difference (P=0.85) in the total complication rate between fully constrained plates (3.20%) and semiconstrained plates (3.66%), or the rate of complications that required a revision (2.17% vs. 2.41%, P=0.82) was identified. However, semiconstrained plates had a nonsignificant increase in total dysphagia rates (odds ratio=1.660, P=0.28) and short-term dysphagia rates (odds ratio=2.349, P=0.10). CONCLUSIONS: In patients undergoing a 1- or 2-level ACDF, there is no significant difference in the fusion or complication rate between fully constrained plates and semiconstrained plates. LEVEL OF EVIDENCE: Level II-systematic review.

Adaptive ß-cell proliferation increases early in high-fat feeding in mice, concurrent with metabolic changes, with induction of islet cyclin D2 expression.

Type 2 diabetes (T2D) is caused by relative insulin deficiency, due in part to reduced ß-cell mass (11, 62). Therapies aimed at expanding ß-cell mass may be useful to treat T2D (14). Although feeding rodents a high-fat diet (HFD) for an extended period (3-6 mo) increases ß-cell mass by inducing ß-cell proliferation (16, 20, 53, 54), evidence suggests that adult human ß-cells may not meaningfully proliferate in response to obesity. The timing and identity of the earliest initiators of the rodent compensatory growth response, possible therapeutic targets to drive proliferation in refractory human ß-cells, are not known. To develop a model to identify early drivers of ß-cell proliferation, we studied mice during the first week of HFD exposure, determining the onset of proliferation in the context of diet-related physiological changes. Within the first week of HFD, mice consumed more kilocalories, gained weight and fat mass, and developed hyperglycemia, hyperinsulinemia, and glucose intolerance due to impaired insulin secretion. The ß-cell proliferative response also began within the first week of HFD feeding. Intriguingly, ß-cell proliferation increased before insulin resistance was detected. Cyclin D2 protein expression was increased in islets by day 7, suggesting it may be an early effector driving compensatory ß-cell proliferation in mice. This study defines the time frame and physiology to identify novel upstream regulatory signals driving mouse ß-cell mass expansion, in order to explore their efficacy, or reasons for inefficacy, in initiating human ß-cell proliferation.