Predictors of 30-Day Hospital Readmission After Posterior Cervical Fusion in 3401 Patients

The significance of metabolic disease in degenerative cervical myelopathy: a systematic review

Introduction

Degenerative cervical myelopathy (DCM) is a form of chronic spinal cord injury, with a natural history of potential for progression over time. Whilst driven by mechanical stress on the spinal cord from degenerative and congenital pathology, the neurological phenotype of DCM is likely to be modified by multiple systemic factors. The role of metabolic factors is therefore of interest, particularly given that ischaemia is considered a key pathological mechanism of spinal cord injury. The objective was therefore to synthesise current evidence on the effect of metabolism on DCM susceptibility, severity, and surgical outcomes.

Methods

A systematic review in MEDLINE and Embase was conducted following PRISMA guidelines. Full-text papers in English, with a focus on DCM and metabolism, including diabetes, cardiovascular disease, anaemia, and lipid profile, were eligible for inclusion. Risk of methodological bias was assessed using the Joanna Briggs Institute (JBI) critical assessment tools. Quality assessments were performed using the GRADE assessment tool. Patient demographics, metabolic factors and the relationships between metabolism and spinal cord disease, spinal column disease and post-operative outcomes were assessed.

Results

In total, 8,523 papers were identified, of which 57 met criteria for inclusion in the final analysis. A total of 91% (52/57) of included papers assessed the effects of diabetes in relation to DCM, of which 85% (44/52) reported an association with poor surgical outcomes; 42% of papers (24/57) discussed the association between cardiovascular health and DCM, of which 88% (21/24) reported a significant association. Overall, DCM patients with diabetes or cardiovascular disease experienced greater perioperative morbidity and poorer neurological recovery. They were also more likely to have comorbidities such as obesity and hyperlipidaemia.

Conclusion

Metabolic factors appear to be associated with surgical outcomes in DCM. However, evidence for a more specific role in DCM susceptibility and severity is uncertain. The pathophysiology and natural history of DCM are critical research priorities; the role of metabolism is therefore a key area for future research focus.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42021268814.

Incidence of Surgical Site Infection Following Lateral Lumbar Interbody Fusion Compared With Posterior/Transforaminal Lumbar Interbody Fusion: A Propensity Score-Weighted Study

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The objective of this study was to compare the incidence of surgical site infection (SSI) after lateral lumbar interbody fusion (LLIF) and posterior/transforaminal lumbar interbody fusion ( P /TLIF).

SUMMARY OF BACKGROUND DATA

Previous studies have shown that LLIF can improve neurological symptoms to a comparable degree to P /TLIF. However, data on the risk of SSI after LLIF is lacking compared with P /TLIF.

MATERIALS AND METHODS

The study was conducted under a retrospective cohort design in patients undergoing LLIF or P /TLIF for lumbar degenerative diseases between 2013 and 2020 using a hospital administrative database. We used propensity score overlap weighting to adjust for confounding factors including age, sex, body mass index, comorbidities, number of fusion levels, hospital size, and surgery year. We estimated weighted odds ratios (ORs) and 95% CIs for SSI within 30 days postoperatively.

RESULTS

We compared the risk of SSI between 2874 patients who underwent LLIF and 24,245 patients who received P/TLIF Patients who had received LLIF were at significantly less risk of experiencing an SSI compared with those receiving P/TLIF (0.7% vs. 1.2%; weighted OR: 0.57; 95% CI: 0.36 -0.92; P=0.02). As a secondary outcome, patients who had received LLIF had less risk of transfusion (7.8% vs. 11.8%; weighted OR: 0.63; 95% CI:0.54 -0.73; P <0.001).

CONCLUSIONS

In this large retrospective cohort study of adults undergoing lumbar interbody fusion, LLIF was associated with a significantly lower risk of SSI than P /TLIF. The small, but significantly, decreased risk of SSI associated with LLIF may inform decisions regarding the technical approach for lumbar interbody fusion.

Modified Frailty Index as a Predictor of Postoperative Complications and Patient-Reported Outcomes after Posterior Cervical Decompression and Fusion

STUDY DESIGN

A retrospective cohort study.

PURPOSE

To determine whether the 11-item modified frailty index (mFI) is associated with readmission rates, complication rates, revision rates, or differences in patient-reported outcome measures (PROMs) for patients undergoing posterior cervical decompression and fusion (PCDF).

OVERVIEW OF LITERATURE

mFI incorporates preexisting medical comorbidities and dependency status to determine physiological reserve. Based on previous literature, it may be used as a predictive tool for identifying postoperative clinical and surgical outcomes.

METHODS

Patients undergoing elective PCDF at our urban academic medical center from 2014 to 2020 were included. Patients were categorized by mFI scores (0-0.08, 0.09-0.17, 0.18-0.26, and ≥0.27). Univariate statistics compared demographics, comorbidities, and clinical/surgical outcomes. Multiple linear regression analysis evaluated the magnitude of improvement in PROMs at 1 year.

RESULTS

A total of 165 patients were included and grouped by mFI scores: 0 (n=36), 0.09 (n=62), 0.18 (n=42), and ≥0.27 (n=30). The severe frailty group (mFI ≥0.27) was significantly more likely to be diabetic (p <0.001) and have a greater Elixhauser comorbidity index (p =0.001). They also had worse baseline Physical Component Score-12 (PCS-12) (p =0.011) and modified Japanese Orthopaedic Association (mJOA) (p =0.012) scores and worse 1-year postoperative PCS-12 (p =0.008) and mJOA (p =0.001) scores. On regression analysis, an mFI score of 0.18 was an independent predictor of greater improvement in ΔVisual Analog Scale neck (β =-2.26, p =0.022) and ΔVAS arm (β =-1.76, p =0.042). Regardless of frailty status, patients had similar 90-day readmission rates (p =0.752), complication rates (p =0.223), and revision rates (p =0.814), but patients with severe frailty were more likely to have longer hospital length of stay (p =0.006) and require non-home discharge (p <0.001).

CONCLUSIONS

Similar improvements across most PROMs can be expected irrespective of the frailty status of patients undergoing PCDF. Complication rates, 90-day readmission rates, and revision rates are not significantly different when stratified by frailty status. However, patients with severe frailty are more likely to have longer hospital stays and require non-home discharge.

Rates and reasons for reoperation within 30 and 90 days following cervical spine surgery: a retrospective cohort analysis of the Michigan Spine Surgery Improvement Collaborative (MSSIC) registry

BACKGROUND CONTEXT

Reoperation following cervical spinal surgery negatively impacts patient outcomes and increases health care system burden. To date, most studies have evaluated reoperations within 30 days after spine surgery and have been limited in scope and focus. Evaluation within the 90-day period, however, allows a more comprehensive assessment of factors associated with reoperation.

PURPOSE

The purpose of this study is to assess the rates and reasons for reoperations after cervical spine surgery within 30 and 90 days.

DESIGN

We performed a retrospective analysis of a state-wide prospective, multi-center, spine-specific database of patients surgically treated for degenerative disease.

PATIENT SAMPLE

Patients 18 years of age or older who underwent cervical spine surgery for degenerative pathologies from February 2014 to May 2019. Operative criteria included all degenerative cervical spine procedures, including those with cervical fusions with contiguous extension down to T3.

OUTCOME MEASURES

We determined causes for reoperation and independent surgical and demographic risk factors impacting reoperation.

METHODS

Patient-specific and surgery-specific data was extracted from the registry using ICD-10-DM codes. Reoperations data was obtained through abstraction of medical records through 90 days. Univariate analysis was done using chi-square tests for categorical variables, t-tests for normally distributed variables, and Wilcoxon rank-sum tests for variables with skewed distributions. Odds ratios for return to the operating room (OR) were evaluated in multivariate analysis.

RESULTS

A total of 13,435 and 13,440 patients underwent cervical spine surgery and were included in the 30 and 90-day analysis, respectively. The overall reoperation rate was 1.24% and 3.30% within 30 and 90 days, respectively. Multivariate analysis showed within 30 days, procedures involving four or more levels, posterior only approach, and longer length of stay had increased odds of returning to the OR (p<.05), whereas private insurance had a decreased odds of return to OR (p<.05). Within 90 days, male sex, coronary artery disease (CAD), previous spine surgery, procedures with 4 or more levels, and longer length of stay had significantly increased odds of returning to the OR (p<.05). Non-white race, independent ambulatory status pre-operatively, and having private insurance had decreased odds of return to the OR (p<.05). The most common specified reasons for return to the OR within 30 days was hematoma (19%), infection (17%), and wound dehiscence (11%). Within 90 days, reoperation reasons were pain (10%), infection (9%), and hematoma (8%).

CONCLUSION

Reoperation rates after elective cervical spine surgery are 1.24% and 3.30% within 30 and 90 days, respectively. Within 30 days, four or more levels, posterior approach, and longer length of stay were risk factors for reoperation. Within 90 days, male sex, CAD, four or more levels, and longer length of hospital stay were risk factors for reoperation. Non-white demographic and independent preoperative ambulatory status were associated with decreased reoperation rates.

Machine learning-driven identification of novel patient factors for prediction of major complications after posterior cervical spinal fusion

PURPOSE

Posterior cervical fusion is associated with increased rates of complications and readmission when compared to anterior fusion. Machine learning (ML) models for risk stratification of patients undergoing posterior cervical fusion remain limited. We aim to develop a novel ensemble ML algorithm for prediction of major perioperative complications and readmission after posterior cervical fusion and identify factors important to model performance.

METHODS

This is a retrospective cohort study of adults who underwent posterior cervical fusion at non-federal California hospitals between 2015 and 2017. The primary outcome was readmission or major complication. We developed an ensemble model predicting complication risk using an automated ML framework. We compared performance with standard ML models and logistic regression (LR), ranking contribution of included variables to model performance.

RESULTS

Of the included 6822 patients, 18.8% suffered a major complication or readmission. The ensemble model demonstrated slightly superior predictive performance compared to LR and standard ML models. The most important features to performance include sex, malignancy, pneumonia, stroke, and teaching hospital status. Seven of the ten most important features for the ensemble model were markedly less important for LR.

CONCLUSION

We report an ensemble ML model for prediction of major complications and readmission after posterior cervical fusion with a modest risk prediction advantage compared to LR and benchmark ML models. Notably, the features most important to the ensemble are markedly different from those for LR, suggesting that advanced ML methods may identify novel prognostic factors for adverse outcomes after posterior cervical fusion.

Discharge to Rehabilitation Predicts Increased Morbidity in Patients Undergoing Posterior Cervical Decompression and Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim was to compare 30-day readmission and postdischarge morbidity for posterior cervical decompression and fusion (PCDF) in patients who were discharged to home versus rehabilitation.

SUMMARY OF BACKGROUND DATA

An increasing number of patients are being discharged to postacute inpatient care facilities following spine surgery. However, little research has been performed to evaluate the effect of this trend on short-term outcomes.

MATERIALS AND METHODS

Patients who underwent PCDF from 2011 to 2018 were identified using the National Surgical Quality Improvements Program (NSQIP)-database. Regression was utilized to compare primary outcomes between home and rehabilitation groups and to control for predictors of outcomes.

RESULTS

We identified 8912 patients. Unadjusted analysis revealed that rehabilitation-discharge patients had greater readmission (10.4% vs. 8.0%, P=0.002) and postdischarge morbidity (7.1% vs. 4.0%, P<0.001) rates. After controlling for patient-related factors, rehabilitation-discharge independently predicted postdischarge morbidity (P<0.001, odds ratio=2.232). Readmission no longer differed between groups (P=0.071, odds ratio=1.311). Rates of discharge to rehabilitation increased from 23.5% in 2011 to 25.3% in 2018, while postdischarge morbidity rates remained stagnant.Patients discharged to rehabilitation were older (66.9 vs. 59.4 y); more likely to be African American (21.4% vs. 13.8%) and have diabetes (27.1% vs. 17.5%), steroid use (6.4% vs. 4.7%, P=0.002), and American Society of Anaesthesiologists (ASA)-class ≥3 (80.2% vs. 57.7%); less likely to be male (53.9% vs. 57.4%, P=0.004) and smokers (20.3% vs. 26.6%); and had greater operative time (198 vs. 170 min) and length of hospital stay (5.9 vs. 3.3 d) (P<0.001).

CONCLUSIONS

Despite controlling for significant factors, discharge to rehabilitation independently predicted a 2.2 times increased odds of postdischarge morbidity. Rates of discharge to rehabilitation increased overtime without an appreciable decrease in postdischarge morbidity, suggesting that greater resources are being utilized in the postacute care period without an obvious justification. Therefore, home-discharge should be prioritized after hospitalization for PCDF when feasible. These findings are notable in light of reform efforts aimed at reducing costs while improving quality of care.

Increased Surgical Site Subcutaneous Fat Thickness Is Associated with Infection after Posterior Cervical Fusion

Background: Previous literature has associated increased body mass index (BMI) with risk of surgical site infection (SSI) after posterior cervical fusion (PCF) surgery. However, few studies have examined the association between local adiposity and risk of SSI, re-admission, and re-operation after PCF. Local adiposity is easily measured on pre-operative magnetic resonance imaging (MRI) and may act as a more accurate predictor compared with BMI. Patients and Methods: Subjects undergoing PCF from 2013-2018 at a single institution were identified retrospectively. Posterior cervical subcutaneous fat thickness, paraspinal muscle thickness, and lamina-to-skin distance measurements were obtained from computed tomography (CT) or MRI scans. Subjects with active infection, malignancy, or revision procedures were excluded. Results: Two hundred five patients were included with 20 developing SSIs. Subjects with SSIs had a longer fusion construct (4.90 vs. 3.71 levels; p = 0.001), higher Elixhauser comorbidity index (ECI; 2.05 vs. 1.34; p = 0.045), had a history of diabetes mellitus (30% vs. 10.8%; p = 0.026), higher subcutaneous fat thickness (30.5 vs. 23.6 mm; p = 0.013), and higher lamina-to-skin distance (66.4 vs. 57.9 mm; p = 0.027). Subcutaneous fat thickness (odds ratio [OR], 1.05; 95% confidence interval [CI], 1.01-1.10]; p = 0.026) and lamina-to-skin distance (OR, 1.05; 95% CI, 1.01-1.09]; p = 0.014) were associated with SSI in multivariable analysis. A subcutaneous fat thickness cutoff value of 23.2 mm had 90% sensitivity and 54.1% specificity for prediction of SSI. There was no association need for re-admission or re-operation. Conclusions: Increased posterior cervical fat may increase the risk of SSI after PCF. Pre-operative advanced imaging may be a valuable tool for assisting with patient counseling, optimization, and risk stratification.

IDENTIFICATION OF RISK FACTORS ASSOCIATED WITH 30-DAY READMISSION OF PATIENTS SUBMITTED TO ANTERIOR OR POSTERIOR ACCESS CERVICAL SPINE SURGERY

ABSTRACT Aim: To conduct a systematic review of the literature to identify risk factors associated with 30-day readmission of patients submitted to anterior or posterior access cervical spine surgery. Methods: The databases used to select the papers were PubMed, Web of Science, and Cochrane, using the following search strategy: patient AND readmission AND (30 day OR “thirty day” OR 30-day OR thirty-day) AND (spine AND cervical). Results: Initially, 179 papers that satisfied the established search stringwere selected. After reading the titles and abstracts, 46 were excluded from the sample for not effectively discussing the theme proposed for this review. Of the 133 remaining papers, 109 were also excluded after a detailed reading of their content, leaving 24 that were included in the sample for the meta-analysis. Conclusions: The average readmission rate in the studies evaluated was 4.85%. Only the occurrence of infections, as well as the presence of patients classified by the American Society of Anesthesiology (ASA) assessment system with scores greater than III, were causal factors that influenced the readmission of patients. No significant differences were noted when comparing the anterior and posterior surgical access routes. Level of evidence II; Systematic Review of Level II or Level I Studies with discrepant results.

The Role of Nutrition in Degenerative Cervical Myelopathy: A Systematic Review

Introduction

Degenerative cervical myelopathy (DCM) is the commonest cause of adult spinal cord impairment worldwide, encompassing chronic compression of the spinal cord, neurological disability and diminished quality of life. Evidence on the contribution of environmental factors is sparse; in particular, the role of nutrition in DCM is unknown. The objective of this review was to assess the effect of nutrition on DCM susceptibility, severity and surgical outcome.

Methods

A systematic review in MEDLINE and Embase was conducted following PRISMA guidelines. Full-text papers in English papers, focussing on cervical myelopathy and nutrition, published before January 2020 were considered eligible. Quality assessments were performed using the GRADE assessment tool. Patient demographics, nutritional factor and DCM outcomes measures were recorded. Relationships between nutritional factors, interventions and disease prognosis were assessed.

Results

In total, 5835 papers were identified of which 44 were included in the final analysis. DCM patients with pathological weight pre-operatively were more likely to see poorer improvements post-surgically. These patients experienced poorer physical and mental health improvements from surgery compared to normal weight patients and were more likely to suffer from post-operative complications such as infection, DVT, PE and hospital readmissions. Two trials reporting benefits of nutritional supplements were identified, with 1 suggesting Cerebrolysin to be significant in functional improvement. An unbalanced diet, history of alcohol abuse and malnourishment were associated with poorer post-operative outcome.

Conclusion

Although the overall strength of recommendation is low, current evidence suggests nutrition may have a significant role in optimising surgical outcome in DCM patients. Although it may have a role in onset and severity of DCM, this is a preliminary suggestion. Further work needs to be done on how nutrition is defined and measured, however, the beneficial results from studies with nutritional interventions suggest nutrition could be a treatment target in DCM.

Invasive Staphylococcus aureus Infection among Patients Undergoing Elective, Posterior, Instrumented Spinal Fusion Surgeries: A Retrospective Cohort Study

Background: Post-surgical invasive Staphylococcus aureus infections among spinal fusion patients are serious complications that can worsen clinical outcomes and increase healthcare utilization. Risk of such infections at the population level remains unknown. This study assessed the post-surgical risk of invasive Staphylococcus aureus infections among patients undergoing elective posterior instrumented spinal fusion surgeries in 129 U.S. hospitals. Patients and Methods: This retrospective cohort study analyzed adult patients ≥18 years of age who underwent thoracolumbar/lumbar and cervical fusion surgeries during 2010 - 2014 using the Premier Healthcare Database, the largest hospital discharge database in the United States. Risks of blood stream infection (BSI), deep or organ/space surgical site infections (SSI) caused by Staphylococcus aureus during 90 and 180 days post-index surgery were estimated. Infections were identified based on positive culture results, related International Classification of Diseases, Ninth Revision (ICD-9) procedure codes, and specific claims information. Results: Among 11,236 patients with thoracolumbar/lumbar fusion, 90- and 180-day BSI/SSI infection risks were higher for multilevel than single level fusion (90-day, 1.52% vs. 1.07%, p = 0.05; 180-day, 1.66% vs. 1.07%, p = 0.014). Among 1,641 patients with cervical fusion, 90- and 180-day BSI/SSI infection risks were also higher in multilevel fusions but not statistically significant (90-day, 1.66% vs. 0.52%, p = 0.350; 180-day, 1.80% vs. 0.51%, p = 0.241). The risk for SSI/BSI was more than twice as high among multilevel thoracolumbar/lumbar fusion patients with more than two comorbidities than those with no comorbidity at both 90-day (2.78% vs. 1.00%, p < 0.05) and 180-day (3.01% vs. 1.10%, p < 0.05). Similar trend without statistical significance was seen in multilevel cervical fusion cohort (90-day, 2.91% vs. 1.25%, p > 0.05; 180-day, 3.88% vs. 1.41%, p > 0.05). Conclusions: The risk of BSI/SSI infection for elective posterior instrumented spinal fusions ranged between 0.5% and 2%. Higher risk was observed in multilevel thoracolumbar/lumbar surgery, with infection risk greatest in patients with more than two comorbidities. These real-world findings highlight the need for additional measures, in addition to antibiotic prophylaxis, to reduce invasive Staphylococcus aureus infections in this setting.

Postoperative Glycemic Variability and Adverse Outcomes After Posterior Cervical Fusion

INTRODUCTION

Posterior cervical decompression and fusion (PCDF) is a procedure commonly performed to help alleviate symptoms and improve quality of life in patients experiencing cervical spondylotic myelopathy, multilevel stenosis, and cervical deformity. Although various risk factors have been linked to adverse outcomes in patients after PCDF, this is the first study that specifically explores postoperative glycemic variability and its association with adverse outcomes.

METHODS

A retrospective cohort study was conducted with a total of 264 patients after PCDF procedures that had available postoperative blood glucose measurements. Patients were divided into tertiles based on their coefficient of variation as an indicator of glycemic variability. Outcomes measured included inpatient complications, length of stay (LOS), 90-day readmission, revision, and surgical site infection rates.

RESULTS

Results showed a significant difference in glycemic variability among tertiles with respect to LOS (P = 0.01). The average LOS for the first, second, and third tertiles was 3.90 (3.20, 4.59), 5.73 (4.45, 7.00), and 6.06 (4.89, 7.22), respectively. Logistic regression analysis showed significantly higher odds of readmission (odds ratio: 4.77; P = 0.03) and surgical site infections (odds ratio: 4.35; P = 0.04) in the high glycemic variability group compared with the low glycemic variability group within 90 days of surgery. No significant difference was noted among tertiles with respect to inpatient complications.

DISCUSSION

This study establishes a relationship between postoperative glycemic variability and LOS, as well as 90-day readmission and surgical site infection rates after PCDF. Our results suggest that limiting fluctuations in blood glucose levels may curtail inpatient healthcare costs related to in-hospital stay. Although immediate postoperative glycemic variability is ultimately acceptable, before discharge, proper glucose management plans should be in place to help prevent adverse patient outcomes.

Unplanned hospital readmission after surgical treatment for thoracic spinal stenosis: incidence and causative factors

BACKGROUND

To assess the incidence and causative factors of unplanned hospital readmission within 90 days after surgical treatment of thoracic spinal stenosis (TSS).

METHODS

Hospital administrative database was queried to identify patients who underwent surgical treatment of TSS from July 2010 through December 2017. All unplanned readmissions within 90 days of discharge were reviewed for causes and the rate of unplanned readmissions was calculated. Patients of unplanned readmission were matched 1:3 to a control cohort without readmission.

RESULTS

Twenty-one patients (incidence of 1.7 % in 1239 patients) presented unplanned hospital readmission within a 90-day period and enrolled as the study group, 63 non-readmission patients (a proportion of 1: 3) were randomly selected as the control group. Causes of readmission include pseudomeningocele (8 patients; 38 %), CSF leakage combined with poor incision healing (6 patients; 29 %), wound dehiscence (2 patient; 9 %), surgical site infection (2 patients; 9 %), spinal epidural hematoma (1 patient; 5 %), inadequate original surgical decompression (2 patients; 9 %). Mean duration from re-admission to the first surgery was 39.6 ± 28.2 days, most of the patients readmitted at the first 40 days (66.7 %, 14/21 patients). When compared to the non-readmitted patients, diagnosis of OPLL + OFL, circumferential decompression, dural injury, long hospital stay were more to be seen in readmitted patients.

CONCLUSIONS

The incidence of 90-day unplanned readmission after surgical treatment for TSS is 1.7 %, CSF leakage and pseudomeningocele were the most common causes of readmission, the peak period of readmission occurred from 10 to 40 days after surgery, patients should be closely followed up within this period.

Nonhome Discharge as an Independent Risk Factor for Adverse Events and Readmission in Patients Undergoing Anterior Cervical Discectomy and Fusion

STUDY DESIGN

A retrospective study of a prospectively collected cohort.

OBJECTIVE

To characterize a cohort of patients who underwent anterior cervical discectomy and fusion (ACDF) and examine whether nonhome discharge (NHD) is associated with postdischarge adverse events (AEs) and readmission.

SUMMARY OF THE BACKGROUND DATA

Predictors of NHD have been elucidated in the spine surgery literature, and NHD has been tied to poor outcomes in the joint arthroplasty literature, but no such analysis exists for patients undergoing ACDF.

MATERIALS AND METHODS

All patients who underwent ACDF from 2012 to 2015 in the National Surgical Quality Improvement Program were identified. Those who underwent concomitant posterior cervical operations were excluded. Patients who were discharged to home were compared with those discharged to nonhome destinations on the basis of demographics and outcomes. Multivariable models were created to assess whether NHD was an independent risk factor for postdischarge AEs and readmission.

RESULTS

NHD patients were significantly older (63.96 vs. 53.57 y; P<0.0001), more functionally dependent (13.87% vs. 1.09%; P<0.0001), more likely to have body mass index >40 (9.38% vs. 7.51%; P=0.004), and more likely to have ASA Class >2 (77.89% vs. 39.57%; P<0.0001). Patients who underwent NHD were significantly more likely to suffer severe AEs (14.44% vs. 0.93%; P<0.0001), minor AEs (7.22% vs. 0.24%; P<0.0001), and infectious complications (3.58% vs. 0.13%; P<0.0001) before discharge. When examining AEs after discharge, patients who underwent NHD were more likely to suffer severe AEs (6.37% vs. 1.34%; P<0.0001), minor AEs (4.09% vs. 0.74%; P<0.0001), death (1.25% vs. 0.07%; P<0.0001), and unplanned readmission (10.12% vs. 3.06%; P<0.0001). In adjusted analysis, NHD was found to independently predict severe AEs after discharge (odds ratio, 2.40; 95% confidence interval, 1.87-3.07; P<0.0001) and readmission (odds ratio, 1.77; 95% confidence interval, 1.46-2.14; P<0.0001).

CONCLUSIONS

NHD patients were significantly sicker than those discharged home. In addition, NHD is associated with higher rates of postdischarge complications.

Minimally Invasive Posterior Cervical Fusion With Facet Cages to Augment High-Risk Anterior Cervical Arthrodesis: A Case Series

STUDY DESIGN

Retrospective case series.

OBJECTIVES

To evaluate the efficacy and results of minimally invasive posterior cervical fusion with facet cages as an augment to high-risk patients and patients status post multilevel anterior cervical decompression and fusion.

METHODS

Thirty-five patients with symptomatic cervical stenosis with high risk for pseudoarthrosis underwent circumferential cervical decompression and fusion via staged anterior and posterior approach. Anterior cervical decompression and fusion was performed first by means of the standard anterior approach, with the patient supine on the operating table. The patients were subsequently flipped into a prone position and minimally invasive posterior cervical facet fusion with DTRAX was performed. The patients were then followed in the outpatient clinic for an average of 312.71 days. Postoperative patient satisfaction scores were obtained via the visual analogue scale (VAS). Preoperative VAS scores were compared with postoperative VAS scores in order to evaluate patient outcomes.

RESULTS

Of the 35 patients evaluated, minimum follow-up was 102 days, with a maximum follow-up of 839 days. Average preoperative and postoperative VAS scores were 7.6 and 2.8, respectively (P < .0001), with an average improvement of 4.86 points. This was an average improvement of 64.70% from preoperative to postoperative. Seventeen patients had excellent outcomes, with a postoperative VAS score ≤2. Seven patients achieved a postoperative VAS score of 0, with 100% improvement of preoperative pain and symptoms. Average blood loss was 70.38 mL. Average length of stay was 1.03 days.

CONCLUSIONS

The results indicate that minimally invasive posterior cervical decompression and fusion with facet cages, when combined with standard anterior cervical decompression and fusion, is an effective means of obtaining circumferential cervical fusion while simultaneously improving patient outcomes.

Using machine learning to predict 30-day readmissions after posterior lumbar fusion: an NSQIP study involving 23,264 patients

OBJECTIVE

Unplanned preventable hospital readmissions within 30 days are a great burden to patients and the healthcare system. With an estimated $41.3 billion spent yearly, reducing such readmission rates is of the utmost importance. With the widespread adoption of big data and machine learning, clinicians can use these analytical tools to understand these complex relationships and find predictive factors that can be generalized to future patients. The object of this study was to assess the efficacy of a machine learning algorithm in the prediction of 30-day hospital readmission after posterior spinal fusion surgery.

METHODS

The authors analyzed the distribution of National Surgical Quality Improvement Program (NSQIP) posterior lumbar fusions from 2011 to 2016 by using machine learning techniques to create a model predictive of hospital readmissions. A deep neural network was trained using 177 unique input variables. The model was trained and tested using cross-validation, in which the data were randomly partitioned into training (n = 17,448 [75%]) and testing (n = 5816 [25%]) data sets. In training, the 17,448 training cases were fed through a series of 7 layers, each with varying degrees of forward and backward communicating nodes (neurons).

RESULTS

Mean and median positive predictive values were 78.5% and 78.0%, respectively. Mean and median negative predictive values were both 97%, respectively. Mean and median areas under the curve for the model were 0.812 and 0.810, respectively. The five most heavily weighted inputs were (in order of importance) return to the operating room, septic shock, superficial surgical site infection, sepsis, and being on a ventilator for > 48 hours.

CONCLUSIONS

Machine learning and artificial intelligence are powerful tools with the ability to improve understanding of predictive metrics in clinical spine surgery. The authors' model was able to predict those patients who would not require readmission. Similarly, the majority of predicted readmissions (up to 60%) were predicted by the model while retaining a 0% false-positive rate. Such findings suggest a possible need for reevaluation of the current Hospital Readmissions Reduction Program penalties in spine surgery.

30- and 90-Day Unplanned Readmission Rates, Causes, and Risk Factors After Cervical Fusion: A Single-Institution Analysis

STUDY DESIGN

Retrospective cohort study OBJECTIVE.: To study 30- and 90-day readmission rates, causes, and risk factors after anterior cervical discectomy and fusion (ACDF) and posterior cervical fusion (PCF).

SUMMARY OF BACKGROUND DATA

Existing data on readmission after cervical fusion is majorly derived from national databases. Given their inherent limitations in accuracy, follow-up available, and missing data, we intend to add to literature from our institutional analysis.

METHODS

Patients who underwent ACDF and PCF for degenerative cervical pathology in 2013 and 2014 were identified for the study. Comprehensive chart review was performed to record demographics and clinical patient profile. Hospital readmission within 30 and 90 days was identified, and the causes and management were recorded. Binary logistic regression analysis was done to study risk factors for readmission. ACDF and PCF were studied separately.

RESULTS

Our analysis included a total of 549 patients, stratified as 389 ACDFs and 160 PCFs. The 30- and 90-day unplanned readmission rate was 5.1% and 7.7% after ACDF. These rates were 11.2% and 16.9% after PCF. The most common cause of readmission was systemic infection and sepsis after ACDF and PCF (31.4% and 25.8% of readmitted, respectively), followed by pulmonary complications after ACDF (14.3% of readmitted) and wound complications after PCF (19.4% of readmitted). Predictors of readmission after ACDF included heart failure, history of malignancy, history of deep vein thrombosis/pulmonary embolism, and any intraoperative complication. In the PCF cohort, history of ischemic heart disease, increasing number of fusion levels and longer length of stay were independently predictive.

CONCLUSION

The rates, causes, and risk factors of readmission after ACDF and PCF have been identified. There is variation in published data regarding the incidence and risk factors for readmission after cervical fusion; however, majority of readmissions occur due to medical complications and systemic infection.

LEVEL OF EVIDENCE

3.

Cost and Hospital Resource Utilization of Staphylococcus aureus Infection Post Elective Posterior Instrumented Spinal Fusion Surgeries in U.S. Hospitals: A Retrospective Cohort Study

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

The aim of this study was to assess hospital resource utilization and costs associated with Staphylococcus aureus infection within 180 days post elective posterior instrumented spinal fusion surgeries (index surgery) between 2010 and 2015.

SUMMARY OF BACKGROUND DATA

Surgical site infections (SSIs) and blood stream infections (BSIs) post spinal fusion surgeries are associated with worse clinical outcomes and increased costs. Economic data specific to the most common pathogen of infections post spinal fusion surgeries, S. aureus, are limited.

METHODS

We analyzed hospital discharge and microbiology data from 129 U.S. hospitals in Premier Healthcare Database. Selection criteria included age ≥ 18 years; had a primary/secondary ICD-9-CM procedure code for index surgery; and had microbiology data during study period. Outcomes included total hospitalization cost, length of stay, and risk of all-cause readmission. Infection status was classified as culture-confirmed invasive (i.e., BSIs, deep or organ/space SSIs), any, and no S. aureus infection. Multivariable regression analyses were used to compare outcome variables between infection groups controlling for known confounders.

RESULTS

Two hundred ninety-four patients had any S. aureus infection (151 had invasive infection) and 12,918 had no infection. Compared with no infection group, invasive and any infection groups had higher total hospitalization cost (adjusted mean in 2015 U.S. dollars: $88,353 and $64,356 vs. $47,366, P < 0.001), longer length of stay (adjusted mean: 20.98 and 13.15 vs. 6.77 days, P < 0.001), and higher risk of all-cause readmission [adjusted risk ratio: 2.15 (95% confidence interval: 2.06-2.25) for invasive and 1.70 (95% confidence interval: 1.61-1.80) for any infection groups].

CONCLUSION

S. aureus infections post elective posterior instrumented spinal fusion surgeries are associated with significantly higher hospitalization cost, length of stay, and 180-day risk of readmission than those with no such infection, which presents substantial burden to hospitals and patients. Reducing such infections may cut costs and hospital resource utilization.

LEVEL OF EVIDENCE

3.

Predictive Risk Factors of Nonhome Discharge Following Elective Posterior Cervical Fusion

OBJECTIVE

To identify risk factors that are predictive of nonhome discharge after elective posterior cervical fusion.

METHODS

We performed a retrospective cohort study of adult patients who underwent elective posterior cervical fusion using the American College of Surgeons National Surgical Quality Improvement Program database from 2010 to 2014. Patients were divided into 2 groups: home discharge and nonhome discharge. Univariate analysis was performed to compare incidence of 30-day postoperative complications between groups. Multivariate analysis was performed to identify complications that were predictive of nonhome discharge.

RESULTS

The cohort included 2875 patients; 24.1% were discharged to a nonhome facility, including skilled and nonskilled care facilities, nursing homes, assisted living facilities, and rehabilitation facilities. Nonhome discharge was associated with higher rates of 30-day pulmonary complication, cardiac complication, venous thromboembolism, urinary tract infection, blood transfusion, sepsis, and reoperation. Significant predictors of nonhome discharge were wound complication (odds ratio [OR] = 1.73; 95% confidence interval [CI], 1.07-2.80; P = 0.024), pulmonary complication (OR = 3.61; 95% CI, 1.96-6.63; P < 0.001), cardiac complication (OR = 6.13; 95% CI, 1.61-23.4; P = 0.008), venous thromboembolism (OR = 2.97; 95% CI, 1.43-6.19; P = 0.004), urinary tract infection (OR = 2.69; 95% CI, 1.50-4.82; P < 0.001), blood transfusion (OR = 1.70; 95% CI, 1.20-2.39; P = 0.003), sepsis (OR = 2.75; 95% CI, 1.25-6.02; P = 0.012), and prolonged length of stay (OR = 4.07; 95% CI, 3.34-4.95; P < 0.001).

CONCLUSIONS

Early identification of patients who are at high risk for nonhome discharge is important to implement early comprehensive discharge planning protocols and minimize hospital-acquired conditions related to prolonged length of stay and associated health care costs.

Postoperative Emergency Department Utilization and Hospital Readmission After Cervical Spine Arthrodesis: Rates, Trends, Causes, and Risk Factors

STUDY DESIGN

Retrospective state database analysis.

OBJECTIVE

To quantify the 30- and 90-day emergency department (ED) utilization and inpatient readmission rates after primary cervical arthrodesis, to stratify these findings by surgical approach, and to describe risk factors and conditions precipitating these events.

SUMMARY OF BACKGROUND DATA

Limited data exist on ED utilization and hospital readmission rates after cervical spine arthrodesis.

METHODS

The New York State all-payer health-care database was queried to identify all 87,045 patients who underwent primary subaxial cervical arthrodesis from 1997 through 2012. Demographic data and clinical information were extracted. Readmission data were available for the entire study period, whereas ED utilization data collection began later and was therefore analyzed starting in 2005. Incidences of these events within 30 and 90 days of discharge as well as trends over time were tabulated. The conditions prompting these encounters were also collected. Data were analyzed with respect to surgical approach.

RESULTS

The hospital readmission rate was 4.2% at 30 days and 6.2% at 90 days postoperatively. Approximately 6.2% of patients were managed in the ED without inpatient admission within 30 days and 11.3% within 90 days of surgery. The most common conditions prompting such events were dysphagia or dysphonia, respiratory complications, and infection. ED utilization and readmission rates were lowest after anterior surgeries. A preoperative Charlson Comorbidity Index of 1 or greater and traumatic pathologies were associated with increased risk of subsequent ED utilization or hospital readmission. Thirty-day hospital readmission rates declined after 2010, whereas 30-day ED utilization continued to increase.

CONCLUSION

Patient comorbidities, traumatic pathologies, and surgical approach are associated with increased postoperative complications. Anterior procedures carry the lowest risk, followed by posterior and then circumferential. Awareness of these findings should help to encourage development of strategies to minimize the rate of postoperative ED utilization and hospital readmission.

LEVEL OF EVIDENCE

3.

Impact of Perioperative Neurologic Deficits on Clinical Outcomes After Posterior Cervical Fusion

BACKGROUND

In the United States, the number of posterior cervical fusions has increased substantially. Perioperative neurologic complications associated with this procedure, such as spinal cord and peripheral nerve injuries, can have significant effects on patient health. We examined the impact of perioperative neurologic deficits on mortality in patients undergoing posterior cervical fusion. The secondary aim was to understand the risk factors for perioperative neurologic complications.

METHODS

Data were collected from the National Inpatient Sample (NIS) Health Cost Utilization Project (HCUP) between 1999 and 2011. Patients younger than 18 years and older than 80 years were excluded, as were patients who underwent posterior cervical fusion caused by trauma. Patient demographics and comorbidities were compiled as well as variables that have been associated with increased risk of perioperative neurologic deficits. We used the van Walraven score, a weighted numeric surrogate for the Elixhauser comorbidity index, as a covariate to assess comorbidities that have been associated with in-hospital mortality and morbidity after posterior cervical fusion. In addition, we performed univariate comparisons between covariates and surgical outcomes. We conducted a multivariable logistic regression, adjusting for many of the covariates, as well as trend analyses.

RESULTS

An analysis of 33,644 patients yielded an overall rate of perioperative neurologic deficits, morbidity, and mortality of 1.08%, 40.44%, and 1.00%, respectively. Perioperative neurologic deficits were independent risk factors predictors of in-hospital mortality (odds ratio, 5.270; P < 0.0001) and morbidity (odds ratio, 2.579; P < 0.0001). Other statistically significant predictors of mortality included increasing van Walraven score, myocardial infarction, metastatic cancer, and weight loss. These were also independent predictors of morbidity along with but not limited to age, device complications, congestive heart failure, paralysis, diabetes with chronic complications, deficiency anemias, device complications, and intraspinal abscess.

CONCLUSIONS

Perioperative neurologic deficits are serious complications of posterior cervical fusion and can independently predict in-hospital mortality and morbidity. As this procedure continues to be used increasingly, attention should be directed toward preventing these complications and intervening earlier in patients who have a neurologic deficit. Future efforts should be geared toward screening for at-risk patients with the initiation of surgical prehabilitation.

High-Risk Subgroup Membership Is a Predictor of 30-Day Morbidity Following Anterior Lumbar Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine if membership in a high-risk subgroup is predictive of morbidity and mortality following anterior lumbar fusion (ALF).

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database was utilized to identify patients undergoing ALF between 2010 and 2014. Multivariate analysis was utilized to identify high-risk subgroup membership as an independent predictor of postoperative complications.

RESULTS

Members of the elderly (≥65 years) (OR = 1.3, P = .02) and non-Caucasian (black, Hispanic, other) (OR = 1.7, P < .0001) subgroups were at greater risk for a LOS ≥5 days. Obese patients (≥30 kg/m² ) were at greater risk for an operative time ≥4 hours (OR = 1.3, P = .005), and wound complications (OR = 1.8, P = .024) compared with nonobese patients. Emergent procedures had a significantly increased risk for LOS ≥5 days (OR = 4.9, P = .021), sepsis (OR = 14.8, P = .018), and reoperation (OR = 13.4, P < .0001) compared with nonemergent procedures. Disseminated cancer was an independent risk factor for operative time ≥4 hours (OR = 8.4, P < .0001), LOS ≥5 days (OR = 15.2, P < .0001), pulmonary complications (OR = 7.4, P = .019), and postoperative blood transfusion (OR = 3.1, P = .040).

CONCLUSIONS

High-risk subgroup membership is an independent risk factor for morbidity following ALF. These groups should be targets for aggressive preoperative optimization, and quality improvement initiatives.

Effect of Preoperative Anemia on the Outcomes of Anterior Cervical Discectomy and Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Preoperative anemia has been associated with an increased need for blood transfusions and postoperative complications. The effects of anemia on the outcomes of anterior cervical discectomy and fusion (ACDF) have not been explored. The present study aimed to evaluate the association between preoperative anemia and 30-day complications following ACDF surgery.

METHODS

Data from the American College of Surgeons National Surgical Quality Improvement Program (2005-2012) was used. Preoperative anemia was defined as hematocrit <39% for males and <36% for females. A bivariate analysis was performed on demographic and perioperative variables. Multivariable logistic regression models were employed, adjusting for patient variables, to identify independent risk factors for complications.

RESULTS

A total of 3500 patients were included of which 444 (12.7%) were anemic patients. Multivariate analysis was used to quantify the predictive power of anemia on key postoperative outcomes, while controlling for the other statistically significant. Preoperative anemia was found to be a statistically significant predictor of any complication (odds ratio [OR] = 1.853; 95% confidence interval [CI] = 1.17-2.934; P = .0086), pulmonary complications (OR = 3.269; 95% CI = 1.745-6.126; P = .0002), intraoperative blood transfusion (OR = 4.364; 95% CI = 1.48-12.866; P = 0.0076), return to operating theatre (OR = 2.655; 95% CI = 1.539-4.582; P = .0005), and length of hospital stay more than 5 days (OR = 2.151; 95% CI = 1.499-3.085; P < .0001).

CONCLUSION

Preoperative anemia appears to be a significant predictor of perioperative complications, reoperation, and extended length of hospital stay in patients undergoing elective ACDF. Future studies should explore outcomes of treatment of preoperative anemia prior to surgery to determine the optimal management strategy.