Predicting Extended Length of Hospital Stay in an Adult Spinal Deformity Surgical Population

Integration of Chronological Age Does Not Improve the Performance of a Mixed-Effect Model Using Comorbidity Burden and Frailty to Predict 90-Day Readmission After Surgery for Degenerative Scoliosis

OBJECTIVE

We evaluated the contributions of chronological age, comorbidity burden, and/or frailty in predicting 90-day readmission in patients undergoing degenerative scoliosis surgery.

METHODS

Patients were identified through the Healthcare Cost and Utilization Project Nationwide Readmissions Database. Frailty was assessed using the Johns Hopkins Adjusted Clinical Groups frailty-defining indicator. Comorbidity was assessed using the Elixhauser Comorbidity Index (ECI). Generalized linear mixed-effects models were created to predict readmission using age, frailty, and/or ECI. Area under the curve (AUC) was compared using DeLong's test.

RESULTS

A total of 8104 patients were identified. Readmission rate was 9.8%, with infection representing the most common cause (3.5%). Our first model utilized chronological age, ECI, and/or frailty as primary predictors. The combination of ECI + frailty + age performed best, but the inclusion of chronological age did not significantly improve performance compared to ECI + frailty alone (AUC 0.603 vs. 0.599, P = 0.290). A second model using only chronological age and frailty as primary predictors performed better, however the inclusion of chronological age worsened performance when compared to frailty alone (AUC 0.747 vs. 0.743, P = 0.043).

CONCLUSIONS

These data support frailty as a predictor of 90-day readmission within a nationally representative sample. Frailty alone performed better than combinations of ECI and age. Interestingly, the integration of chronological age did not dramatically improve the model's performance. Limitations include the use of a national registry and a single frailty index. This provides impetus to explore biological age, rather than chronological age, as a potential tool for surgical risk assessment.

Preoperatively-determined Red Distribution Width (RDW) predicts prolonged length of stay after single-level spinal fusion in elderly patients

Introduction

Elderly patients receiving lumbar fusion surgeries present with a higher risk profile, which necessitates a robust predictor of postoperative outcomes. The Red Distribution Width (RDW) is a preoperative routinely determined parameter that reflects the degree of heterogeneity of red blood cells. Thereby, RDW is associated with frailty in hospital-admitted patients.

Research question

This study aims to elucidate the potential of RDW as a frailty biomarker predictive of prolonged hospital stays following elective mono-segmental fusion surgery in elderly patients.

Material and methods

In this retrospective study, we included all patients with age over 75 years that were treated via lumbar single-level spinal fusion from 2015 to 2022 at our tertiary medical center. Prolonged length of stay (pLOS) was defined as a length ≥ the 3rd quartile of LOS of all included patients. Classical correlation analysis, Receiver-operating characteristic (ROC) and new machine learning algorithms) were used.

Results

A total of 208 patients were included in the present study. The median age was 77 (IQR 75-80) years. The median LOS of the patients was 6 (IQR 5-8) days. The data shows a significant positive correlation between RDW and LOS. RDW is significantly enhanced in the pLOS group. New machine learning approaches with the imputation of multiple variables can enhance the performance to an AUC of 71%.

Discussion and conclusion

RDW may serve as a predictor for a pLOS in elderly. These results are compelling because the determination of this frailty biomarker is routinely performed at hospital admission. An improved prognostication of LOS could enable healthcare systems to distribute constrained hospital resources efficiently, fostering evidence-based decision-making processes.

Ensemble learning-assisted prediction of prolonged hospital length of stay after spine correction surgery: a multi-center cohort study

PURPOSE

This research aimed to develop a machine learning model to predict the potential risk of prolonged length of stay in hospital before operation, which can be used to strengthen patient management.

METHODS

Patients who underwent posterior spinal deformity surgery (PSDS) from eleven medical institutions in China between 2015 and 2022 were included. Detailed preoperative patient data, including demographics, medical history, comorbidities, preoperative laboratory results, and surgery details, were collected from their electronic medical records. The cohort was randomly divided into a training dataset and a validation dataset with a ratio of 70:30. Based on Boruta algorithm, nine different machine learning algorithms and a stack ensemble model were trained after hyperparameters tuning visualization and evaluated on the area under the receiver operating characteristic curve (AUROC), precision-recall curve, calibration, and decision curve analysis. Visualization of Shapley Additive exPlanations method finally contributed to explaining model prediction.

RESULTS

Of the 162 included patients, the K Nearest Neighbors algorithm performed the best in the validation group compared with other machine learning models (yielding an AUROC of 0.8191 and PRAUC of 0.6175). The top five contributing variables were the preoperative hemoglobin, height, body mass index, age, and preoperative white blood cells. A web-based calculator was further developed to improve the predictive model's clinical operability.

CONCLUSIONS

Our study established and validated a clinical predictive model for prolonged postoperative hospitalization duration in patients who underwent PSDS, which offered valuable prognostic information for preoperative planning and postoperative care for clinicians. Trial registration ClinicalTrials.gov identifier NCT05867732, retrospectively registered May 22, 2023, https://classic.

CLINICALTRIALS

gov/ct2/show/NCT05867732 .

Association of frailty with healthcare resource utilization after open thoracic/thoracolumbar posterior spinal fusion for adult spinal deformity

PURPOSE

The Hospital Frailty Risk Score (HFRS) is a frailty-identifying metric developed using ICD-10-CM codes. While other studies have examined frailty in adult spinal deformity (ASD), the HFRS has not been assessed in this population. The aim of this study was to utilize the HFRS to investigate the impact of frailty on outcomes in ASD patients undergoing posterior spinal fusion (PSF).

METHODS

A retrospective study was performed using the 2016-2019 National Inpatient Sample database. Adults with ASD undergoing elective PSF were identified using ICD-10-CM codes. Patients were categorized into HFRS-based frailty cohorts: Low (HFRS < 5) and Intermediate-High (HFRS ≥ 5). Patient demographics, comorbidities, intraoperative variables, and outcomes were assessed. Multivariate regression analyses were used to determine whether HFRS independently predicted extended length of stay (LOS), non-routine discharge, and increased cost.

RESULTS

Of the 7500 patients identified, 4000 (53.3%) were in the Low HFRS cohort and 3500 (46.7%) were in the Intermediate-High HFRS cohort. On average, age increased progressively with increasing HFRS scores (p < 0.001). The frail cohort experienced more postoperative adverse events (p < 0.001), greater LOS (p < 0.001), accrued greater admission costs (p < 0.001), and had a higher rate of non-routine discharge (p < 0.001). On multivariate analysis, Intermediate-High HFRS was independently associated with extended LOS (OR: 2.58, p < 0.001) and non-routine discharge (OR: 1.63, p < 0.001), though not increased admission cost (OR: 1.01, p = 0.929).

CONCLUSION

Our study identified HFRS to be significantly associated with prolonged hospitalizations and non-routine discharge. Other factors that were found to be associated with increased healthcare resource utilization include age, Hispanic race, West hospital region, large hospital size, and increasing number of AEs.

Association of inpatient opioid consumption on postoperative outcomes after open posterior spinal fusion for adult spine deformity

INTRODUCTION

Opioids are the most commonly used analgesic in the postoperative setting. However, few studies have analyzed the impact of high inpatient opioid use on outcomes following surgery, with no current studies assessing its effect on patients undergoing spinal fusion for an adult spinal deformity (ASD). Thus, the aim of this study was to investigate risk factors for high inpatient opioid use, as well as to determine the impact of high opioid use on outcomes such as adverse events (AEs), hospital length of stay (LOS), cost of hospital admission, discharge disposition, and readmission rates in patients undergoing spinal fusion for ASD.

METHODS

A retrospective cohort study was performed using the Premier healthcare database from the years 2016 and 2017. All adult patients > 40 years old who underwent thoracic or thoracolumbar fusion for ASD were identified using the ICD-10-CM diagnostic and procedural coding system. Patients were then categorized into three cohorts based on inpatient opioid use: Low MME (morphine milligram equivalents), Medium MME, and High MME. Patient demographics, comorbidities, treating hospital characteristics, intraoperative variables, postoperative AEs, LOS, discharge disposition, and total cost of hospital admission were assessed in the analysis. Multivariate regression analysis was done to determine independent predictors of high inpatient MME, prolonged LOS, and increased hospital cost.

RESULTS

Of 1673 patients included, 417 (24.9%) were classified as Low MME, 840 (50.2%) as Medium MME, and 416 (24.9%) as High MME. Age significantly decreased with increasing MME (Low: 71.0% 65 + years vs Medium: 62.0% 65 + years vs High: 47.4% 65 + years, p < 0.001), while the proportions of patients presenting with three or more comorbidities were similar across the cohorts (Low: 20.1% with 3 + comorbidities vs Medium: 18.0% with 3 + comorbidities vs High: 24.3% with 3 + comorbidities, p = 0.070). With respect to postoperative outcomes, the proportion of patients who experienced any AE (Low: 60.2% vs Medium: 68.8% vs High: 70.9%, p = 0.002), extended LOS (Low: 6.7% vs Medium: 20.7% vs High: 45.4%, p < 0.001), or non-routine discharge (Low: 66.6% vs Medium: 73.5% vs High: 80.1%, p = 0.003) each increased along with total MME. In addition, rates of 30-day readmission were greatest among the High MME cohort (Low: 8.4% vs Medium: 7.9% vs High: 12.5%, p = 0.022). On multivariate analysis, medium and high MME were associated with prolonged LOS [Medium: OR 4.41, CI (2.90, 6.97); High: OR 13.99, CI (8.99, 22.51), p < 0.001] and increased hospital cost [Medium: OR 1.69, CI (1.21, 2.39), p = 0.002; High: OR 1.66, CI (1.12, 2.46), p = 0.011]. Preadmission long-term opioid use [OR 1.71, CI (1.07, 2.7), p = 0.022], a prior opioid-related disorder [OR 11.32, CI (5.92, 23.49), p < 0.001], and chronic pulmonary disease [OR 1.39, CI (1.06, 1.82), p = 0.018] were each associated with a high inpatient MME on multivariate analysis.

CONCLUSION

Our study demonstrated that increasing inpatient MME consumption was associated with extended LOS and increased hospital cost in patients undergoing spinal fusion for ASD. Further studies identifying risk factors for increased MME consumption may provide better risk stratification for postoperative opioid use and healthcare resource utilization.

Impact of Affective Disorders on Inpatient Opioid Consumption and Hospital Outcomes Following Open Posterior Spinal Fusion for Adult Spine Deformity

OBJECTIVE

Affective disorders (ADs) are common and have a profound impact on surgical recovery, though few have studied the impact of ADs on inpatient narcotic consumption. The aim of this study was to assess the impact of ADs on inpatient narcotic consumption and healthcare resource utilization in patients undergoing spinal fusion for adult spinal deformity.

METHODS

A retrospective cohort study was performed using the 2016-2017 Premier Healthcare Database. Adults who underwent adult spinal deformity surgery were identified using International Classification of Disease, Tenth Revision, codes. Patients were grouped based on comorbid diagnosis of an AD. Demographics, comorbidities, intraoperative variables, complications, length of stay, admission costs, and nonroutine discharge rates were assessed. Increased inpatient opioid use was categorized by morphine milligram equivalents consumption greater than the 75th percentile. Multivariate regression analysis was used to identify predictors of increased healthcare recourse utilization.

RESULTS

Of the 1831 study patients, 674 (36.8%) had an AD. A smaller proportion of patients in the AD cohort were 65+ years of age (P = 0.001), while a greater proportion of patients in the AD cohort identified as non-Hispanic White (P < 0.001). A greater proportion of patients in the AD cohort had increased morphine milligram equivalents consumption (P < 0.001). The AD cohort also had a longer mean length of stay (P < 0.001). A greater proportion of patients in the AD cohort had nonroutine discharges (P = 0.039) and unplanned 30-day readmission (P = 0.041). On multivariate analysis, AD was significantly associated with increased cost (odds ratio: 1.61, P < 0.001) and nonroutine discharge (odds ratio: 1.36, P = 0.035).

CONCLUSIONS

ADs may be associated with increased inpatient opioid consumption and healthcare resource utilization.

Low Preoperative Albumin Associated With Increased Risk of Superficial Surgical Site Infection Following Midfoot, Hindfoot, and Ankle Fusion

BACKGROUND

This study investigates the effect of malnutrition, defined by hypoalbuminemia, on rates of complication, readmission, reoperation, and mortality following midfoot, hindfoot, or ankle fusion.

METHODS

The National Surgical Quality Improvement Program (NSQIP) database was queried from 2005 to 2019 to identify 500 patients who underwent midfoot (n = 233), hindfoot (n = 261), or ankle (n = 117) fusion. Patients were stratified into normal (n = 452) or low (n = 48) albumin group, which was defined by preoperative serum albumin level <3.5 g/dL. Demographics, medical comorbidities, hospital length of stay (LOS), and 30-day complication, readmission, and reoperation rates were compared between groups. The mean age of the cohort was 58.7 (range, 21-89) years.

RESULTS

Hypoalbuminemia patients were significantly more likely to have diabetes (P < .001), be on dialysis (P < .001), and be functionally dependent (P < .001). The LOS was significantly greater among the low albumin group (P < .001). The hypoalbuminemia cohort also exhibited a significantly increased likelihood of superficial infection (P = .048). Readmission (P = .389) and reoperation (P = .611) rates did not differ between the groups.

CONCLUSION

This study shows that malnourished patients have an increased risk of superficial infection following foot and ankle fusions but are not at an increased risk of readmission or reoperation, suggesting that low albumin confers an elevated risk of surgical site infection.

LEVELS OF EVIDENCE

Level III, Retrospective cohort study.

Timing of inpatient medical complications after adult spinal deformity surgery: early ambulation matters

BACKGROUND

The substantial risk for medical complication after adult spinal deformity (ASD) surgery is well known. However, the timing of medical complications during the inpatient stay have not been previously described. Accurate anticipation of complications and adverse events may improve patient counseling and postoperative management.

PURPOSE

(1) Describe the rate of medical complication and adverse events by postoperative day after ASD surgery and (2) determine whether early ambulation is protective for complications.

STUDY DESIGN/SETTING

Single institution retrospective cohort study.

PATIENT SAMPLE

Two hundred thirty-five patients with ASD who underwent posterior-only fusion of the lumbar spine (≥5 levels to the pelvis) between 2013 and 2020.

OUTCOME MEASURES

Medical complications, categorized per the International Spine Study Group-AO system (cardiopulmonary [CP], gastrointestinal [GI], central nervous system [CNS], infectious [nonsurgical site], and renal) and adverse events (postoperative blood transfusion, urinary retention, and electrolyte abnormalities).

METHODS

Patients were identified from an institutional ASD database. Outcome measures were classified by the first postoperative day the event was recognized. Demographics, year of surgery, surgical factors, radiographic parameters, surgical invasiveness (ASD-S Index), frailty (Modified Frailty Index-5 [mFI-5]), Charlson Comorbidity Index (CCI), obstructive sleep apnea (OSA), smoking, preoperative opioid use, depression, and post-operative day of ambulation were assessed as risk factors for inpatient medical complications.

RESULTS

After exclusions of patients with incomplete medical chart data, 191 patients were available for analysis, mean age 66±10 y, BMI 28±5 kg/m2, PI-LL 24±20°, T1PA 28±13°. Inpatient medical complications occurred in 55 (28.8%) patients; adverse events occurred in 137 (71.7%). Length of stay was higher in patients with medical complications (mean 8.5±3.8 vs. 5.8±2.3 days, p<.001). However, for patients who had an adverse event, but no medical complication, LOS was comparable (p>.05). Most medical complications occurred by POD3 (58% of all complications). Risk (defined as the proportion of patients with that complication out of all inpatients that day) of CNS, CP, and GI complication peaked early in the postoperative course (CNS on POD1 [2.1% risk]; GI on POD2 [3.7%]; CP on POD3 [2.7%]). Risk for infectious and renal complications (infectious POD8 [2.7%]; renal POD7 [0.9%]) peaked later (Figure 1). On univariate analysis, patients with medical complications had higher rates of OSA (9.1% vs. 2.2%, p=.045), ASD-S (45.9 vs. 40.8, p=.04), max coronal cobb (46.9 vs. 36.7°, p=.003), ASA class (2.5 vs. 2.3, p=.01), and POD of ambulation (1.9 vs. 1.3, p=.01). On multivariate logistic regression (c-statistic 0.78), larger coronal cobb and later POD of ambulation were independent risk factors for complications (OR 1.04, 95% CI 1.01-1.07 and OR 2.3, 95% CI 1.2-4.7, respectively).

CONCLUSIONS

Our data may inform peri-operative management and patient expectations for hospitalization after ASD surgery. Early ambulation may reduce the risk of complications.

Predictive Models for Length of Stay and Discharge Disposition in Elective Spine Surgery: Development, Validation, and Comparison to the ACS NSQIP Risk Calculator

STUDY DESIGN

A retrospective study at a single academic institution.

OBJECTIVE

The purpose of this study is to utilize machine learning to predict hospital length of stay (LOS) and discharge disposition following adult elective spine surgery, and to compare performance metrics of machine learning models to the American College of Surgeon's National Surgical Quality Improvement Program's (ACS NSQIP) prediction calculator.

SUMMARY OF BACKGROUND DATA

A total of 3678 adult patients undergoing elective spine surgery between 2014 and 2019, acquired from the electronic health record.

METHODS

Patients were divided into three stratified cohorts: cervical degenerative, lumbar degenerative, and adult spinal deformity groups. Predictive variables included demographics, body mass index, surgical region, surgical invasiveness, surgical approach, and comorbidities. Regression, classification trees, and least absolute shrinkage and selection operator (LASSO) were used to build predictive models. Validation of the models was conducted on 16% of patients (N=587), using area under the receiver operator curve (AUROC), sensitivity, specificity, and correlation. Patient data were manually entered into the ACS NSQIP online risk calculator to compare performance. Outcome variables were discharge disposition (home vs. rehabilitation) and LOS (days).

RESULTS

Of 3678 patients analyzed, 51.4% were male (n=1890) and 48.6% were female (n=1788). The average LOS was 3.66 days. In all, 78% were discharged home and 22% discharged to rehabilitation. Compared with NSQIP (Pearson R2 =0.16), the predictions of poisson regression ( R2 =0.29) and LASSO ( R2 =0.29) models were significantly more correlated with observed LOS ( P =0.025 and 0.004, respectively). Of the models generated to predict discharge location, logistic regression yielded an AUROC of 0.79, which was statistically equivalent to the AUROC of 0.75 for NSQIP ( P =0.135).

CONCLUSION

The predictive models developed in this study can enable accurate preoperative estimation of LOS and risk of rehabilitation discharge for adult patients undergoing elective spine surgery. The demonstrated models exhibited better performance than NSQIP for prediction of LOS and equivalent performance to NSQIP for prediction of discharge location.

Preoperative characteristics are associated with increased likelihood of low early postoperative mobility after adult spinal deformity surgery

BACKGROUND CONTEXT

Low early postoperative mobility (LEPOM) has been shown to be associated with increased length of hospital stay, complication rates, and likelihood of nonhome discharge. However, few studies have examined preoperative characteristics associated with LEPOM in adult spinal deformity (ASD) patients.

PURPOSE

To investigate which preoperative patient characteristics may be associated with LEPOM after ASD surgery.

DESIGN

Retrospective review.

PATIENT SAMPLE

Included were 86 ASD patients with fusion of ≥5 levels for whom immediate-postoperative AM-PAC Basic Mobility Inpatient Short Form (6-Clicks) scores had been obtained.

OUTCOME MEASURES

The primary outcome of this study was the likelihood of LEPOM, defined as an AM-PAC score ≤15, which is associated with inability to stand for more than 1 minute.

METHODS

Significant cutoffs for preoperative characteristics associated with LEPOM were determined via threshold linear regression. Multivariable logistic regression was used to assess the impact of preoperative characteristics on the likelihood of LEPOM.

RESULTS

LEPOM was recorded in 38 patients (44.2%). Threshold regression identified the following cutoffs to be associated with LEPOM: preoperative Patient Reported Outcomes Measurement Information System (PROMIS) scores of ≥68 for Pain, <28.3 for Physical Function, and ≥63.4 for Anxiety; preoperative Oswestry disability index (ODI) score of ≥60; and body mass index (BMI) of ≥35.2. On multivariate analysis, preoperative PROMIS scores of ≥68 for Pain (odds ratio [OR] 5.3, confidence interval [CI] 1.2-22.8, p=.03), <28.3 for Physical Function (OR 10.1, CI 1.8-58.2, p=.01), and ≥63.4 for Anxiety (OR 4.7, CI 1.1-20.8, p=.04); preoperative ODI score ≥60 (OR 38.8, CI 4.0-373.6, p=.002); BMI ≥35.2 (OR 14.2, CI 1.3-160.0, p=.03), and male sex (OR 5.4, CI 1.2-23.7, p=.03) were associated with increased odds of LEPOM.

CONCLUSIONS

Preoperative PROMIS Pain, Physical Function, and Anxiety scores; ODI score; BMI; and male sex were associated with LEPOM. Several of these characteristics are modifiable risk factors and thus may be candidates for optimization before surgery.

LEVEL OF EVIDENCE

III.

Geriatric relationship with inpatient opioid consumption and hospital outcomes after open posterior spinal fusion for adult spine deformity

OBJECTIVE

As the population ages, increasing attention has been placed on identifying risk factors for poor surgical outcomes in the elderly. The aim of this study was to assess the impact of geriatric status on inpatient narcotic consumption and healthcare resource utilization in patients undergoing spinal fusion for adult spinal deformity.

METHODS

A retrospective study was performed using the Premier Healthcare Database (2016-2017). All adult patients who underwent thoracic/thoracolumbar fusion for spine deformity were identified using ICD-10-CM codes. Patients were categorized by age: 18-49 years-old (Young), 50-64 years-old (Older), and 65 + years-old (Geriatric). Patient demographics, comorbidities, hospital characteristics, intraoperative variables, adverse events (AEs), and healthcare resource utilization were assessed. Increased inpatient opioid use was categorized by MME (morphine milligram equivalents) admission consumption greater than the 75th percentile of the cohort. Multivariate logistic regression analysis was used to identify independent predictors of increased opioid usage, increased cost, and non-routine discharge (NRD).

RESULTS

Of the 1831 patients identified, 199 (10.9 %) were in the Young cohort, 599 (32.7 %) were in the Older cohort, and 1033 (56.4 %) were in the Geriatric cohort. The Geriatric cohort had a greater proportion of patients who were Non-Hispanic White (p < 0.001) and government-insured (p < 0.001). Comorbidities [CCI (p < 0.001)] and frailty [mFI-5 (p < 0.001)] increased with age. AEs occurred at similar rates between cohorts. A greater proportion of Older patients consumed an increased amount of MMEs during their hospital stay (Young: 24.9 % vs. Older: 33.1 % vs. Geriatric: 20.2 %, p < 0.001). A greater proportion of Geriatric patients experienced high costs (p = 0.018), longer LOS (p = 0.011), and 30-day readmission (p = 0.004) compared to other cohorts. A significantly greater proportion of the Geriatric cohort experienced NRD (Young: 25.3 % vs. Older: 58.8 % vs. Geriatric: 83.0 %, p < 0.001) On multivariate analysis, Geriatric age was independently associated with NRD (OR: 11.59, p < 0.001), and inversely associated with increased MME use (OR: 0.66, p = 0.038). However, Older age was independently associated with increased MME use (OR: 1.58, p = 0.026) and NRD (OR: 4.27, p < 0.001), though not increased cost (OR: 1.49, p = 0.077).

CONCLUSION

Our study demonstrates that geriatric patients may require fewer opioids than younger patients but require greater resource utilization on discharge. Additional studies investigating the impact of aging are necessary to improve patient risk stratification, healthcare delivery, and patient outcomes.

Cardiac Complications After 3-Column Osteotomy for Adult Spinal Deformity Patients With Formal Cardiac Clearance: Identifying Key Risk Factors and Threshold Cutoffs Via Recursive Partitioning Analysis

BACKGROUND

Despite formal cardiac clearance, a subset of 3-column osteotomy (3CO) patients still experience cardiac complications (CCs).

OBJECTIVE

To define the incidence and risk factors for CC in 3CO patients who had formal cardiac clearance and assess the utility of the Revised Cardiac Risk Index (RCRI) and preoperative metabolic equivalent (MET) functional ability in predicting perioperative CC.

METHODS

Patients with adult spinal deformity (ASD) who underwent 3CO deformity correction from 2006 to 2019 were retrospectively reviewed. Multivariate and recursive partitioning analyses were performed to assess risk factors.

RESULTS

A total of 390 patients with ASD were included. The mean age was 64.6 years, and 60.3% were female. The CC rate was 9.7%. Patients with CCs were older ( P &lt; .001), had an increased history of heart disease ( P = .001), and higher blood loss ( P = .045). RCRI score ( P = .646) or MET functional ability ( P = .493) were not associated with CC. On multivariate analysis, age ( P &lt; .001), blood loss ( P = .008), and prior spinal fusion ( P = .025) were independent risk factors for CC. Patients age older than 81 years had a significantly higher CC rate than those younger than 81 years. In patients age 81 years and younger, if blood loss was &gt;3900 mL, CC rate was significantly higher. Among patients age 81 years and younger and with &gt;3900 mL blood loss, CC rate is significantly higher in patients with ejection fraction (EF) ≤54.5%.

CONCLUSION

RCRI and MET functional ability are limited risk assessment tools in ASD 3CO patients with formal cardiac clearance. Patients older than 81 years are at high risk for CC. In younger patients, cardiac EF and blood loss are significant components to risk stratify for CC.

Performance of Artificial Intelligence-Based Algorithms to Predict Prolonged Length of Stay after Lumbar Decompression Surgery

Background: Decompression of the lumbar spine is one of the most common procedures performed in spine surgery. Hospital length of stay (LOS) is a clinically relevant metric used to assess surgical success, patient outcomes, and socioeconomic impact. This study aimed to investigate a variety of machine learning and deep learning algorithms to reliably predict whether a patient undergoing decompression of lumbar spinal stenosis will experience a prolonged LOS. Methods: Patients undergoing treatment for lumbar spinal stenosis with microsurgical and full-endoscopic decompression were selected within this retrospective monocentric cohort study. Prolonged LOS was defined as an LOS greater than or equal to the 75th percentile of the cohort (normal versus prolonged stay; binary classification task). Unsupervised learning with K-means clustering was used to find clusters in the data. Hospital stay classes were predicted with logistic regression, RandomForest classifier, stochastic gradient descent (SGD) classifier, K-nearest neighbors, Decision Tree classifier, Gaussian Naive Bayes (GaussianNB), support vector machines (SVM), a custom-made convolutional neural network (CNN), multilayer perceptron artificial neural network (MLP), and radial basis function neural network (RBNN) in Python. Prediction accuracy and area under the curve (AUC) were calculated. Feature importance analysis was utilized to find the most important predictors. Further, we developed a decision tree based on the Chi-square automatic interaction detection (CHAID) algorithm to investigate cut-offs of predictors for clinical decision-making. Results: 236 patients and 14 feature variables were included. K-means clustering separated data into two clusters distinguishing the data into two patient risk characteristic groups. The algorithms reached AUCs between 67.5% and 87.3% for the classification of LOS classes. Feature importance analysis of deep learning algorithms indicated that operation time was the most important feature in predicting LOS. A decision tree based on CHAID could predict 84.7% of the cases. Conclusions: Machine learning and deep learning algorithms can predict whether patients will experience an increased LOS following lumbar decompression surgery. Therefore, medical resources can be more appropriately allocated to patients who are at risk of prolonged LOS.

Single-level TLIF Versus LLIF at L4-5: A Comparison of Patient-reported Outcomes and Recovery Ratios

INTRODUCTION

Both transforaminal lumbar interbody fusion (TLIF) and lateral lumbar interbody fusion (LLIF) are suitable for achievement of lumbar arthrodesis. Comparative studies have observed complications and outcomes without stratification by lumbar level. This study aims to assess patient-reported outcome measures (PROMs) and recovery in TLIF and LLIF at L4-5.

METHODS

Patients undergoing primary, elective, single-level, TLIF or LLIF procedures at L4-5 were grouped. Demographics, perioperative characteristics, and postoperative complication rates were collected. PROMs included Patient-Reported Outcome Measurement Information System Physical Function, visual analog scale (VAS) back and leg, Oswestry Disability Index, and 12-Item Short-Form Physical Component Summary, and Mental Component Summary and were collected at preoperative, 6-week, 12-week, 6-month, 1-year, and 2-year time points. Delta values and recovery ratios (RRs) were calculated for all PROMs at all time points. Demographics, perioperative characteristics, and postoperative complications were compared using chi-squared and Student t-test for categorical and continuous variables, respectively. Differences in mean PROMs, delta values, and RR at each time point were evaluated using unpaired Student's t-test.

RESULTS

Three hundred sixty TLIF and 46 LLIF patients were included. Most (54.3%) were men, mean age 56.3 years, and mean body mass index 30.8 kg/m2. Body mass index and insurance significantly differed (P ≤ 0.045, all). TLIF showed significantly greater mean operative time, length of stay, and postoperative narcotic consumption (P < 0.033, all) and greater postoperative nausea/vomiting (P = 0.004). No preoperative PROMs significantly differed. TLIF cohort had significantly greater VAS back at 6 months and VAS leg at 12 weeks and 6 months (P < 0.034, all). No mean delta PROMs or RRs significantly differed.

DISCUSSION

LLIF demonstrated significantly reduced length of stay, postoperative narcotic consumption, and postoperative nausea/vomiting and significantly improved VAS back at 6 months and VAS leg at 12 weeks and 6 months versus TLIF. Although 2-year PROMs and RRs did not significantly differ, our findings may suggest improved midterm follow-up pain scores for LLIF patients.

Surgical Factors and Treatment Severity for Perioperative Complications Predict Hospital Length of Stay in Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective review of prospectively collected multicenter registry data.

OBJECTIVE

The aim of this study was to determine whether surgical variables and complications as graded by treatment severity impact postoperative hospital length of stay (LOS).

SUMMARY OF BACKGROUND DATA

Surgical treatment can substantially improve quality of life for patients with adult spinal deformity (ASD). However, surgical treatment is associated with high complication rates, which may impact hospital LOS. Classifying complications by severity of subsequent treatment may allow surgeons to better understand complications and predict their impact on important outcome metrics, including LOS.

METHODS

Patients enrolled in a multicenter, prospectively enrolled database for ASD were assessed for study inclusion. Complications were graded based on intervention severity. Associations between LOS, complication intervention severity, and surgical variables (fusion length, use of interbody fusion, use of major osteotomy, primary versus revision surgery, same day vs. staged surgery, and surgical approach), were assessed. Two multivariate regression models were constructed to assess for independent associations with LOS.

RESULTS

Of 1183 patients meeting inclusion criteria, 708 did not and 475 did experience a perioperative complication during their index hospitalization, with 660 and 436 included in the final cohorts, respectively. Among those with complications, intervention severities included 14.9% with no intervention, 68.6% with minor, 8.9% with moderate, and 7.6% with severe interventions. Multivariate regression modeling demonstrated that length of posterior fusion, use of major osteotomy, staged surgery, and severity of intervention for complications were significantly associated with LOS.

CONCLUSION

Careful selection of surgical factors may help reduce hospital LOS following surgery for ASD. Classification of complications by treatment severity can help surgeons better understand and predict the implications of complications, in turn assisting with surgical planning and patient counseling.Level of Evidence: 4.

The impact of preoperative supine radiographs on surgical strategy in adult spinal deformity

OBJECTIVE

Preoperative planning for adult spinal deformity (ASD) surgery is essential to prepare the surgical team and consistently obtain postoperative alignment goals. Positional imaging may allow the surgeon to evaluate spinal flexibility and anticipate the need for more invasive techniques. The purpose of this study was to determine whether spine flexibility, defined by the change in alignment between supine and standing imaging, is associated with the need for an osteotomy in ASD surgery.

METHODS

A single-center, dual-surgeon retrospective analysis was performed of adult patients with ASD who underwent correction of a thoracolumbar deformity between 2014 and 2018 (pelvis to upper instrumented vertebra between L1 and T9). Patients were stratified into osteotomy (Ost) and no-osteotomy (NOst) cohorts according to whether an osteotomy was performed (Schwab grade 2 or higher). Demographic, surgical, and radiographic parameters were compared. The sagittal correction from intraoperative prone positioning alone (sagittal flexibility percentage [Sflex%]) was assessed by comparing the change in lumbar lordosis (LL) between preoperative supine to standing radiographs and preoperative to postoperative alignment.

RESULTS

Demographics and preoperative and postoperative sagittal alignment were similar between the Ost (n = 60, 65.9%) and NOst (n = 31, 34.1%) cohorts (p > 0.05). Of all Ost patients, 71.7% had a grade 2 osteotomy (mean 3 per patient), 21.7% had a grade 3 osteotomy, and 12.5% underwent both grade 3 and grade 2 osteotomies. Postoperatively, the NOst and Ost cohorts had similar pelvic incidence minus lumbar lordosis (PI-LL) mismatch (mean PI-LL 5.2° vs 1.2°; p = 0.205). Correction obtained through positioning (Sflex%) was significantly lower for in the osteotomy cohort (38.0% vs 76.3%, p = 0.004). A threshold of Sflex% < 70% predicted the need for osteotomy at a sensitivity of 78%, specificity of 56%, and positive predictive value of 77%.

CONCLUSIONS

The flexibility of the spine is quantitatively related to the use of an osteotomy. Prospective studies are needed to determine thresholds that may be used to standardize surgical decision-making in ASD surgery.

Machine Learning Prediction of Length of Stay in Adult Spinal Deformity Patients Undergoing Posterior Spine Fusion Surgery

(1) Background: Length of stay (LOS) is a commonly reported metric used to assess surgical success, patient outcomes, and economic impact. The focus of this study is to use a variety of machine learning algorithms to reliably predict whether a patient undergoing posterior spinal fusion surgery treatment for Adult Spine Deformity (ASD) will experience a prolonged LOS. (2) Methods: Patients undergoing treatment for ASD with posterior spinal fusion surgery were selected from the American College of Surgeon's NSQIP dataset. Prolonged LOS was defined as a LOS greater than or equal to 9 days. Data was analyzed with the Logistic Regression, Decision Tree, Random Forest, XGBoost, and Gradient Boosting functions in Python with the Sci-Kit learn package. Prediction accuracy and area under the curve (AUC) were calculated. (3) Results: 1281 posterior patients were analyzed. The five algorithms had prediction accuracies between 68% and 83% for posterior cases (AUC: 0.566-0.821). Multivariable regression indicated that increased Work Relative Value Units (RVU), elevated American Society of Anesthesiologists (ASA) class, and longer operating times were linked to longer LOS. (4) Conclusions: Machine learning algorithms can predict if patients will experience an increased LOS following ASD surgery. Therefore, medical resources can be more appropriately allocated towards patients who are at risk of prolonged LOS.

Factors Associated With Short Length of Stay After Long Fusions for Adult Spinal Deformity: Initial Steps Toward Developing an Enhanced Recovery Pathway

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

The identification of case types and institutional factors associated with reduced length of stay (LOS) is a key initial step to inform the creation of clinical care pathways that can assist hospitals to maximize the benefit of value-based payment models. The objective of this study was to identify preoperative, intraoperative, and postoperative factors associated with shorter than expected LOS after adult spinal deformity (ASD) surgery.

METHODS

A retrospective cohort study was performed of 82 patients with ASD who underwent ≥5 levels of fusion to the pelvis between 2013 and 2018. A LOS <6 days was determined as a basis for comparison, as 5.7 days was the "expected LOS" generated through Poisson regression modeling of the sample. Clinical, radiographic, surgical, and postoperative factors were compared between those staying ≥6 days (L group) and <6 days (S group). Logistic regression was used to identify factors associated with LOS <6 days.

RESULTS

A total of 35 patients were in group S (42.7%). Gender, age, body mass index, ASA (American Society of Anesthesiologists) class, and use of preoperative narcotics, revision surgery, day of admission, and surgical complications did not vary between the cohorts (P > .05). Mild-moderate preoperative sagittal deformity (sagittal Schwab modifiers 0 or +), lower estimated blood loss (<1200 mL), fewer levels fused (7 vs 10 levels), shorter operating room time, procedure end time before 15:00, and no intensive care unit stay, were associated with short LOS (P < .05). Only 1 major medical complication occurred in the short LOS group (P < .05).

CONCLUSIONS

This study identifies the ASD "case phenotype," intra-, and postoperative benchmarks associated with shorter LOS, providing targets for pathways designed to reduce LOS.

Do Adult Spinal Deformity Patients Undergoing Surgery Continue to Improve From 1-Year to 2-Years Postoperative?

OBJECTIVE

Evaluate clinical improvement as measured by patient-reported outcomes (PROs) during the 1 to 2-year interval.

STUDY DESIGN

Retrospective Cohort.

METHODS

A single-institution registry of ASD patients undergoing surgery was queried for patients with ≥6 level fusions. Demographics and radiographic variables were collected. PROs collected were the ODI and SRS-22r scores at: preoperative, 1-year and 2-years. Outcome measures of clinical improvement during the 1-2 year time interval were: 1) group medians, 2) percent minimum clinically important difference (MCID), and 3) percent minimal symptom scale (MSS)(ODI < 20 or SRS-pain + function >8). Wilcoxon rank-sum tests, chi-squared tests, Kruskal-Wallis tests, and logistic regression were performed.

RESULTS

157 patients undergoing ASD surgery with minimum of 1-year follow-up were included. Mean age was 53.2 and mean instrumented levels was 13.1. Preoperative alignment was: Neutral Alignment (NA) 49%, Coronal Malalignment (CM) 17%, Sagittal Malalignment (SM 17%), and Combined Coronal/Sagittal Malalignment (CCSM) 18%. Preoperative to 1-year, and preoperative to 2-years, all ODI/SRS-22r significantly improved (P < .001). In all patients, the only significant improvement in PROs between 1-and 2-year postoperative were those reaching ODI MCID (69% 1-year vs. 84% 2-years; P < .001). Subgroup analysis: ≥55 years had an improved median ODI (18 vs. 8; P = .047) and an improved percent achieving ODI MCID (73% vs. 84%, P = .048). CCSM patients experienced significant improvement in SRS-appearance score (75% vs. 100%; P = .050), along with those with severe preoperative SM >7.5 cm (73% vs. 100%; P = .032).

CONCLUSIONS

Most ASD patients experience the majority of PRO improvement by 1-year postoperative. However, subsets of patients that may continue to improve up to 2-years postoperative include patients ≥55 years, combined coronal/sagittal malalignment, and those with severe sagittal malalignment ≥7.5 cm.

Complications After Adult Spinal Deformity Surgeries: All Are Not Created Equal

BACKGROUND

Data on timing of complications are important for accurate quality assessments. We sought to better define pre- and postdischarge complications occurring within 90 days of adult spinal deformity (ASD) surgery and quantify the effect of multiple complications on recovery.

METHODS

We performed a review of 1040 patients who underwent ASD surgery (age: 46 ± 23; body mass index: 25 ± 7, American Society of Anesthesiologists [ASA] score: 2.5 ± 0.6, levels: 10 ± 4, revision: 9%, 3-column osteotomy: 13%). We assessed pre- and postdischarge complications and risk factors for isolated versus multiple complications, as well as the impact of multiple complications.

RESULTS

The 90-day complication rate was 17.7%. 85 patients (8.2%) developed a predischarge complication, most commonly ileus (12%), and pulmonary embolism (PE; 7.1%). The most common causes of predischarge unplanned reoperation were neurologic injury (12.9%) and surgical site drainage (8.2%). Predictors of a predischarge complication included smoking (odds ratio [OR]: 2.2, P = .02), higher ASA (OR: 1.8, P = .008), hypertension (HTN; OR: 2.0, P = .004), and iliac fixation (OR: 4.3, P < .001). Ninety-nine patients (9.5%) developed a postdischarge complication, most commonly infection (34%), instrumentation failure (13.4%), and proximal junctional failure (10.4%). Predictors of postdischarge complications included chronic obstructive pulmonary disease (OR: 3.6, P < .0001), congestive heart failure (OR: 4.4, P = .016), HTN (OR: 2.3, P < .0001), and multiple rod construct (OR: 1.8, P = .02). Patients who developed multiple complications (9.3%) had a longer length of stay, and increased risk for readmission and unplanned reoperation.

CONCLUSIONS

Knowledge regarding timing of postoperative complications in relation to discharge may better inform quality improvement measures. PE and implant-related complications play a prominent role in perioperative complications and need for readmission, with several modifiable risk factors identified.

LEVEL OF EVIDENCE

Level 3.

CLINICAL RELEVANCE

Advances in surgical techniques and instrumentation have improved postoperative radiographic and clinical outcomes after ASD surgery. The rate of complications after complex ASD surgery remains high, both at early postoperative and long term follow-up. This study reviews complications within 90 days of surgery, with an assessment of patient and surgical risk factors. We found that modifiable risk factors for early complications after ASD surgery include COPD, and current smoking. The data presented in this study also provide surgeons with knowledge of the most common complications encountered after ASD surgery, to aid in preoperative patient discussion.

Drivers of Prolonged Hospitalization Following Spine Surgery: A Game-Theory-Based Approach to Explaining Machine Learning Models

BACKGROUND

Understanding the interactions between variables that predict prolonged hospital length of stay (LOS) following spine surgery can help uncover drivers of this risk in patients. This study utilized a novel game-theory-based approach to develop explainable machine learning models to understand such interactions in a large cohort of patients treated with spine surgery.

METHODS

Of 11,150 patients who underwent surgery for degenerative spine conditions at a single institution, 3,310 (29.7%) were characterized as having prolonged LOS. Machine learning models predicting LOS were built for each patient. Shapley additive explanation (SHAP) values were calculated for each patient model to quantify the importance of features and variable interaction effects.

RESULTS

Models using features identified by SHAP values were highly predictive of prolonged LOS risk (mean C-statistic = 0.87). Feature importance analysis revealed that prolonged LOS risk is multifactorial. Non-elective admission produced elevated SHAP values, indicating a clear, strong risk of prolonged LOS. In contrast, intraoperative and sociodemographic factors displayed bidirectional influences on risk, suggesting potential protective effects with optimization of factors such as estimated blood loss, surgical duration, and comorbidity burden.

CONCLUSIONS

Meticulous management of patients with high comorbidity burdens or Medicaid insurance who are admitted non-electively or spend clinically indicated time in the intensive care unit (ICU) during their hospitalization course may be warranted to reduce their risk of unanticipated prolonged LOS following spine surgery.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Predictive factors of a prolonged length of stay in a community Nursing-Led unit: A retrospective cohort study

AIMS AND OBJECTIVES

To describe the care provided to patients admitted into a community Nursing-Led inpatient unit and to identify factors predicting a length of stay exceeding an established threshold.

BACKGROUND

Few studies have been conducted to describe the care provided in a Nursing-Led unit. No studies have investigated factors affecting length of stay in these services.

DESIGN

Retrospective cohort study.

METHODS

Consecutive patients admitted to a community Nursing-Led unit between 2009-2015 were enrolled. Sociodemographic, medical and nursing care (diagnoses and activities) variables were collected from electronic health records. Descriptive analysis and a backward stepwise logistic regression model were applied. The study followed the STROBE guidelines.

RESULTS

The study enrolled 904 patients (mean age: 77.7 years). The most frequent nursing diagnoses were bathing self-care deficit and impaired physical mobility. The nursing activities most provided were enteral medication administration and vital signs measurement. Approximately 37% of the patients had a length of stay longer than the established threshold. Nine covariates, including being discharged to home, having an impaired memory nursing diagnosis or being treated for advanced wound care, were found to be independent predictors of prolonged length of stay. Variables related to medical conditions did not affect the length-of-stay threshold.

CONCLUSIONS

The length of stay in the community Nursing-Led unit was mainly predicted by conditions related to sociodemographic factors, nursing complexity and functional status. This result confirms that the medical and nursing needs of a community Nursing-Led unit population substantively differ from those of hospitalised acute patients.

RELEVANCE TO CLINICAL PRACTICE

The nursing complexity and related nursing care to be provided may be adopted as a criterion to establish the appropriate length of stay in the community Nursing-Led unit for each individual patient.

Obesity negatively affects cost efficiency and outcomes following adult spinal deformity surgery

BACKGROUND CONTEXT

Obesity has risen to epidemic proportions within the United States. As the rates of obesity have increased, so has its prevalence among patients undergoing adult spinal deformity (ASD) surgery. The effect of obesity on the cost efficiency of corrective procedures for ASD has not been effectively evaluated.

PURPOSE

To investigate differences in cost efficiency of ASD surgery for patients stratified by body mass index (BMI).

STUDY DESIGN/SETTING

Retrospective review of a single-center ASD database.

PATIENT SAMPLE

Five hundred five ASD patients.

OUTCOME MEASURES

Complications, revisions, costs, EuroQol-5D (EQ5D), quality-adjusted life years (QALYs), cost per QALY.

METHODS

ASD patients (scoliosis≥20°, SVA≥5 cm, PT≥25°, or TK ≥60°) ≥18, undergoing ≥4 level fusions were included. Patients were stratified into NIH-defined obesity groups based on their preoperative BMI: underweight 18.5< (U), normal 18.5 to 24.9 (N), overweight 25.0 to 29.9 (O), obese I 30.0 to 34.9 (OI), obese II 35.0 to 39.9 (OII), and obesity class III 40.0+ (OIII). Total surgery costs for each ASD obesity group were calculated. Costs were calculated using the PearlDiver database, which reflects both private insurance and Medicare reimbursement claims. Overall complications and major complications were assessed according to CMS definitions. QALYs and cost per QALY for obesity groups were calculated using an annual 3% discount up to life expectancy (78.7 years).

RESULTS

In all, 505 patients met inclusion criteria. Baseline demographics and surgical details were: age 60.8±14.8, 67.6% female, BMI 28.8±7.30, 81.0% posterior approach, 18% combined approach, 10.1±4.2 levels fused, op time 441.2±146.1 minutes, EBL 1903.8±1594.7 cc, and LOS 8.7±10.7 days. There were 17 U, 154 N patients, 151 O patients, 100 OI, 51 OII, and 32 OIII patients. Revision rates by obesity group were: 0% U, 3% N patients, 3% O patients, 5% OI, 4% OII, and 6% for OIII patients. The total surgery costs by obesity group were: $48,757.86 U, $49,688.52 N, $47,219.93 O, $50,467.66 OI, $51,189.47 OII, and $53,855.79 OIII. In an analysis of patients with baseline and 1 Y EQ5D follow-up, the cost per QALY by obesity group was: $153,737.78 U, $229,222.37 N, $290,361.68 O, $493,588.47 OI, $327,876.21 OII, and $171,680.00 OIII. If that benefit was sustained to life expectancy, the cost per QALY was $8,588.70 U, $12,805.72 N, $16,221.32 O, $27,574.77 OI, $18,317.11 OII, and $9,591.06 for OIII.

CONCLUSIONS

Among adult spinal deformity patients, those with BMIs in the obesity I, obesity II, or obesity class III range had more expensive total surgery costs. When assessing 1 year cost per QALY, obese patients had costs 32% higher than nonobese patients ($224,440.61 vs. $331,048.23). Further research is warranted on the utility of optimizing modifiable preoperative health factors for patients undergoing corrective adult spinal deformity surgery.

SURGERY FOR ADULT SPINAL SCOLIOSIS: DO THE BENEFITS OUTWEIGH THE RISKS?

ABSTRACT Around 6% of the elderly population over 65 years of age are affected by adult spinal deformity (ASD). The increasing prevalence of ASD with aging has prompted discussion regarding the use of various techniques for its treatment, such as surgery and conservative treatment. The objective of this study is to investigate whether surgical treatment demonstrates significant benefits as compared to conservative treatment. A literature review was conducted, focusing on the most relevant papers on the topic published in the last five years. Surgical treatment, which costs an average of US$ 99,114 per procedure, enables almost instant improvement of the pain and disability of ASD. The rate of perioperative complications in ASD is approximately 7.5%, and the average improvement in back pain is 6.2 times higher in the surgical approach than in conservative treatment. In addition, the use of modern operative techniques, such as minimally invasive surgery (MIS), reduces the complications and greatly improves patients’ quality of life, compared to open surgery. Therefore, the expected benefits of surgical treatment meets the patient’s expectations by eliminating the pain caused by ASD. Although surgical treatment has a higher cost and a greater risk of complications, the use of minimally invasive techniques give the ASD patient a better quality of life. Level of evidence III; Non-Systematic Review.

Predicting extended operative time and length of inpatient stay in cervical deformity corrective surgery

It's increasingly common for surgeons to operate on more challenging cases and higher risk patients, resulting in longer op-time and inpatient LOS. Factors predicting extended op-time and LOS for cervical deformity (CD) patients are understudied. This study identified predictors of extended op-time and length of stay (LOS) after CD-corrective surgery. CD patients with baseline (BL) radiographic data were included. Patients were stratified by extended LOS (ELOS; >75th percentile) and normal LOS (N-LOS; <75th percentile). Op-time analysis excluded staged cases, cases >12 h. A Conditional Variable Importance Table used non-replacement sampling set of Conditional Inference trees to identify influential factors. Mean comparison tests compared LOS and op-time for top factors. 142 surgical CD patients (61 yrs, 62%F, 8.2 levels fused). Op-time and LOS were 358 min and 7.2 days; 30% of patients experienced E-LOS (14 ± 13 days). Overlapping predictors of E-LOS and op-time included levels fused (>7 increased LOS 2.7 days; >5 increased op-time 96 min, P < 0.001), approach (anterior reduced LOS 3.0 days; combined increased op-time 69 min, P < 0.01), BMI (>38 kg/m² increased LOS 8.1 days; >39 kg/m² increased op-time 17 min), and osteotomy (LOS 2.0 days, op-time 62 min, P < 0.005). BL cervical parameters increased LOS and op-time: cSVA (>42 mm increased LOS; >50 mm increased op-time, P < 0.030), C0 slope (>@-0.9° increased LOS, >0.3° increased op-time, P < 0.003.) Additional op-time predictors: prior cervical surgery (p = 0.004) and comorbidities (P = 0.015). Other predictors of E-LOS: EBL (P < 0.001), change in mental status (P = 0.001). Baseline cervical malalignment, levels fused, and osteotomy predicted both increased op-time and LOS. These results can be used to better optimize patient care, hospital efficiency, and resource allocation.

Predictors of Prolonged Length of Stay After Lumbar Interbody Fusion: A Multicenter Study

STUDY DESIGN

Retrospective analysis of a prospectively database.

OBJECTIVES

To identify factors associated with prolonged length of stay (LOS) in posterior /transforaminal lumbar interbody fusion (PLIF/TLIF).

METHODS

The subjects were patients who underwent PLIF/TLIF at 10 facilities from 2012 to 2014. A total of 1168 such patients with a mean age of 65.9 ± 12.5 years (range 18-87 years) were identified in the database. Operations were PLIF (n = 675), TLIF (n = 443), minimally invasive surgery (MIS)-PLIF (n = 22), and MIS-TLIF (n = 32). Age, gender, body mass index, ambulatory status, comorbidities, perioperative American Society of Anesthesiologists (ASA) grade, operative factors, and complications were examined. LOS was defined as the number of calendar days from the operation to hospital discharge. LOS was categorized as normal (<75th percentile) or prolonged (≥75th percentile).

RESULTS

The average LOS was 20.8 ± 9.8 days (range 7-77 days). There was a significant correlation between LOS and age (P < .05). Reoperation during hospitalization was performed in 20 cases for surgical site infection (n = 12), epidural hematoma (n = 5), and screw misplacement (n = 3). In multivariate analysis, prolonged LOS was associated with preoperative variables of age ≥70 years (odds ratio [OR] 1.87, 95% CI 1.38-2.54), and ASA class ≥III (OR 1.52, 95% CI 1.04-2.25); surgical variables of open procedures (OR 5.84, 95% CI 1.74-19.63), fused levels ≥3 (OR 5.17, 95% CI 3.17-8.43), operative time ≥300 minutes (OR 1.88, 95% CI 1.15-3.07), and estimated blood loss ≥500 mL (OR 1.71, 95% 1.07-2.75).

CONCLUSIONS

The factors identified in this study should help with obtaining informed consent, surgical planning and complication prevention to reduce health care costs associated with prolonged LOS.

The Current State of Minimally Invasive Approaches to Adult Spinal Deformity

PURPOSE OF REVIEW

Minimally invasive approaches to adult spinal deformity (ASD) surgery have seen a large increase in popularity over the last decade, largely because these techniques are viewed as a potential improvement to the lengthy recovery and high complication rates observed after traditional open surgery for this pathology. The purpose of this review is to present a summary of the latest minimally invasive techniques used in adult spinal deformity surgery, examine whether MIS surgery can accomplish the goals of ASD surgery, and investigate whether MIS surgery is safer than traditional approaches.

RECENT FINDINGS

While minimally invasive approaches have been able to achieve similar patient-reported outcomes as open approaches, they are associated with their own unique complications. Furthermore, they are limited in their ability to correct severe sagittal imbalance. Emerging techniques, such as anterior column realignment and mini-open posterior column osteotomy, have been developed to address these limitations. The minimally invasive spinal deformity surgery algorithm (MISDEF) can help guide surgeons on which approaches may be appropriate for a particular case. To maximize the benefits of a minimally invasive approach without compromising the goals of ASD surgery, surgeons must be selective in choosing which cases are amenable to an MIS approach. Leading experts continue to develop algorithms to guide surgical decision-making. As we learn to better define our indications, understand treatment goals, and refine our techniques, MIS approaches will likely play an even larger role in a comprehensive ASD treatment strategy.

The Impact of Comorbidity Burden on Complications, Length of Stay, and Direct Hospital Costs After Minimally Invasive Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

A retrospective cohort.

OBJECTIVE

The aim of this study was to determine whether comorbidity as determined by Charlson Comorbidity Index (CCI) is associated with inpatient complication rate, length of stay (LOS), or direct hospital costs after minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).

SUMMARY OF BACKGROUND DATA

In the spine literature, comorbidity burden has been associated with an increased risk for complications, prolonged LOS, and greater hospital costs. Few studies have investigated the influence of comorbidity burden on these outcomes in minimally invasive spine surgery populations.

METHODS

A prospectively maintained surgical registry of patients undergoing primary, single-level MIS-TLIF was retrospectively reviewed. Patients were stratified by CCI and tested for association with preoperative demographics and perioperative characteristics using Chi-squared analysis or one-way analysis of variance for categorical and continuous variables, respectively. Complication rates, LOS, and direct hospital costs were compared between groups using a one-way analysis of variance.

RESULTS

Two hundred ninety-eight patients were included. About 19.8% had a CCI of 0, 41.3% had a CCI of 1 to 2, 27.2% had a CCI of 3 to 4, and 11.7% had a CCI ≥ 5. Elevated CCI was associated with older age, smoking, and insurance status. Elevated CCI was significantly associated with a greater total inpatient complication rate. Regarding LOS and total direct hospital costs, there were no associations identified. However, elevated CCI was associated with greater costs accrued in the intensive care unit, laboratory costs, and cardiology-related costs.

CONCLUSION

Greater comorbidity burden as reflected by higher CCI was associated with increased postoperative complication rates following primary, single-level MIS-TLIF. However, this did not lead to prolongations in hospital stay or increased total direct hospital costs. This lack of association may suggest that the limited tissue trauma and operative exposure utilized in minimally invasive approaches may limit the utility of CCI as a predictor of surgical outcomes and costs.

LEVEL OF EVIDENCE

4.

The cost effectiveness of minimally invasive spine surgery in the treatment of adult degenerative scoliosis: a comparison of transpsoas and open techniques

INTRODUCTION

Surgical treatment improves quality of life in patients with adult degenerative scoliosis (ADS). However, open ADS surgeries are complex, large magnitude operations associated with a high rate of complications. The lateral transpsoas interbody fusion technique is a less invasive alternative to open ADS surgery, but less invasive techniques tend to be more expensive. The objective of this study was to evaluate the cost effectiveness of the transpsoas technique for patients with ADS over a 12-month time horizon from a public payer perspective.

METHODS

A cost-effectiveness analysis was performed based on a consecutive case series of patients who underwent ADS surgeries between 2006 and 2012. Effectiveness was expressed as the difference in patient reported preoperative and 12-month postoperative health-related quality of life (HRQOL), which was measured in quality-adjusted life years. Health-care resource use was tabulated based on a clinical chart review on an item-by-item basis. Unit cost data were obtained from published provincial costs in Alberta, Canada. All costs were adjusted to 2015 Canadian dollars. The base case analysis included costs for the surgery, initial hospitalization, and treatment for complications over a 12-month follow-up period. The uncomplicated case analysis included costs for the surgery and initial hospitalization only. The joint uncertainty surrounding the cost and HRQOL differences was estimated using bootstrapping with 10,000 replicates.

RESULTS

A total of 10 open technique and 12 transpsoas technique T11-pelvis fusions were included in the analysis. In the base case analysis, the transpsoas technique was less costly compared with the open technique, total cost of $83,513 (95% CI: $72,772-$94,253) versus $111,381 (95% CI: $36,340-$186,423), respectively (incremental cost $27,869), and was associated with 0.06 more quality-adjusted life years and/or patient. However, in the uncomplicated case, the open technique was less costly compared with the transpsoas technique ($47,795 [95% CI: $39,003-$56,586] vs $76,510 [95% CI: $72,273-$80,746]), respectively, with an incremental cost of $28,715. Based on the probabilistic analysis of 10,000 bootstrap iterations for the base case analysis, the transpsoas technique was more effective and less costly compared with the open technique 57% of time. One-way deterministic sensitivity analysis by adjusting bone-morphogenetic protein-2 dosage further improved cost effectiveness of the transpsoas technique by lowering overall costs.

CONCLUSIONS

Transpsoas surgeries were associated with better outcomes in terms of HRQOL and lower costs over 1-year follow-up period compared with more invasive open technique. This study should be viewed as a pilot evaluation and should be replicated in a larger prospective multicenter controlled study.

Risk factors for nonroutine discharge in adult spinal deformity surgery

BACKGROUND CONTEXT

Surgery for adult spinal deformity (ASD) is increasingly common. Although outcomes of ASD surgery have been studied extensively, to our knowledge, no data exist regarding factors predicting nonroutine discharge in this population. Nonroutine discharge is defined as discharge to a health care facility after surgery rather than to home.

PURPOSE

To determine which patient and surgical factors predict nonroutine discharge after ASD surgery.

DESIGN

This is a retrospective study.

PATIENTS SAMPLE

We conducted a retrospective single-center study of 303 patients who underwent arthrodesis of five or more spinal levels to treat ASD between 2009 and 2014.

OUTCOME MEASURES

Patients were stratified into two groups according to discharge disposition: home or nonroutine.

METHODS

Objective preoperative characteristics, intraoperative course, and postoperative recovery were analyzed to identify pre- and perioperative factors associated with nonroutine discharge. Univariate analysis was performed first. All factors with P values < .2 on univariate analysis were included in a logistic regression model. Additionally, to understand the relationship between subjective patient-reported outcome measures and nonroutine discharge, we compared the two groups with respect to mean Oswestry Disability Index and Scoliosis Research Society-22r domains using Student t-tests.

RESULTS

On univariate analysis, objective measures that differed significantly (P < .05) between the two cohorts were age (≥65 years), osteoporosis, Charlson Comorbidity Index score of ≥2, prolonged hospital stay (>8 days), and blood transfusion. Given the above logistic regression inclusion criteria, we controlled for the performance, and type, of osteotomy (P = .055). On multivariate analysis, older age, osteoporosis, prolonged hospital stay, blood transfusion, and 3-column osteotomy were independently associated with nonroutine discharge. Subjective patient-reported outcome measures, including Oswestry Disability Index and Scoliosis Research Society-22r physical function and pain domain scores, were significantly worse in the nonroutine discharge cohort (P < .05).

CONCLUSION

To our knowledge, this is the first study to evaluate pre- and perioperative factors associated with nonroutine discharge after ASD surgery. Elderly patients who undergo complex surgery and receive blood transfusions are at particularly high risk of nonroutine discharge. Surgeons should consider these factors during surgical planning and preoperative patient counseling.

Readmissions, Length of Stay, and Mortality After Primary Surgery for Adult Spinal Deformity: A 10-Year Danish Nationwide Cohort Study

STUDY DESIGN

Cohort study.

OBJECTIVE

To report outcome after primary surgery for adult spinal deformity (ASD), and assess risk factors for extended length of stay (extLOS) and readmission within 90 days.

SUMMARY OF BACKGROUND DATA

Complications after ASD surgery have been reported in 20% to 50% of patients. A few studies have focused on detailed information concerning postoperative morbidity.

METHODS

Patients >18 years undergoing primary instrumented surgery for ASD in Denmark in the period 2006 to 2016 were included. Patients were identified in the Danish National Patient Registry (DNPR) using procedure codes for instrumented spine surgery combined with diagnosis of spinal deformity. Information on length of stay (LOS), readmissions, and mortality were retrieved from the DNPR. Medical records were reviewed for causes of extLOS (LOS >10 days) and readmission within 90 days after surgery. Charlson Comorbidity Index (CCI) was calculated for all patients based on DNPR.

RESULTS

We included 892 patients. Median LOS was 8 days (interquartile range, IQR, 7-11). A total of 175 (28.0%) patients had extLOS; 81% because of "medically" related complications. Most common medically related reason (>50%) for extLOS was pain/mobilization difficulties. The 90-days readmission risk was 13.8%; 74.5% of readmissions were "medically" related, primarily opioid related side effects (18.2%), and pain/mobilization issues (15.2%); 25.5% of readmissions were "surgically" related and 16.7% of patients required revision surgery. Ninety-days mortality was 0.9%. Age groups 61 to 70 years, >70 years, CCI score 1 to 2 and CCI score ≥3 were associated with increased risk of extLOS (odds ratio, OR = 1.79, 2.01, 1.81, and 2.49, respectively). Age group >70 years and CCI score 1 to 2 were associated with increased risk of readmission (OR = 2.21 and 1.83).

CONCLUSION

Increasing age and comorbidity were associated with increased risk extLOS and readmission. Pain/mobilization difficulties were the most common postoperative complications. A future focus on early mobilization and pain management may improve outcome of ASD patients.

LEVEL OF EVIDENCE

3.

Trends of postoperative length of stay in spine surgery over 10 years in Japan based on a prospective multicenter database

OBJECTIVES

To identify factors associated with prolonged length of stay (LOS) in spine surgery, with the goal of establishing details of LOS for multiple diseases and surgical procedures.

PATIENTS AND METHODS

The subjects were patients who underwent spine surgery at 10 facilities in the Nagoya Spine Group from January 2005 to December 2015. Data were collected for patient background, primary spinal pathology, anatomical location of the lesion, and surgical methods. The primary outcome was LOS, which was defined as the calendar days from surgery to hospital discharge.

RESULTS

A total of 10,829 patients (5953 males, 4876 females; age 5-93 years, mean 60.2 ± 28.8 years) were identified in the database. Average follow-up was 61 months (range: 13-120 months). Average LOS was 22.3 ± 21.3 days, and there was a gradual decrease in LOS over the study period. LOS was significantly correlated with age, and prolonged LOS was significantly associated with thoracic spine surgery and significantly longer after surgery with instrumentation. Average LOS was >30 days for intramedullary tumor resection and posterior cervical fusion, but only 10.2 days for microendoscopic discectomy. Reoperation was performed in 210 patients (1.9%) and these patients had a significantly higher average LOS of 43.1 days.

CONCLUSION

These results will assist quality improvement in spine surgery. The identified risk factors for prolonged LOS will also assist in planning of surgery, postoperative care, and discharge, with the goal of reducing health care costs.

What provides a better value for your time? The use of relative value units to compare posterior segmental instrumentation of vertebral segments

BACKGROUND CONTEXT

Relative value units (RVUs) are a compensation model based on the effort required to provide a procedure or service to a patient. Thus, procedures that are more complex and require greater technical skill and aftercare, such as multilevel spine surgery, should provide greater physician compensation. However, there are limited data comparing RVUs with operative time. Therefore, this study aims to compare mean (1) operative times; (2) RVUs; and (3) RVU/min between posterior segmental instrumentation of 3-6, 7-12, and ≥13 vertebral segments, and to perform annual cost difference analysis.

METHODS

A total of 437 patients who underwent instrumentation of 3-6 segments (Cohort 1, current procedural terminology [CPT] code: 22842), 67 patients who had instrumentation of 7-12 segments (Cohort 2, CPT code: 22843), and 16 patients who had instrumentation of ≥13 segments (Cohort 3, CPT code: 22844) were identified from the National Surgical Quality Improvement Program (NSQIP) database. Mean operative times, RVUs, and RVU/min, as well as an annualized cost difference analysis, were calculated and compared using Student t test. This study received no funding from any party or entity.

RESULTS

Cohort 1 had shorter mean operative times than Cohorts 2 and 3 (217 minutes vs. 325 minutes vs. 426 minutes, p<.05). Cohort 1 had a lower mean RVU than Cohorts 2 and 3 (12.6 vs. 13.4 vs. 16.4). Cohort 1 had a greater RVU/min than Cohorts 2 and 3 (0.08 vs. 0.05, p<.05; vs. 0.08 vs. 0.05, p>.05). A $112,432.12 annualized cost difference between Cohorts 1 and 2, a $176,744.76 difference between Cohorts 1 and 3, and a $64,312.55 difference between Cohorts 2 and 3 were calculated.

CONCLUSION

The RVU/min takes into account not just the value provided but also the operative times required for highly complex cases. The RVU/min for fewer vertebral level instrumentation being greater (0.08 vs. 0.05), as well as the $177,000 annualized cost difference, indicates that compensation is not proportional to the added time, effort, and skill for more complex cases.

Differences in primary and revision deformity surgeries: following 1,063 primary thoracolumbar adult spinal deformity fusions over time

Background

This study aims to describe properties of adult spinal deformity (ASD) revisions relative to primary surgeries and determine clinical variables that can predict revision. ASD is a common pathology that can lead to decreased quality of life, pain, physical limitations, and dissatisfaction with self-image. Durability of interventions for deformity treatment is of paramount concern to surgeons, as revision rates remain high.

Methods

Patients undergoing thoracolumbar fusion, five or more levels, for scoliosis (primary diagnosis ICD-9 737.x) were identified on a state-wide database. Primary and revision (returning for re-fusion procedure) surgeries were compared based on demographic, hospital stay, and clinical characteristics. Differences between primary and revision surgeries, and predictors of primary surgeries requiring revision, utilized binary logistic regression controlling for age, comorbidity burden, and levels fused.

Results

A total of 1,063 patients (average 7.4 levels fused, mean age: 47.6 years, 69.0% female) undergoing operative treatment for ASD were identified, of which 123 (average 7.1 levels fused, 11.6%, mean age 61.43, 80.5% female) had surgical revision. Primary surgeries were ~0.3 levels longer (P=0.013), used interbody ~11% more frequently (P=0.020), and used BMP ~12% less frequently (P=0.008). Revisions occurred 176.4 days after the primary on average. The most frequent causes of revisions were: 43.09% implant failure, 24.39% acquired kyphosis, and 14.63% enduring scoliosis. After controlling for age, comorbidities, and levels fused older, more comorbid, female, and white-race patients were more likely to be revised. Upon multivariate regression, after controlling for age and levels fused, overall complications remained non-different (OR: 0.8, 95% CI: 0.6-1.2). However, revision remained an independent predictor for infection (OR: 5.5, 95% CI: 2.8-10.5).

Conclusions

In a statewide database with individual patient follow up of up to 4 years 10% of ASD patients undergoing scoliosis correction required revision. Revision surgeries had higher infection incidence.

Increasing Body Mass Index is Associated With Worse Perioperative Outcomes and Higher Costs in Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective review.

OBJECTIVE

To investigate associations of obesity with outcomes and costs of adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

Increasing body mass index (BMI) is a risk factor for complications after nondeformity spine surgery, but its effect on ASD surgery is unknown.

METHODS

We reviewed records of 244 ASD patients who underwent spinal arthrodesis of ≥5 levels from 2010 to 2014 and categorized them by World Health Organization BMI groups: BMI < 30, nonobese (64%); BMI = 30-34.99, class-I obese (21%); and BMI ≥ 35, class-II/III obese (15%). We used multivariate logistical regression to determine odds of transfusion, inpatient complications, prolonged intensive care unit (ICU) stay (>2 days), prolonged total length of hospital stay (LOS) (>1 week), and high episode-of-care costs (>$80,000).

RESULTS

Preoperative characteristics were similar among groups, except sex, preoperative hemoglobin concentration, and performance/type of osteotomy (all, P = 0.01). On univariate analysis, the groups differed in rates of prolonged ICU stay (P < 0.001), prolonged total LOS (P = 0.016), and high episode-of-care costs (P = 0.013). Inpatient complication rates were similar among groups (P = 0.218). On multivariate analysis, compared with nonobese patients, class I obese patients had greater odds of prolonged ICU stay (odds ratio [OR] = 2.24, 95% confidence interval [CI]: 1.06, 4.71). Class II/III obese patients also had greater odds of prolonged total LOS (OR = 2.21, 95% CI: 1.03, 4.71), and high episode-of-care costs (OR = 2.91, 95% CI: 1.31, 6.50).

CONCLUSION

In ASD surgery, BMI ≥35 is associated with significantly worse perioperative outcomes and higher costs compared with those of nonobese patients.

LEVEL OF EVIDENCE

3.

Predictors for Non-Home Patient Discharge Following Elective Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Adult spinal deformity (ASD) surgery encompasses a wide variety of spinal disorders and is associated with a morbidity rate between 20% and 80%. The utilization of spinal surgery has increased and this trend is expected to continue. To effectively deal with an increasing patient volume, identifying variables associated with patient discharge destination can expedite placement and reduce length of stay.

METHODS

The 2013-2014 American College of Surgeons National Surgical Quality Improvement Program database was queried using Current Procedural Terminology and International Classification of Diseases, Ninth Revision diagnosis codes relevant to ASD. Patients were divided based on discharge destination. Bivariate and multivariate logistic regression analyses were employed to identify predictors for patient discharge destination and hospital length of stay.

RESULTS

A total of 4552 patients met inclusion criteria, of which 1102 (24.2%) had non-home discharge. Multivariate regression revealed total relative value unit (odds ratio [OR] = 1.01, 95% confidence interval [CI] = 1.00-1.01); female sex (OR = 1.54, 95% CI = 1.32-1.81); American Indian, Alaska Native, Asian, Native Hawaiian, or Pacific Islander versus black race (OR = 0.52, 95% CI = 0.35-0.78, P = .002); age ≥65 years (OR = 3.72, 95% CI = 3.19-4.35); obesity (OR = 1.18, 95% CI = 1.01-1.38, P = .034); partially/totally functionally dependent (OR = 2.11, 95% CI = 1.49-2.99); osteotomy (OR = 1.42, 95% CI = 1.12-1.80, P = .004) pelvis fixation (OR = 2.38, 95% CI = 1.82-3.11); operation time ≥4 hours (OR = 1.74, 95% CI = 1.47-2.05); recent weight loss (OR = 7.66, 95% CI = 1.52-38.65; P = .014); and American Society of Anesthesiologists class ≥3 (OR = 1.80, 95% CI = 1.53-2.11) as predictors of non-home discharge. P values were <.001 unless otherwise noted. Additionally, multivariate regression found non-home discharge to be a significant variable in prolonged length of stay.

CONCLUSIONS

The authors suggest these results can be used to inform patients preoperatively of expected discharge destination, anticipate patient discharge needs postoperatively, and reduce health care costs and morbidity associated with prolonged LOS.

Improved accuracy of screw implantation could decrease the incidence of post-operative hydrothorax? O-arm navigation vs. free-hand in thoracic spinal deformity correction surgery

PURPOSE

The purpose of this study was to analyze the occurrence of PE after intra-operative O-arm navigation-assisted surgery and determine whether the post-operative PE incidence could be decreased by using O-arm navigation as compared to conventional free-hand technique.

METHODS

A cohort of 27 patients with spinal deformity who were operated upon with an O-arm navigated system (group A) between 2013 and 2016 were enrolled in the study. A total of 27 curve-matched patients treated by conventional free-hand technique were included as the control group (group B). Whole spine posterior-anterior and lateral radiographs, and CT scans were taken pre and post-operation. Radiologic parameters and volume of PE were measured and compared between the two groups.

RESULTS

There were no significant differences in age, Cobb angle, and sagittal contour between the two groups pre-operatively. The mean total volume of post-operative PE was significantly larger in the free-hand group (p < 0.001). In the O-arm group, 59 malpositioned screws were identified in 22 patients. In the free-hand group, 88 malpositioned screws were found among 26 patients. The screw perforation rate was higher in the free-hand group than in the O-arm group (p = 0.007). In the O-arm group, the mean volume of PE was significantly larger among patients with malpositioned screws than those without malpositioned screws (p < 0.001), as well as in the free-hand group.

CONCLUSION

The volume of PE after correction surgery can be significantly decreased by application of O-arm navigation system as compared to conventional free-hand technique. We ascribed the improvement to the accuracy of screw implantation navigated by O-arm.