Does Obesity Correlate With Worse Patient-Reported Outcomes Following Elective Anterior Cervical Discectomy and Fusion?

Obesity Does Not Negatively Affect Patient-perceived Outcomes After Cervical Disc Replacement for Disc Herniation

STUDY DESIGN

Retrospective review.

OBJECTIVE

To assess the impact of Body Mass Index (BMI) on patient-reported outcome measures (PROMs) after cervical disc replacement (CDR).

BACKGROUND

BMI may affect PROMs after spine surgery.

METHODS

Primary CDR recipients for herniated disc(s) with BMI <40 were retrospectively selected from a single-surgeon registry. Cohorts were divided into non-obese (BMI <30) and obese (BMI ≥30). Intercohort in-hospital complication rates were compared through independent samples t tests. Pre/postoperative PROMs were compared between cohorts through multivariable regression accounting for demographic differences. Final follow-up dates between patients averaged 11.8 ± 9.3 months. PROMs assessed included Patient-reported Outcomes Measurement Information System-Physical Function, Neck Disability Index, Visual Analog Scale-Neck, Visual Analog Scale-Arm, and the 9-item Patient Health Questionnaire. Improvements in PROMs were evaluated and compared at each follow-up within cohorts through paired t tests. The magnitude of improvement in PROMs from preoperative baseline at 6-week follow-up (∆PROM-6W) and final follow-up (∆PROM-FF) along with achievement rates of minimum clinically important differences were compared between cohorts through multivariable regression accounting for demographic differences.

RESULTS

Of 153 patients, 53 patients were noted as obese. Demographic differences included age, prevalence of hypertension and diabetes, and comorbidity burden scores ( P ≤ 0.011, all). No significant variations in in-hospital complications were found. The non-obese cohort demonstrated improvements in all PROMs at 6 weeks and final follow-up periods ( P ≤ 0.005, all). The obese cohort demonstrated improvements in all postoperative PROMs besides 9-item Patient Health Questionnaire at 6 weeks ( P ≤ 0.015, all). After accounting for age and comorbidity variations, there were no significant intercohort differences in raw PROM scores, ∆PROM-6W, ∆PROM-FF, or minimum clinically important difference achievement rates.

CONCLUSIONS

Regardless of BMI, patients experience significant improvements in physical function, disability, pain, and mental health after CDR for disc herniation. Patients with obesity do not suffer inferior patient-perceived outcomes after CDR. These findings may help surgeons counsel patients in the preoperative period.

The Effect of Hyperlipidemia as a Risk Factor on Postoperative Complications in Patients Undergoing Anterior Cervical Discectomy and Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To analyze the effect of hyperlipidemia (HLD) on postoperative complications in patients who underwent anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

ACDF represents the standard procedure performed for focal anterior nerve root or spinal cord compression with low complication rates. HLD is well known as a risk factor for major complications after vascular and transplant surgery, and orthopedic surgery. To date, there have been no studies on HLD as a risk factor for cervical spine surgery.

PATIENTS AND METHODS

Patients who underwent ACDF from 2010 through quarter 3 of 2020 were enrolled using the MSpine subset of the PearlDiver Patient Record Database. The patients were divided into single-level ACDF and multilevel ACDF groups. In addition, each group was divided into subgroups according to the presence or absence of HLD. The incidence of surgical and medical complications was queried using relevant International Classification of Disease and Current Procedural Terminology codes. Charlson Comorbidity Index was used as a broad measure of comorbidity. χ 2 analysis, with populations matched for age, sex, and Charlson Comorbidity Index, was performed.

RESULTS

A total of 24,936 patients who underwent single-level ACDF and 26,921 patients who underwent multilevel ACDF were included. In the multilevel ACDF group, wound complications were significantly higher in the patients with HLD. Among medical complications, myocardial infarction, renal failure, and urinary tract infection/urinary incontinence were significantly higher in the patients with HLD in both groups. Revision surgery and readmission were significantly higher in the patients with HLD who underwent multilevel ACDF.

CONCLUSIONS

In patients who underwent ACDF, several surgical and medical complications were found to be higher in patients with HLD than in patients without HLD. Preoperative serum lipid concentration levels and management of HLD should be considered during preoperative planning to prevent postoperative complications in patients undergoing ACDF.

Perioperative Management of Comorbidities in Spine Surgery

The number of spinal operations performed in the United States has significantly increased in recent years. Along with these rising numbers, there has been a corresponding increase in the number of patient comorbidities. The focus of this article is to review comorbidities in Spine surgery patients and outline strategies to optimize patients and avoid complications.

Morbid Obesity Increases Length of Surgery in Elective Anterior Cervical Discectomy and Fusion Procedures but Not Readmission or Reoperation Rates: A Cohort Study

BACKGROUND

As the obesity epidemic grows, the number of morbidly obese patients undergoing anterior cervical discectomy and fusion (ACDF) continues to increase. Despite the association of obesity with perioperative complications in anterior cervical surgery, the impact of morbid obesity on ACDF complications remains controversial, and studies examining morbidly obese cohorts are limited.

METHODS

A single-institution, retrospective analysis of patients undergoing ACDF from September 2010 to February 2022 was performed. Demographic, intraoperative, and postoperative data were collected via review of the electronic medical record. Patients were categorized as nonobese (body mass index [BMI] <30), obese (BMI 30-39.9), or morbidly obese (BMI ≥40). Associations of BMI class with discharge disposition, length of surgery, and length of stay were assessed using multivariable logistic regression, multivariable linear regression, and negative binomial regression, respectively.

RESULTS

The study included 670 patients undergoing single-level or multilevel ACDF: 413 (61.6%) nonobese, 226 (33.7%) obese, and 31 (4.6%) morbidly obese patients. BMI class was associated with prior history of deep venous thrombosis (P < 0.01), pulmonary thromboembolism (P < 0.05), and diabetes mellitus (P < 0.001). In bivariate analysis, there was no significant association between BMI class and reoperation or readmission rates at 30, 60, or 365 days postoperatively. In multivariable analysis, greater BMI class was associated with increased length of surgery (P = 0.03), but not length of stay or discharge disposition.

CONCLUSIONS

For patients undergoing ACDF, greater BMI class was associated with increased length of surgery, but not reoperation rate, readmission rate, length of stay, or discharge disposition.

Anterior surgical treatment for cervical degenerative radiculopathy: a prediction model for non-success

PURPOSE

By using data from the Norwegian Registry for Spine Surgery, we wanted to develop and validate prediction models for non-success in patients operated with anterior surgical techniques for cervical degenerative radiculopathy (CDR).

METHODS

This is a multicentre longitudinal study of 2022 patients undergoing CDR surgery and followed for 12 months to find prognostic models for non-success in neck disability and arm pain using multivariable logistic regression analysis. Model performance was evaluated by area under the receiver operating characteristic curve (AUC) and a calibration test. Internal validation by bootstrapping re-sampling with 1000 repetitions was applied to correct for over-optimism. The clinical usefulness of the neck disability model was explored by developing a risk matrix for individual case examples.

RESULTS

Thirty-eight percent of patients experienced non-success in neck disability and 35% in arm pain. Loss to follow-up was 35% for both groups. Predictors for non-success in neck disability were high physical demands in work, low level of education, pending litigation, previous neck surgery, long duration of arm pain, medium-to-high baseline disability score and presence of anxiety/depression. AUC was 0.78 (95% CI, 0.75, 0.82). For the arm pain model, all predictors for non-success in neck disability, except for anxiety/depression, were found to be significant in addition to foreign mother tongue, smoking and medium-to-high baseline arm pain. AUC was 0.68 (95% CI, 0.64, 0.72).

CONCLUSION

The neck disability model showed high discriminative performance, whereas the arm pain model was shown to be acceptable. Based upon the models, individualized risk estimates can be made and applied in shared decision-making with patients referred for surgical assessment.

Obesity and Spine Surgery: A Qualitative Review About Outcomes and Complications. Is It Time for New Perspectives on Future Researches?

STUDY DESIGN

Literature review.

OBJECTIVES

An increasing number of obese patients requires operative care for degenerative spinal disorders. The aim of this review is to analyze the available evidence regarding the role of obesity on outcomes after spine surgery. Peri-operative complications and clinical results are evaluated for both cervical and lumbar surgery. Furthermore, the contribution of MIS techniques for lumbar surgery to play a role in reducing risks has been analyzed.

METHODS

Only articles published in English in the last 10 years were reviewed. Inclusion criteria of the references were based on the scope of this review, according to PRISMA guidelines. Moreover, only paper analyzing obesity-related complications in spine surgery have been selected and thoroughly reviewed. Each article was classified according to its rating of evidence using the Sacket Grading System.

RESULTS

A total number of 1636 articles were found, but only 130 of them were considered to be relevant after thorough evaluation and according to PRISMA checklist. The majority of the included papers were classified according to the Sacket Grading System as Level 2 (Retrospective Studies).

CONCLUSION

Evidence suggest that obese patients could benefit from spine surgery and outcomes be satisfactory. A higher rate of peri-operative complications is reported among obese patients, especially in posterior approaches. The use of MIS techniques plays a key role in order to reduce surgical risks. Further studies should evaluate the role of multidisciplinary counseling between spine surgeons, nutritionists and bariatric surgeons, in order to plan proper weight loss before elective spine surgery.

Cervical alignment in the obese population following posterior cervical fusion for cervical myelopathy

STUDY DESIGN

Retrospective cohort study OBJECTIVE: The aim of this study was to investigate the effect of body mass index (BMI) on the reoperation rate and cervical sagittal alignment of patients who underwent posterior cervical decompression and fusion for cervical spondylotic myelopathy (CSM).

SUMMARY OF BACKGROUND DATA

Cervical sagittal balance has been correlated with postoperative clinical outcomes. Previous studies have shown worse postoperative sagittal alignment and higher reoperation rates in patients with high BMI undergoing anterior decompression and fusion. Similar evidence for the impact of obesity in postoperative sagittal alignment for patients with (CSM) undergoing posterior cervical decompression and fusion (PCF) is lacking.

METHODS

A retrospective analysis of 198 patients who underwent PCF for cervical myelopathy due to degenerative spine disease was performed. Demographics, need for reoperation, and perioperative radiographic parameters were collected. Cervical lordosis (CL), C2-7 sagittal vertical axis (SVA), and T1 slope (T1S) was measured on standing lateral radiographs. Comparative analysis of the patient cohort was performed by stratifying the sample population into three BMI categories (<25, 25-30, ≥30).

RESULT

Of the 198 patients that met inclusion criteria, 53 had BMI normal (<25), 65 were overweight (25-30), and 80 were obese (≥30). Mean SVA increased postoperatively in all groups, 4 mm in the normal group, 13 mm in the overweight group, and 13 mm in the obese group (p = 0.003). There was no significant difference in the postoperative change of cervical lordosis or T1 slope between the groups. Multivariate analysis demonstrated fusions involving the cervicothoracic junction and those involving 5 or more levels significantly affected alignment parameters. There were 27 complications requiring reoperation (14%) with no significant differences among the groups stratified by BMI (p = 0.386).

CONCLUSIONS

Overweight patients (BMI>25) with CSM undergoing PCF had a greater increase in SVA than normal weight patients while reoperation rates were similar. In addition, preoperative CL increased with increasing BMI, although this trend was not Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation significant and there was not found to be a significant difference between the change in CL from baseline to post-fusion between BMI cohorts. This study further highlights the importance of considering BMI when attempting to optimize sagittal alignment in patients undergoing PCF.

The Role of Nutrition in Degenerative Cervical Myelopathy: A Systematic Review

Introduction

Degenerative cervical myelopathy (DCM) is the commonest cause of adult spinal cord impairment worldwide, encompassing chronic compression of the spinal cord, neurological disability and diminished quality of life. Evidence on the contribution of environmental factors is sparse; in particular, the role of nutrition in DCM is unknown. The objective of this review was to assess the effect of nutrition on DCM susceptibility, severity and surgical outcome.

Methods

A systematic review in MEDLINE and Embase was conducted following PRISMA guidelines. Full-text papers in English papers, focussing on cervical myelopathy and nutrition, published before January 2020 were considered eligible. Quality assessments were performed using the GRADE assessment tool. Patient demographics, nutritional factor and DCM outcomes measures were recorded. Relationships between nutritional factors, interventions and disease prognosis were assessed.

Results

In total, 5835 papers were identified of which 44 were included in the final analysis. DCM patients with pathological weight pre-operatively were more likely to see poorer improvements post-surgically. These patients experienced poorer physical and mental health improvements from surgery compared to normal weight patients and were more likely to suffer from post-operative complications such as infection, DVT, PE and hospital readmissions. Two trials reporting benefits of nutritional supplements were identified, with 1 suggesting Cerebrolysin to be significant in functional improvement. An unbalanced diet, history of alcohol abuse and malnourishment were associated with poorer post-operative outcome.

Conclusion

Although the overall strength of recommendation is low, current evidence suggests nutrition may have a significant role in optimising surgical outcome in DCM patients. Although it may have a role in onset and severity of DCM, this is a preliminary suggestion. Further work needs to be done on how nutrition is defined and measured, however, the beneficial results from studies with nutritional interventions suggest nutrition could be a treatment target in DCM.

Comorbidity Influence on Postoperative Outcomes Following Anterior Cervical Discectomy and Fusion

Objective

This study aims to detail the association between comorbidity burden and achieving minimum clinically important difference (MCID) following anterior cervical discectomy and fusion (ACDF).

Methods

A prospective surgical registry was retrospectively reviewed. Patients with missing preoperative Patient-Reported Outcomes Measurement Information System physical function (PROMIS PF) were excluded. Patients were stratified by Charlson Comorbidity Index (CCI): no comorbidities = 0 point; low CCI = 1–2 points; high CCI = ≥ 3 points. Demographic and perioperative characteristics were collected and evaluated for differences. Visual analogue scale (VAS), 12-item Short Form health survey (SF-12), and PROMIS PF were collected pre- and postoperatively and assessed for differences. Differences in achievement of MCID were compared using established values: VAS neck = 2.6, VAS arm = 4.1, NDI = 8.5, SF-12 physical composite score (SF-12 PCS) = 8.1, PROMIS PF = 4.5.

Results

One hundred twenty-five ACDF patients were included: 37 had no comorbidities, 64 with low CCI, and 24 with high CCI. Higher CCI groups were older, nonsmokers, diabetic, arthritic, hypertensive, and had cancer. Multilevel fusions, operative time, length of stay, and later discharge day were associated with high CCI. VAS neck differed preoperatively by group. SF-12 PCS and PROMIS PF were inversely associated with CCI groups. CCI did not impact achievement of MCID for all outcomes. A lower rate of reaching MCID was demonstrated at 3 months for SF-12 PCS.

Conclusion

Regardless of comorbidity burden, patients undergoing ACDF for cervical pathology demonstrated a similar rate of achieving MCID for VAS neck, VAS arm, NDI, and PROMIS PF. Regardless of CCI score, ACDF can have a significant benefit for patients.

Factors affecting functional outcome after anterior cervical discectomy and fusion: A multicenter study

Background

Although anterior cervical discectomy and fusion (ACDF) represents a standardized procedure for surgical treatment of a cervical herniated disc, several variables could affect patients' clinical and radiological outcome. We evaluated the impact of sex, age, body mass index (BMI), myelopathy, one- or two-level ACDF, and the use of postoperative collars on functional and radiological outcomes in a large series of patients operated for ACDF.

Materials and Methods

Databases of three institutions were searched, resulting in the enrollment of 234 patients submitted to one- or two-level ACDF from January 2013 to December 2017 and followed as outpatients at 6- and 12-month follow-up. The impact of variables on functional and radiological outcomes was evaluated using univariate and multivariate logistic regression analysis.

Results

At univariate analysis, female sex, higher BMI, two-level ACDF, and postoperative collar correlated with a significantly worse early and late Neck Disability Index (NDI). Multivariate analysis showed that male patients had a lower risk of worse early (P = 0.01) and late NDIs (P = 0.009). Patients with myelopathy showed better early NDI (P = 0.004). Cervical collar negatively influenced both early and late NDIs (P < 0.0001), with a higher risk of early nonfusion (P = 0.001) but a lower risk of late nonfusion (P = 0.01). Patients operated for two-level ACDF have a worse early NDI (P = 0.005), a worse late NDI (P = 0.01), and a higher risk of early nonfusion (P = 0.048). BMI and age did not influence outcome.

Conclusions

Female sex, two-level surgery, and the use of postoperative collars significantly correlate with worse functional outcomes after one- or two-level ACDF.

Effects of Body Mass Index on Perioperative Outcomes in Patients Undergoing Anterior Cervical Discectomy and Fusion Surgery

Objective

Obesity has become a public health crisis and continues to be on the rise. An elevated body mass index has been linked to higher rates of spinal degenerative disease requiring surgical intervention. Limited studies exist that evaluate the effects of obesity on perioperative complications in patients undergoing anterior cervical discectomy and fusion (ACDF). Our study aims to determine the incidence of obesity in the ACDF population and the effects it may have on postoperative inpatient complications.

Methods

The National Inpatient Sample was evaluated from 2004 to 2014 and discharges with International Classification of Diseases procedure codes indicating ACDF were identified. This cohort was stratified into patients with diagnosis codes indicating obesity. Separate univariable followed by multivariable logistic regression analysis were performed for the likelihood of perioperative inpatient outcomes among the patients with obesity.

Results

From 2004 to 2014, estimated 1,212,475 ACDFs were identified in which 9.2% of the patients were obese. The incidence of obesity amongst ACDF patients has risen dramatically during those years from 5.8% to 13.4%. Obese ACDF patients had higher inpatient likelihood of dysphagia, neurological, respiratory, and hematologic complications as well as pulmonary emboli, and intraoperative durotomy.

Conclusion

Obesity is a well-established modifiable comorbidity that leads to increased perioperative complications in various surgical specialties. We present one of the largest retrospective analyses evaluating the effects of obesity on inpatient complications following ACDF. Our data suggest that the number of obese patients undergoing ACDF is steadily increasing and had a higher inpatient likelihood of developing perioperative complications.

The Effect of Body Mass Index on Long-Term Patient-Reported Outcome Scores after Anterior Cervical Discectomy and Fusion in an Asian Population: A 2-Year Study

Study Design

Retrospective cohort study.

Purpose

This study aims to analyze the relationship between body mass index (BMI) subjective patient-reported outcomes (PRO) after 1- and 2-level anterior cervical discectomy and fusion (ACDF).

Overview of Literature

The prevalence of cervical spondylosis and ACDF in expected to continue rising among the aging population of Asia. Moreover, the prevalence of obesity is also increasing. However, limited information is available about the mechanism by which BMI affects PRO after ACDF.

Methods

Total 878 patients underwent ACDF between 2000 and 2015. After excluding patients with previous cervical instrumentation, >2 levels fused, missing BMI measurement, or neoplastic/trauma indication for surgery, 535 patients were included. The PRO measures of the Neck Disability Index, Numerical Pain Rating Scale (NPRS) for Neck Pain, NPRS for Limb Pain, American Academy of Orthopaedic Surgeons–Neurogenic Symptom Score, and Japanese Orthopaedic Association myelopathy score were used. Patients were grouped based on their preoperative BMI, as per the World Health Organization guidelines for Asian populations. PRO scores were collected preoperatively, at 6 months postoperatively, and 2 years postoperatively. A generalized linear model was used to analyze the relationship of BMI category with the individual score, accounting for several factors that are likely to affect the outcomes.

Results

Total 19 (3.4%) were underweight, 155 (28.0%) were normal weight, 112 (20.3%) were overweight, and 267 (48.3%) were obese. Patients across all BMI categories experienced significant and similar improvements in their postoperative PRO scores. There were no significant differences in the preoperative, 6-month postoperative, and 2-year postoperative PRO scores of the groups. Rate of reoperation was highest in patients with grade II obesity at 8.07%; however, the difference was not statistically significant.

Conclusions

Irrespective of the BMI, all patients exhibited similar satisfactory outcomes following ACDF. The results support surgery in all subgroups of patients with symptomatic nerve compression in the cervical spine.

Factors Associated With Extended Length of Stay and 90-Day Readmission Rates Following ACDF

STUDY DESIGN

Retrospective.

OBJECTIVE

Identify patient risk factors for extended length of stay (LOS) and 90-day hospital readmissions following elective anterior cervical discectomy and fusion (ACDF).

METHODS

Included ACDF patients from 2013 to 2017 at a single institution. Eligible patients were subset into LOS <2 and LOS ≥2 days, and no 90-day hospital readmission and yes 90-day hospital readmission. Patient and surgical factors were compared between the LOS and readmission groups. Multivariable logistic regression analysis was utilized to determine the association of independent factors with LOS and 90-day readmission rates.

RESULTS

Our sample included 1896 patients; 265 (14%) had LOS ≥2 days, and 121 (6.4%) had a readmission within 90 days of surgery. Patient and surgical factors associated with LOS included patient age ≥65 years (odds ratio [OR] 1.72, 95% confidence interval [CI] 1.15-2.56), marriage (OR 0.57, 95% CI 0.43-0.79), private health insurance (OR 0.28, 95% CI 0.15-0.50), American Society of Anesthesiologists (ASA) score (OR 1.52, 95% CI 1.12-1.86), African American race (OR 1.95, 95% CI 1.38-2.72), and harvesting iliac crest autograft (OR 4.94, 95% CI 2.31-10.8). Patient and surgical factors associated with 90-day hospital readmission included ASA score (OR 1.81, 95% CI 1.32-2.49), length of surgery (OR 1.002, 95% CI 1.001-1.004), and radiculopathy as indication for surgery (OR 0.60, 95% CI 0.39-0.96).

CONCLUSIONS

Extended LOS and 90-day hospital readmissions may lead to poorer patient outcomes and increased episode of care costs. Our study identified patient and surgical factors associated with extended LOS and 90-day readmission rates. In general, preoperative patient factors affected these outcomes more than surgical factors.

Retrospective Data Analysis and Literature Review for a Development of Enhanced Recovery after Surgery Pathway for Anterior Cervical Discectomy and Fusion

Objective

While enhanced recovery after surgery (ERAS) protocols are associated with shorter length of stay and improved outcomes in multiple surgical specialties, its application to spine surgery has been limited. Anterior cervical discectomy and fusion (ACDF) is a common spinal procedure with a relative efficacy and safety profile that makes it suitable for the application of ERAS principles. Reviewing our outcomes and practice and incorporating evidence-based clinical studies, we propose the development of an ERAS pathway for ACDF.

Methods

This is a retrospective review of ACDF cases performed at a single institution by a single surgeon from 2014 to 2017. Primary outcome measures included length of stay, complications, and 30-day readmission rates. The 1- and 2-level and the 3- and 4-level groups were also each consolidated into a single cohort for comparison. A comprehensive review of evidence-based literature pertaining to ACDF was then performed. Best-practice recommendations derived from the literature were incorporated into the proposed ERAS protocol.

Results

In this series of 75 1-level, 77 2-level, 44 3-level and 20 4-level ACDF procedures, the average surgical time (minutes) was 68, 90, 118 and 141; length of stay (days) was 1, 1, 1.4, and 1.7; drain usage (%) was 1.3, 2.6, 13.6 and 10; and 30-day readmission rates (%) were 2.7, 3.9, 4.5, and 15, respectively. Combining the 1- and 2-level as a single group and 3- and 4-level as another cohort, the 3- and 4-level cohort had a significantly higher rate of drain usage and estimated blood loss (EBL) but there was not a difference in length-of-stay, complications or 30-day readmission rates.

Conclusions

Given the relative equivalent safety profile between 1- and 2-level as compared to 3- and 4-level ACDF, the proposed ERAS pathway can be applied to all patients, and not just restricted to 1-level or 2-level ACDF. Taking into account feasibility parameters as deduced from a review of institutional outcomes, this pathway can streamline same-day discharge and improve the patient experience. Its success will be predicated on an iterative improvement process deriving from optimal prospective outcome measurements.

Impact of Elevated Body Mass Index on Surgical Outcomes for Patients Undergoing Cervical Fusion Procedures: A Systematic Review and Meta-Analysis

To investigate whether high body mass index (BMI) had adverse effects on the postoperative outcomes for patients who underwent anterior or posterior cervical fusion procedures. A literature search were conducted in PubMed, Embase, and Web of Science. Comparative or controlled studies that examined the influences of high BMI on postoperative outcomes after cervical fusion procedures were included. Using a fixed‐effect model or random‐effect model, the effects of high BMI were determined by weight mean difference (WMD) with 95% confidence interval (95% CI) or risk ratio (RR) with 95% CI. A total of seven studies were included in this meta‐analysis. The pooled estimate showed that high BMI was associated with longer hospital stay (WMD = 1.61 days, 95% CI: 0.51, 2.71; P = 0.004), longer surgical time (WMD = 4.55, 95% CI: 1.04, 8.07; P = 0.011), higher mortality rate (RR = 3.01, 95% CI: 2.75, 3.29; P < 0.001), and higher postoperative rates of cardiac complication (RR = 1.30, 95% CI: 1.11, 1.52; P = 0.001), deep venous thromboembolism (RR = 2.29, 95% CI: 1.36, 3.86; P = 0.002), and wound complication (RR = 1.69, 95% CI: 1.26, 2.28; P < 0.001). However, there was no significant differences between high and normal BMI groups in terms of Neck Disability Index (WMD = 1.49, 95% CI: −2.34, 5.32; P = 0.447), SF‐36 Mental Component Score (MCS) (WMD = −0.87, 95% CI: −2.09, 0.35; P = 0.164), overall complications (RR = 1.18, 95% CI: 0.80, 1.76; P = 0.399), central nervous system (CNS) complications (RR = 0.68, 95% CI: 0.17, 2.76; P = 0.586), pulmonary complications (RR = 1.46, 95% CI: 0.87, 2.46; P = 0.150), and septic complications (RR = 0.87, 95% CI: 0.32, 2.38; P = 0.785).High BMI seemed to be associated with longer hospital stay, surgical time, and higher postoperative complication rates compared to normal BMI. Therefore, high BMI patients should be counseled carefully regarding the risk of postoperative complications and surgical outcomes after cervical fusion procedures.

Clinical outcomes for anterior cervical discectomy and fusion with silicon nitride spine cages: a multicenter study

BACKGROUND

Intervertebral spacers made of silicon nitride (Si3N4) are currently used in cervical and thoracolumbar fusion. While basic science data demonstrate several advantages of Si3N4 over other biomaterials, large-scale clinical results on its safety and efficacy are lacking. This multicenter retrospective study examined outcomes for anterior cervical discectomy and fusion (ACDF) using Si3N4 cages. Results were compared to compiled metadata for other ACDF materials.

METHODS

Pre-operative patient demographics, comorbidities, changes in visual analog scale (VAS) pain scores, complications, adverse events, and secondary surgical interventions were collected from the medical records of 860 patients who underwent Si3N4 ACDF at four surgical centers. For comparison, MEDLINE/PubMed and Google Scholar searches were performed for ACDF using other cage or spacer materials. Nine studies with 13 cohorts and 736 patients met the inclusion criteria for this control group.

RESULTS

Overall, the mean last-follow-up for all patients was 319±325 days (10.6±10.8 months), with the longest follow-up being 6.5 years. In comparison to the metadata, patients from the Si3N4 groups were older (57.9±12.2 vs. 56.8±11.1 y, P=0.06) and had higher BMI values (30.0±6.3 vs. 28.1±6.5, P<0.01), but gender and smoking were not different. The Si3N4 patients reported significant improvements in VAS pain scores at last follow-up (i.e., pre-op of 71.0±22.1 vs. follow-up of 36.4±31.5, P<0.01). Although both preoperative and last-follow-up pain scores were higher for Si3N4 patients than the control, the overall change in scores (ΔVAS) was similar. From pre-op to last-follow up, ΔVAS values were 35.4±34.3 for patients receiving the Si3N4 implants versus 34.4±27.3 for patients from the meta-analysis (P=0.56). The complication and reoperation rate for the Si3N4 and the metadata were also comparable (i.e., 7.39% and 0.31% versus 9.79% and 0%, P=0.17 and 0.25, respectively).

CONCLUSIONS

ACDF outcomes using Si3N4 implants matched the clinical efficacy of other cage biomaterials.

Obesity does not impact clinical outcome but affects cervical sagittal alignment and adjacent segment degeneration in short term follow-up after an anterior cervical decompression and fusion

BACKGROUND CONTEXT

Obesity increases complications and cost following spine surgery. However, the impact on sagittal alignment and adjacent segment degeneration (ASD) after anterior cervical decompression and fusion is less understood.

PURPOSE

To compare clinical and radiographic outcomes after anterior cervical decompression and fusion between obese and nonobese patients.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

In all, 467 patients that underwent an anterior cervical decompression and fusion procedure from January 2008 through December 2015 were assessed. Surgery indications were radiculopathy, myelopathy, or myeloradiculopathy that had failed nonoperative treatments. Exclusion criteria included patients who had postoperative follow-up less than 6 months. Of 467 patients originally identified, 399 fulfilled the inclusion and exclusion criteria.

OUTCOME MEASURES

The following patient-reported outcomes were obtained: Neck Disability Index and Visual Analog Scale scores for the neck and arm pain. Radiographic assessments included: C2-C7 lordosis, T1 angle, levels fused, sagittal vertical axis (SVA), fusion mass lordosis, proximal and distal adjacent segment lordosis, ASD, and presence of fusion.

METHODS

Plain radiographs were performed preoperatively, immediately postoperatively, and final follow-up. Demographic information was collected on all patients. Baseline patient characteristics were compared using chi-squared analysis and independent sample t tests for categorical and continuous data, respectively. For analysis, patients were divided into 4 groups based on obesity stratification as defined by Center for Disease Control: body mass index (BMI) <25 kg/m² (normal weight), BMI≥25 kg/m² to <30 kg/m² (overweight), ≥30 kg/m² to <35 kg/m² (Class I obesity), BMI≥35 kg/m² to <40 kg/m² (Class II obesity), and BMI≥40 kg/m² (Class III obesity). Additionally, obese (≥30 kg/m²) and nonobese (<30 kg/m²) patients were compared in a separate analysis. Multivariate analysis was used to compare clinical and radiographic outcomes among all BMI classes, as well as between BMI≥30 kg/m² versus BMI<30 kg/m² study groups. Multivariate analyses controlled for differences in baseline patient characteristics and included age, sex, smoking, American Society of Anesthesiologists Physical Status Score, diabetes mellitus, and number of levels.

RESULTS

Of the 399 patients assessed, 97 were identified as normal weight, 157 as overweight, 81 with Class I obesity, 45 with Class II obesity, and 19 with Class III obesity. On multivariate analysis, despite having similar SVA measurements on preoperative radiographs, increase in BMI was associated with increase in postoperative SVA (p=0.041) along with significantly larger SVA in immediate postoperative (p=0.004) and final follow-up radiographs (p=0.003) for patients with BMI≥30 kg/m² versus BMI<30 kg/m². Furthermore, patients with BMI≥30 kg/m² had smaller preoperative (p=0.012), immediate postoperative (p=0.017), and final lordosis (p<0.001) in addition to smaller immediate postoperative (p=0.025) and final fusion segment lordosis (p=0.015) and smaller preoperative (p=0.024) and final distal lordosis (p=0.021) compared with patients with BMI<30 kg/m². Additionally, greater BMI was associated with lower final Visual Analog Scale neck scores (p=0.008). Radiographic early ASD rates were higher in patients BMI≥30 kg/m² versus BMI<30 kg/m² (p=0.028).

CONCLUSIONS

Overall, obese patients who underwent anterior cervical decompression and fusion had similar patient-reported outcomes compared with nonobese patients but had worse radiographic parameters and higher rates of ASD development compared with nonobese patients. This underscores the importance of patient selection and surgical approach for both patient populations.

Risk Factors Associated With Failure to Reach Minimal Clinically Important Difference in Patient-Reported Outcomes Following Anterior Cervical Discectomy and Fusion

Background

The minimum clinically importance difference (MCID) represents a threshold for improvements in patient-reported outcomes (PROs) that patients deem important. No previous study has comprehensively examined risk factors for failure to achieve MCID after anterior cervical discectomy and fusion (ACDF) procedures for radiculopathic symptomatology. The purpose of this study is to determine risk factors for failure to reach MCID for Neck Disability Index (NDI), Visual Analog Scale (VAS) neck pain, and VAS arm pain in patients undergoing 1- or 2-level ACDF procedures.

Methods

A surgical registry of patients who underwent primary, 1- or 2-level ACDF from 2014 to 2016 was reviewed. Rates of MCID achievement for NDI, VAS neck pain, and VAS arm pain at final follow-up were calculated based on published MCID values. Patients were then categorized into demographic and procedural categories. Bivariate regression was used to test for association of demographic and procedural characteristics with failure to reach MCID for each PRO. The final multivariate model including all demographic and procedural categories as controls was created using backward stepwise regression.

Results

Eighty-three, 84, and 77 patients were included in the analysis for VAS neck, VAS arm, and NDI, respectively. Rates of MCID achievement for VAS neck, VAS arm, and NDI were 55.4%, 36.9%, and 76.6%, respectively. On bivariate analysis, patients with Charlson Comorbidity Index (CCI) ≥ 2 were less likely to achieve MCID for NDI than patients with CCI < 2 (P = .025). On multivariate analysis, CCI ≥ 2 (P = .025) was further associated with failure to reach MCID for NDI.

Conclusions

The results of this study suggest that the majority of patients do not reach MCID for arm pain. Additionally, higher comorbidity burden as evidenced by higher CCI scores is a negative predictive factor for the achievement of MCID in neck disability following ACDF.

Level of Evidence

3.

Intersurgeon Cost Variability in Anterior Cervical Discectomy and Fusion

STUDY DESIGN

Retrospective review of prospective patient outcomes and cost data.

OBJECTIVE

To analyze the contribution of surgeon-specific variability in cost and patient-reported outcomes (PROs) to overall variability in anterior cervical discectomy and fusion (ACDF), whereas adjusting for patient comorbidities.

SUMMARY OF BACKGROUND DATA

Cost reduction in surgical care has received increased attention. Patient factors contributing to cost variability in ACDF have been described; however, intersurgeon cost and outcome variability has received less attention in the literature.

METHODS

Adult patients undergoing elective primary ACDF by five different surgeons were analyzed from a prospective registry database. Direct and indirect 90-day costs were compared across each surgeon, along with PROs. Predicted costs were calculated based on patient co-morbidities, and an "observed versus expected" cost differential was measured for each surgeon; this O/E cost ratio was then compared with PROs.

RESULTS

A total of 431 patients were included in the analysis. There were no differences in comorbidities, age, smoking status, or narcotic use. There was significant variation between surgeons in total 90-day costs, as well as variation between each surgeon's observed versus expected cost ratio. Despite these surgeon-specific cost variations, there were no differences in PROs across the participating surgeons.

CONCLUSION

Intersurgeon cost variation in elective ACDF persists even after adjusting for patient comorbidities. There was no apparent correlation between increased surgeon-specific costs and 90-day PROs. These findings show there is opportunity for improvement in inter-surgeon cost variation without compromise in PROs.

LEVEL OF EVIDENCE

3.

Poorer Fusion Outcomes in Diabetic Cervical Spondylotic Myelopathy Patients Undergoing Single-level Anterior Cervical Discectomy and Fusion Does Not Compromise Functional Outcomes and Quality of Life

STUDY DESIGN

Retrospective matched pair cohort study using prospectively collected registry data.

OBJECTIVES

The aim of this study was to determine whether patients with DM have poorer patient-reported outcomes and poorer fusion rates after undergoing a single-level anterior cervical discectomy and fusion (ACDF) for cervical myelopathy.

SUMMARY OF BACKGROUND DATA

ACDF remains the most common procedure in the treatment of cervical spondylotic myelopathy (CSM); however, there is a paucity of literature with regards to patient-reported outcome measures (PROMs), health-related quality-of-life (HRQOL) scores, and fusion rates post-ACDF in diabetic patients with CSM.

METHODS

From 2002 to 2012, 29 diabetic patients were matched with 29 nondiabetic controls. Patient demographics, perioperative data, and validated spine-specific scores including the Numerical Pain Rating Scale on Neck Pain and Upper Limb Pain, American Academy of Orthopaedic Surgeons (AAOS) neck pain and disability scores, AAOS Neurogenic Symptoms Score, Neck Disability Index, Japanese Orthopaedic Association Cervical Myelopathy Score, and Short Form 36 Physical/Mental Component Summaries were recorded. Fusion rates based on Bridwell grading were assessed at 2 years.

RESULTS

After matching, there were no significant preoperative differences in patient demographics, clinical outcomes, PROMs or HRQoL measures between the DM and control group (P > 0.05). There was no difference in either length of hospital stay (P = 0.92) or length of surgery (P = 0.92) between the two groups. At 2 years postoperatively, there were no significant differences between validated spine-specific scores, PROMs, HRQoL scores, satisfaction rates, or fulfilment of expectations between the two groups. Significant poorer Bridwell fusion grades were noted in the DM group at 2 years postoperatively (P < 0.05). Subgroup analysis within the DM group demonstrated that glycated hemoglobin levels had no impact on functional outcomes, fulfilment of expectations, or patient satisfaction at 2 years (P > 0.05).

CONCLUSION

Despite poorer fusion outcomes following single-level ACDF for symptomatic CSM, there was no significant difference in validated spine outcome scores, PROMs, HRQoL measures, or satisfaction levels when compared to nondiabetic controls at short-term follow-up.

LEVEL OF EVIDENCE

3.

Impact of body mass index on surgical outcomes, narcotics consumption, and hospital costs following anterior cervical discectomy and fusion

OBJECTIVE Given the increasing prevalence of obesity, more patients with a high body mass index (BMI) will require surgical treatment for degenerative spinal disease. In previous investigations of lumbar spine pathology, obesity has been associated with worsened postoperative outcomes and increased costs. However, few studies have examined the association between BMI and postoperative outcomes following anterior cervical discectomy and fusion (ACDF) procedures. Thus, the purpose of this study was to compare surgical outcomes, postoperative narcotics consumption, complications, and hospital costs among BMI stratifications for patients who have undergone primary 1- to 2-level ACDF procedures. METHODS The authors retrospectively reviewed a prospectively maintained surgical database of patients who had undergone primary 1- to 2-level ACDF for degenerative spinal pathology between 2008 and 2015. Patients were stratified by BMI as follows: normal weight (< 25.0 kg/m²), overweight (25.0-29.9 kg/m²), obese I (30.0-34.9 kg/m²), or obese II-III (≥ 35.0 kg/m²). Differences in patient demographics and preoperative characteristics were compared across the BMI cohorts using 1-way ANOVA or chi-square analysis. Multivariate linear or Poisson regression with robust error variance was used to determine the presence of an association between BMI category and narcotics utilization, improvement in visual analog scale (VAS) scores, incidence of complications, arthrodesis rates, reoperation rates, and hospital costs. Regression analyses were controlled for preoperative demographic and procedural characteristics. RESULTS Two hundred seventy-seven patients were included in the analysis, of whom 20.9% (n = 58) were normal weight, 37.5% (n = 104) were overweight, 24.9% (n = 69) were obese I, and 16.6% (n = 46) were obese II-III. A higher BMI was associated with an older age (p = 0.049) and increased comorbidity burden (p = 0.001). No differences in sex, smoking status, insurance type, diagnosis, presence of neuropathy, or preoperative VAS pain scores were found among the BMI cohorts (p > 0.05). No significant differences were found among these cohorts as regards operative time, intraoperative blood loss, length of hospital stay, and number of operative levels (p > 0.05). Additionally, no significant differences in postoperative narcotics consumption, VAS score improvement, complication rates, arthrodesis rates, reoperation rates, or total direct costs existed across BMI stratifications (p > 0.05). CONCLUSIONS Patients with a higher BMI demonstrated surgical outcomes, narcotics consumption, and hospital costs comparable to those of patients with a lower BMI. Thus, ACDF procedures are both safe and effective for all patients across the entire BMI spectrum. Patients should be counseled to expect similar rates of postoperative complications and eventual clinical improvement regardless of their BMI.