Randomized controlled trials for degenerative lumbar spondylolisthesis: which patients benefit from lumbar fusion?

Impact of Preoperative Intervertebral Disc Degeneration on Patient-Reported Outcome Measures After Lumbar Fusion

OBJECTIVE

The Pfirrmann scoring system classifies lumbosacral disc degeneration based on magnetic resonance imaging signal intensity. The relationship between pre-existing disc degeneration and patient-reported outcome measures (PROMs) after one-level lumbar fusion is not well documented. The purpose of this study was to investigate the relationship between the severity of preoperative intervertebral disc degeneration and preoperative and postoperative PROMs in patients undergoing one-level lumbar fusion.

METHODS

All adult patients who underwent posterior lumbar decompression and fusion or transforaminal lumbar interbody fusion between 2014 and 2022 were included. Patient demographics and comorbidities were extracted from medical records. Lumbar intervertebral discs on sagittal magnetic resonance imaging T2-weighted images were assessed by 2 independent graders utilizing Pfirrmann criteria. Grades I-III were categorized as low-grade disc degeneration, while IV-V were considered high grade. Multivariable linear regression assessed the impact of disc degeneration on PROMs.

RESULTS

A total of 150 patients were included, of which 69 (46%) had low-grade disc degeneration, while 81 (54%) had high-grade degeneration. Patients with high-grade degeneration had increased preoperative visual analog scale (VAS)-Leg scores (6.10 vs. 4.54, P = 0.005) and displayed greater 1-year postoperative improvements in VAS-Back scores (-2.11 vs. -0.66, P = 0.002). Multivariable regression demonstrated Pfirrmann scores as independent predictors for both preoperative VAS-Leg scores (P = 0.004) and postoperative VAS-Back improvement (P = 0.005).

CONCLUSIONS

In patients undergoing one-level lumbar fusion, higher Pfirmann scores were associated with increased preoperative leg pain and greater 1-year postoperative improvement in back pain. Further studies into the relationship of preoperative disc degeneration and their impact on postoperative outcomes may help guide clinical decision-making and patient expectations.

Development and Validation of Machine Learning-Based Predictive Model for Prolonged Hospital Stay after Decompression Surgery for Lumbar Spinal Canal Stenosis

Introduction

Precise prediction of hospital stay duration is essential for maximizing resource utilization during surgery. Existing lumbar spinal stenosis (LSS) surgery prediction models lack accuracy and generalizability. Machine learning can improve accuracy by considering preoperative factors. This study aimed to develop and validate a machine learning-based model for estimating hospital stay duration following decompression surgery for LSS.

Methods

Data from 848 patients who underwent decompression surgery for LSS at three hospitals were examined. Twelve prediction models, using 79 preoperative variables, were developed for postoperative hospital stay estimation. The top five models were chosen. Fourteen models predicted prolonged hospital stay (≥14 days), and the most accurate model was chosen. Models were validated using a randomly divided training sample (70%) and testing cohort (30%).

Results

The top five models showed moderate linear correlations (0.576-0.624) between predicted and measured values in the testing sample. The ensemble of these models had moderate prediction accuracy for final length of stay (linear correlation 0.626, absolute mean error 2.26 days, standard deviation 3.45 days). The c5.0 decision tree model was the top predictor for prolonged hospital stay, with accuracies of 89.63% (training) and 87.2% (testing). Key predictors for longer stay included JOABPEQ social life domain, facility, history of vertebral fracture, diagnosis, and Visual Analogue Scale (VAS) of low back pain.

Conclusions

A machine learning-based model was developed to predict postoperative hospital stay after LSS decompression surgery, using data from multiple hospital settings. Numerical prediction of length of stay was not very accurate, although favorable prediction of prolonged stay was accomplished using preoperative factors. The JOABPEQ social life domain score was the most important predictor.

10-year Longitudinal MRI Study of Intervertebral Disk Degeneration in Patients With Lumbar Spinal Canal Stenosis After Posterior Lumbar Decompression Surgery

STUDY DESIGN

A prospective longitudinal magnetic resonance imaging (MRI) study.

OBJECTIVE

The objective of this study was to describe the progression of intervertebral disk (IVD) degeneration in patients who underwent posterior decompression surgery for lumbar spinal canal stenosis (LSS).

SUMMARY OF BACKGROUND DATA

IVD degeneration contributes to the pathogenesis of LSS; however, the long-term consequences of degenerative changes after decompression surgery remain unknown.

MATERIALS AND METHODS

Of 258 consecutive patients who underwent posterior lumbar decompression surgery for LSS, 62 who underwent MRI at their 10-year follow-up were included; 17 age-matched asymptomatic volunteers were analyzed as controls. Three MRI findings representing IVD degeneration were graded on their severity: decrease in signal intensity, posterior disk protrusion (PDP), and disk space narrowing (DSN). Clinical outcome was assessed using the low back pain (LBP) score from the Japanese Orthopaedic Association scoring system. We examined the association between the progression of degenerative changes on MRI and LBP/associated factors using logistic regression adjusting for age at baseline and sex.

RESULTS

The severity of IVD degeneration tended to be higher in patients with LSS than asymptomatic volunteers at both baseline and follow-up. IVD degeneration progressed in all patients during the 10-year follow-up period. Progression of decrease in signal intensity and PDP was observed at L1/2 in 73% and at L2/3 in 34%, respectively (the highest frequencies in the lumbar spine). Progression of DSN was highest at L4/5 in 42%. The rates of PDP and DSN progression during the 10-year follow-up period tended to be greater in patients with LSS than in asymptomatic volunteers. No significant difference in the proportion of LBP deterioration was evident for individuals with and without MRI findings of progression.

CONCLUSIONS

Our study reveals a natural history of the long-term postoperative course of IVD degeneration after posterior decompression surgery for LSS. Compared with healthy controls, patients with LSS seemed to be predisposed to IVD degeneration. Lumbar decompression surgery may promote the progression of DSN; however, progression of IVD degeneration after lumbar decompression surgery was not associated with worsening LBP scores.

Development and validation of machine learning-based predictive model for clinical outcome of decompression surgery for lumbar spinal canal stenosis

BACKGROUND CONTEXT

Although the results of decompression surgery for lumbar spinal canal stenosis (LSS) are favorable, it is still difficult to predict the postoperative health-related quality of life of patients before surgery.

PURPOSE

The purpose of this study was to develop and validate a machine learning model to predict the postoperative outcome of decompression surgery for patients with LSS.

STUDY DESIGN/SETTING

A multicentered retrospective study.

PATIENT SAMPLE

A total of 848 patients who underwent decompression surgery for LSS at an academic hospital, tertiary center, and private hospital were included (age 71±9 years, 68% male, 91% LSS, level treated 1.8±0.8, operation time 69±37 minutes, blood loss 48±113 mL, and length of hospital stay 12±5 days).

OUTCOME MEASURES

Baseline and 2 years postoperative health-related quality of life.

METHODS

The subjects were randomly assigned in a 7:3 ratio to a model building cohort and a testing cohort to test the models' accuracy. Twelve predictive algorithms using 68 preoperative factors were used to predict each domain of the Japanese Orthopedic Association Back Pain Evaluation Questionnaire and visual analog scale scores at 2 years postoperatively. The final predictive values were generated using an ensemble of the top five algorithms in prediction accuracy.

RESULTS

The correlation coefficients of the top algorithms for each domain established using the preoperative factors were excellent (correlation coefficient: 0.95-0.97 [relative error: 0.06-0.14]). The performance evaluation of each Japanese Orthopedic Association Back Pain Evaluation Questionnaire domain and visual analog scale score by the ensemble of the top five algorithms in the testing cohort was favorable (mean absolute error [MAE] 8.9-17.4, median difference [MD] 8.1-15.6/100 points), with the highest accuracy for mental status (MAE 8.9, MD 8.1) and the lowest for buttock and leg numbness (MAE 1.7, MD 1.6/10 points). A strong linear correlation was observed between the predicted and measured values (linear correlation 0.82-0.89), while 4% to 6% of the subjects had predicted values of greater than±3 standard deviations of the MAE.

CONCLUSIONS

We successfully developed a machine learning model to predict the postoperative outcomes of decompression surgery for patients with LSS using patient data from three different institutions in three different settings. Thorough analyses for the subjects with deviations from the actual measured values may further improve the predictive probability of this model.

Surgical outcomes of patients who fail to reach minimal clinically important differences: comparison of minimally invasive versus open transforaminal lumbar interbody fusion

OBJECTIVE

Treatment of degenerative lumbar diseases has been shown to be clinically effective with open transforaminal lumbar interbody fusion (O-TLIF) or minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Despite this, a substantial proportion of patients do not meet minimal clinically important differences (MCIDs) in patient-reported outcomes (PROs). The objectives of this study were to compare the proportions of patients who did not meet MCIDs after O-TLIF and MIS-TLIF and to determine potential clinical factors associated with failure to achieve MCID.

METHODS

The authors performed a retrospective analysis of consecutive patients who underwent O-TLIF or MIS-TLIF for lumbar degenerative disorders and had been prospectively enrolled in the Canadian Spine Outcomes and Research Network. The authors analyzed the Oswestry Disability Index (ODI) scores, physical and mental component summary scores of SF-12, numeric rating scale (NRS) scores for leg and back pain, and EQ-5D scores of the patients in each group who did not meet the MCID of ODI at 2 years postoperatively.

RESULTS

In this study, 38.8% (137 of 353) of patients in the O-TLIF cohort and 41.8% (51 of 122) of patients in the MIS-TLIF cohort did not meet the MCID of ODI at 2 years postoperatively (p = 0.59). Demographic variables and baseline PROs were similar between groups. There were improvements across the PROs of both groups through 2 years, and there were no differences in any PROs between the O-TLIF and MIS-TLIF cohorts. Multivariable logistic regression analysis demonstrated that higher baseline leg pain score (p = 0.017) and a diagnosis of spondylolisthesis (p = 0.0053) or degenerative disc disease (p = 0.022) were associated with achieving the MCID at 2 years after O-TLIF, whereas higher baseline leg pain score was associated with reaching the MCID after MIS-TLIF (p = 0.038).

CONCLUSIONS

Similar proportions of patients failed to reach the MCID of ODI at 2 years after O-TLIF or MIS-TLIF. Higher baseline leg pain score was predictive of achieving the MCID in both cohorts, whereas a diagnosis of spondylolisthesis or degenerative disc disease was predictive of reaching the MCID after O-TLIF. These data provide novel insights for patient counseling and suggest that either MIS-TLIF or O-TLIF does not overcome specific patient factors to mitigate clinical success or failure in terms of the intermediate-term PROs associated with 1- to 2-level lumbar fusion surgical procedures for degenerative pathologies.

Effect of interbody fusion compared with posterolateral fusion on lumbar degenerative spondylolisthesis: a systematic review and meta-analysis

BACKGROUND CONTEXT

Lumbar degenerative spondylolisthesis is a relatively common pathology, and surgical treatment is an option in selected cases. The common use of anterior column support by interbody fusion (IBF) has not been adequately studied.

PURPOSE

The primary objective of this systematic review and meta-analysis was to compare the functional and surgical outcomes after posterolateral fusion (PLF) and IBF for the treatment of degenerative spondylolisthesis.

STUDY DESIGN

A systematic review and meta-analysis was conducted to identify studies analyzing the effects of IBF compared to those of instrumented PLF on degenerative spondylolisthesis.

PATIENT SAMPLE

A total of 1,063 patients were included in the analysis. Of them, 470 patients were treated with PLF and 593 with IBF.

OUTCOME MEASURES

The outcomes analyzed were the visual analog scale and numerical rating scale scores for back pain, Oswestry Disability Index (ODI), 36-Item Short Form Health Survey (SF-36) score, 12-Item Short Form Health Survey (physical and mental components) score, blood loss amount, surgical time, hospital stay duration, fusion rate, lumbar lordosis, sacral slope, and postoperative complications.

METHODS

A search was conducted using the MEDLINE, Cochrane, and Google Scholar databases for studies published between January 1985 and February 2021. Both retrospective and prospective studies that compared between IBF and PLF were included.

RESULTS

A total of 2,819 articles were screened, and 38 full-text articles were selected for a detailed investigation, of which 12 articles were found to match all the inclusion criteria and were included in the meta-analysis. There was an improvement in the sacral slope (mean difference [MD] = 3 [95% confidence interval {CI} = 0.83-5.17]) and fusion rate (odds ratio [OR] = 0.47 [95% CI = 0.26-0.86]) in the IBF group. The incidence of neural injury was higher in the IBF group (OR = 0.28 [95% CI = 0.13-0.60]) than in the PLF group. There were no differences in the back pain scores, ODI, SF-36 score, blood loss amount, surgical time, hospital stay duration, lumbar lordosis, infection, and durotomy between the groups.

CONCLUSIONS

IBF for the treatment of lumbar degenerative spondylolisthesis showed better results in terms of the fusion rate and sacral slope, but which did not translate into better clinical outcomes. Further randomized and prospective studies are necessary to elucidate the optimal therapeutic options.

How Decompression Surgery Improves the Lower Back Pain in Patient with Lumbar Degenerative Stenosis: A Propensity-score-matched Analysis

STUDY DESIGN

Multicenter retrospective case series of patients treated surgically for lumbar spinal stenosis (LSS).

OBJECTIVE

We investigated how laminectomy improves lower back pain (LBP) and the factors associated with poor improvement.

SUMMARY OF BACKGROUND DATA

Lumbar laminectomy is effective for alleviating neurological symptoms caused by LSS, whereas its effect on LBP is still controversial.

METHODS

A retrospective review of prospectively collected data from 436 patients (age 72 yrs, 69% males) who underwent laminectomy for LSS with 2 years of follow-up. We analyzed the following risk factors for residual LBP by uni- and multivariate analyses: age, sex, smoking, occupation, comorbidities, frailty, joint replacement, vertebral fracture, DISH, HRQOL, complications, and the presence of spinal instability. The LBP of male and female patients was analyzed after propensity score matching of known confounders. Patient-reported outcomes (JOABPEQ and VAS scores) were obtained at baseline and the 2-year postoperative follow-up.

RESULTS

LBP was significantly improved at 2 years post operation (VAS change 2.3 [95% CI 2.0-2.6], P < 0.01). Fifty-five percent of the patients achieved an MCID, with 67% having no or mild LBP. In the multivariate analysis, sex and baseline LBP were independent risk factors (female: OR 1.9 [1.2-3.0], baseline LBP [VAS≥7.5]: OR 1.9 [1.2-3.1]). Furthermore, the independent risk factors for severe baseline LBP were sex and mental status (female: OR 1.7 [1.1-2.7], P = 0.03, mental status: OR 3.8 [2.4-6.0], P < 0.01). However, an analysis of 102 pairs of propensity-score-matched male and female patients showed no difference in the improvement of LBP (male vs. female: VAS 3.8 ± 2.8 vs. 4.0 ± 2.9, P = 0.61, VAS change 3.1 ± 2.9 vs. 2.7 ± 3.0, P = 0.38).

CONCLUSION

Decompression surgery for LSS significantly improved LBP. Sex and baseline LBP were risk factors for residual LBP. However, when males and females were matched by confounders, no difference was found in the LBP after surgery. Patients with severe baseline LBP may need further evaluation for their mental status because these patients are likely to have mental problems that potentially contribute to persistent LBP.Level of Evidence: 4.

Classifying Patients Operated for Spondylolisthesis: A K-Means Clustering Analysis of Clinical Presentation Phenotypes

BACKGROUND

Trials of lumbar spondylolisthesis are difficult to compare because of the heterogeneity in the populations studied.

OBJECTIVE

To define patterns of clinical presentation.

METHODS

This is a study of the prospective Quality Outcomes Database spondylolisthesis registry, including patients who underwent single-segment surgery for grade 1 degenerative lumbar spondylolisthesis. Twenty-four-month patient-reported outcomes (PROs) were collected. A k-means clustering analysis-an unsupervised machine learning algorithm-was used to identify clinical presentation phenotypes.

RESULTS

Overall, 608 patients were identified, of which 507 (83.4%) had 24-mo follow-up. Clustering revealed 2 distinct cohorts. Cluster 1 (high disease burden) was younger, had higher body mass index (BMI) and American Society of Anesthesiologist (ASA) grades, and globally worse baseline PROs. Cluster 2 (intermediate disease burden) was older and had lower BMI and ASA grades, and intermediate baseline PROs. Baseline radiographic parameters were similar (P > .05). Both clusters improved clinically (P < .001 all 24-mo PROs). In multivariable adjusted analyses, mean 24-mo Oswestry Disability Index (ODI), Numeric Rating Scale Back Pain (NRS-BP), Numeric Rating Scale Leg Pain, and EuroQol-5D (EQ-5D) were markedly worse for the high-disease-burden cluster (adjusted-P < .001). However, the high-disease-burden cluster demonstrated greater 24-mo improvements for ODI, NRS-BP, and EQ-5D (adjusted-P < .05) and a higher proportion reaching ODI minimal clinically important difference (MCID) (adjusted-P = .001). High-disease-burden cluster had lower satisfaction (adjusted-P = .02).

CONCLUSION

We define 2 distinct phenotypes-those with high vs intermediate disease burden-operated for lumbar spondylolisthesis. Those with high disease burden were less satisfied, had a lower quality of life, and more disability, more back pain, and more leg pain than those with intermediate disease burden, but had greater magnitudes of improvement in disability, back pain, quality of life, and more often reached ODI MCID.

How Preoperative Motor Weakness Affects the Extent of Recovery After Elective Spine Surgery in Patients with Degenerative Lumbar Spinal Stenosis

STUDY DESIGN

Retrospective review.

OBJECTIVE

This study sought to determine how baseline motor weakness (MW) affects elective spine surgery in patients with degenerative lumbar spinal stenosis (LSS).

SUMMARY OF BACKGROUND DATA

Favorable clinical outcomes have been described for elective spine surgery in patients with LSS. However, the way preoperative MW affects the patient's health-related quality of life (HRQoL) after surgery is not well understood.

METHODS

A retrospective review of prospectively collected data from 305 surgically treated patients with LSS who had 2-year follow-up was performed (age 71 ± 9 yrs, male 62%). Demographic, radiographic, and clinical outcomes were analyzed at baseline and at 1-year, 2-year, and 3-year postoperation. The Japanese Orthopedic Association Back Pain Evaluation Questionnaire was used to assess the HRQoLs. The HRQoLs were compared between those with or without preop MW. Adjusted multivariate logistic regression analyses were performed to determine whether MW affected HRQoLs.

RESULTS

One hundred sixteen patients (38%) were categorized as MW+. The patient background including age, sex, presence of degenerative spondylolisthesis, type of surgery, and presence of neurological claudication were similar between the two groups. However, the 1-, 2-, and 3-year postoperative visual analogue scale of back pain, leg pain, leg numbness, the Japanese Orthopedic Association Back Pain Evaluation Questionnaire lumbar function, social life, mental health, and walking ability were all inferior in the MW+ group, whereas a similar percentage of patients achieved a minimum clinically important difference in all subdomains at 3 years. The adjusted multivariate logistic regression analyses showed that having ≥2 muscles with MW, and severity of MW (manual motor test grade) were independent risk factors for both difficulty climbing stairs and walking >15 minutes. (muscles with MW≥2; stair climbing: OR 6.4[2.3-17.4], walking: OR 3.2[1.4-7.3], severity of MW; stair climbing: OR 2.5[1.4-4.4], walking: OR 2.2[1.3-3.7]).

CONCLUSION

The patients with baseline MW had inferior HRQoL for up to 3 years compared with that of those without MW; however, the amount of improvement in HRQoL was comparable. Timely follow-up is important to find out the deterioration of motor function.Level of Evidence: 4.

Static Versus Expandable Polyether Ether Ketone (PEEK) Interbody Cages: A Comparison of One-Year Clinical and Radiographic Outcomes for One-Level Transforaminal Lumbar Interbody Fusion

OBJECTIVE

To examine the effect of static versus expandable polyether ether ketone (PEEK) cages on both clinical and radiographic outcomes.

METHODS

A retrospective cohort study was conducted on patients who underwent one-level transforaminal lumbar interbody fusion with either a static or expandable PEEK cage. Patient outcomes were obtained from chart review and radiographic outcomes were measured using standing, lateral radiographs. Recovery ratios and the proportion of patients achieving the minimally clinically important difference were calculated for Oswestry Disability Index (ODI), Physical Component Score-12, Mental Component Score-12, visual analogue scale for back, and visual analogue scale for leg at 1 year and compared between groups. Multivariate linear regression analysis was performed to determine the effect of cage type on the change in patient-reported outcome measures, controlling for demographic factors.

RESULTS

A total of 240 patients (137 static, 103 expandable) were included in the final analysis. ΔPhysical Component Score-12 scores at 3 months were significantly greater for the static group (16.0 vs. 10.0, P = 0.043) compared with the expandable group. Multivariate regression demonstrated that use of an expandable cage was associated with greater improvements in ΔODI (β: -7.82, P = 0.048) at 1 year. No differences were found in the perioperative change in sagittal spinal alignment within or between groups at 1 year. Subsidence rates failed to show any statistically significant difference between the 2 groups.

CONCLUSIONS

Transforaminal lumbar interbody fusion with an expandable PEEK cage is an independent predictor of improved ODI scores at 1 year. Our study showed no significant differences in subsidence rates or changes in sagittal spinal alignment between static and expandable PEEK cages.

Reoperations after decompression with or without fusion for L4-5 spinal stenosis with or without degenerative spondylolisthesis: a study of 6,532 patients in Swespine, the national Swedish spine register

Background and purpose - There are different opinions on how to surgically address lumbar spinal stenosis with concomitant degenerative spondylolisthesis (DS). We investigated reoperation rates at the index and adjacent levels after L4-5 fusion surgery in a large cohort of unselected patients registered in Swespine, the national Swedish spine register.Patients and methods - 6,532 patients, who underwent surgery for L4-5 spinal stenosis with or without DS between 2007 and 2012, were followed up to 2017 to identify reoperations at the index and adjacent levels. The reoperation rates for decompression and fusion were compared with the reoperation rates for decompression only and for patients with or without DS. Patient-reported outcome data were collected preoperatively, and at 1 and 2 years after surgery and used to evaluate differences in outcome between index operations and reoperations.Results - For spinal stenosis with DS, the reoperation rate at the index level was 3.0% for decompression and fusion and 6.0% for decompression only. At the adjacent level, the corresponding numbers were 9.7% and 4.2% respectively. For spinal stenosis without DS, the reoperation rate at the index level was 3.7% for decompression and fusion and 6.2% after decompression only. At the adjacent level, the corresponding numbers were 8.1% and 3.8% respectively. For the reoperations at the adjacent level, there was no difference in patient-reported outcome between extended fusion or decompression only.Interpretation - Single-level lumbar fusion surgery is associated with an increased rate of reoperations at the adjacent level compared with decompression only. When reoperations at the index level are included there is no difference in reoperation rates between fusion and decompression only.

Spinal Care in the Aging Athlete

Aging athletes face unique, increased adversities related to increased mobility and age-related spine issues, such as spinal stenosis, osteoporosis complicated by fragility fractures, and degenerative disk disease. This article covers various spine pathologies that aging athletes experience and ideal treatment of this population to allow safe return to activity.

Outcomes and Complications With Age in Spondylolisthesis: An Evaluation of the Elderly From the Quality Outcomes Database

STUDY DESIGN

Prospective database analysis.

OBJECTIVE

To assess the effect of age on patient-reported outcomes (PROs) and complication rates after surgical treatment for spondylolisthesis SUMMARY OF BACKGROUND DATA.: Degenerative lumbar spondylolisthesis affects 3% to 20% of the population and up to 30% of the elderly. There is not yet consensus on whether age is a contraindication for surgical treatment of elderly patients.

METHODS

The Quality Outcomes Database lumbar registry was used to evaluate patients from 12 US academic and private centers who underwent surgical treatment for grade 1 lumbar spondylolisthesis between July 2014 and June 2016.

RESULTS

A total of 608 patients who fit the inclusion criteria were categorized by age into the following groups: less than 60 (n = 239), 60 to 70 (n = 209), 71 to 80 (n = 128), and more than 80 (n = 32) years. Older patients showed lower mean body mass index (P < 0.001) and higher rates of diabetes (P = 0.007), coronary artery disease (P = 0.0001), and osteoporosis (P = 0.005). A lower likelihood for home disposition was seen with higher age (89.1% in <60-year-old vs. 75% in >80-year-old patients; P = 0.002). There were no baseline differences in PROs (Oswestry Disability Index, EuroQol health survey [EQ-5D], Numeric Rating Scale for leg pain and back pain) among age categories. A significant improvement for all PROs was seen regardless of age (P < 0.05), and most patients met minimal clinically important differences (MCIDs) for improvement in postoperative PROs. No differences in hospital readmissions or reoperations were seen among age groups (P < 0.05). Multivariate analysis demonstrated that, after controlling other variables, a higher age did not decrease the odds of achieving MCID at 12 months for the PROs.

CONCLUSION

Our results indicate that well-selected elderly patients undergoing surgical treatment of grade 1 spondylolisthesis can achieve meaningful outcomes. This modern, multicenter US study reflects the current use and limitations of spondylolisthesis treatment in the elderly, which may be informative to patients and providers.

LEVEL OF EVIDENCE

4.

Development and Validation of Machine Learning Algorithms for Predicting Adverse Events After Surgery for Lumbar Degenerative Spondylolisthesis

BACKGROUND

Preoperative prognostication of adverse events (AEs) for patients undergoing surgery for lumbar degenerative spondylolisthesis (LDS) can improve risk stratification and help guide the surgical decision-making process. The aim of this study was to develop and validate a set of predictive variables for 30-day AEs after surgery for LDS.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program was used for this study (2005-2016). Logistic regression (enter, stepwise, and forward) and LASSO (least absolute shrinkage and selection operator) methods were performed to identify and select variables for analyses, which resulted in 26 potential models. The final model was selected based on clinical criteria and numeric results.

RESULTS

The overall 30-day rate of AEs for 80,610 patients who underwent surgery for LDS in this database was 4.9% (n = 3965). The median age of the cohort was 58.0 years (range, 18-89 years). The model with the following 10-predictive factors (age, gender, American Society of Anesthesiologists grade, autogenous iliac bone graft, instrumented fusion, levels of surgery, surgical approach, functional status, preoperative serum albumin [g/dL] and serum alkaline phosphatase [IU/L]) performed well on the discrimination, calibration, Brier score, and decision analyses to develop machine learning algorithms. Logistic regression showed higher areas under the curve than did LASSO methods across the different models. The predictive probability derived from the best model is uploaded on an open-access Web application, which can be found at: https://spine.massgeneral.org/drupal/Lumbar-Degenerative-AdverseEvents.

CONCLUSIONS

It is feasible to develop machine learning algorithms from large datasets to provide useful tools for patient counseling and surgical risk assessment.

Early Discharged Lumbar Spine Fusion Reduced Postoperative Readmissions: A Retrospective Cohort Study

Early discharge (ED) has emerged and gained popularity in spine surgery. However, the benefits of ED in lumbar fusion have not yet been validated by large cohort studies. To evaluate the effects of ED on readmissions and reoperations in lumbar fusion, this study utilized a national database to enroll patients who had undergone lumbar fusion surgery at age 50–70 years, and grouped them into an ED group or a comparison group. In the comprehensive follow-up of 180 days post-operation, the two groups were compared. There were 18,008 patients in the cohort, including 2172 in the ED group and 15,836 in the comparison group. The ED group was slightly younger (59.9 vs. 60.7 years, p < 0.001), more male predominant (44.9% vs. 36.9%, p < 0.001), and had fewer medical comorbidities. The ED group had less incidences of readmission than the comparison group. (Crude hazard ratio = 0.73, and adjusted HR = 0.75, both p < 0.001). Overall, the cumulative incidences of readmission in the ED group (9.5%) were lower than those in the comparison group (12.8%, p < 0.001), whereas reoperations were insignificantly different (1.5% vs. 1.2%, p = 0.189). For patients aged 50–70 years and who require lumbar fusion surgery, ED could yield a 25% reduced risk of readmission for any cause within 180 days post-operation. Since the reoperation rates remained similar, our results suggest that ED may be a promising option for elderly patients undergoing lumbar spinal fusion surgery.

Risk Factors for Negative Global Treatment Outcomes in Lumbar Spinal Stenosis Surgery: A Mixed Effects Model Analysis of Data from an International Spine Registry

OBJECTIVE

To determine risk factors for negative global treatment outcomes as self-assessed by patients undergoing surgical treatment for lumbar spinal stenosis (LSS).

METHODS

Patients from the Spine Tango registry undergoing first-time surgery for LSS were analyzed. The primary outcome was global treatment outcomes measured at the last available follow-up ≥3 months postoperatively using a single question rating how much the operation had helped the patient's back problem (negative = no change/operation made things worse). A 2-level logistic mixed effects model with the treating department as the random effect was used to assess factors associated with a negative outcome.

RESULTS

A total of 4504 patients from 39 departments in 10 countries were included. Overall, 14.4% of patients reported a negative global treatment outcome after an average follow-up of 1.3 years. In patients with dominant leg pain, negative outcome was associated with higher baseline back pain; in those with dominant back pain, it was associated with higher baseline back pain, ASA (American Society of Anesthesiologists) ≥3, lower age, not having rigid stabilization, not having disc herniation, and the vertebral level of the most severely affected segment (L5/S1 vs. L3/4). Four departments had significantly higher odds of a negative outcome, whereas 1 department had significantly lower odds. Three out of the 4 negative effects were related to 2 departments from 1 country.

CONCLUSIONS

LSS surgery fails to help at least 1 in 10 patients. High baseline back pain is the most important factor associated with a negative treatment outcome. Department-level and potentially country-level factors of unknown origin explained a nonnegligible variation in the treatment results.

Utilization and Outcomes for Spine Surgery in the United States and Canada

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

The aim of this study was to examine variation in spine surgery utilization between the province of Ontario and state of New York among all patients and pre-specified patient subgroups.

SUMMARY OF BACKGROUND DATA

Spine surgery is common and costly. Within-country variation in utilization is well studied, but there has been little exploration of variation in spine surgery utilization between countries.

METHODS

We used population-level administrative data from Ontario (years 2011-2015) and New York (2011-2014) to identify all adults who underwent inpatient spinal decompression or fusion surgery using relevant procedure codes. Patients were stratified according to age and surgical urgency (elective vs. emergent). We calculated standardized utilization rates (procedures per-10,000 population per year) for each jurisdiction. We compared Ontario and New York with respect to patient demographics and the percentage of hospitals performing spine surgery. We compared utilization rates of spinal decompression and fusion surgery in Ontario and New York among all patients and after stratifying by surgical urgency and patient age.

RESULTS

Patients in Ontario were older than patients in New York for both decompression (mean age 58.8 vs. 51.3 years; P < 0.001) and fusion (58.1 vs. 54.9; P < 0.001). A smaller percentage of hospitals in Ontario than New York performed decompression (26.1% vs. 54.9%; P < 0.001) or fusion (15.2% vs. 56.7%; P < 0.001). Overall, utilization of spine surgery (decompression plus fusion) in Ontario was 6.6 procedures per-10,000 population per-year and in New York was 16.5 per-10,000 per-year (P < 0.001). Ontario-New York differences in utilization were smaller for emergent cases (2.0 per 10,000 in Ontario vs. 2.5 in New York; P < 0.001), but larger for elective cases (4.6 vs. 13.9; P < 0.001). The lower utilization in Ontario was particularly large among younger patients (age <60 years).

CONCLUSION

We found significantly lower utilization of spine surgery in Ontario than in New York. These differences should inform policy reforms in both jurisdictions.

LEVEL OF EVIDENCE

3.

Summary of Guidelines for the Treatment of Lumbar Spondylolisthesis

Degenerative lumbar spondylolisthesis is a common cause of low back pain, affecting about 11.5% of the United States population. Patients with symptomatic lumbar spondylolisthesis may first be treated with conservative management strategies including, but not limited to, non-narcotic and narcotic pain medications, epidural steroid injections, transforaminal injections, and physical therapy. For well-selected patients who fail conservative management strategies, surgical management is appropriate. This article summarizes the guidelines for the treatment of lumbar spondylolisthesis.

Future Studies and Directions for the Optimization of Outcomes for Lumbar Spondylolisthesis

Randomized prospective studies show clear benefits for operative versus nonoperative management of symptomatic lumbar spondylolisthesis, but there is no universally accepted surgical treatment. This article presents options for surgical management of lumbar spondylolisthesis, reviews the clinical trials delineating the role and type of surgical intervention, and explores the directions of future investigations. The next decade will add further clarity to the surgical management of spondylolisthesis, not by randomized prospective trials, but by surgical registries. The power of "big data" offered by registries will likely become the vehicle best suited to amass data on current and novel therapies.

Surgical Versus Nonsurgical Treatment of Lumbar Spondylolisthesis

Degenerative spine disease with low back pain affects ∼80% of the U.S. population, and spinal stenosis and degenerative spondylolisthesis affect ∼20% of the population. Nonoperative and operative interventions have both been studied extensively to better our understanding of how these strategies enable us to improve outcomes in patients with degenerative lumbar spondylolisthesis. This review aims to compare nonoperative and operative strategies and describe the use of incremental cost-effectiveness ratios to assess treatment options in this patient population.

Laminectomy alone versus fusion for grade 1 lumbar spondylolisthesis in 426 patients from the prospective Quality Outcomes Database

OBJECTIVEThe AANS launched the Quality Outcomes Database (QOD), a prospective longitudinal registry that includes demographic, clinical, and patient-reported outcome (PRO) data to measure the safety and quality of spine surgery. Registry data offer "real-world" insights into the utility of spinal fusion and decompression surgery for lumbar spondylolisthesis. Using the QOD, the authors compared the initial 12-month outcome data for patients undergoing fusion and those undergoing laminectomy alone for grade 1 degenerative lumbar spondylolisthesis.METHODSData from 12 top enrolling sites were analyzed and 426 patients undergoing elective single-level spine surgery for degenerative grade 1 lumbar spondylolisthesis were found. Baseline, 3-month, and 12-month follow-up data were collected and compared, including baseline clinical characteristics, readmission rates, reoperation rates, and PROs. The PROs included Oswestry Disability Index (ODI), back and leg pain numeric rating scale (NRS) scores, and EuroQol-5 Dimensions health survey (EQ-5D) results.RESULTSA total of 342 (80.3%) patients underwent fusion, with the remaining 84 (19.7%) undergoing decompression alone. The fusion cohort was younger (60.7 vs 69.9 years, p < 0.001), had a higher mean body mass index (31.0 vs 28.4, p < 0.001), and had a greater proportion of patients with back pain as a major component of their initial presentation (88.0% vs 60.7%, p < 0.001). There were no differences in 12-month reoperation rate (4.4% vs 6.0%, p = 0.93) and 3-month readmission rates (3.5% vs 1.2%, p = 0.45). At 12 months, both cohorts improved significantly with regard to ODI, NRS back and leg pain, and EQ-5D (p < 0.001, all comparisons). In adjusted analysis, fusion procedures were associated with superior 12-month ODI (β -4.79, 95% CI -9.28 to -0.31; p = 0.04).CONCLUSIONSSurgery for grade 1 lumbar spondylolisthesis-regardless of treatment strategy-was associated with significant improvements in disability, back and leg pain, and quality of life at 12 months. When adjusting for covariates, fusion surgery was associated with superior ODI at 12 months. Although fusion procedures were associated with a lower rate of reoperation, there was no statistically significant difference at 12 months. Further study must be undertaken to assess the durability of either surgical strategy in longer-term follow-up.

Cost-effectiveness of lumbar fenestration surgery in the Japanese universal health insurance system

BACKGROUND

Healthcare costs are a global concern, and cost-effectiveness analyses of interventions have become important. However, data regarding cost-effectiveness are limited to a few medical fields. The purpose of our study was to examine the Japanese universal health insurance system cost per quality-adjusted life year (QALY) for lumbar fenestration surgery.

METHODS

Forty-eight patients who underwent fenestration for lumbar degenerative spinal canal stenosis between July 2013 and September 2015 were included. Effectiveness was evaluated by measuring the EuroQOL 5-dimension (EQ-5D), Short-Form 8 physical component summary (PCS), and visual analog scale (VAS). Cost was analyzed from the perspective of the public healthcare payer. Effectiveness and cost were measured 1 year after surgery. QALYs were calculated by multiplying the utility value (EQ-5D) and life years. Only direct costs based on actual reimbursements were included. Cost per QALY with a 5-year time horizon with a 2% discount rate was estimated. Sensitivity analysis was performed by varying the time horizon (2 years or 10 years).

RESULTS

Mean total cost 1 year after fenestration surgery was 1,254,300 yen (standard deviation [SD], 430,000 yen; median, 1,172,300 yen). Operative cost was 406,800 yen (SD, 251,500 yen; median, 363,000 yen). Mean gained score was 0.21 for EQ-5D (SD, 0.18; median, 0.24), 11 for PCS (SD, 10; median, 12), and -43 for VAS (SD, 34; median, -38). Cost per QALY was 1,268,600 yen. Sensitivity analysis demonstrated that cost per QALY with a 10-year time horizon was 679,300 yen and that with a 2-year time horizon was 3,004,600 yen.

CONCLUSIONS

Cost per QALY of lumbar fenestration with a 5-year time horizon was 1,268,600 yen (11,532 US dollar), which was below the widely accepted benchmark (cost per QALY <5,000,000-6,500,000 yen (50,000 US dollars)). Fenestration is a cost-effective intervention.

Comparisons of direct costs, outcomes, and cost-utility of decompression surgery with fusion versus decompression alone for degenerative lumbar spondylolisthesis

BACKGROUND

Cost-utility analysis of surgery for degenerative lumber spondylolisthesis (DS) is essential for healthcare providers and patients to select appropriate treatment. The purpose of this study was to review the cost-utility of decompression alone versus decompression with fusion for DS.

METHODS

A retrospective review of 99 consecutive patients who were treated for Meyerding grade 1 DS at two representative spine centers was performed. Patients with significant spinal instability were treated by decompression with fusion (F group, 40 patients); all others were treated by decompression surgery alone (D group, 59 patients). All patients were followed for three years. Demographic and radiographic data, health-related quality of life (HRQoL), and the direct cost for surgery were analyzed, and the incremental cost-effectiveness ratio (ICER) was determined using cost/quality-adjusted life years (QALY).

RESULTS

There were no differences between the groups in baseline demographics (D vs. F: age 68 ± 9 vs. 66 ± 7 years; 37% vs. 40% female) or HRQoL (ODI: D, 41 ± 16 vs. F, 46 ± 13%). The F group had a higher initial-surgery cost ($18,992 ± 2932) but lower reoperation frequency (7%) than the D group ($7660 ± 2182 and 12%, respectively). The three-year total direct cost was higher for F than for D ($19,222 ± 3332 vs. $9668 ± 6,168, p = .01). ICER was higher for F at one year ($136,408 ± 187,911 vs. $237,844 ± 212,049, p < .01), but was comparable for F and D at three years (D, $41,923 ± 44,503 vs. F, $51,313 ± 32,849, p = .17).

CONCLUSION

At the three-year follow-up, the two methods had comparable cost-utility. Both methods were cost-effective (defined as an ICER within three times the per-capita gross domestic product).

The impact of obesity measured by outer abdominal fat on instability of the adjacent segments after rigid pedicle screw fixation

Previous studies have shown coherence between obesity and higher rates of complications following spinal surgery. However, there is a lack of information about the influence of obesity and the mass of outer abdominal fat (OAF) on adjacent segment instability after spinal fusion surgery. Radiographs of 194 patients with spinal fusion surgery were assessed retrospectively. Radiographs were performed after surgery during two years' follow-up and signs of adjacent segment instability were documented. Patients were classified regarding their BMI and extent of OAF was assessed using CT at the umbilical level. In 20 patients (10.3%) instability of adjacent segments occurred during followup. In this cohort mean OAF was significantly thicker (28.07 mm) compared to the patients without instability (22.39) (P=0.038). A total of 45% of patients with instability showed OAF of more than 30 mm at time of intervention compared to 10% in those without signs of instability. There exists significant correlation between the extent of OAF and development of adjacent segment instability postoperatively. Thus, weight reduction before spinal surgery could potentially decrease risk of adjacent segment instability.

Effectiveness of a Decision-Making Protocol for the Surgical Treatment of Lumbar Stenosis with Grade 1 Degenerative Spondylolisthesis

BACKGROUND

Addition of fusion to decompression for stenosis with grade 1 degenerative spondylolisthesis is a controversial topic, and the question remains if fusion provides any benefit to the patient that warrants the increased health care utilization and perioperative morbidity. There is no consensus on indications for use of fusion over decompression alone.

METHODS

Patients received fusion or decompression according to a decision-making protocol based on their pattern of complaints, location of the compression, and facet angles and effusion as proven predictors of postoperative instability. Propensity score matching of patients was done for baseline data.

RESULTS

The study comprised 102 patients in 2 equally sized groups. No intergroup differences in numeric rating scale and Oswestry Disability Index were detected at any follow-up point (all P > 0.05). Duration of surgery, length of stay, estimated blood loss, and radiation doses were higher in the fusion group (all P < 0.001). Cumulative reoperation rate was similar with 6% for fusion and 8% for decompression (P > 0.05), as was the complication rate (8% vs. 6%, P > 0.05). Postoperative iatrogenic progression of spondylolisthesis requiring fusion surgery was seen in only 2% in the decompression group.

CONCLUSIONS

Use of a decision-making protocol led to a low rate of iatrogenically increased spondylolisthesis after decompression, while retaining outcomes. These data suggest that a decision-making protocol based on clinical history, location of nerve root compression, and proven radiologic predictors of postoperative instability assigns patients to fusion or decompression in a safe and effective manner.