Impact of Obesity on Surgical Outcomes Following Laminectomy for Spinal Metastases

Development of Machine-Learning Models to Predict Ambulation Outcomes Following Spinal Metastasis Surgery

STUDY DESIGN

Retrospective cohort study.

PURPOSE

This study aimed to develop machine-learning algorithms to predict ambulation outcomes following surgery for spinal metastasis.

OVERVIEW OF LITERATURE

Postoperative ambulation status following spinal metastasis surgery is currently difficult to predict. The improved ability to predict this important postoperative outcome would facilitate management decision-making and help in determining realistic treatment goals.

METHODS

This retrospective study included patients who underwent spinal metastasis at a university-based medical center in Thailand between January 2009 and November 2021. Collected data included preoperative parameters and ambulatory status 90 and 180 days following surgery. Thirteen machine-learning algorithms, namely, artificial neural network, logistic regression, CatBoost classifier, linear discriminant analysis, extreme gradient boosting, extra trees classifier, random forest classifier, gradient boosting classifier, light gradient boosting machine, naïve Bayes, K-neighbor classifier, Ada boost classifier, and decision tree classifier were developed to predict ambulatory status 90 and 180 days following surgery. Model performance was evaluated using the area under the receiver operating characteristic curve (AUC) and F1-score.

RESULTS

In total, 167 patients were enrolled. The number of patients classified as ambulatory 90 and 180 days following surgery was 140 (81.9%) and 137 (82.0%), respectively. The extreme gradient boosting algorithm was found to most accurately predict 180-day ambulatory outcome (AUC, 0.85; F1-score, 0.90), and the decision tree algorithm most accurately predicted 90-day ambulatory outcome (AUC, 0.94; F1-score, 0.88).

CONCLUSIONS

Machine-learning algorithms were effective in predicting ambulatory status following surgery for spinal metastasis. Based on our data, the extreme gradient boosting and decision tree best predicted postoperative ambulatory status 180 and 90 days after spinal metastasis surgery, respectively.

Life-threatening perioperative complications among older adults with spinal metastases: An analysis based on a nationwide inpatient sample of the US

INTRODUCTION

We aimed to investigate the prognostic determinants of life-threatening and fatal complications in patients <80 and ≥ 20 years of age and those ≥80 years who were undergoing surgery for spinal metastases.

MATERIALS AND METHODS

Based on data between 2005 and 2018 extracted from National Inpatient Sample as the largest longitudinal hospital inpatient databases in the United States, statistical analyses were performed to identify prognostic factors (age, sex, household income, insurance status, major comorbidities, primary site of malignancy, types of surgery, surgical approaches, types of hospital admission, and hospital-related characteristics) for major and fatal perioperative complications among older adult patients.

RESULTS

A total of 31,925 patients aged ≥ 20y who were undergoing surgery for spinal metastasis were identified (< 80 y: n = 28,448; ≥ 80 y: n = 35,37). After adjustment, age ≥80 y was significantly associated with greater risk of perioperative cardiac arrest (adjusted odds ratio [aOR]: 1.34, 95% confidence interval [CI]: 1.03-1.73) and acute kidney injury (AKI) (aOR: 1.23, 95% CI: 1.07-1.41) but lower risk of venous thromboembolic event (VTE) (aOR: 0.80, 95% CI: 0.66-0.96) than <80y. Factors predicting life-threatening complications among patients ≥ 80y were: male sex (<80 y: aOR = 1.14; ≥ 80 y: aOR = 1.35), higher score on Charlson Comorbidity Index (CCI) (80 y, aOR = 1.21-2.67; ≥ 80 y: aOR = 1.25-2.55), open surgery (<80 y: aOR = 1.24; ≥ 80 y: aOR = 1.35), and greater Metastatic Spinal Tumor Frailty Index (MSTFI) (<80 y: aOR = 2.48-10.03; ≥ 80 y: aOR = 2.69-11.21). Among patients <80y, factors predicting life-threatening complications were: male sex, Black race, greater CCI score, primary tumor at kidney, hematologic cancer, other/unspecified primary site, certain surgical procedures, open surgery, greater MSTFI, emergent admission, and low hospital volume.

DISCUSSION

This study identifies a list of independent risk factors for the presence of life-threatening complications among patients <80 and ≥ 80y who were undergoing surgery for spinal metastasis. The findings contribute to the development of clinical strategies for the surgical management of spinal metastasis, especially for octogenarians, and lower the risk of unfavorable inpatient outcomes.

Development and External Validation of the Spinal Tumor Surgery Risk Index

BACKGROUND

Patients undergoing surgical procedures for spinal tumors are vulnerable to major adverse events (AEs) and death in the postoperative period. Shared decision making and preoperative optimization of outcomes require accurate risk estimation.

OBJECTIVE

To develop and validate a risk index to predict short-term major AEs after spinal tumor surgery.

METHODS

Prospectively collected data from multiple medical centers affiliated with the American College of Surgeons National Surgical Quality Improvement Program from 2006 to 2020 were reviewed. Multiple logistic regression was used to assess sociodemographic, tumor-related, and surgery-related factors in the derivation cohort. The spinal tumor surgery risk index (STSRI) was built based on the resulting scores. The STSRI was internally validated using a subgroup of patients from the American College of Surgeons National Surgical Quality Improvement Program database and externally validated using a cohort from a single tertiary center.

RESULTS

In total, 14 982 operations were reviewed and 4556 (16.5%) major AEs occurred within 30 days after surgery, including 209 (4.5%) deaths. 22 factors were independently associated with major AEs or death and were included in the STSRI. Using the internal and external validation cohorts, the STSRI produced an area under the curve of 0.86 and 0.82, sensitivity of 80.1% and 79.7%, and specificity of 74.3% and 73.7%, respectively. The STSRI, which is freely available, outperformed the modified frailty indices, the American Society of Anesthesiologists classification, and the American College of Surgeons risk calculator.

CONCLUSION

In patients undergoing surgery for spinal tumors, the STSRI showed the highest predictive accuracy for major postoperative AEs and death compared with other current risk predictors.

Impact of Obesity on Perioperative Complications on Treatment of Spinal Metastases: A Multicenter Surveillance Study from the German Spine Registry (DWG-Register)

Background  The spine is a common location for the development of primary and metastatic tumors, spinal metastases being the most common tumor in the spine. Spinal surgery in obesity is challenging due to difficulties with anesthesia, intravenous access, positioning, and physical access during surgery. The objective was to investigate the effect of obesity on perioperative complications by discharge in patients undergoing surgery for spinal metastases.

Methods  Retrospective analysis of data from the DWG-register on patients undergoing surgery for metastatic disease in the spine from January 2012 to December 2016. Preoperative variables included obesity (≥ 30 kg/m ² ), age, gender, and smoking status. In addition, the influence of pre-existing medical comorbidity was determined, using the American Society of Anesthesiologists (ASA) score.

Results  In total, 528 decompressions with and without instrumentation undergoing tumor debulking, release of the neural structures, or tumor extirpation in metastatic disease of the spine were identified; 143 patients were obese (body mass index [BMI] ≥ 30 kg/m ² ), and 385 patients had a BMI less than 30 kg/m ² . The mean age in the group with BMI 30 kg/m ² or higher (group 1) was 67 years (56.6%). In the group with BMI less than 30 kg/m ² (group 2), the mean age was 64 years. Most of the patients had preoperatively an ASA score of 3 and 4 (patients with severe general disease). The likelihood of being obese in the logistic regression model seems to be protective by 47.5-fold for blood loss 500 mL or higher. Transfusions occurred in 321/528 (60.7%) patients (group 1, n  = 122 and group 2, n  = 299; p  = 0.04). A total of 19 vertebroplasties with percutaneous stabilization (minimally invasive spine [MIS]), 6 vertebroplasties, and 31 MIS alone were identified. The variables between these groups, with exception of preoperative status (ASA-score; p  = 0.02), remained nonsignificant.

Conclusion  Obese patients were predisposed to have blood loss more than 500 mL more often than nonobese patients undergoing surgery for spinal metastases but with perioperative blood transfusions, invasiveness, nor prolonged hospitalization. Early postoperative mobilization and a low threshold for perioperative venous thromboembolism (VTE) are important in obese patients to appropriately diagnose, treat complications, and minimize morbidity.

Evaluating frailty, mortality, and complications associated with metastatic spine tumor surgery using machine learning-derived body composition analysis

OBJECTIVE

Cancer patients with spinal metastases may undergo surgery without clear assessments of prognosis, thereby impacting the optimal palliative strategy. Because the morbidity of surgery may adversely impact recovery and initiation of adjuvant therapies, evaluation of risk factors associated with mortality risk and complications is critical. Evaluation of body composition of cancer patients as a surrogate for frailty is an emerging area of study for improving preoperative risk stratification.

METHODS

To examine the associations of muscle characteristics and adiposity with postoperative complications, length of stay, and mortality in patients with spinal metastases, the authors designed an observational study of 484 cancer patients who received surgical treatment for spinal metastases between 2010 and 2019. Sarcopenia, muscle radiodensity, visceral adiposity, and subcutaneous adiposity were assessed on routinely available 3-month preoperative CT images by using a validated deep learning methodology. The authors used k-means clustering analysis to identify patients with similar body composition characteristics. Regression models were used to examine the associations of sarcopenia, frailty, and clusters with the outcomes of interest.

RESULTS

Of 484 patients enrolled, 303 had evaluable CT data on muscle and adiposity (mean age 62.00 ± 11.91 years; 57.8% male). The authors identified 2 clusters with significantly different body composition characteristics and mortality risks after spine metastases surgery. Patients in cluster 2 (high-risk cluster) had lower muscle mass index (mean ± SD 41.16 ± 7.99 vs 50.13 ± 10.45 cm2/m2), lower subcutaneous fat area (147.62 ± 57.80 vs 289.83 ± 109.31 cm2), lower visceral fat area (82.28 ± 48.96 vs 239.26 ± 98.40 cm2), higher muscle radiodensity (35.67 ± 9.94 vs 31.13 ± 9.07 Hounsfield units [HU]), and significantly higher risk of 1-year mortality (adjusted HR 1.45, 95% CI 1.05-2.01, p = 0.02) than individuals in cluster 1 (low-risk cluster). Decreased muscle mass, muscle radiodensity, and adiposity were not associated with a higher rate of complications after surgery. Prolonged length of stay (> 7 days) was associated with low muscle radiodensity (mean 30.87 vs 35.23 HU, 95% CI 1.98-6.73, p < 0.001).

CONCLUSIONS

Body composition analysis shows promise for better risk stratification of patients with spinal metastases under consideration for surgery. Those with lower muscle mass and subcutaneous and visceral adiposity are at greater risk for inferior outcomes.

Systemic considerations for the surgical treatment of spinal metastatic disease: a scoping literature review

Systemic assessment is a pillar in the neurological, oncological, mechanical, and systemic (NOMS) decision-making framework for the treatment of patients with spinal metastatic disease. Despite this importance, emerging evidence relating systemic considerations to clinical outcomes following surgery for spinal metastatic disease has not been comprehensively summarised. We aimed to conduct a scoping literature review of this broad topic. We searched MEDLINE, Embase, Scopus, Cochrane Central Register of Controlled Trials, Web of Science, and CINAHL databases from Jan 1, 2000, to July 31, 2021. 61 articles were included, accounting for a total of 22 335 patients. Preoperative systemic variables negatively associated with postoperative clinical outcomes included demographics (eg, older age [>60 years], Black race, male sex, low or elevated body-mass index, and smoking status), medical comorbidities (eg, cardiac, pulmonary, hepatic, renal, endocrine, vascular, and rheumatological), biochemical abnormalities (eg, hypoalbuminaemia, atypical blood cell counts, and elevated C-reactive protein concentration), low muscle mass, generalised motor weakness (American Spinal Cord Injury Association Impairment Scale grade and Frankel grade) and poor ambulation, reduced performance status, and systemic disease burden. This is the first comprehensive scoping review to broadly summarise emerging evidence relevant to the systemic assessment component of the widely used NOMS framework for spinal metastatic disease decision making. Medical, surgical, and radiation oncologists can consider these findings when prognosticating spinal metastatic disease-related surgical outcomes on the basis of patients' systemic condition. These factors might inform a shared decision-making approach with patients and their families.

Functional outcome and morbidity after microsurgical resection of spinal meningiomas

OBJECTIVE

The aim of this study was to evaluate functional outcome, surgical morbidity, and factors that affect outcomes of surgically treated patients.

METHODS

The authors retrospectively analyzed patients who underwent microsurgical resection for spinal meningiomas between 2009 and 2020. Patient data and potential variables were collected and evaluated consecutively. Functional outcomes were evaluated using univariate and multivariate analyses.

RESULTS

A total of 119 patients underwent microsurgical resection of spinal meningioma within the study period. After a mean follow-up of 25.4 ± 37.1 months, the rates of overall complication, tumor recurrence, and poor functional outcome were 9.2%, 7.6%, and 5%, respectively. Age, sex, revision surgery, and tumor recurrence were identified as independent predictors of poor functional outcome. Obesity and surgeon's experience had an impact on the complication rate, whereas extent of resection and tumor calcification affected the rate of tumor recurrence.

CONCLUSIONS

Microsurgical resection of spinal meningiomas remains safe. Nevertheless, some aspects, such as obesity and experience of the surgeons that result in a higher complication rate and ultimately affect clinical outcome, should be considered when performing surgery.

A Novel Clinical Scoring System for Perioperative Morbidity in Metastatic Spinal Tumor Surgery: The Spine Oncology Morbidity Assessment Score

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To evaluate a scoring system to predict morbidity for patients undergoing metastatic spinal tumor surgery (MSTS).

SUMMARY OF BACKGROUND DATA

Multiple scoring systems exist to predict survival for patients with spinal metastasis. The potential benefits and risks of surgery need to be evaluated for patients with disseminated cancer and limited life expectancy. Few scoring systems exist to predict perioperative morbidity after MSTS.

METHODS

We reviewed records of patients who underwent MSTS at our institution between 2013 and 2019. All perioperative complications occurring within 30 days were recorded. A clinical scoring system consisting of five variables (age ≥ 70 yr, hypoalbuminemia, poor preoperative functional status [Karnofsky ≤ 40], Frankel Grade A-C, and multilevel disease ≥2 continuous vertebral bodies) was evaluated as a predictive tool for morbidity; every parameter was assigned a value of 0 if absent or 1 if present (total possible score = 5). The effect of the scoring system on morbidity was evaluated using stepwise multiple logistic regression. Model accuracy was calculated by receiver operating characteristic analysis.

RESULTS

One hundred and five patients were identified, with a male prevalence of 58.1% and average age at surgery of 61 years. The overall 30-day complication rate was 36.2%. The perioperative morbidity was 4.6%, 30.0%, 53.9%, and 64.7% for patients with scores of 0, 1, 2, and ≥3 points, respectively (P < 0.001). On multiple logistic regression analysis controlling for covariates not present in the model, the scoring system was significantly associated with 30-day morbidity (OR 3.11; 95% CI, 1.72-5.59; P < 0.001). The model's accuracy was estimated at 0.75.

CONCLUSION

Our proposed model was found to accurately predict perioperative morbidity after MSTS. The Spine Oncology Morbidity Assessment (SOMA) score may prove useful for risk stratification and possibly decision-making, though further validation is needed.Level of Evidence: 4.

Laparoscopic Sleeve Gastrectomy Affects Coagulation System of Obese Patients

BACKGROUND

Laparoscopic sleeve gastrectomy (LSG) is nowadays the most popular bariatric procedure for obesity. However, whether LSG increases the risk of thrombosis remains unclear. The aim of this study was to investigate potential effects of LSG on coagulation system.

METHODS

Fifty-five obese patients underwent LSG between 2016 and 2018. The LSG was performed with pneumoperitoneum pressure maintained at 13 mmHg. Venous blood specimens were collected from each patient before surgery, at the end of pneumoperitoneum (i.e., 0 h after surgery), and at 24 h after surgery to determine prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FIB), platelet count (PLT), D-dimer (D-D), red blood cell count (RBC), hematocrit (HCT), plateletcrit (PCT), cholesterol (CHOL), triglyceride (TRIG), and serum calcium (Ca). All patients were examined on the veins of the lower limbs by color Duplex sonography (CDS) before surgery and at 24 h after surgery, respectively.

RESULTS

All patients successfully underwent LSG. No severe surgery-related complications were observed during 1-month follow-up after operation. Preoperative BMI was 43.6 ± 8.3 kg/m². The levels of coagulation factors were within the normal range before surgery, except a relatively higher PLT. The PT and D-D were increased at 0 h and 24 h after surgery (P < 0.05), whereas APTT was decreased (P < 0.05). The postoperative FIB remained similar to the preoperative one (P > 0.05). The CDS identified no thrombus in the veins of the lower limbs, either before surgery or at 24 h after surgery.

CONCLUSIONS

LSG may cause postoperative hypercoagulability of patients with obesity.