Patients Undergoing Lumbar Fusion Research Articles

Does Age Younger Than 65 Affect Clinical Outcomes in Medicare Patients Undergoing Lumbar Fusion?

This was a retrospective cohort study. To determine if age (younger than 65) and Medicare status affect patient outcomes following lumbar fusion. Medicare is a common spine surgery insurance provider, but most qualifying patients are older than age 65. There is a paucity of literature investigating clinical outcomes for Medicare patients under the age of 65. Patients 40 years and older who underwent lumbar fusion surgery between 2014 and 2019 were queried from electronic medical records. Patients with >2 levels fused, >3 levels decompressed, incomplete patient-reported outcome measures (PROMs), revision procedures, and tumor/infection diagnosis were excluded. Patients were placed into 4 groups based on Medicare status and age: no Medicare under 65 years (NM<65), no Medicare 65 years or older (NM≥65), yes Medicare under 65 (YM<65), and yes Medicare 65 years or older (YM≥65). T tests and χ 2 tests analyzed univariate comparisons depending on continuous or categorical type. Multivariate regression for ∆PROMs controlled for confounders. Alpha was set at 0.05. Of the 1097 patients, 567 were NM<65 (51.7%), 133 were NM≥65 (12.1%), 42 were YM<65 (3.8%), and 355 were YM≥65 (32.4%). The YM<65 group had significantly worse preoperative Visual Analog Scale back ( P =0.01) and preoperative and postoperative Oswestry Disability Index (ODI), Short-Form 12 Mental Component Score (MCS-12), and Physical Component Score (PCS-12). However, on regression analysis, there were no significant differences in ∆PROMs for YM <65 compared with YM≥65, and NM<65. NM<65 (compared with YM<65) was an independent predictor of decreased improvement in ∆ODI following surgery (β=12.61, P =0.007); however, overall the ODI was still lower in the NM<65 compared with the YM<65. Medicare patients younger than 65 years undergoing lumbar fusion had significantly worse preoperative and postoperative PROMs. The perioperative improvement in outcomes was similar between groups with the exception of ∆ODI, which demonstrated greater improvement in Medicare patients younger than 65 compared with non-Medicare patients younger than 65. Level III (treatment).

Application of enhanced recovery after surgery care protocol in the perioperative care of patients undergoing lumbar fusion and internal fixation

BackgroundTo explore the effects and deficiencies of the enhanced recovery after surgery (ERAS) care protocol on patients undergoing lumbar fusion and internal fixation in perioperative care.MethodsA total of 166 patients with lumbar fusion and internal fixation were collected and divided into two groups, among which 86 patients received ERAS care protocol were attributed into ERAS group, while the other 80 patients received traditional perioperative care protocol were assigned to control group. Then, the degree of pain, self-care ability and the degree of recovery were assessed using the visual analogue scale (VAS), Barthel index (BI) rating scale and the Sino-version Oswestry Disability Index (ODI) questionnaire, respectively. Moreover, further analysis was performed based on patients’ different age, gender, body mass index (BMI) and education of patients in ERAS group.ResultsThe hospitalization time and the incidence of complication in the ERAS group were obviously lower than those in control group (both, P < 0.05). There was no significant difference in hospitalization expenses between the two groups (P > 0.05). The BI score of the ERAS group was higher than that of the control group (P < 0.05), and the percentage of ODI score in ERAS group was significantly downregulated in comparison with that in control group (P < 0.05). Intra-group analysis in ERAS showed that, compared with older patients, younger patients had higher BI scores (P < 0.05) and lower ODI scores (P < 0.05); meanwhile, overweight patients had lower BI scores (P < 0.05), and the ODI score decreased with the increase in education level of the patients.ConclusionsERAS care protocol can significantly shorten the hospitalization time and reduce the occurrence of postoperative complications of patients, significantly enhance the self-care ability of patients after discharge and promote the rapid recovery of patients after surgery.

The Impact of Computer-Assisted Navigation on Charges and Readmission in Lumbar Spinal Fusion.

Retrospective National Database Study. The purpose of this study is to evaluate the cost and patient outcomes associated with the utilization of computer-assisted navigation (CAN) utilization on patients undergoing lumbar spinal fusion. CAN systems have demonstrated comparable outcomes with instrumentation and procedural speed when compared with traditional techniques. In recent years, CAN systems have seen increased adoption in spinal surgery as they allow for better contextualization of anatomical structures with the goal of improving surgical accuracy and reproducibility. The 2016 National Readmission Database was queried for patients with lumbar spinal fusion ICD-10 codes, with 2 subgroups created based on computer-aided navigation ICD-10 codes. Nonelective cases and patients below 18 years of age were excluded. Univariate analysis on demographics, surgical data, and total charges was performed. Postoperative complication rates were calculated based on diagnosis. Lastly, multivariate analysis was performed to assess navigation's impact on cost and postoperative outcomes. A total of 88,445 lumbar fusion surgery patients were identified. Of the total, 2478 (2.8%) patients underwent lumbar fusion with navigation utilization, while 85,967 (97.2%) patients underwent surgery without navigation. The average total charges were $150,947 ($150,058, $151,836) and $161,018 ($155,747, $166,289) for the non-CAN and CAN groups, respectively ( P <0.001). The 30-day readmission rates were 5.3% for the non-CAN cohort and 3.1% for the CAN cohort ( P <0.05). The 90-day readmission rates were 8.8% for the non-CAN cohort and 5.2% for the CAN cohort ( P <0.001). CAN use was found to be significantly associated with increased cost and decreased 30-day and 90-day readmissions. Although patients operated on with CAN had increased routine discharge and decreased readmission risk, future studies must continue to evaluate the cost-benefit of CAN. Limitations include ICD-10 codes for CAN utilization being specific to region of surgery, not to exact type. Level III.

Rehabilitation to improve outcomes of lumbar fusion surgery: a systematic review with meta-analysis.

To evaluate the effectiveness of rehabilitation strategies on disability, pain, pain-related fear, and return-to-work in patients undergoing lumbar fusion surgery for degenerative conditions or adult isthmic spondylolisthesis. Six electronic databases were systematically searched for randomized controlled trials (RCTs) evaluating the effect of rehabilitation (unimodal or multimodal). The estimated effect size was calculated for interventions with homogeneous content using a random-effects model. Certainty of evidence was assessed by GRADE. In total, 18 RCTs, including 1402 unique patients, compared specific rehabilitation to other rehabilitation strategies or usual care. Most described indications were degenerative disc disease and spondylolisthesis. All rehabilitation interventions were delivered in the postoperative period, and six of them also included a preoperative component. Intervention dose and intensity varied between studies (ranging from one session to daily sessions for one month). Usual care consisted mostly of information and postoperative mobilization. At short term, low quality of evidence shows that exercise therapy was more effective for reducing disability and pain than usual care (standardized mean difference [95% CI]: -0.41 [-0.71; -0.10] and -0.36 [-0.65; -0.08], four and five studies, respectively). Multimodal rehabilitation consisted mostly of exercise therapy combined with cognitive behavioral training, and was more effective in reducing disability and pain-related fear than exercise therapy alone (-0.31 [-0.49; -0.13] and -0.64 [-1.11; -0.17], six and four studies, respectively). Effects disappeared beyond one year. Rehabilitation showed a positive tendency towards a higher return-to-work rate (pooled relative risk [95% CI]: 1.30 [0.99; 1.69], four studies). There is low-quality evidence showing that both exercise therapy and multimodal rehabilitation are effective for improving outcomes up to six months after lumbar fusion, with multimodal rehabilitation providing additional benefits over exercise alone in reducing disability and pain-related fear. Additional high-quality studies are needed to demonstrate the effectiveness of rehabilitation strategies in the long term and for work-related outcomes.

Comparison of Operative Time and Blood Loss With the FFX® Device Versus Pedicle Screw Fixation During Surgery for Lumbar Spinal Stenosis: A Retrospective Cohort Study.

BackgroundPedicle screw (PS) placement can be associated with soft tissue damage and blood loss. The study objective was to evaluate differences in operative time and blood loss between PS fixation and an implantable facet fusion device in patients undergoing lumbar fusion surgery.Materials and methodsA retrospective analysis was performed on patients undergoing lumbar fusion surgery with PS fixation or the lumbar Facet FiXation (FFX) device. Procedures were performed by the same surgeon at a single institution. The PS group included patients from 2016 and the FFX group included patients from 2018. Variables including age, sex, levels operated on, operative time, and operative blood loss were collected.ResultsA total of 70 patients were included in the study. Twenty-eight in the PS arm and 42 in the FFX arm. The PS group had a mean age of 67.5 ± 9.3 years compared to 70.4 ± 11.5 years for the FFX group. The PS group had a higher percentage of females (57.1%) versus the FFX group (31.0%); p = 0.025. Mean number of levels operated on were similar between the PS and FFX groups (2.3 ± 1 .1 vs. 2.2 ± 1.0, respectively; p = 0.89). Mean operative time was significantly longer for the PS group versus the FFX group (152.5 ± 39.4 vs. 99.4 ± 44.0 minutes; p < 0.001). Mean operative blood loss was significantly greater for the PS group versus the FFX group (446.5 ± 272.0 vs. 251.0 ± 315.9 mL; p < 0.01). Differences were independent of the number of levels operated on.ConclusionPlacement of the FFX device is associated with a significant reduction in operative time and blood loss compared to PS fixation in patients undergoing spinal fusion surgery.

459 Association Between Vitamin D Deficiency and Surgical Site Infection Following Elective Lumbar Fusions

INTRODUCTION: Vitamin D deficiency has been associated with higher rates of SSI following a variety of surgical procedures. However, this association has been under-investigated for spinal procedures. METHODS: Patients who underwent lumbar fusions between 2011-2014 were reviewed from the HCUP-NIS database. Propensity score matching was utilized to minimize the effect of confounding variables between the 2 groups (normal vitamin D vs vitamin D deficiency). RESULTS: A total of 238,875 cases of lumbar fusions met inclusion criteria for analysis. These included posterior/transforaminal lateral interbody fusions (PLIF/TLIF), Anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF). 22,454 (9.4%) patients carried the diagnosis of vitamin D deficiency and were significantly more likely to be non-white (26.5% vs. 19.9%) and obese (21.1% vs. 15.4%) as compared to patients without deficiency. Other patient characteristics, socioeconomic factors, and hospital setting were comparable between two groups. SSI rates were compared between matched cohorts (18,350 patients in each). In patients without vitamin D deficiency, there were 202 (1.1%) cases of SSI recorded, while there were 1266 (6.9%) cases of SSI recorded in patients with vitamin D deficiency (P&lt;0.001). Patients with vitamin D deficiency had higher incidence of thromboembolic events (2.6% vs. 0.3%), length of hospital stay (5.7 vs. 3.4 days) as well as increased hospital charges (87,812$ vs. 79,650), (P &lt;0.05). CONCLUSION: Optimizing preoperative vitamin D level could be potentially a cost-effective strategy to reduce the rate of SSI, thromboembolic events and prolonged hospital stay in patients undergoing lumbar fusion. Further cost-effectiveness analyses are encouraged to make definitive claims regarding pre-operative vitamin D screening/supplementation in these patients.

158 Comparison of Cost and Complication Rates for Profiling Hospital Performance in Lumbar Fusion for Spondylolisthesis

INTRODUCTION: Despite growing interest among payers in profiling both the cost and safety of common surgeries, such as lumbar fusion, there is sparse evidence describing the statistical reliability of such measures when applied to lumbar fusion for spondylolisthesis. METHODS: We used State Inpatient Databases from nine states to study patients undergoing lumbar fusion for spondylolisthesis from 2010-2017. The study outcome was the statistical reliability of three distinct quality/value metrics. Statistical reliability was measured as the amount of variation between hospitals relative to the total amount of variation for each measure. Total variation includes both between-hospital variation (“signal”) and within-hospital variation (“statistical noise”). Thus, reliability equals signal over (signal plus noise) and ranges from 0-1. We evaluated the reliability of each measure by study year and examined the number of hospitals meeting different thresholds of reliability. RESULTS: We included 66,571 elective lumbar fusion surgeries performed at 244 hospitals. 12.0% of patients experienced a complication within 90 days of surgery, including 7.8% with a serious complication. The median reliability of 90-day cost ranged from 0.97-0.99 across study years. By comparison, the median reliability for the overall complication metric ranged from 0.22-0.44, and the reliability of the serious complication measure ranged from 0.30-0.49 across the study years. While some low-volume hospitals had reliabilities for cost as low as 0.51, at least 96% of hospitals had high (&gt;0.7) reliability for cost in any year. By comparison, the reliability of the overall and serious complication rate varied substantially by hospital case volume, and only 0-9% and 0-11% of hospitals had high (&gt;0.7) reliability in any year. CONCLUSION: 90-day inpatient costs following lumbar fusion for spondylolisthesis are highly reliable for assessing variation across hospitals, whereas overall and serious complications are only moderately reliable for profiling performance.

The Usefulness of Trabecular CT Attenuation Measurement at L4 Level to Predict Screw Loosening After Degenerative Lumbar Fusion Surgery: Consider Number of Fused Levels and Postoperative Sagittal Balance.

Retrospective study. To evaluate the absolute value of L4 trabecular region-of-interest (t-ROI) computed tomography (CT) attenuation, which can predict pedicle screw loosening, and determine the changes in value according to number of fused levels and sagittal balance in patients undergoing lumbar fusion surgery. Although osteoporosis was not diagnosed in spinal dual x-ray absorptiometry preoperatively, we encountered several cases of screw loosening within 1 year of lumbar fusion surgery. We enrolled 478 patients and analyzed factors related to screw loosening. We evaluated the association between L4 t-ROI CT attenuation and screw loosening and determined the best cutoff value of t L4 t-ROI CT attenuation for predicting screw loosening. The number of fused levels, postoperative C7-S1 sagittal vertical axis (SVA), and L4 t-ROI CT attenuation were independently correlated with screw loosening. According to number of fused level and postoperative C7-T1 SVA (≥36.9 mm or <36.9 mm), in patients with one-level fusion and C7-S1 SVA less than 36.9 mm, the optimal cutoff point of the L4 t-ROI CT attenuation predicting screw loosening was 106.5 Hounsfield unit (HU). L4 t-ROI attenuation did not change until two-level fusions. In patients with three-level fusions and C7-S1 SVA less than 36.9 mm, the optimal cutoff point of the L4 t-ROI CT attenuation predicting screw loosening was 159.0 HU. The optimal cutoff point of L4 t-ROI CT attenuation in patients with three-level fusions and C7-S1 SVA more than or equal to 36.9 mm was 191.0 HU. L4 t-ROI CT attenuation value considering number of fused levels and sagittal balance is an accurate measurement method to predict screw loosening. Spine surgeons should be aware of the L4 t-ROI attenuation before surgery to improve the fusion rate and reduce instrument-related complications of lumbar spine surgery in osteoporotic patients. 3.

The association between paraspinal muscle parameters and vertebral pedicle microstructure in patients undergoing lumbar fusion surgery

The association between paraspinal muscle parameters and vertebral pedicle microstructure in patients undergoing lumbar fusion surgery

A 24-month retrospective update: follow-up hospitalization charges and readmissions in US lumbar fusion surgeries using a cellular bone allograft (CBA) versus recombinant human bone morphogenetic protein-2 (rhBMP-2)

BackgroundThe objectives of this study were to build upon previously-reported 12-month findings by retrospectively comparing 24-month follow-up hospitalization charges and potentially-relevant readmissions in US lumbar fusion surgeries that employed either recombinant human bone morphogenetic protein-2 (rhBMP-2) or a cellular bone allograft comprised of viable lineage-committed bone cells (V-CBA) via a nationwide healthcare system database.MethodsA total of 16,172 patients underwent lumbar fusion surgery using V-CBA or rhBMP-2 in the original study, of whom 3,792 patients (23.4%) were identified in the current study with all-cause readmissions during the 24-month follow-up period. Confounding baseline patient, procedure, and hospital characteristics found in the original study were used to adjust multivariate regression models comparing differences in 24-month follow-up hospitalization charges (in 2020 US dollars) and lengths of stay (LOS; in days) between the groups. Differences in potentially-relevant follow-up readmissions were also compared, and all analyses were repeated in the subset of patients who only received treatment at a single level of the spine.ResultsThe adjusted cumulative mean 24-month follow-up hospitalization charges in the full cohort were significantly lower in the V-CBA group ($99,087) versus the rhBMP-2 group ($124,389; P < 0.0001), and this pattern remained in the single-level cohort (V-CBA = $104,906 vs rhBMP-2 = $125,311; P = 0.0006). There were no differences between groups in adjusted cumulative mean LOS in either cohort. Differences in the rates of follow-up readmissions aligned with baseline comorbidities originally reported for the initial procedure. Subsequent lumbar fusion rates were significantly lower for V-CBA patients in the full cohort (10.12% vs 12.00%; P = 0.0002) and similar between groups in the single-level cohort, in spite of V-CBA patients having significantly higher rates of baseline comorbidities that could negatively impact clinical outcomes, including bony fusion.ConclusionsThe results of this study suggest that use of V-CBA for lumbar fusion surgeries performed in the US is associated with substantially lower 24-month follow-up hospitalization charges versus rhBMP-2, with both exhibiting similar rates of subsequent lumbar fusion procedures and potentially-relevant readmissions.

Effects of preoperative nutritional status on complications and readmissions after posterior lumbar decompression and fusion for spondylolisthesis: A propensity-score analysis

IntroductionMalnutrition, common in the elderly, may adversely affect healthcare outcomes. In spine surgery, malnutrition is associated with higher rates of perioperative complications, unplanned readmission, and prolonged length of stay (LOS). The aim of this study was to determine the effect of malnutrition on adverse events (AEs), unplanned readmission, and LOS in patients undergoing spine surgery for spondylolisthesis. MethodsA retrospective cohort study was performed using the American College of Surgeons National Surgical Quality Improvement Program database from 2010 to 2016. Adult patients who underwent posterior decompression or fusion for spondylolisthesis were identified using the ICD-9-CM coding systems. Patients were divided into two cohorts based on preoperative serum albumin levels. propensity-score (PS) matching was used to create an age- and sex-matched Nourished cohort. Patient demographics, comorbidities, LOS, and postoperative complications were collected. Multivariate logistic regression analysis was performed to identify predictors of prolonged LOS, unplanned readmission, and AEs. ResultsOf the 2196 patients identified, 4.5% were malnourished. Patients in the Malnourished cohort were found to have significantly longer average LOS (Malnourished: 4.51 ± 3.1 days vs PS-Matched Not Nourished: 3.7 ± 3.7, p = 0.002), higher rates of AEs (Malnourished: 14.3% vs PS-Matched Nourished: 5.8%, p = 0.007), reoperation (Malnourished: 8.4% vs PS-Matched Nourished: 3.2%, p = 0.026), and unplanned readmission (Malnourished: 15.3% vs PS-Matched Nourished: 6.1%, p = 0.003). On multivariate analysis considering only preoperative data, malnutrition was a significant independent predictor of AEs [OR: 2.13, CI (1.02, 4.46), p = 0.045]. However, after correcting for the occurrence of AEs, malnutrition was not associated with total LOS [aRR: 0.29, CI (−0.37, 0.95), p = 0.392] or 30-day unplanned readmissions [aOR: 2.24, CI (0.89, 5.60), p = 0.086]. ConclusionOur study found that malnourished patients undergoing lumbar fusion for spondylolisthesis have significantly higher rates of AEs, unplanned readmission, and prolonged LOS than nourished patients. Further studies are necessary to corroborate our findings.

Timing of Total Hip Arthroplasty Affects Lumbar Spinal Fusion Outcomes.

This is a retrospective cohort study of consecutive patients undergoing lumbar spinal fusion (LSF) within the PearlDiver Humana research database from 2010 to 2018. The aim of this study was to determine if timing of total hip arthroplasty (THA) affects LSF outcomes. In patients with both spine and hip pathology, outcomes of THA have been shown to be affected by the timing of THA relative to LSF. However, few studies have assessed postoperative outcomes following LSF in this clinical scenario. A national database was queried for patients undergoing lumbar fusion and divided into 4 groups: (1) those who underwent LSF without THA (No THA); (2) those who underwent THA at least 2 years before LSF (>2 Prior THA); (3) those who underwent THA in the 2 years before LSF (0-2 Prior THA); and (4) those who underwent THA after LSF (THA After). We assessed lumbar-specific outcomes, including pseudarthrosis, revision, mechanical failure, and adjacent segment disease (ASD); as well as systemic complications. Controlling for age, sex, and Charlson comorbidity index, complication rates between all groups were assessed using univariate and multivariate logistic regression analysis. Post hoc comparisons were performed using the Fisher exact test with Bonferroni correction to account for multiple pairwise comparisons, resulting in an adjusted threshold for statistical significance of P<0.007. When compared with the no THA group, those in the THA After group had a higher rate of ASD on multivariate analysis [adjusted odds ratio: 1.53, 95% confidence interval: 1.20-1.94, P<0.001]. When compared with all patients who underwent THA before LSF, patients who underwent THA after LSF had an increased risk of ASD (adjusted odds ratio: 3.80, 95% confidence interval: 2.21-6.98, P<0.001). Patients who undergo THA after LSF have an increased rate of lumbar-related complications both when compared with patients who do not undergo THA and when compared with patients who undergo THA before LSF.

The incidence of incision infections after lumbar fusion and the significance of dynamically monitoring serum albumin and C-reactive protein levels.

To explore the incidence of incision infections and dynamically monitor albumin (ALB) and C-reactive protein (CRP) levels after lumbar fusion. A total of 1,773 patients undergoing lumbar fusion in our hospital from March 2011 to March 2021 were selected and divided into the infection group and the non-infection group according to whether incision infections occurred postoperatively. The incidence of postoperative incision infections, the pathogenic characteristics and drug resistance of the pathogenic bacteria in patients in the infection group were analyzed. The general clinical data, serum ALB and CRP levels at different time points were compared between the two groups of patients, and the correlation between ALB and CRP levels was analyzed. ROC curve was used to evaluate the predictive value of serum ALB and CRP levels on the incidence of postoperative incision infections. Of the 1,773 patients, 41 (2.31%) experienced postoperative incision infections. A total of 57 pathogens were detected, including 36 gram-negative bacteria (63.16%), 18 gram-positive bacteria (31.58%), and 3 fungi (5.26%). Among gram-negative bacteria, Pseudomonas aeruginosa had the highest resistance to ampicillin. Among gram-positive bacteria, Staphylococcus aureus had the highest resistance to penicillin and erythromycin. The age, BMI, the number of diabetes patients, levels of serum tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and procalcitonin (PCT) IL-8 at 1 d after operation in the infection group were significantly higher than those in the non-infection group (P<0.05). The serum ALB and CRP levels of the two groups differed over time, and the differences were statistically significant in terms of time, inter-group, time and inter-group interaction factors (P<0.05). Correlation analysis showed that ALB was significantly negatively correlated with CRP expression. Receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) value of combined ALB and CRP detection was 0.856, which was significantly higher than that of single detection with ALB or CRP (P<0.05). Gram-negative bacterial infection was the main type of incision infection in patients after lumbar fusion. The changes in ALB and CRP levels were related to the incidence of postoperative incision infections.

P53. Clinical risk factors for adjacent segment disease following lumbar spine fusion surgeries: A systematic review and meta-analysis

BACKGROUND CONTEXT Adjacent segment disease (ASD) is a possible complication following lumbar surgeries, particularly lumbar fusion. PURPOSE To investigate the clinical risk factors associated with developing radiological and/or clinical ASD following lumbar fusion. STUDY DESIGN/SETTING Systematic review and meta-analysis. PATIENT SAMPLE Adult patients undergoing lumbar fusion. OUTCOME MEASURES Clinical risk factors associated with the development of ASD. METHODS We performed a comprehensive literature search to find the relevant studies using PubMed, Embase, Medline, Scopus, and the Cochrane library databases from the beginning to December 2019. The titles and abstracts were used for initial screening, followed by a full-text review. The methodological index for non‐randomized studies (MINORS) criteria were used to evaluate the methodological quality of the included studies. A meta-analysis was conducted to calculate the odds ratio (OR) with the 95% confidence interval (CI) for dichotomous variables and mean difference (MD) with 95% CI for continuous variables. Both fixed and random-effects models were used to pool the data according to the observed heterogeneity. RESULTS Thirty-five studies were included in the final qualitative analysis. Twenty-two of these studies were included in the risk factors meta-analyses. The mean quality score of the included studies was 12.4±1.9 (range, 8-16) points, based on the MINORS criteria. The level of evidence was low for many risk factors. Overall, 1,266 (17.2%) patients acquired ASD following lumbar fusion, and 6108 (82.8%) patients did not develop ASD, within a follow-up ranging between 20.5 - 165.6 months. Four clinical variables were found to have statistically significant risk factors for ASD, including higher preoperative body mass index (BMI) (mean difference [MD] = 1.97 kg/m2; 95% confidence interval [CI] = 1.49, 2.45; P CONCLUSIONS High preoperative BMI, floating fusion, superior facet joint violation, and decompression outside fusion construct are associated with a significant risk of developing ASD in patients undergoing lumbar fusion. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

P29. Gram negative vs gram positive cultures: A comparison of gram type on washouts & antibiotic duration

P29. Gram negative vs gram positive cultures: A comparison of gram type on washouts & antibiotic duration

P30. Development of a machine learning algorithm for prediction of complications and readmission after lumbar spinal fusion

<h3>BACKGROUND CONTEXT</h3> Lumbar spinal fusion represents a large and growing fraction of the health care system, with a 15-fold increase in cases since 2002. The average age and number of medical comorbidities of patients undergoing lumbar fusion has similarly increased. Accurately risk-stratifying patients who undergo lumbar fusion would be of great utility, given the significant cost and morbidity associated with developing major perioperative complications. There is a paucity of accurate and validated prediction models that can be used to preoperatively risk-stratify patients for lumbar fusion. Advanced machine learning (ML) methods have grown in popularity across numerous medical disciplines due to their ability to recognize complex, non-linear relationships. <h3>PURPOSE</h3> We aim to develop an optimized ML algorithm for prediction of major perioperative complication after lumbar fusion. Our secondary aim is to compare its performance against logistic regression (LR). <h3>STUDY DESIGN/SETTING</h3> Retrospective, cohort study. <h3>PATIENT SAMPLE</h3> Patients 18 years or older at a non-federal California hospital who underwent lumbar spinal fusion. <h3>OUTCOME MEASURES</h3> Readmission within 30 days, major perioperative complications (readmission within 30 days, venous thromboembolism within 30 days, myocardial infarction within 7 days, pneumonia within 7 days, systemic infection within 7 days, surgical site bleeding within 90 days, and wound complications within 90 days). <h3>METHODS</h3> This is a retrospective cohort study of adult patients who underwent lumbar spinal fusion at any California hospital between 2015-2017. We build LR and ML models that span different classes of modeling approaches. Discrimination and calibration were assessed using area under the receiver operating characteristic curve (AUROC) and Brier score, respectively. We ranked the contribution of the included variables to model performance. <h3>RESULTS</h3> A total of 38,788 patients met inclusion criteria for this study. There were 4,470 major complications (11.5%). The XGBoost algorithm demonstrates the highest discrimination (AUROC: 0.687 + 0.01) compared to LR (0.675 + 0.01), outperforming the three other ML models. This model was well calibrated with a Brier score of 0.094 + 0.001. The variables most important to XGBoost performance include angina pectoris, metastatic cancer, teaching hospital status, history of concussion, number of comorbidities, and workers' compensation insurance. Teaching hospital status and concussion history were not found to be among the most important features in the LR model. <h3>CONCLUSIONS</h3> Major perioperative complications and unplanned readmissions after lumbar fusion are a source of significant cost and morbidity. Wereport an optimized ML algorithm for prediction of major perioperative complications and 30-day readmission after lumbar spinal fusion. The predictors most important for XGBoost differ from those for LR, suggesting that the superior performance of XGBoost for prediction of major complications in this dataset is due to the ability of advanced ML methods to capture relationships between variables that LR is unable to detect. By providing accurate prognostic information, this algorithm may facilitate preoperative shared decision-making and aid with appropriate patient selection. A physician must be able to provide patients with comprehensive and accurate information regarding risks and benefits in order for the patient to provide true informed consent. This tool may identify and address potentially modifiable risk factors, helping to accurately risk-stratify patients and decrease likelihood of major complications. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

149. Opioid sparing anesthesia for lumbar spinal fusion surgery reduces opioid consumption, blood loss and operative time: A propensity matched analysis

<h3>BACKGROUND CONTEXT</h3> The recent opioid crisis in the US highlights opioid related side-effects and the dire need to reduce opioid exposure with alternative approaches. Prior studies reported that as many as 25% of opioid naive patients undergoing lumbar fusion surgery are still consuming opioids at 2 years postoperative. Currently, opioids are a primary component of anesthesia during spinal surgery. We developed an opioid sparing anesthesia (OSA) protocol for lumbar spinal fusion surgery to mitigate opioid exposure. <h3>PURPOSE</h3> To compare surgical, peri- and postoperative process measures and in-hospital opioid consumption in patients receiving OSA vs traditional anesthesia. <h3>STUDY DESIGN/SETTING</h3> Retrospective, single center propensity-matched observational cohort study. <h3>PATIENT SAMPLE</h3> Patients who underwent 1-4 level lumbar fusion for degenerative conditions. <h3>OUTCOME MEASURES</h3> Daily and total opioid consumption in morphine milligram equivalents (MME). <h3>Methods</h3> Patients undergoing < 5-level lumbar fusion for degenerative conditions were identified. Patients taking opioids preoperatively were excluded. Patients receiving OSA were propensity-matched to non-OSA patients based on sex, smoking status, BMI, ASA grade and revision vs primary procedure. Preoperatively patients receive an oral regimen of cyclobenzaprine (10mg), gabapentin (300-600mg), acetaminophen (650-1g), Celebrex (200mg), and/or methadone (5-10mg). The intraoperative OSA protocol includes a combination of IV propofol, lidocaine, ketamine, magnesium, dexmedetomidine, and esmolol as needed. Anesthesia was maintained with inhalational agents or TIVA. Postoperatively patients received a bilateral transverse abdominis plane or erector spinae block with 0.25% Ropivacaine/4mg decadron mixture. A standard opioid escalation protocol was also utilized in the hospital postoperatively. We evaluated surgical parameters (EBL and OR Time), immediate perioperative parameters (emergence time, PACU time, pain score on transfer in/out of PACU), and length of stay (LOS). <h3>Results</h3> Of 143 OSA patients meeting inclusion criteria, 134 OSA patients were successfully propensity matched to 134 non-OSA patients. Consistent with propensity matching, there was no difference in baseline demographic parameters between cohorts. Patients undergoing OSA had reduced EBL (197mL vs 324mL, p=0.000) and OR time (153min vs 193min, p=0.000) compared to non-OSA. Emergence time (9.9min vs 11.6min, p=0.151) and PACU time (90min vs 88min, p=0.688) was similar between cohorts. There was no difference in LOS (3.3day vs 3.5 days, p=0.599). Daily opioid consumption was reduced from POD 1 (114MME vs 139MME, p=0.002) and maintained each day with decreased total consumption (195MME vs 272MME, p=0.002). Pain score on transfer out of PACU was decreased for OSA patients as well (4.8 vs 6.0, p=0.000). <h3>Conclusions</h3> In a matched comparison of OSA vs traditional anesthesia for 1-4 lumbar spinal fusions in degenerative conditions we found a reduction in EBL, OR Time, PACU pain scores, and daily/total opioid in hospital consumption. The findings of this pilot study justify ongoing efforts to optimize OSA and undertake larger prospective studies of OSA protocols. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

21. Adoption of enhanced recovery after surgery (ERAS) protocol for lumbar fusion decreases in hospital postoperative opioid consumption

<h3>BACKGROUND CONTEXT</h3> Enhanced recovery after surgery (ERAS) is an evidence-based multidisciplinary perioperative protocol intended to reduce surgical morbidity and improve recovery. <h3>PURPOSE</h3> We sought to evaluate the impact of ERAS on in-hospital and 90-day postoperative opioid consumption, length of stay, urinary catheter removal and postoperative ambulation after lumbar fusion for degenerative conditions. <h3>STUDY DESIGN/SETTING</h3> Single center retrospective observational cohort study. <h3>PATIENT SAMPLE</h3> A total of 290 patients undergoing lumbar fusion surgery during the transition period prior to (N=174) and after (N=116) adoption of ERAS. <h3>OUTCOME MEASURES</h3> In-hospital and 90-day postop opioid consumption in morphine milligram equivalents (MME), pre- and postoperative pain scores, length of stay, urinary catheter removal and ambulation after surgery. <h3>METHODS</h3> We evaluated patients undergoing lumbar fusion surgery in the transition period prior to (N=174) and after (N=116) adoption of ERAS, comparing in-hospital and 90-day postop opioid consumption. Regression analysis was used to control for confounders. Secondary analysis was preformed to evaluate the association between ERAS and length of stay, urinary catheter removal and ambulation after surgery. <h3>RESULTS</h3> Mean age of the cohort was 52.6 years with 62 (47%) females. Demographic characteristics were similar between the pre-ERAS and ERAS groups. ERAS patients had better 3-month pain scores, ambulated earlier, had urinary catheters removed earlier and decreased in-hospital opioid consumption compared to Pre-ERAS patients. There was no difference in 90-day opioid consumption between the two groups. Regression analysis showed that ERAS was strongly associated with in-hospital opioid consumption, accounting for 30% of the variability in MME. In-hospital opioid consumption was also associated with preoperative pain scores, number of surgical levels, and insurance type (private vs government). Preoperative pain sores, but not ERAS were associated with 90-day opioid consumption. Secondary analysis showed that ERAS was associated with a shorter length of stay and earlier ambulation. <h3>CONCLUSIONS</h3> This study showed ERAS has the potential to improved recovery after lumbar fusion for degenerative conditions with reduced in-hospital opioid consumption and improved postoperative pain scores. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Characteristics of the DXA Measurements in Patients Undergoing Lumbar Fusion for Lumbar Degenerative Diseases: A Retrospective Analysis of Over 1000 Patients.

PurposeTo explore the characteristics and reliability of dual-energy x-ray absorptiometry (DXA) measurements in patients undergoing lumbar fusion for lumbar degenerative diseases (LDD).Patients and MethodsA total of 1041 patients aged ≥50 years undergoing lumbar fusion for LDD were reviewed. The BMDs and T-scores of DXA were retrospectively analysed. The diagnosis of osteoporosis was in accordance with World Health Organization (WHO) criteria. Based on the guidelines of International Society for Clinical Densitometry (ISCD), an abnormal lumbar segment is identified as having unreliable T-scores when there is more than a 1.0 T-score difference between two adjacent vertebrae.ResultsThe prevalence of osteoporosis diagnosed on DXA was 42.3%, and it was higher in women than in men (50.2% vs 31.8%, P < 0.001). Increasing age resulted in higher prevalence of osteoporosis in females. The prevalence of osteoporosis significantly declined with increasing BMI. The lowest lumbar T-score was mostly found at L1. Unreliable T-scores were mostly seen in the lower lumbar segment (L3–L4) and were the least common in L1–L2. The average amount of abnormal lumbar segments increased with age (P = 0.003) and BMI (P = 0.021). Furthermore, those with degenerative lumbar scoliosis had more abnormal segments (P < 0.001). Of the 95 patients with at least one fractured vertebra, 39 (41.1%) were not diagnosed as having osteoporosis on lumbar DXA.ConclusionFemale, older age and low BMI are the risk factors for osteoporosis in patients undergoing lumbar fusion for LDD. Lower lumbar segments, such as L3–L4, are more likely to have unreliable T-scores. Patients with older age, higher BMI or degenerative scoliosis have more abnormal segments with unreliable T-scores. Lumbar DXA measurements are not sensitive enough to identify patients with vertebral fracture.

Prediction of Major Complications and Readmission After Lumbar Spinal Fusion: A Machine Learning–Driven Approach

Given the significant cost and morbidity of patients undergoing lumbar fusion, accurate preoperative risk-stratification would be of great utility. We aim to develop a machine learning model for prediction of major complications and readmission after lumbar fusion. We also aim to identify the factors most important to performance of each tested model. We identified 38,788 adult patients who underwent lumbar fusion at any California hospital between 2015 and 2017. The primary outcome was major perioperative complication or readmission within 30 days. We build logistic regression and advanced machine learning models: XGBoost, AdaBoost, Gradient Boosting, and Random Forest. Discrimination and calibration were assessed using area under the receiver operating characteristic curve and Brier score, respectively. There were 4470 major complications (11.5%). The XGBoost algorithm demonstrates the highest discrimination of the machine learning models, outperforming regression. The variables most important to XGBoost performance include angina pectoris, metastatic cancer, teaching hospital status, history of concussion, comorbidity burden, and workers' compensation insurance. Teaching hospital status and concussion history were not found to be important for regression. We report a machine learning algorithm for prediction of major complications and readmission after lumbar fusion that outperforms logistic regression. Notably, the predictors most important for XGBoost differed from those for regression. The superior performance of XGBoost may be due to the ability of advanced machine learning methods to capture relationships between variables that regression is unable to detect. This tool may identify and address potentially modifiable risk factors, helping risk-stratify patients and decrease complication rates.