Weekend Admission Increases Risk of Readmissions Following Elective Thoracolumbar Spinal Fusion

STUDY DESIGN

Retrospective database study.

OBJECTIVES

The goal of this study was to assess the influence of weekend admission on patients undergoing elective thoracolumbar spinal fusion by investigating hospital readmission outcomes and analyzing differences in demographics, comorbidities, and postoperative factors.

METHODS

The 2016-2018 Nationwide Readmission Database was used to identify adult patients who underwent elective thoracolumbar spinal fusion. The sample was divided into weekday and weekend admission patients. Demographics, comorbidities, complications, and discharge status data were compiled. The primary outcomes were 30-day and 90-day readmission. Univariate logistic regression analyzed the relationship between weekday or weekend admission and 30- or 90-day readmission, and multivariate regression determined the impact of covariates.

RESULTS

177,847 patients were identified in total, with 176,842 in the weekday cohort and 1005 in the weekend cohort. Multivariate regression analysis found that 30-day readmissions were significantly greater for the weekend cohort after adjusting for sex, age, Medicare or Medicaid status, and comorbidity status (OR 2.00, 95% CI: 1.60-2.48; P < .001), and 90-day readmissions were also greater for the weekend cohort after adjustment (OR 2.01, 95% CI: 1.68-2.40, P < .001).

CONCLUSIONS

Patients undergoing elective thoracolumbar spinal fusion surgery who are initially admitted on weekends are more likely to experience hospital readmission. These patients have increased incidence of deep vein thrombosis, postoperative infection, and non-routine discharge status. These factors are potential areas of focus for reducing the impact of the "weekend effect" and improving outcomes for elective thoracolumbar spinal fusion.

Perioperative pain protocols following surgery for adolescent idiopathic scoliosis: a snapshot of current treatments utilized by attending orthopedic surgeons

PURPOSE

Perioperative management after adolescent idiopathic scoliosis (AIS) surgery varies extensively between surgeons and institutions. We devised a questionnaire to assess surgeon baseline characteristics, practice settings, and pain regimens to assess what factors contribute to perioperative pain protocols.

METHODS

A multiple-choice questionnaire including 130 independent variables regarding baseline characteristics, practice environments, and pain regimen protocols was distributed to elicit information among surgeons performing AIS fusion surgery. Pairwise bivariate analysis between practice location, length of practice, and practice environment vs. type of post-operative analgesia was completed using two-tailed Fisher's exact test.

RESULTS

85 respondents participated, all identified as practicing orthopedic surgeons. The largest group of respondents reported 20-40% of their total practice was dedicated to AIS (36%). Respondents were predominantly hospital-employed academic physicians (67%). The most common pain medication administered preoperatively was gabapentin (54%). Postoperative regimens were highly varied. Discharge pain regimens most commonly included short-acting opiates (89%), acetaminophen (86%), antispasmodics (59%), and NSAIDs (51%). Bivariate analysis revealed that fentanyl PCA was significantly associated with practice location (p < 0.05). Utilization of NSAIDs was significantly associated with length in training, with older physicians utilizing anti-inflammatories more regularly than younger physicians (p < 0.05).

CONCLUSION

This study identifies common perioperative regimens utilized in AIS surgery. Of interest, younger surgeons are less likely to prescribe NSAIDs post-operatively than surgeons who have been in practice for longer periods of time, which may represent a bias against anti-inflammatory medications in younger surgeons.

An examination of mindfulness on Mu suppression and pain empathy and its relation to trait empathy

There have been multiple benefits reported from the practice of mindfulness meditation. Recently social functioning, including empathy, has emerged as one such possible benefit. However, the literature is mixed and it is unknown if mindfulness has an effect on the neural mechanism involved in empathy. Therefore, we conducted a large-scale experimental study involving over 100 participants that were either enrolled in a behavioral or EEG experiment to examine pain empathy and mu suppression, respectively. We also measured state and trait mindfulness and trait empathy. Results did not show a change in pain empathy or mu suppression in response to an acute mindfulness manipulation. However, pain empathy responses were able to be predicted significantly better when the component of state mindfulness involving decentering was incorporated into a regression model compared to trait empathy alone. Also, trait empathy was related to trait mindfulness. Collectively, state decentering may be involved in increased pain empathy, while trait mindfulness appears more related to general trait empathy. Further research is warranted to better understand the potential benefit a brief mindfulness meditation may produce in the realm of brain activity and social functioning.

Addition of dexamethasone to prolong peripheral nerve blocks: a ChatGPT-created narrative review

Chat Generative Pre-trained Transformer (ChatGPT), an artificial intelligence chatbot, produces detailed responses and human-like coherent answers, and has been used in the clinical and academic medicine. To evaluate its accuracy in regional anesthesia topics, we produced a ChatGPT review on the addition of dexamethasone to prolong peripheral nerve blocks. A group of experts in regional anesthesia and pain medicine were invited to help shape the topic to be studied, refine the questions entered in to the ChatGPT program, vet the manuscript for accuracy, and create a commentary on the article. Although ChatGPT produced an adequate summary of the topic for a general medical or lay audience, the review that were created appeared to be inadequate for a subspecialty audience as the expert authors. Major concerns raised by the authors included the poor search methodology, poor organization/lack of flow, inaccuracies/omissions of text or references, and lack of novelty. At this time, we do not believe ChatGPT is able to replace human experts and is extremely limited in providing original, creative solutions/ideas and interpreting data for a subspecialty medical review article.

Weekend Admission Increases Risk of Readmissions Following Elective Cervical Spinal Fusion

Objective: The “weekend effect” occurs when patients cared for during weekends versus weekdays experience worse outcomes. But reasons for this effect are unclear, especially amongst patients undergoing elective cervical spinal fusion (ECSF). Our aim was to analyze whether index weekend admission affects 30- and 90-day readmission rates post-ECSF.Methods: All ECSF patients > 18 years were retrospectively identified from the 2016–2018 Healthcare Cost and Utilization Project Nationwide Readmissions Database (NRD), using unique patient linkage codes and International Classification of Diseases, Tenth Revision codes. Patient demographics, comorbidities, and outcomes were analyzed. Univariate logistic regression analyzed primary outcomes of 30- and 90-day readmission rates in weekday or weekend groups. Multivariate regression determined the impact of complications on readmission rates.Results: Compared to the weekday group (n = 125,590), the weekend group (n = 1,026) held a higher percentage of Medicare/Medicaid insurance, incurred higher costs, had longer length of stay, and fewer routine home discharge (all p < 0.001). There was no difference in comorbidity burden between weekend versus weekday admissions, as measured by the Elixhauser Comorbidity Index (p = 0.527). Weekend admissions had higher 30-day (4.30% vs. 7.60%, p < 0.001) and 90-day (7.80% vs. 16.10%, p < 0.001) readmission rates, even after adjusting for sex, age, insurance status, and comorbidities. All-cause complication rates were higher for weekend admissions (8.62% vs. 12.7%, p < 0.001), specifically deep vein thrombosis, infection, neurological conditions, and pulmonary embolism.Conclusion: Index weekend admission increases 30- and 90-day readmission rates after ECSF. In patients undergoing ECSF on weekends, postoperative care for patients at risk for specific complications will allow for improved outcomes and health care utilization.

Can a Novel Natural Language Processing Model and Artificial Intelligence Automatically Generate Billing Codes From Spine Surgical Operative Notes?

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

Billing and coding-related administrative tasks are a major source of healthcare expenditure in the United States. We aim to show that a second-iteration Natural Language Processing (NLP) machine learning algorithm, XLNet, can automate the generation of CPT codes from operative notes in ACDF, PCDF, and CDA procedures.

METHODS

We collected 922 operative notes from patients who underwent ACDF, PCDF, or CDA from 2015 to 2020 and included CPT codes generated by the billing code department. We trained XLNet, a generalized autoregressive pretraining method, on this dataset and tested its performance by calculating AUROC and AUPRC.

RESULTS

The performance of the model approached human accuracy. Trial 1 (ACDF) achieved an AUROC of .82 (range: .48-.93), an AUPRC of .81 (range: .45-.97), and class-by-class accuracy of 77% (range: 34%-91%); trial 2 (PCDF) achieved an AUROC of .83 (.44-.94), an AUPRC of .70 (.45-.96), and class-by-class accuracy of 71% (42%-93%); trial 3 (ACDF and CDA) achieved an AUROC of .95 (.68-.99), an AUPRC of .91 (.56-.98), and class-by-class accuracy of 87% (63%-99%); trial 4 (ACDF, PCDF, CDA) achieved an AUROC of .95 (.76-.99), an AUPRC of .84 (.49-.99), and class-by-class accuracy of 88% (70%-99%).

CONCLUSIONS

We show that the XLNet model can be successfully applied to orthopedic surgeon's operative notes to generate CPT billing codes. As NLP models as a whole continue to improve, billing can be greatly augmented with artificial intelligence assisted generation of CPT billing codes which will help minimize error and promote standardization in the process.

Harmonizing Definitions for Diagnostic Criteria and Prognostic Assessment of Transplantation-Associated Thrombotic Microangiopathy: A Report on Behalf of the European Society for Blood and Marrow Transplantation, American Society for Transplantation and Cellular Therapy, Asia-Pacific Blood and Marrow Transplantation Group, and Center for International Blood and Marrow Transplant Research

Transplantation-associated thrombotic microangiopathy (TA-TMA) is an increasingly recognized complication of hematopoietic cell transplantation (HCT) associated with significant morbidity and mortality. However, TA-TMA is a clinical diagnosis, and multiple criteria have been proposed without universal application. Although some patients have a self-resolving disease, others progress to multiorgan failure and/or death. Poor prognostic features also are not uniformly accepted. The lack of harmonization of diagnostic and prognostic markers has precluded multi-institutional studies to better understand incidence and outcomes. Even current interventional trials use different criteria, making it challenging to interpret the data. To address this urgent need, the American Society for Transplantation and Cellular Therapy, Center for International Bone Marrow Transplant Research, Asia-Pacific Blood and Marrow Transplantation, and European Society for Blood and Marrow Transplantation nominated representatives for an expert panel tasked with reaching consensus on diagnostic and prognostic criteria. The panel reviewed literature, generated consensus statements regarding diagnostic and prognostic features of TA-TMA using the Delphi method, and identified future directions of investigation. Consensus was reached on 4 key concepts: (1) TA-TMA can be diagnosed using clinical and laboratory criteria or tissue biopsy of kidney or gastrointestinal tissue; however, biopsy is not required; (2) consensus diagnostic criteria are proposed using the modified Jodele criteria with additional definitions of anemia and thrombocytopenia. TA-TMA is diagnosed when ≥4 of the following 7 features occur twice within 14 days: anemia, defined as failure to achieve transfusion independence despite neutrophil engraftment; hemoglobin decline by ≥1 g/dL or new-onset transfusion dependence; thrombocytopenia, defined as failure to achieve platelet engraftment, higher-than-expected transfusion needs, refractory to platelet transfusions, or ≥50% reduction in baseline platelet count after full platelet engraftment; lactate dehydrogenase (LDH) exceeding the upper limit of normal (ULN); schistocytes; hypertension; soluble C5b-9 (sC5b-9) exceeding the ULN; and proteinuria (≥1 mg/mg random urine protein-to-creatinine ratio [rUPCR]); (3) patients with any of the following features are at increased risk of nonrelapse mortality and should be stratified as high-risk TA-TMA: elevated sC5b-9, LDH ≥2 times the ULN, rUPCR ≥1 mg/mg, multiorgan dysfunction, concurrent grade II-IV acute graft-versus-host disease (GVHD), or infection (bacterial or viral); and (4) all allogeneic and pediatric autologous HCT recipients with neuroblastoma should be screened weekly for TA-TMA during the first 100 days post-HCT. Patients diagnosed with TA-TMA should be risk-stratified, and those with high-risk disease should be offered participation in a clinical trial for TA-TMA-directed therapy if available. We propose that these criteria and risk stratification features be used in data registries, prospective studies, and clinical practice across international settings. This harmonization will facilitate the investigation of TA-TMA across populations diverse in race, ethnicity, age, disease indications, and transplantation characteristics. As these criteria are widely used, we expect continued refinement as necessary. Efforts to identify more specific diagnostic and prognostic biomarkers are a top priority of the field. Finally, an investigation of the impact of TA-TMA-directed treatment, particularly in the setting of concurrent highly morbid complications, such as steroid-refractory GVHD and infection, is critically needed.

ATP-Sensitive Potassium Channel Opener Diazoxide Reduces Myocardial Stunning in a Porcine Regional With Subsequent Global Ischemia Model

Background ATP-sensitive potassium channels are inhibited by ATP and open during metabolic stress, providing endogenous myocardial protection. Pharmacologic opening of ATP potassium channels with diazoxide preserves myocardial function following prolonged global ischemia, making it an ideal candidate for use during cardiac surgery. We hypothesized that diazoxide would reduce myocardial stunning after regional ischemia with subsequent prolonged global ischemia, similar to the clinical situation of myocardial ischemia at the time of revascularization. Methods and Results Swine underwent left anterior descending occlusion (30 minutes), followed by 120 minutes global ischemia protected with hyperkalemic cardioplegia±diazoxide (N=6 each), every 20 minutes cardioplegia, then 60 minutes reperfusion. Cardiac output, time to wean from cardiopulmonary bypass, left ventricular (LV) function, caspase-3, and infarct size were compared. Six animals in the diazoxide group separated from bypass by 30 minutes, whereas only 4 animals in the cardioplegia group separated. Diazoxide was associated with shorter but not significant time to wean from bypass (17.5 versus 27.0 minutes; P=0.13), higher, but not significant, cardiac output during reperfusion (2.9 versus 1.5 L/min at 30 minutes; P=0.05), and significantly higher left ventricular ejection fraction at 30 minutes (42.5 versus 15.8%; P<0.01). Linear mixed regression modeling demonstrated greater left ventricular developed pressure (P<0.01) and maximum change in ventricular pressure during isovolumetric contraction (P<0.01) in the diazoxide group at 30 minutes of reperfusion. Conclusions Diazoxide reduces myocardial stunning and facilitates separation from cardiopulmonary bypass in a model that mimics the clinical setting of ongoing myocardial ischemia before revascularization. Diazoxide has the potential to reduce myocardial stunning in the clinical setting.

Selected Transesophageal Echocardiographic Parameters of Left Ventricular Diastolic Function Predict Length of Stay Following Coronary Artery Bypass Graft-A Prospective Observational Study

(1) Importance: Abnormal left ventricular (LV) diastolic function, with or without a diagnosis of heart failure, is a common finding that can be easily diagnosed by intra-operative transesophageal echocardiography (TEE). The association of diastolic function with duration of hospital stay after coronary artery bypass (CAB) is unknown. (2) Objective: To determine if selected TEE parameters of diastolic dysfunction are associated with length of hospital stay after coronary artery bypass surgery (CAB). (3) Design: Prospective observational study. (4) Setting: A single tertiary academic medical center. (5) Participants: Patients with normal systolic function undergoing isolated CAB from September 2017 through June 2018. (6) Exposures: LV function during diastole, as assessed by intra-operative TEE prior to coronary revascularization. (7) Main Outcomes and Measures: The primary outcome was duration of postoperative hospital stay. Secondary intermediate outcomes included common postoperative cardiac, respiratory, and renal complications. (8) Results: The study included 176 participants (mean age 65.2 ± 9.2 years, 73% male); 105 (60.2%) had LV diastolic dysfunction based on selected TEE parameters. Median time to hospital discharge was significantly longer for subjects with selected parameters of diastolic dysfunction (9.1/IQR 6.6−13.5 days) than those with normal LV diastolic function (6.5/IAR 5.3−9.7 days) (p < 0.001). The probability of hospital discharge was 34% lower (HR 0.66/95% CI 0.47−0.93) for subjects with diastolic dysfunction based on selected TEE parameters, independent of potential confounders, including a baseline diagnosis of heart failure. There was a dose−response relation between severity of diastolic dysfunction and probability of discharge. LV diastolic dysfunction based on those selected TEE parameters was also associated with postoperative cardio-respiratory complications; however, these complications did not fully account for the relation between LV diastolic dysfunction and prolonged length of hospital stay. (9) Conclusions and Relevance: In patients with normal systolic function undergoing CAB, diastolic dysfunction based on selected TEE parameters is associated with prolonged duration of postoperative hospital stay. This association cannot be explained by baseline comorbidities or common post-operative complications. The diagnosis of diastolic dysfunction can be made by TEE.

The Effects of the Combination of Mesenchymal Stromal Cells and Nanofiber-Hydrogel Composite on Repair of the Contused Spinal Cord

A bone marrow-derived mesenchymal stromal cell (MSC) transplant and a bioengineered nanofiber-hydrogel composite (NHC) have been shown to stimulate nervous tissue repair in the contused spinal cord in rodent models. Here, these two modalities were combined to assess their repair effects in the contused spinal cord in adult rats. Cohorts of contused rats were treated with MSC in NHC (MSC-NHC), MSC in phosphate-buffered saline (MSC-PBS), NHC, or PBS injected into the contusion site at 3 days post-injury. One week after injury, there were significantly fewer CD68+ cells in the contusion with MSC-NHC and NHC, but not MSC-PBS. The reduction in CD86+ cells in the injury site with MSC-NHC was mainly attributed to NHC. One and eight weeks after injury, we found a greater CD206+/CD86+ cell ratio with MSC-NHC or NHC, but not MSC-PBS, indicating a shift from a pro-inflammatory towards an anti-inflammatory milieu in the injury site. Eight weeks after injury, the injury size was significantly reduced with MSC-NHC, NHC, and MSC-PBS. At this time, astrocyte, and axon presence in the injury site was greater with MSC-NHC compared with MSC-PBS. We did not find a significant effect of NHC on MSC transplant survival, and hind limb function was similar across all groups. However, we did find fewer macrophages at 1 week post-injury, more macrophages polarized towards a pro-regenerative phenotype at 1 and 8 weeks after injury, and reduced injury volume, more astrocytes, and more axons at 8 weeks after injury in rats with MSC-NHC and NHC alone compared with MSC-PBS; these findings were especially significant between rats with MSC-NHC and MSC-PBS. The data support further study in the use of an NHC-MSC combination transplant in the contused spinal cord.

Understanding Artificial Intelligence and Predictive Analytics: A Clinically Focused Review of Machine Learning Techniques

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Machine learning and artificial intelligence have seen tremendous growth in recent years and have been applied in numerous studies in the field of orthopaedics.

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Machine learning will soon become critical in the day-to-day operations of orthopaedic practice; therefore, it is imperative that providers become accustomed to and familiar with not only the terminology but also the fundamental techniques behind the technology.

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A foundation of knowledge regarding machine learning is critical for physicians so they can begin to understand the details in the algorithms that are being developed, which provide improved accuracy compared with clinicians, decreased time required, and a heightened ability to triage patients.

Abstract B27: A link between small noncoding RNAs and mRNA translation elongation: The let7-eEF2K axis in pediatric tumor adaptation to nutrient deprivation

Background: Medulloblastoma (MB) and neuroblastoma (NB) are the most common pediatric solid cancers and the leading cause of childhood cancer-related deaths. Genetic amplifications of the MYC and MYCN oncogenes are the strongest independent predictor of adverse outcomes in MB and NB, underscoring a dire need to improve therapeutic approaches. Tumors continually weather stress from acute microenvironmental changes, including limited nutrient availability. The let-7 family of small noncoding RNAs (miRNAs) inhibits tumor progression and regulates metabolism by selectively targeting and degrading mRNAs, including MYC and MYCN. Indeed, let-7 miRNAs are frequently repressed in several cancers, including in MYC-driven MB and NB. We previously reported that the mRNA translation elongation regulator eukaryotic eEF2K is a pivotal mediator of cancer cell adaptation to nutrient deprivation. Our preliminary data indicate that the eEF2K 3´ untranslated region (UTR) harbors a potential binding site for let-7 miRNAs. In addition, eEF2K mRNA and let-7 miRNA expressions negatively correlate in MB and NB. We therefore hypothesized that let-7 downregulation induces eEF2K expression, thereby supporting MYC-driven MB and NB adaptation to nutrient deprivation and tumor progression.

Methods: Effects of eEF2K pharmacologic and genetic inhibition on MB and NB cell death were evaluated in vitro by flow cytometry, while cellular mRNA translation rates were studied by polysome fractionation and Click chemistry. The ability of let-7 to degrade eEF2K mRNA was assessed by let-7 miRNAs transfection into MB cells, followed by RT-PCR and Western blotting for eEF2K. Binding of let-7 to the eEF2K 3´UTR was validated by luciferase reporter assay. Finally, NB xenograft mouse models confirmed in vitro observations.

Results: Inhibition of eEF2K significantly reduces survival of MYC/MYCN-amplified NB and MB cell lines under nutrient deprivation, altering their mRNA translation rates. Let-7 miRNAs transfection decreases eEF2K mRNA and protein levels by 40-50%. Downregulation of luciferase activity by let-7 miRNAs is impaired upon mutation of the let-7 binding site on the eEF2K 3´UTR. eEF2K knockdown decreases growth twofold in MYCN-amplified NB xenografts in mice under calorie-restriction diets.

Conclusions: Let-7 miRNAs degrade the eEF2K mRNA by binding to its 3´UTR, indicating that let-7 repression in MYC-driven NB and MB is partially responsible for increased eEF2K levels. Moreover, the let-7-eEF2K axis constitutes a critical mechanism for MYC-driven MB and NB adaptation to acute metabolic stress, representing a promising therapeutic target. Future therapeutic studies will aim to combine eEF2K inhibition with caloric restriction mimetic drugs, as eEF2K activity appears critical under metabolic stress conditions.

Citation Format: Alberto Delaidelli, Gian Luca Negri, Xue Qi Wang, Simran Sidhu, Brian Cho, Gabriel Leprivier, Volker Hovestadt, Stefan Pfister, Michael Taylor, Marcel Kool, Poul Sorensen. A link between small noncoding RNAs and mRNA translation elongation: The let7-eEF2K axis in pediatric tumor adaptation to nutrient deprivation [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr B27.

Nanofiber-hydrogel composite-mediated angiogenesis for soft tissue reconstruction

Soft tissue losses from tumor removal, trauma, aging, and congenital malformation affect millions of people each year. Existing options for soft tissue restoration have several drawbacks: Surgical options such as the use of autologous tissue flaps lead to donor site defects, prosthetic implants are prone to foreign body response leading to fibrosis, and fat grafting and dermal fillers are limited to small-volume defects and only provide transient volume restoration. In addition, large-volume fat grafting and other tissue-engineering attempts are hampered by poor vascular ingrowth. Currently, there are no off-the-shelf materials that can fill the volume lost in soft tissue defects while promoting early angiogenesis. Here, we report a nanofiber-hydrogel composite that addresses these issues. By incorporating interfacial bonding between electrospun poly(ε-caprolactone) fibers and a hyaluronic acid hydrogel network, we generated a composite that mimics the microarchitecture and mechanical properties of soft tissue extracellular matrix. Upon subcutaneous injection in a rat model, this composite permitted infiltration of host macrophages and conditioned them into the pro-regenerative phenotype. By secreting pro-angiogenic cytokines and growth factors, these polarized macrophages enabled gradual remodeling and replacement of the composite with vascularized soft tissue. Such host cell infiltration and angiogenesis were also observed in a rabbit model for repairing a soft tissue defect filled with the composite. This injectable nanofiber-hydrogel composite augments native tissue regenerative responses, thus enabling durable soft tissue restoration outcomes.

Risk Factors for 90-day Readmissions With Fluid and Electrolyte Disorders Following Posterior Lumbar Fusion

STUDY DESIGN

Retrospective cohort study of the 2012 to 2014 Healthcare Cost and Utilization Project Nationwide Readmissions Database.

OBJECTIVE

To identify risk factors for 30- and 90-day readmission due to fluid and electrolyte disorders following posterior lumbar fusion.

SUMMARY OF BACKGROUND DATA

Thirty- and 90-day readmission rates are important quality and outcome measures for hospitals and physicians. These measures have been tied to financial penalties for abnormally high rates of readmission. Furthermore, complex and high cost surgeries have been increasingly reimbursed in the form of bundled disease resource group payments, where any treatment within 90-day postdischarge is covered within the original bundled payment scheme.

METHODS

A total of 65,121 patients in the Healthcare Cost and Utilization Project Nationwide Readmissions Database met our inclusion criteria, of which 1128 patients (1.7%) were readmitted within 30 days, and 1669 patients (2.6%) were readmitted within 90 days due to fluid and electrolyte abnormalities. A bivariate analysis was performed to compare baseline characteristics between patients readmitted with fluid and electrolyte disorders and the remainder of the cohort. A multivariate regression analysis was then performed to identify independent risk factors for readmission due to fluid and electrolyte disorders at 30 and 90 days.

RESULTS

The strongest independent predictors of 30-day readmissions were age ≥80 years, age 65 to 79 years, age 55 to 64 years, liver disease, and drug use disorder. The five strongest predictors of 90-day readmissions were age ≥80 years, age 65 to 79 years, age 55 to 64 years, liver disease, and fluid and electrolyte disorders.

CONCLUSION

Patients with baseline liver disease, previously diagnosed fluid and electrolyte disorders, age older than 55 years, or drug use disorders are at higher risk for readmissions with fluid and electrolyte disorders following posterior lumbar fusion. Close monitoring of fluid and electrolyte balance in the perioperative period is essential to decrease complications and reduce unplanned readmissions.

LEVEL OF EVIDENCE

3.

The effect of a nanofiber-hydrogel composite on neural tissue repair and regeneration in the contused spinal cord

An injury to the spinal cord causes long-lasting loss of nervous tissue because endogenous nervous tissue repair and regeneration at the site of injury is limited. We engineered an injectable nanofiber-hydrogel composite (NHC) with interfacial bonding to provide mechanical strength and porosity and examined its effect on repair and neural tissue regeneration in an adult rat model of spinal cord contusion. At 28 days after treatment with NHC, the width of the contused spinal cord segment was 2-fold larger than in controls. With NHC treatment, tissue in the injury had a 2-fold higher M2/M1 macrophage ratio, 5-fold higher blood vessel density, 2.6-fold higher immature neuron presence, 2.4-fold higher axon density, and a similar glial scar presence compared with controls. Spared nervous tissue volume in the contused segment and hind limb function was similar between groups. Our findings indicated that NHC provided mechanical support to the contused spinal cord and supported pro-regenerative macrophage polarization, angiogenesis, axon growth, and neurogenesis in the injured tissue without any exogenous factors or cells. These results motivate further optimization of the NHC and delivery protocol to fully translate the potential of the unique properties of the NHC for treating spinal cord injury.

The Effects of Preoperative Steroid Therapy on Perioperative Morbidity and Mortality After Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective cohort analysis.

OBJECTIVES

To identify the effects of preoperative steroid therapy on 30-day perioperative complications after adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

Chronic steroid therapy has demonstrated therapeutic effects in the treatment of various medical conditions but is also known to be associated with surgical complications. There remains a gap in the literature regarding the impact of chronic steroid therapy in predisposing patients to perioperative complications after elective surgery for ASD.

METHODS

We performed a retrospective analysis of data from the 2008-2015 American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. Patients were divided into two groups based on preoperative steroid therapy. Differences in baseline patient characteristics, comorbidities, and operative variables were assessed. Univariate analysis was performed to compare the incidence of perioperative complications. Multivariate stepwise logistic regression models were then used to adjust for baseline patient and operative variables in order to identify perioperative complications that were associated with preoperative steroid therapy.

RESULTS

We identified 7,936 patients who underwent surgery for ASD, of which 418 (5.3%) were on preoperative steroid therapy. Preoperative steroid therapy was an independent risk factor for four perioperative complications, including mortality (odds ratio [OR] 2.42, 95% confidence interval [CI] 1.30, 4.51; p = .005), wound dehiscence (OR 3.12, 95% CI 1.45, 6.70; p = .004), deep vein thrombosis (DVT) (OR 2.10, 95% CI 1.24, 3.55; p = .006), and blood transfusion (OR 1.34, 95% CI 1.08, 1.66; p < .007).

CONCLUSIONS

Patients on preoperative steroid therapy are at increased risk of 30-day mortality, wound dehiscence, DVT, and blood transfusion after surgery for ASD. An interdisciplinary approach to the perioperative management of steroid regimens is critical.

LEVEL OF EVIDENCE

Level III.

Abstract 3660: A link between miRNAs and mRNA translation elongation: The let7-eEF2K axis in MYC-driven pediatric tumors adaptation to nutrient deprivation

BACKGROUND/OBJECTIVES: MYC family proteins are implicated in many human cancers, but their therapeutic targeting has proven challenging. MYCN and MYC amplification in childhood neuroblastoma (NB) and medulloblastoma (MB) are associated with aggressive disease and high mortality, underscoring a dire need for novel therapies. Let-7 microRNAs (miRNAs) inhibit tumor progression and regulate metabolism by degrading several mRNAs, including MYC. Let-7 miRNAs are therefore frequently repressed in cancer, including MYC-driven NB and MB. We previously reported that the mRNA translation elongation regulator eukaryotic Elongation Factor-2 Kinase (eEF2K) is a pivotal mediator of cancer cells adaptation to nutrient deprivation (ND). Publicly available transcriptomic database analyses indicate that eEF2K expression significantly correlate with MYCN and MYC expression in multiple tumor cohorts. Our preliminary data also indicate that the eEF2K 3’ untranslated region (UTR) harbors a potential binding site for let-7 miRNAs. In addition, eEF2K mRNA and let-7 miRNA expression negatively correlates in NB and MB, suggesting a potential regulation of the former by the latter. We therefore hypothesized that let-7 down-regulation induces eEF2K expression, thereby supporting MYC-driven NB and MB adaptation to ND and tumor progression.

METHODS: Immunohistochemistry for eEF2K substrate (p-eEF2) was performed on NB and MB tissue microarrays to link results with MYC expression and outcome. Effects of eEF2K pharmacological and genetic inhibition on NB and MB cell survival were evaluated in vitro by MTT assay and PI staining. The ability of let-7 to degrade eEF2K mRNA was assessed by let-7 miRNAs transfection into MB cells, followed by RT-PCR and Western Blotting for eEF2K. Binding of let-7 to the eEF2K 3’UTR was validated by luciferase reporter assay. Finally, NB xenograft mouse models were used to confirm in vitro observations.

RESULTS: High eEF2K activity is linked to MYC over-expression and reduced survival in NB and MB (p&lt;0.05). Pharmacological and genetic inhibition of eEF2K significantly reduces survival of MYC/MYCN-amplified NB and MB cell lines under ND. Let-7 miRNAs transfection decreases eEF2K mRNA and protein levels (by ~40-50%), and down-regulation of luciferase activity by let-7 miRNAs is impaired upon mutation of the let-7 binding site on the eEF2K 3’UTR. Knockdown of eEF2K determines a twofold growth decrease of MYCN-amplified NB xenografts when mice are kept under caloric restriction diet.

CONCLUSIONS: Let-7 miRNAs degrade eEF2K mRNA by binding to its 3'UTR, indicating that let-7 repression in MYC-driven NB and MB is partially responsible for eEF2K increased levels and activity. Moreover, the let-7-eEF2K axis represents a critical mechanism for MYC-driven NB and MB adaptation to ND, constituting a promising therapeutic target.

Citation Format: Alberto Delaidelli, Gian Luca Negri, Brian Cho, Simran Sidhu, Stefan Pfister, Michael Taylor, Gabriel Leprivier, Marcel Kool, Poul Soresnsen. A link between miRNAs and mRNA translation elongation: The let7-eEF2K axis in MYC-driven pediatric tumors adaptation to nutrient deprivation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3660.

Dosimetric analysis of stereotactic rotational versus static intensity-modulated radiation therapy for pancreatic cancer

PURPOSE

Stereotactic body radiation therapy is a promising treatment modality for locally advanced pancreatic cancer. To determine the optimal radiation treatment, we compared the plan characteristics of volumetric-modulated arc therapy and intensity-modulated radiation therapy when administered with stereotactic body radiation therapy to treat pancreatic cancer.

PATIENTS AND METHODS

Fifteen patients with locally advanced pancreatic cancer were treated by stereotactic body radiation therapy at a dose of 24-32Gy in four fractions with marker-guided gated volumetric-modulated arc therapy. Four dimensional-computed tomography scans were used to assess the target and surrounding normal organs. The same images, contours, and dose constraints were used for dual-arc volumetric-modulated arc therapy and 9-field intensity-modulated radiation therapy planning. Plans were compared using dosimetric parameters and treatment performance.

RESULTS

Volumetric-modulated arc therapy required significantly lower monitor units (1726 vs. 4188; P<0.001) and shorter treatment delivery time in comparison with intensity-modulated radiation therapy (22.5min vs. 52.4min; P<0.001). Regarding target volume coverage, both modalities demonstrated comparable results (V_95%, 99.3% vs. 99.4%; P=0.796). Both modalities satisfied the dosimetric determinants for duodenal toxicity and the maximum and mean doses administered to normal organ were also statistically similar.

CONCLUSION

In comparison with 9-field intensity-modulated radiation therapy, volumetric-modulated arc therapy significantly reduces the number of monitoring units and treatment delivery times while administering similar dosimetric quality. Based on these results, volumetric-modulated arc therapy might be an appropriate treatment for locally advanced pancreatic cancer when combined with stereotactic body radiation therapy.

Vascularized Bone Grafting for Reconstruction of Oncologic Defects in the Spine: A Systematic Review and Pooled Analysis of the Literature

Background Resection of primary spinal tumors requires reconstruction for restoration of spinal column stability. Traditionally, some combination of bone grafting and instrumentation is implemented. However, delayed healing environments are associated with pseudoarthrodesis and failure. Implementation of vascularized bone grafting (VBG) to complement hardware may present a solution. We evaluated the use of VBG in oncologic spinal reconstruction via systematic review and pooled analysis of literature.

Methods We searched PubMed/MEDLINE, Embase, Cochrane, and Scopus for studies published through September 2017 according to the PRISMA guidelines and performed a pooled analysis of studies with n > 5. Additionally, we performed retrospective review of patients at the Johns Hopkins Hospital that received spinal reconstruction with VBG.

Results We identified 21 eligible studies and executed a pooled analysis of 12. Analysis indicated an 89% (95% confidence interval [CI]: 0.75–1.03) rate of successful union when VBG is employed after primary tumor resection. The overall complication rate was 42% (95% CI: 0.23–0.61) and reoperation rate was 27% (95% CI: 0.12–0.41) in the pooled cohort. Wound complication rate was 18% (95% CI: 0.11–0.26). Fifteen out of 209 patients (7.2%) had instrumentation failure and mean time-to-union was 6 months. Consensus in the literature and in the patients reviewed is that introduction of VBG into irradiated or infected tissue beds proves advantageous given decreased resorption, increased load bearing, and faster consolidation. Downsides to this technique included longer operations, donor-site morbidity, and difficulty in coordinating care.

Conclusions Our results demonstrate that complication rates using VBG are similar to those reported in studies using non-VBG for similar spinal reconstructions; however, fusion rates are better. Given rapid fusion and possible hardware independence, VBG may be useful in reconstructing defects in patients with longer life expectancies and/or with a history of chemoradiation and/or infection at the site of tumor resection.

Effects of Ketamine on Icam-1 Expression during Lipopolysaccharide Induced Acute Lung Injury in Rats

Introduction

Intercellular adhesion molecule-1 (ICAM-1) serves very important roles in lung injury, and increases in ICAM-1 are associated with severity of lung injury. We intended to examine whether ketamine could have favourable effects on ICAM-1 expression in lipopolysaccharide (LPS)-induced acute lung injury in the rat.

Methods

The acute lung injury was induced by instilling LPS into the tracheas of 72 anaesthetised rats. The animals were divided into four groups including a sham group with intratracheal saline, an LPS group with intratracheal LPS and intraperitoneal saline, and two ketamine treatment groups with intratracheal LPS and treated with 1 mg/kg or 10 mg/kg doses of intraperitoneal ketamine hydrochloride. Half of the animals were sacrificed at three hours and the remaining animals were sacrificed at six hours. Real time PCR was performed on the lung tissues obtained. Concentration of the soluble ICAM-1 was measured in the bronchoalveolar lavage fluid. Expression of ICAM-1 was measured.

Results

The transcriptional activity of ICAM-1 mRNA increased 9.92 fold in the LPS group compared to the sham group but decreased by 84.1% and 83.3%, respectively, in the 1 and 10 mg/kg ketamine treatment groups. The concentration of soluble ICAM-1 in bronchoalveolar lavage fluid increased 2.23 fold in the LPS group compared to the sham group while decreasing by 75.0% and 74.5% respectively in the 1 mg/kg and 10 mg/kg ketamine treatment groups. The intensity of immunohistochemical staining for ICAM-1 was also decreased in both ketamine treatment groups.

Conclusion

Ketamine attenuates ICAM-1 expression during acute lung injury in rats. (Hong Kong j.emerg.med. 2011;18:397-405)