Preoperative Hemoglobin Level is Associated with Increased Health Care Use After Elective Spinal Fusion (≥3 Levels) in Elderly Male Patients with Spine Deformity

Impact of Iron Deficiency Anemia on Postoperative Outcomes of Thoracolumbar Spinal Fusion (2+ levels) on Patients with Adult Spinal Deformity with Minimum 2-Year Follow-Up

Introduction

Iron deficiency anemia (IDA) is a common hematological disorder and cause of low hemoglobin. Preoperative anemia has been demonstrated to increase the risk of adverse outcomes after posterior cervical fusion and other spinal surgeries. The need for a transfusion during lumbar fusion has been shown to increase length of stay. This study aimed to assess the impact of IDA on outcomes after spinal fusion for adult spinal deformity (ASD).

Methods

The New York Statewide Planning and Research Cooperative System (SPARCS) database was searched from 2009 to 2013 to identify all patients undergoing ≥2-level thoracolumbar spinal fusion (primary and revision) for ASD with a 2-year follow-up. The patients were then stratified by the presence or absence of IDA. Patients with IDA and patients without IDA were subjected to 1:1 propensity score matching based on age, sex, and obesity. Univariate analysis was employed to compare demographics, hospital parameters, and rates of adverse outcomes. Multivariate binary logistic regression with odds ratio (OR) was employed to identify independent risk factors for adverse postoperative outcomes.

Results

A total of 524 patients (262 with IDA and 262 without IDA) were identified. Patients with IDA experienced higher rates of overall surgical complications (50.4% vs 23.7%, P<0.001), wound complications (3.4% vs 0.4%, P=0.011), and blood transfusion (10.3% vs 6.5%, P<0.001). No difference was observed in the rate of overall medical complications. Patients with and without IDA had comparable rates of readmission (8.0% vs 13.0%, P=0.064), although patients with IDA had lower rates of reoperation (7.6% vs 13.0%, P=0.044). There was no mortality in either cohort. IDA was independently associated with wound complications (OR=10.6, P=0.028), blood transfusion (OR=3.9, P<0.001), and surgical complications (OR=3.5, P<0.001).

Conclusions

Baseline IDA was predictive of increased wound complications, postoperative blood transfusion, and overall surgical complications after thoracolumbar fusion surgery for ASD. Our findings could inform potential medical interventions to mitigate the risks of adverse outcomes in patients with IDA. Level of Evidence: III, retrospective cohort.

Preoperative anemia is associated with increased length of stay in adult spinal deformity surgery: evaluation of a large single-center patient cohort and future suggestions for patient optimization

PURPOSE

This study aimed to investigate the relationship of preoperative hemoglobin levels as an independent prognostic factor for hospital and intensive care unit (ICU) length of stay (LOS) in patients undergoing surgery for adult spinal deformity (ASD), with the intent of determining whether there exists a correlation and enhancing patient preoperative optimization protocols.

METHODS

The authors reviewed consecutive patients who underwent elective thoracolumbosacral posterior spinal fusion (PSF) involving six or more vertebrae for ASD from January 1, 2013, to December 13, 2021, with a minimum follow-up period of two years. This study primarily investigated the association of preoperative hemoglobin levels with hospital and ICU LOS. To analyze the data, both unadjusted and adjusted generalized linear models (GLM), incorporating cubic splines for non-linear variables, were applied.

RESULTS

A total of 598 patients were included. GLMs for hospital and ICU LOS demonstrated nonlinear relationships with preoperative hemoglobin levels. Specifically, hospital LOS decreased with increasing preoperative hemoglobin until a significance threshold of 13.5 g/dl. Similarly, ICU LOS significantly decreased with increasing preoperative hemoglobin until 13.0 g/dl. Lower preoperative hemoglobin was associated with more perioperative transfusions, less likely discharge to home, and greater risk of reoperation.

CONCLUSIONS

Preoperative anemia is an independent non-linear risk factor that significantly affects LOS, disposition, and outcomes after surgery for ASD. These findings advocate for a systemic preoperative approach and highlight the need for future research to improve postoperative outcomes and reduce hospital resource utilization.

LEVEL OF EVIDENCE

IV.

Preoperative Optimization Strategies in Elective Spine Surgery

» Although spine surgery is effective in reducing pain and improving functional status, it is associated with unacceptably high rates of complications, thus necessitating comprehensive preoperative patient optimization.» Numerous risk factors that can impact long-term surgical outcomes have been identified, including malnutrition, cardiovascular disease, osteoporosis, substance use, and more.» Preoperative screening and personalized, evidence-based interventions to manage medical comorbidities and optimize medications can enhance clinical outcomes and improve patient satisfaction following spine surgery.» Multidisciplinary team-based approaches, such as enhanced recovery after surgery protocols and multidisciplinary conferences, can further facilitate coordinated care from across specialties and reduce overall hospital length of stay.

The Effect of Varying Preoperative Hemoglobin Levels on the Risk of Major Complications and Surgical Site Infections After Single Level Lumbar Fusion

INTRODUCTION

Blood transfusions are associated with an increased risk of complications after lumbar fusion, and current anemia hemoglobin thresholds are not surgery specific. We aimed to calculate single-level lumbar fusion-specific preoperative hemoglobin strata that observe the likelihood of 90-day transfusion and evaluate whether these strata are associated with increased risk of 90-day complications and 2-year infections.

METHODS

A national database identified patients undergoing primary single-level lumbar fusion with preoperative hemoglobin values (g/dL). Stratum-specific likelihood ratio analysis calculated sex-based hemoglobin strata associated with the risk of 90-day transfusion. Incidence and risk of 90-day major complications and 2-year infections were observed between strata.

RESULTS

Three female (hemoglobin strata, likelihood ratio [<10.9, 2.41; 11.0 to 12.4, 1.35; 12.5 to 17.0, 0.78]) and male (<11.9, 2.95; 12.0 to 13.4, 1.46; 13.5 to 13.9, 0.71) strata were associated with varying likelihood of 90-day blood transfusion. Increased 90-day complication risk was associated with two female strata (hemoglobin strata, relative risk [11.0 to 12.4, 1.52; <10.9, 3.40]) and one male stratum (<11.9, 2.02). Increased 2-year infection risk was associated with one female (<10.9, 3.67) and male stratum (<11.9, 2.11).

CONCLUSION

Stratum-specific likelihood ratio analysis established sex-based single-level lumbar fusion-specific hemoglobin strata that observe the likelihood of 90-day transfusion and the risk of 90-day major complications and 2-year infections. These thresholds are a unique addition to the literature and can assist in counseling patients on their postoperative risk profile and in preoperative patient optimization.

LEVEL OF EVIDENCE

Level III.

Predicting postoperative delirium after percutaneous transluminal angioplasty and stenting in patients with intracranial atherosclerotic stenosis

OBJECTIVE

Known as a major surgical complication, postoperative delirium (POD) has not been well studied in patients with intracranial atherosclerotic stenosis (ICAS). This study aimed to investigate the correlation between perioperative clinical characteristics and the occurrence of POD.

METHODS

Patients' demographic characteristics and perioperative testing data were collected. Binary logistic regression was conducted for assessing related risk factors. A nomogram was developed to predict the occurrence of POD after percutaneous transluminal angioplasty and stenting (PTAS) in patients with ICAS.

RESULTS

The occurrence of POD in this study was 30.67%. Among all the clinical and laboratory characteristics in patients, age (OR = 1.234, 95%CI = 1.004-1.517, p = 0.046), gender (OR = 5.676, 95%CI = 1.028-31.334, p = 0.046), preoperative MMSE scores (OR = 2.298, 95%CI = 1.005-5.259, p = 0.049), the degree of stenosis (OR = 6.294, 95%CI = 1.043-37.974, p = 0.045), operating time (OR = 1.088, 95%CI = 1.023-1.157, p = 0.006), and HbA1c levels (OR = 2.226, 95%CI = 1.199-4.130, p = 0.011) were the independent risk factors.

CONCLUSION

Male patients with advanced-age, lower preoperative MMSE scores, severe stenosis, longer operating time, and higher HbA1c levels are closely related to POD after PTAS. Fully perioperative assessments may play an important role in predicting the occurrence of POD.

Preoperative Optimization for Adult Spinal Deformity Surgery: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVE

The purpose of this review is to identify modifiable risk factors in patients undergoing adult spinal deformity surgery and compile literature recommendations for the preoperative optimization of these risk factors.

SUMMARY OF BACKGROUND DATA

Optimization of modifiable risk factors not only benefits the patient but also lessens resource and cost burdens on the health care system, allowing for better quality and value-based care. There is limited but applicable literature discussing preoperative optimization in adult spinal deformity surgery patients specifically.

METHODS

We searched PubMed for studies that looked at one of the variables of interest (eg, osteoporosis, prehabilitation and functional status, multidisciplinary preoperative screening, infection, obesity, nutrition, smoking, diabetes, blood loss, chronic opioid use, and psychosocial factors) in adult patients with spinal deformity according to Preferred Reporting Items for Systematic Reviews and Meta-Analyse guidelines.

RESULTS

Seventy studies were included in the final review and synthesis of information. Guidelines and recommendations from these studies were compared and compiled into evidence-based action items for preoperative optimization of modifiable risk factors before adult spinal deformity surgery.

CONCLUSIONS

While the approach of preoperative optimization of modifiable risk factors may incur additional planning efforts and patient care time, it has the potential to significantly reduce perioperative complications and reduce morbidity and mortality during surgery, thus allowing for improved outcomes, increased quality of life, and satisfaction from this patient population.

LEVEL OF EVIDENCE

3.

Postoperative Delirium in Patients Receiving Hip Bipolar Hemiarthroplasty for Displaced Femoral Neck Fractures: The Risk Factors and Further Clinical Outcomes

BACKGROUND

Postoperative delirium in patients who have hip fractures may lead to poor outcomes. This study aimed to determine perioperative risk factors and clinical outcomes of postoperative delirium in patients undergoing hip bipolar hemiarthroplasty for displaced femoral neck fractures.

METHODS

Among 1,353 patients who underwent hemiarthroplasty at our institution during 2013-2021, we identified 78 patients with postoperative delirium diagnosed with the confusion assessment method. The mean delirium duration was 28 hours (range: 15-520). We also included 1:2 sex- and age-matched patients who did not have postoperative delirium after the same surgery as a matching cohort for comparison. Patient comorbidities, perioperative data, delirium occurrence, and outcomes were collected for analyses.

RESULTS

A Charlson Comorbidity Index (CCI) score ≥6 (odds ratio (OR): 2.08, P = .017), nighttime surgery (OR: 3.47, p =<.001), surgical delays (OR: 1.01, P = .012), preoperative anemia (OR: 2.1, P = .012), and blood transfusions (OR: 2.47, P = .01) may increase the risk of postoperative delirium. The presentation of delirium was associated with sepsis (OR: 3.77, P = .04), longer hospital stays (P < .001), higher 1-year mortality (OR: 3.97, P = .002), and overall mortality (OR: 2.1, P = .02).

CONCLUSION

Postoperative delirium predicted poor outcomes. Our results emphasized the importance of early identification of patients at risk and optimization of the medical conditions before and after surgery.

Increased Severity of Anemia Is Associated with Postoperative Complications following a Adult Spinal Deformity Surgery

BACKGROUND

Anemia is a modifiable risk factor for postoperative complications following surgery. This study aimed to determine the impact of preoperative anemia severity on 30-day postoperative complications following adult spinal deformity (ASD) surgery.

METHODS

Adults undergoing spinal fusion for ASD from 2012 to 2018 were identified in the National Surgical Quality Improvement Program database. Patients were substratified into 3 cohorts-non-anemia, mild anemia, and moderate-to-severe anemia-based on World Health Organization definitions. We assessed 30-day wound, cardiac, pulmonary, renal, and thromboembolic complications, as well as sepsis, mortality, postoperative transfusions, extended length of stay, and reoperation. Bivariate analyses and multivariable logistic regression were performed.

RESULTS

Of 2173 patients, 1694 (78%) had no anemia, 307 (14%) had mild anemia, and 172 (8%) had moderate or severe anemia. Following adjustments, patients with mild anemia were more likely to have postoperative blood transfusions (odds ratio [OR] 1.80, P < 0.001) and extended length of stay (OR 1.43, P < 0.001). Patients with moderate-to-severe anemia were at increased risk of organ space infection (OR 3.27, P = 0.028), death (OR 13.15, P = 0.001), postoperative blood transfusion (OR 2.81, P < 0.001), and extended length of stay (OR 3.02, P < 0.001).

CONCLUSIONS

We found a stepwise and approximately two-fold increase in the odds ratio of postoperative transfusion and length of stay with increasing severity of anemia. Moderate-to-severe anemia was associated with increased odds of death and organ space infection. Patients with moderate-to-severe anemia should be medically optimized before ASD surgery.

Influence of Preoperative Handgrip Strength on Length of Stay after Lumbar Fusion Surgery

Preoperative sarcopenic status can affect length of hospital stay and patient outcomes after surgery. The aim of this study was to investigate the impacts of preoperative handgrip strength (HGS) on length of stay (LOS) and outcomes after lumbar fusion surgery. HGS was measured preoperatively, and the cut-off value for low HGS was <28 kg for men and <18 kg for women. Perioperative patient outcomes were compared between patients with low and normal HGS. A total of 225 patients, consisting of 86 and 139 patients in the low and normal HGS groups, respectively, fully satisfied the study criteria for analysis. A longer LOS (median 10 vs. 8 days, p = 0.013) and a higher incidence of serious postoperative complications (15.1 vs. 3.6%, p = 0.002) were observed in the low HGS group. In the multivariate analysis, a low HGS (odds ratio (OR) = 1.917, 95% confidence interval (CI) = 1.046−3.513, p = 0.035) was significantly associated with a longer LOS after surgery. Preoperative HGS below the reference values by sex appeared to be an independent factor associated with longer LOS after lumbar fusion surgery.

Preoperative Polypharmacy in Geriatric Patients is Associated with Increased 90-Day All-Cause Hospital Readmission After Surgery for Adult Spinal Deformity Patients

OBJECTIVE

To investigate the effect of preoperative polypharmacy (PP) on 90-day all-cause readmission rate in older adults undergoing corrective surgery for ASD.

METHODS

Older adults with a diagnosis of ASD undergoing spinal surgery at a quaternary medical center from January 2016 to March 2019 were enrolled in this study. Patients were dichotomized into two groups stratified by the number of preoperative prescription medications; with PP defined as 5 or more prescription medications. The primary outcome measure was 90-day all-cause readmission rate. Secondary outcomes included postoperative changes in health-related quality of life measures.

RESULTS

Among 161 patients (mean [SD], 69.59[8.79] years), 97 patients were included in PP cohort and 64 in non-polypharmacy (non-PP) cohort. Both groups were balanced at baseline. The duration of hospital (5.82[1.93] vs. 6.50[4.00] days), mean number of fusion levels, and duration of surgery was statistically similar between both groups (p>0.05). There was no difference in the proportion of patients discharged directly home (31.25% vs. 40.42%, p=0.36). 90-day all-cause readmission rate was 3-fold higher in the PP cohort compared with the non-PP cohort. After adjusting for preoperative patient optimization, ASA grade, surgical invasiveness, smoking, depression and baseline functional disability, older adults with PP had a 9.79 increased odds of 90-day all-cause hospital readmission (p=0.04). Change in HRQOL measures were similar between both groups.

CONCLUSION

This study's findings indicate that despite preoperative optimization, older adults exposed to polypharmacy are at a significantly increased risk of hospital readmission within 90-days of surgery.

Prediction of Long-Term Recovery From Disability Using Hemoglobin-Based Models: Results From a Cohort of 1,392 Patients Undergoing Spine Surgery

Hemoglobin and its associated blood values are important laboratory biomarkers that mirror the strength of constitution of patients undergoing spine surgery. Along with the clinical determinants available during the preadmission visit, it is important to explore their potential for predicting clinical success from the patient's perspective in order to make the pre-admission visit more patient-centered. We analyzed data from 1,392 patients with spine deformity, disc disease, or spondylolisthesis enrolled between 2016 and 2019 in our institutional Spine Registry. Patient-reported outcome measure at 17 months after surgery was referred to the Oswestry disability index. High preoperative hemoglobin was found to be the strongest biochemical determinant of clinical success along with high red blood cells count, while low baseline disability, prolonged hospitalization, and long surgical times were associated with poor recovery. The neural network model of these predictors showed a fair diagnostic performance, having an area under the curve of 0.726 and a sensitivity of 86.79%. However, the specificity of the model was 15.15%, thus providing to be unreliable in forecasting poor patient-reported outcomes. In conclusion, preoperative hemoglobin may be one of the key biomarkers on which to build appropriate predictive models of long-term recovery after spine surgery, but it is necessary to include multidimensional variables in the models to increase the reliability at the patient's level.

Hemoglobin Concentration and Post-Operative Delirium in Elderly Patients Undergoing Femoral Neck Fracture Surgery

This study aimed to determine the relationship between hemoglobin (Hb) concentration and post-operative delirium (POD) in elderly patients undergoing femoral neck fracture (FNF) surgery and to investigate whether the change in Hb concentration is associated with POD and the risk factors for POD. A total of 889 patients admitted with FNF between January 2016 and December 2020 were enrolled in this single-center, retrospective, case–control study. Hb concentrations were determined at admission and post-operative day 1 and the change in Hb concentration was defined as the absolute value of difference in pre-operative and post-operative Hb concentration. POD was assessed using the Confusion Assessment Method for the Intensive Care Unit (ICU) or the Confusion Assessment Method once a daily after surgery. The logistic regression analysis was performed for statistical analysis. In total, 172 (19.3%) patients developed POD and 151 (87.8%) patients developed POD within post-operative 3 days. Low pre-operative Hb concentration [p = 0.026, odds ratio (OR) = 0.978] and significant change in Hb concentration (p = 0.006, OR = 1.033) were significantly associated with POD. After excluding change in Hb concentration or pre-operative Hb concentration, neither of them was significantly associated with POD (p > 0.05). The interaction analysis of change in Hb concentration and pre-operative Hb concentration in the logistic regression model was negative. There was no significant relationship between post-operative Hb concentration and POD. Age (p < 0.001, OR = 1.072), stroke history (p = 0.003, OR = 2.489), post-operative ICU transfer (p = 0.007, OR = 1.981), and visual analog scale score within post-operative 2 days (p₁ = 0.016 and p₂ = 0.006) were independently associated with POD in the logistic regression analysis. Patients with low pre-operative Hb concentrations and high changes in Hb concentration seem to have an increased risk of POD and should receive more attention. Old age, stroke history, post-operative ICU transfer, and pain within post-operative 2 days were significantly associated with POD.

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.

Risk Factors for 30-Day Non-Neurological Morbidity and Cerebrospinal Fluid Leak in Patients Undergoing Surgery for Vestibular Schwannoma

Introduction  We analyzed perioperative risk factors for morbidity and mortality for the patients undergoing surgical intervention for vestibular schwannoma along with rates of cerebrospinal fluid (CSF) leaks that required surgery. Materials and Methods  Patients undergoing surgery vestibular schwannoma were identified in the American College of Surgeons National Surgical Quality Improvement Program database from 2012 to 2016 using current procedural terminology (CPT) codes for posterior fossa surgical approaches and International Classification of Diseases 9th revision (ICD 9) and ICD 10 codes for peripheral nerve sheath tumor. Preoperative laboratories, comorbidities, and operative times were analyzed along with CSF leaks and unplanned returns to the operating room. Results  Nine-hundred ninety-three patients fit the inclusion criteria. Average age was 51, 41% were male, and 58% were female. Mortality within 30 days of the operation was very low at 0.4%, complications were 7% with infection being the most common at 2.3%, and unplanned reoperations happened in 7.4% of the cases. Dependent functional status (odds ratio [OR]: 5.7, 95% confidence interval [CI]: 1.9-16.6, p  = 0.001), preoperative anemia (OR: 2.4, 95% CI: 1.2-4.5, p  = 0.009), and operative time over 8 hours (OR: 1.9, 95% CI: 1.1-3.4, p  = 0.017) were the only significant predictors of perioperative complications. CSF leak postoperatively occurred in 37 patients (3.7%). Reoperation for CSF leak was necessary in 56.3% of the cases. Operative time over 8 hours was the only independent significant predictor of postoperative CSF leak (OR: 2.2, 95% CI: 1.1-4.3, p  = 0.028). Conclusion  Dependent functional status preoperatively, preoperative anemia, and duration of surgery over 8 hours are the greatest predictors of complications in the 30-day postoperative period.

Comparison of Reoperation after Fusion and after Decompression for Degenerative Lumbar Spinal Stenosis: A Single-Center Experience of 987 Cases

BACKGROUND AND STUDY AIM

 Reoperation for lumbar spinal stenosis (LSS) is technically challenging. Studies comparing preoperative risk factors and reoperation outcomes between spinal fusion and spinal decompression are limited. Thus this study compared fusion and decompression with respect to reoperation rates, preoperative factors related to re-surgery, and clinical outcomes.

PATIENTS AND METHODS

 This retrospective cohort study included prospectively collected data from patients who underwent revision surgeries for degenerative LSS between May 2001 and March 2015. The reoperation rate, risk factors (proportional hazards analysis of index surgery), surgery type, main reason for revision, and final clinical outcomes (pain, quality-of-life modification, patient satisfaction, and complication rate) were analyzed and compared between the fusion and decompression surgeries.

RESULTS

 Among 987 cases during 13 years, 25 cases of reoperation after fusion and 23 cases of reoperation after decompression were identified, accounting for reoperation rates of 5.88% and 4.00%, respectively. Combined comorbidities (hazard ratio [HR]: 1.98 for fusion; multilevel involvement [with fusion, HR: 2.92; decompression, HR: 1.95]) were strongly correlated with preoperative demographic risk factor for each procedure. The main reason for reoperation in fusion cases was proximal junctional kyphosis (40%) and implant failure (20%), and in decompression cases, recurrent lesions (48.8%) and incomplete surgery (17.4%) An additional fusion after initial fusion and re-decompression without fusion after initial decompression were the most common surgical procedure. Back pain and patient satisfaction after fusion were better compared with those after decompression.

CONCLUSION

 The reoperation rate, preoperative risk factors, reason for revision, reoperation type, clinical outcomes, patient satisfaction, and time interval between index and re-surgery were different between the primary fusion and primary decompression. A better understanding of disease pathophysiology and surgical procedure characteristics will facilitate improvement in disease management and the development of treatment strategies.

Decision Tree-based Modelling for Identification of Predictors of Blood Loss and Transfusion Requirement After Adult Spinal Deformity Surgery

Background

Multilevel fusions and complex osteotomies to restore global alignment in adult spinal deformity (ASD) surgery can lead to increased operative time and blood loss. In this regard, we assessed factors predictive of perioperative blood product transfusion in patients undergoing long posterior spinal fusion for ASD.

Methods

A single-institution retrospective review was conducted on 909 patients with ASD, age > 18 years, who underwent surgery for ASD with greater than 4 levels fused. Using conditional inference tree analysis, a machine learning methodology, we sought to predict the combination of variables that best predicted increased risk for intraoperative percent blood volume lost and perioperative blood product transfusion.

Results

Among the 909 patients included in the study, 377 (41.5%) received red blood cell (RBC) transfusion. The conditional inference tree analysis identified greater than 13 levels fused, American Society of Anesthesiologists (ASA) score > 1, a history of hypertension, 3-column osteotomy, pelvic fixation, and operative time > 8 hours, as significant risk factors for perioperative RBC transfusion. The best predictors for the subgroup with the highest risk for intraoperative percent blood volume lost (subgroup mean: 53.1% ± 42.9%) were greater than 13 levels fused, ASA score > 1, preoperative hemoglobin < 13.6 g/dL, 3-column osteotomy, posterior column osteotomy, and pelvic fixation. Patients who underwent major blood transfusion intraoperatively had significantly longer length of stay (8.5 days) versus those who did not (6.1 days) (P < .0001). The overall 90-day complication rate in patients who underwent major blood transfusion intraoperatively was 49%, compared with 19% in those who did not (P < .0001). By multivariate regression analysis, patients with a preoperative hemoglobin > 13.0 were less likely to require major blood transfusion (odds ratio: 0.52, P = .046).

Conclusions

Using a supervised learning technique, this study demonstrates that greater than 13 levels fused, ASA score > 1, 3-column osteotomy, and pelvic fixation are consistent risk factors for increased intraoperative percent blood volume lost and perioperative RBC transfusion. The addition of having a preoperative hemoglobin < 13.6 g/dL or undergoing a posterior column osteotomy conferred the highest risk for intraoperative blood loss. This information can assist spinal deformity surgeons in identifying at-risk individuals and allocating healthcare resources.

Level of Evidence

3.

Independent Association Between Type of Intraoperative Blood Transfusion and Postoperative Delirium After Complex Spinal Fusion for Adult Deformity Correction

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine whether type of intraoperative blood transfusion used is associated with increased incidence of postoperative delirium after complex spine fusion involving five levels or greater.

SUMMARY OF BACKGROUND DATA

Postoperative delirium after spine surgery has been associated with age, cognitive status, and several comorbidities. Intraoperative allogenic blood transfusions have previously been linked to greater complication risks and length of hospital stay. However, whether type of intraoperative blood transfusion used increases the risk for postoperative delirium after complex spinal fusion remains relatively unknown.

METHODS

The medical records of 130 adult (≥18 years old) spine deformity patients undergoing elective, primary complex spinal fusion (more than or equal to five levels) for deformity correction at a major academic institution from 2010 to 2015 were reviewed. We identified 104 patients who encountered an intraoperative blood transfusion. Of the 104, 15 (11.5%) had Allogenic-only, 23 (17.7%) had Autologous-only, and 66 (50.8%) had Combined transfusions. The primary outcome investigated was the rate of postoperative delirium.

RESULTS

There were significant differences in estimated blood loss (Combined: 2155.5 ± 1900.7 mL vs. Autologous: 1396.5 ± 790.0 mL vs. Allogenic: 1071.3 ± 577.8 mL vs. None: 506.9 ± 427.3 mL, P < 0.0001) and amount transfused (Combined: 1739.7 ± 1127.6 mL vs. Autologous: 465.7 ± 289.7 mL vs. Allogenic: 986.9 ± 512.9 mL, P < 0.0001). The Allogenic cohort had a significantly higher proportion of patients experiencing delirium (Combined: 7.6% vs. Autologous: 17.4% vs. Allogenic: 46.7% vs. None: 11.5%, P = 0.002). In multivariate nominal-logistic regression analysis, Allogenic (odds ratio [OR]: 24.81, 95% confidence interval [CI] [3.930, 156.702], P = 0.0002) and Autologous (OR: 6.43, 95% CI [1.156, 35.772], P = 0.0335) transfusions were independently associated with postoperative delirium.

CONCLUSION

Our study suggests that there may be an independent association between intraoperative autologous and allogenic blood transfusions and postoperative delirium after complex spinal fusion. Further studies are necessary to identify the physiological effect of blood transfusions to better overall patient care and reduce healthcare expenditures.

LEVEL OF EVIDENCE

3.

Incidence and Risk Factors for Postoperative Delirium in Patients Undergoing Spine Surgery: A Systematic Review and Meta-Analysis

Background

The present study aims to investigate the incidence and risk factors associated with postoperative delirium in patients undergoing spine surgery.

Methods

PubMed, EMBASE, Cochrane Library, and Science Citation Index were searched up to August 2019 for studies examining postoperative delirium following spine surgery. Incidence and risk factors associated with delirium were extracted. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for outcomes. The Newcastle-Ottawa Scale (NOS) was used for the study quality evaluation.

Results

The final analysis includes a total of 40 studies. The pooled analysis reveals that incidence of delirium is 8%, and there are significant differences for developing delirium in age (OR 1.07; 95% CI 1.04-1.09), age more than 65 (OR 4.77; 95% CI 4.37-5.16), age more than 70 (OR 15.87; 95% CI 6.03-41.73), and age more than 80 (OR 1.91; 95% CI 1.78-2.03) years, male (OR 0.81; 95% CI 0.76-0.86), a history of alcohol abuse (OR 2.11; 95% CI 1.67-2.56), anxiety (OR 1.74; 95% CI 1.04-2.44), congestive heart failure (OR 1.4; 95% CI 1.21-1.6), depression (OR 2.5; 95% CI 1.52-3.49), hypertension (OR 1.12; 95% CI 1.04-1.2), kidney disease (OR 1.41; 95% CI 1.16-1.66), neurological disorder (OR 4.66; 95% CI 4.22-5.11), opioid use (OR 1.86; 95% CI 1.18-2.54), psychoses (OR 2.77; 95% CI 2.29-3.25), pulmonary disease (OR 1.81; 95% CI 1.27-2.35), higher mini-mental state examination (OR 0.7; 95% CI 0.5-0.89), preoperative pain (OR 1.88; 95% CI 1.11-2.64), and postoperative urinary tract infection (OR 5.68; 95% CI 2.41-13.39).

Conclusions

A comprehensive understanding of incidence and risk factors of delirium can improve prevention, diagnosis, and management. Risk of postoperative delirium can be reduced based upon identifiable risk factors.

Development of machine learning algorithms for prediction of prolonged opioid prescription after surgery for lumbar disc herniation

BACKGROUND CONTEXT

Spine surgery has been identified as a risk factor for prolonged postoperative opioid use. Preoperative prediction of opioid use could improve risk stratification, shared decision-making, and patient counseling before surgery.

PURPOSE

The primary purpose of this study was to develop algorithms for prediction of prolonged opioid prescription after surgery for lumbar disc herniation.

STUDY DESIGN/SETTING

Retrospective, case-control study at five medical centers.

PATIENT SAMPLE

Chart review was conducted for patients undergoing surgery for lumbar disc herniation between January 1, 2000 and March 1, 2018.

OUTCOME MEASURES

The primary outcome of interest was sustained opioid prescription after surgery to at least 90 to 180 days postoperatively.

METHODS

Five models (elastic-net penalized logistic regression, random forest, stochastic gradient boosting, neural network, and support vector machine) were developed to predict prolonged opioid prescription. Explanations of predictions were provided globally (averaged across all patients) and locally (for individual patients).

RESULTS

Overall, 5,413 patients were identified, with sustained postoperative opioid prescription of 416 (7.7%) at 90 to 180 days after surgery. The elastic-net penalized logistic regression model had the best discrimination (c-statistic 0.81) and good calibration and overall performance; the three most important predictors were: instrumentation, duration of preoperative opioid prescription, and comorbidity of depression. The final models were incorporated into an open access web application able to provide predictions as well as patient-specific explanations of the results generated by the algorithms. The application can be found here: https://sorg-apps.shinyapps.io/lumbardiscopioid/ CONCLUSION: Preoperative prediction of prolonged postoperative opioid prescription can help identify candidates for increased surveillance after surgery. Patient-centered explanations of predictions can enhance both shared decision-making and quality of care.