Obesity Is an Independent Risk Factor of Early Complications After Revision Spine Surgery

Comprehensive guidelines for prehabilitation in spine surgery

Study Design

Literature review.

Objectives

Review prehabilitation techniques used for elective spine surgery to create a comprehensive list of recommendations.

Methods

A systematic review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines by searching three electronic databases from 1997 to 2021. Pertinent literature reporting information on prehabilitation, applicable to spine surgery, was identified. Seventy studies were selected for further analysis. Findings from the literature were reinforced by practices employed by the authors.

Results

Preoperative smoking cessation should be achieved 3-4 weeks before elective spine surgery. Preoperative weight loss programs to reach a goal BMI <35 kg/m2 may be a viable solution to minimize wound complications and surgical site infections. To minimize the negative impact of cardiopulmonary comorbidities, patients can enroll in an exercise program prior to surgery. Patients should abstain from alcohol before elective spine surgery. Patients with osteoporosis may benefit from supplementation with Vitamin D, calcium, and parathyroid hormone. Opioids should be weaned to complete cessation 6-8 weeks before surgery. Preoperative cognitive behavioral therapy (CBT) and education seem to be the most beneficial in reducing complications associated with psychiatric comorbidities. Patients should engage in a comprehensive prehabilitation regimen.

Conclusion

Targeting patient risk factors with personalized interventions can improve postoperative outcomes in patients undergoing elective spine surgery.

The Collective Influence of Social Determinants of Health on Individuals Who Underwent Lumbar Spine Revision Surgeries: A Retrospective Cohort Study

OBJECTIVE

To analyze the collective effect of social determinants of health (SDH) on lumbar spine revision surgery outcomes using a retrospective cohort study design.

METHODS

Data from the Quality Outcomes Database were used, including 7889 adults who received lumbar spine revision surgery and completed 3 and 12 months' follow-up. The SDH of interest included race/ethnicity, educational attainment, employment status, insurance payer, and sex. A stepwise regression model using each number of SDH conditions present (0 of 5, 1 of 5, 2 of 5, ≥3 of 5) was used to assess the collective influence of SDH. The odds of demonstrating a minimum clinically important difference was evaluated in back and leg, disability, quality of life, and patient satisfaction at 3-months and 12-months follow-up.

RESULTS

An additive effect for SDH was found across all outcome variables at 3 and 12 months. Individuals with ≥3 SDH were at the lowest odds of meeting the minimum clinically important difference of each outcome. At 12 months, individuals with ≥3 SDH had a 67%, 65%, 71%, 65%, and 46% decrease in the odds of a clinically meaningful outcome in back and leg pain, disability, quality of life, and patient satisfaction.

CONCLUSIONS

Health care teams should evaluate SDH in individuals who may be considered for lumbar spine revision surgery. Viewing social factors in aggregate may be useful as a screening tool for lumbar spine revision surgeries to identify at risk patients who may require pre-emptive care strategies and postoperative resources to mitigate these risks.

Role of obesity in less radiographic correction and worse health-related quality-of-life outcomes following minimally invasive deformity surgery

OBJECTIVE

Minimally invasive surgery (MIS) for adult spinal deformity (ASD) can offer deformity correction with less tissue manipulation and damage. However, the impact of obesity on clinical outcomes and radiographic correction following MIS for ASD is poorly understood. The goal of this study was to determine the role, if any, that obesity has on radiographic correction and health-related quality-of-life measures in MIS for ASD.

METHODS

Data were collected from a multicenter database of MIS for ASD. This was a retrospective review of a prospectively collected database. Patient inclusion criteria were age ≥ 18 years and coronal Cobb angle ≥ 20°, pelvic incidence-lumbar lordosis mismatch ≥ 10°, or sagittal vertical axis (SVA) > 5 cm. A group of patients with body mass index (BMI) < 30 kg/m2 was the control cohort; BMI ≥ 30 kg/m2 was used to define obesity. Obesity cohorts were categorized into BMI 30-34.99 and BMI ≥ 35. All patients had at least 1 year of follow-up. Preoperative and postoperative health-related quality-of-life measures and radiographic parameters, as well as complications, were compared via statistical analysis.

RESULTS

A total of 106 patients were available for analysis (69 control, 17 in the BMI 30-34.99 group, and 20 in the BMI ≥ 35 group). The average BMI was 25.24 kg/m2 for the control group versus 32.46 kg/m2 (p < 0.001) and 39.5 kg/m2 (p < 0.001) for the obese groups. Preoperatively, the BMI 30-34.99 group had significantly more prior spine surgery (70.6% vs 42%, p = 0.04) and worse preoperative numeric rating scale leg scores (7.71 vs 5.08, p = 0.001). Postoperatively, the BMI 30-34.99 cohort had worse Oswestry Disability Index scores (33.86 vs 23.55, p = 0.028), greater improvement in numeric rating scale leg scores (-4.88 vs -2.71, p = 0.012), and worse SVA (51.34 vs 26.98, p = 0.042) at 1 year postoperatively. Preoperatively, the BMI ≥ 35 cohort had significantly worse frailty (4.5 vs 3.27, p = 0.001), Oswestry Disability Index scores (52.9 vs 44.83, p = 0.017), and T1 pelvic angle (26.82 vs 20.71, p = 0.038). Postoperatively, after controlling for differences in frailty, the BMI ≥ 35 cohort had significantly less improvement in their Scoliosis Research Society-22 outcomes questionnaire scores (0.603 vs 1.05, p = 0.025), higher SVA (64.71 vs 25.33, p = 0.015) and T1 pelvic angle (22.76 vs 15.48, p = 0.029), and less change in maximum Cobb angle (-3.93 vs -10.71, p = 0.034) at 1 year. The BMI 30-34.99 cohort had significantly more infections (11.8% vs 0%, p = 0.004). The BMI ≥ 35 cohort had significantly more implant complications (30% vs 11.8%, p = 0.014) and revision surgery within 90 days (5% vs 1.4%, p = 0.034).

CONCLUSIONS

Obese patients who undergo MIS for ASD have less correction of their deformity, worse quality-of-life outcomes, more implant complications and infections, and an increased rate of revision surgery compared with their nonobese counterparts, although both groups benefit from surgery. Appropriate counseling should be provided to obese patients.

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.

Systemic Complications of Obesity in Operative Acetabular Fractures

OBJECTIVE

To determine the effect of obesity on rates of systemic complications in operatively treated acetabular fractures.

DESIGN

Retrospective Case-Control study.

SETTING

Level 1 Trauma Center.

PATIENTS/PARTICIPANTS

All patients with acetabular fractures managed operatively from January 2015 to December 2019. Patients were divided into groups based on their body mass index (BMI) (normal weight = BMI <25 kg/m2, overweight = BMI 25-30, obese = BMI 30-40, and morbidly obese = BMI >40).

INTERVENTION

Operative management of an acetabular fracture.

MAIN OUTCOME MEASUREMENT

Systemic complications, including mortality, sepsis, pneumonia, acute respiratory distress syndrome, deep vein thrombosis, pulmonary embolism, or venous thrombotic event.

RESULTS

A total of 428 patients were identified. One hundred nine patients (25.4%) were in normal weight, 133 (31.1%) were overweight, 133 (31.1%) were obese, and 53 (12.4%) were morbidly obese. The rate of systemic complications was 17.5%, and overall mortality rate was 0.005%. There were no significant differences between the different BMI groups in all-cause complications or any individual complications. When the morbidly obese group was compared with all other patients, there were also no significant differences in all-cause complications or any individual complications.

CONCLUSION

In conclusion, in this study, there was no association with increasing BMI and inpatient systemic complications after operative management of acetabular fractures. As we continue to refine our understanding of how obesity affects outcomes after acetabular fracture surgery, other indices of obesity might prove more useful in predicting complications. In the obese population, there are well-documented risks of postoperative infections and challenges in obtaining an anatomic reduction, but the fear of postoperative systemic complications should not deter surgeons from undertaking operative management of acetabular fractures in the obese population. Because the prevalence of obesity in trauma patients continues to increase, it is incumbent on us to continue to improve our understanding of optimal treatment for our patients.

LEVEL OF EVIDENCE

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

Burn Outcomes at Extremes of Body Mass Index- Underweight is as problematic as Morbid Obesity

Limited evidence suggests that obesity adversely affects burn outcomes. However, the impacts of body mass index (BMI) across the continuum has not been fully characterized. Therefore, we aimed to characterize outcomes after burn injury across the BMI continuum. We hypothesized that 'normal' BMI (18.5-24.9) would have the lowest mortality and complication rates. The US National Trauma Data Bank (NTDB) was queried for adult burn-injured patients from 2007-2015. Admission BMI was calculated and grouped according to World Health Organization (WHO) classification. The primary outcome was in-hospital mortality. Secondary outcomes of time to wound closure, length of stay (LOS), and inpatient complications were similarly assessed. Of the 116,008 burn patient encounters that were identified, 7,243 underwent at least one operation for wound closure. Mortality was lowest in the overweight (p=0.039) and obese I cohorts (BMI 25-29.9, 30.0-34.9) at 2.9% and increased in both directions of the BMI continuum to 4.1% in the underweight (p=0.032) and 5.1% in the morbidly obese (class III) group (p=0.042). Time to final wound closure was longest in the two BMI extremes. BMI >40 was associated with increased ICU days, ventilator days, renal and cardiac complications. BMI <18.5 had increased hospital days and rates of sepsis. Aberrations in metabolism associated with both increases and decreases of body weight may cause pathophysiologic changes that lead to worsened outcomes in burn-injured patients. In addition to morbidly obese patients, underweight patients also experience increased burn-related death and complications. In contrast, overweight BMI patients may have greater physiologic reserves without the burden of obesity or sarcopenia.

Indications for early revision surgery for material failure in spinal instrumentation: experience at a level 1 center for spinal surgery - a single-center study

Posterior instrumentation is an established treatment for a range of spinal disorders. Material failure is not uncommon, and the indications for a revision are very heterogeneous. This study aimed to evaluate the indications and timing for early revision spinal surgery due to material failure.In this retrospective, single-center cohort study, patients underwent spinal posterior instrumentation between January 2017 and July 2019. They were followed up at 3, 12, and 18 months postoperatively. The time of onset of material failure which led to revision surgery was analyzed. In addition, the relationship between the indications for revision surgery and independent variables was examined using a multivariate logistic regression model.A total of one hundred thirty-five patients were enrolled. Radiolucent zones were found in 30 patients (20%) after 3 months, whereas 48 patients (31%) had radiolucent zones after 12 months. Revision surgery was performed in 13 patients (8.5%). The peak time for revision due to instability was within the first four months of the primary surgery. Multivariate analysis revealed that location, pathology, ASA score, and smoking had no significant impact on the indication for revision surgery, and neither did BMI (P = .042). Non-fusion (P = .007) and radiolucent zones (P = .004), in combination with increased pain (P = .006), were predictors for revision.Our data show that the peak time for early revision of material failure after posterior instrumentation was within the first 4 months of primary surgery. The abnormalities (e.g., radiolucent zones) surrounding the screws without fusion, including persistence of pain, were predictors for revision surgery.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines for Perioperative Spine: Preoperative Surgical Risk Assessment

BACKGROUND

Patient factors (increased body mass index [BMI], smoking, and diabetes) may impact outcomes after spine surgery. There is a lack of consensus regarding which factors should be screened for and potentially modified preoperatively to optimize outcome.

OBJECTIVE

The purpose of this evidence-based clinical practice guideline is to determine if preoperative patient factors of diabetes, smoking, and increased BMI impact surgical outcomes.

METHODS

A systematic review of the literature for studies relevant to spine surgery was performed using the National Library of Medicine PubMed database and the Cochrane Library. Clinical studies evaluating the impact of diabetes or increased BMI with reoperation and/or surgical site infection (SSI) were selected for review. In addition, the impact of preoperative smoking on patients undergoing spinal fusion was reviewed.

RESULTS

A total of 699 articles met inclusion criteria and 64 were included in the systematic review. In patients with diabetes, a preoperative hemoglobin A1c (HbA1c) >7.5 mg/dL is associated with an increased risk of reoperation or infection after spine surgery. The review noted conflicting studies regarding the relationship between increased BMI and SSI or reoperation. Preoperative smoking is associated with increased risk of reoperation (Grade B). There is insufficient evidence that cessation of smoking before spine surgery decreases the risk of reoperation.

CONCLUSION

This evidence-based guideline provides a Grade B recommendation that diabetic individuals undergoing spine surgery should have a preoperative HbA1c test before surgery and should be counseled regarding the increased risk of reoperation or infection if the level is >7.5 mg/dL. There is conflicting evidence that BMI correlates with greater SSI rate or reoperation rate (Grade I). Smoking is associated with increased risk of reoperation (Grade B) in patients undergoing spinal fusion.The full guidelines can be accessed at https://www.cns.org/guidelines/browse-guidelines-detail/2-preoperative-surgical-risk-assessement.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines for Perioperative Spine: Preoperative Pulmonary Evaluation and Optimization

BACKGROUND

There are no current recommendations for preoperative pulmonary evaluation and management of patients undergoing elective spine surgery.

OBJECTIVE

The aim of this guideline is to determine preoperative risk factors for perioperative and postoperative pulmonary adverse events and to determine the optimal preoperative evaluation and management of at-risk patients.

METHODS

A systematic review of the literature was performed using the National Library of Medicine PubMed database and the Cochrane Library for studies relevant to postoperative pulmonary adverse events in patients undergoing spine surgery. Clinical studies evaluating preoperative patient risk factors and preoperative diagnostic and treatment interventions were selected for review.

RESULTS

The literature search yielded 152 abstracts relevant to the PICO (patient/population, intervention, comparison, and outcomes) questions included in this chapter. The task force selected 65 articles for full-text review, and 24 were selected for inclusion in this systematic review. Twenty-three articles addressed preoperative patient risk factors. One article addressed preoperative diagnostic studies of pulmonary function. There were no studies meeting the inclusion criteria for preoperative pulmonary treatment.

CONCLUSION

There is substantial evidence for multiple preoperative patient factors that predict an increased risk of a postoperative pulmonary adverse event. Individuals with these risk factors (functional dependence, advanced age [≥65 yr], chronic obstructive pulmonary disease, congestive heart failure, weight loss, and obstructive sleep apnea) who are undergoing spine surgery should be counseled regarding the potential increased risk of a perioperative and postoperative pulmonary adverse events. There is insufficient evidence to support any specific preoperative diagnostic test for predicting the risk of postoperative pulmonary adverse events or any treatment intervention that reduces risk. It is suggested, however, to consider appropriate preoperative pulmonary diagnostic testing and treatment to address active pulmonary symptoms of existing or suspected disease.The full guidelines can be accessed at https://www.cns.org/guidelines/browse-guidelines-detail/5-preoperative-pulmonary-evaluation-optimization.

Comparison of Plastic Surgeon and Spine Surgeon Closure in Revision Short Segment Thoracolumbar Spinal Fusions

STUDY DESIGN

Retrospective cohort analysis.

OBJECTIVE

To compare outcomes of plastic versus spine surgeon wound closure in revision 1 to 4 level thoracolumbar fusions.

SUMMARY OF BACKGROUND DATA

Plastic surgeons perform layered musculocutaneous flap closures in high-risk spine patients such as revision posterior spinal fusion and complex deformity correction surgeries. Few studies have assessed outcomes of revision fusion performed with plastic surgical closures, particularly in nondeformity thoracolumbar spinal surgery.

METHODS

A retrospective review of 1 to 4 level revision thoracolumbar fusion performed by Orthopedic or Neurosurgical spine surgeons. Patient charts were reviewed for demographics and perioperative outcomes. Patients were divided into two cohorts: wound closures performed by spine surgeons and those closed by plastic surgeons. Outcomes were analyzed before and after propensity score match for prior levels fused, iliac fixation, and levels fused at index surgery. Significance was set at P < 0.05.

RESULTS

Three hundred fifty-seven (87.3%) spine surgeon (SS) and 52 (12.7%) plastic surgeon (PS) closures were identified. PS group had significantly higher number of levels fused at index (PS 2.7 ± 1.0 vs. SS 1.8 ± 0.9, P < 0.001) and at prior surgeries (PS 1.8 ± 1.2 vs. SS 1.0 ± 0.9, P < 0.001), and rate of iliac instrumentation (PS 17.3% vs. SS 2.8%, P < 0.001). Plastics closure was an independent risk factor for length of stay  > 5 days (odds ratio 2.3) and postoperative seroma formation (odds ratio 7.8). After propensity score match, PS had higher rates of seromas (PS 36.5% vs. SS 3.8%, P < 0.001). There were no differences between PS and SS groups in surgical outcomes, perioperative complication, surgical site infection, seroma requiring aspiration, or return to operating room at all time points until follow-up (P > 0.05 for all).

CONCLUSION

Plastic spinal closure for 1 to 4 level revision posterior thoracolumbar fusions had no advantage in reducing wound complications over spine surgeon closure but increased postoperative seroma formation.Level of Evidence: 4.

The influence of modifiable risk factors on short-term postoperative outcomes following cervical spine surgery: A retrospective propensity score matched analysis

BACKGROUND

Modifiable risk factors (MRFs) represent patient variables associated with increased complication rates that may be prevented. There exists a paucity of studies that comprehensively analyze MRF subgroups and their independent association with postoperative complications in patients undergoing cervical spine surgery. Therefore, the purpose of this study is to compare outcomes between patients receiving cervical spine surgery with reported MRFs.

METHODS

Retrospective analysis of the Nationwide Readmissions Database (NRD) from the years 2016 and 2017, a publicly available and purchasable data source, to include adult patients undergoing cervical fusion. MRF cohorts were separated into three categories: substance abuse (alcohol, tobacco/nicotine, opioid abuse); vascular disease (hypertension, dyslipidemia); and dietary factors (malnutrition, obesity). Three-way nearest-neighbor propensity score matching for demographics, hospital, and surgical characteristics was implemented.

FINDINGS

We identified 9601 with dietary MRFs (D-MRF), 9654 with substance abuse MRFs (SA-MRF), and 9503 with vascular MRFs (V-MRF). Those with d-MRFs had significantly higher rates of medical complications (9.3%), surgical complications (8.1%), and higher adjusted hospital costs compared to patients with SA-MRFs and V-MRFs. Patients with d-MRFs (16.3%) and V-MRFs (14.0%) were independently non-routinely discharged at a significantly higher rate compared to patients with SA-MRFs (12.6%) (p<0.0001 and p = 0.0037). However, those with substance abuse had the highest readmission rate and were more commonly readmitted for delayed procedure-related infections.

INTERPRETATION

A large proportion of patients who receive cervical spine surgery have potential MRFs that uniquely influence their postoperative outcomes. A thorough understanding of patient-specific MRF subgroups allows for improved preoperative risk stratification, tailored patient counseling, and postoperative management planning.

FUNDING

None.

Patients with abnormal microarchitecture have an increased risk of early complications after spinal fusion surgery

Spine fusion is one of the most common orthopedic surgeries, with more than 400,000 cases performed annually. While these procedures correct debilitating pain and deformities, complications occur in up to 45%. As successful fusion rests upon early stability of hardware in bone, patients with structural skeletal deficits may be at particular risk for complications. Few studies have investigated this relationship, and none have used higher order imaging to evaluate microstructural mechanisms for complications. Standard DXA measurements are subject to artifact in patients with spinal disease and therefore provide limited information. The goal of this prospective study was to investigate pre-operative bone quality as a risk factor for early post-operative complications using high resolution peripheral QCT (HR-pQCT) measurements of volumetric BMD (vBMD) and microarchitecture. We hypothesized that patients with low vBMD and abnormal microarchitecture at baseline would have more skeletal complications post-operatively. Conversely, we hypothesized that pre-operative DXA measurements would not be predictive of complications. Fifty-four subjects (mean age 63 years, BMI 27 kg/m²) were enrolled pre-operatively and followed for 6 months after multi-level lumbar spine fusion. Skeletal complications occurred in 14 patients. Patients who developed complications were of similar age and BMI to those who did not. Baseline areal BMD and Trabecular Bone Score by DXA did not differ. In contrast, HR-pQCT revealed that patients who developed complications had lower trabecular vBMD, fewer and thinner trabeculae at both the radius and tibia, and thinner tibial cortices. In summary, abnormalities of both trabecular and cortical microarchitecture were associated the development of complications within the first six months following spine fusion surgery. Our results suggest a mechanism for early skeletal complications after fusion. Given the burgeoning number of fusion surgeries, further studies are necessary to investigate strategies that may improve bone quality and lower the risk of post-operative complications.

High Prevalence of Biofilms on Retrieved Implants from Aseptic Pseudarthrosis Cases

INTRODUCTION

Recent literature has associated pseudarthrosis and pedicle screw loosening with subchronic infection at the pedicle of the vertebra. The positive culture results of a previous retrieval analysis show that such patients have a high frequency of bacterial contamination. The objective of this study is to visually capture the architecture of these undiagnosed infections, which have been described in other studies as biofilms on supposedly "aseptic" screw loosening.

METHODS

Explants from 10 consecutive patients undergoing revision spine surgery for pseudarthrosis were collected and fixed in glutaraldehyde solution. Each of these implants was imaged thoroughly by using scanning electron microscopy and x-ray spectroscopy to evaluate the architecture of the biofilm. Additionally, eight patient swabs from tissues around the implants were sent for cultures to assess bacterial infiltration in tissues beyond the biofilm. The implants were also analyzed using energy dispersive x-ray spectroscopy. The exclusion criteria included clinically diagnosed infection (current or previous) and/or mechanical failure of the implant due to falls/accidents.

RESULTS

The study was successful in capturing the visual architecture of the biofilm on retrieved implants. A total of 77% of pseudarthrosis cases presented with loose pedicle screws, which were diagnosed by a preoperative computed tomography scan showing radiolucency along the screw track and were confirmed intraoperatively, and 72% of the cases showed biofilm on explants.

CONCLUSIONS

In the absence of the clinical presentation of infection, impregnated bacteria could form a biofilm around an implant, and this biofilm can remain undetected via contemporary diagnostic methods, including swabbing. Implant biofilm is frequently present in "aseptic" pseudarthrosis cases.

The impact of obesity on perioperative complications in patients undergoing anterior lumbar interbody fusion

OBJECTIVE

Anterior approaches to the lumbar spine provide wide exposure that facilitates placement of large grafts with high fusion rates. There are limited data on the effects of obesity on perioperative complications.

METHODS

Data from consecutive patients undergoing anterior lumbar interbody fusion (ALIF) from 2007 to 2016 at a single academic center were analyzed. The primary outcome was any perioperative complication. Complications were divided into those occurring intraoperatively and those occurring postoperatively. Multivariate logistic regression was used to assess the association of obesity and other variables with these complications. An estimation table was used to identify a body mass index (BMI) threshold associated with increased risk of postoperative complication.

RESULTS

A total of 938 patients were identified, and the mean age was 57 years; 511 were females (54.5%). The mean BMI was 28.7 kg/m2, with 354 (37.7%) patients classified as obese (BMI ≥ 30 kg/m2). Forty patients (4.3%) underwent a lateral transthoracic approach, while the remaining 898 (95.7%) underwent a transabdominal retroperitoneal approach. Among patients undergoing transabdominal retroperitoneal ALIF, complication rates were higher for obese patients than for nonobese patients (37.0% vs 28.7%, p = 0.010), a difference that was driven primarily by postoperative complications (36.1% vs 26.0%, p = 0.001) rather than intraoperative complications (3.2% vs 4.3%, p = 0.416). Obese patients had higher rates of ileus (11.7% vs 7.2%, p = 0.020), wound complications (11.4% vs 3.4%, p < 0.001), and urinary tract infections (UTI) (5.0% vs 2.5%, p = 0.049). In a multivariate model, age, obesity, and number of ALIF levels fused were associated with an increased risk of postoperative complication. An estimation table including 19 candidate cut-points, odds ratios, and adjusted p values found a BMI ≥ 31 kg/m2 to have the highest association with postoperative complication (p = 0.012).

CONCLUSIONS

Obesity is associated with increased postoperative complications in ALIF, including ileus, wound complications, and UTI. ALIF is a safe and effective procedure. However, patients with a BMI ≥ 31 kg/m2 should be counseled on their increased risks and warrant careful preoperative medical optimization and close monitoring in the postoperative setting.

Readmission following complex spine surgery in a prospective cohort of 679 patients - 2-years follow-up using the Spine AdVerse Event Severity (SAVES) system

BACKGROUND CONTEXT

Recent studies suggest that prospective registration more accurately reflects the true incidence of adverse events (AEs). To our knowledge, no previous study has investigated prospectively registered AEs' influence on hospital readmission following spine surgery.

PURPOSE

To determine the frequency and type of unplanned readmissions after complex spine surgery, and to investigate if prospectively registered AEs can predict readmissions.

DESIGN

This is a prospective, consecutive cohort study.

PATIENT SAMPLE

We conducted a single-center study of 679 consecutive patients who underwent complex spine surgery defined as conditions deemed too complicated for surgery at a secondary institute, or patients with severe comorbidities requiring multidisciplinary observation and treatment.

OUTCOME MEASURES

The outcomes in this study were (1) readmission to any hospital department within 30 days of discharge and (2) readmission to a surgical spine center at any time in follow-up.

METHODS

All patients undergoing complex spine surgery, at our tertiary referral center, were consecutively, and prospectively, included from January 1 to December 31, 2013. Demographics and perioperative AEs were registered using the Spine AdVerse Events Severity (SAVES) system. Patients were followed for a minimum of two years. A competing risk survival model was used to estimate rates of readmissions with death as a competing risk. Patient characteristics, surgical parameters and perioperative AEs were analyzed to identify factors associated with readmission. Analyses of 30-day readmission were performed using logistic regression models. A proportional odds model, with death as competing risk, was used for readmissions to a spine center at any time in follow-up. Results were reported as odds ratios with 95% confidence intervals (95% CI).

RESULTS

Within 2 years of index discharge, 443 (65%) were readmitted. Only 20% of readmissions were to a spine center. Cumulative incidence (95% CI) of readmission was estimated to 13% (10%-16%) at 30 days, 26% (23%-30%) at 90 days, 50% (46%-54%) at 1 year, and 59% (55%-63%) at 2 years following discharge. Rates were markedly lower for readmissions to a spine center. Increased odds of 30-day readmission were correlated to intraoperative hypotension (p=.02) and major intraoperative blood loss (p<.01). Readmission to a spine center was associated with the number of instrumented vertebrae (p=.047), major intraoperative AE (p=.01), and intraoperative hypotension (p<.01).

CONCLUSIONS

To the best of our knowledge, this is the first study to analyze prospectively registered AEs' association to readmission up to 2 years after complex spine surgery. We found that readmissions were more frequent than previously reported when including readmissions to any department or hospital. Factors related to major intraoperative blood loss were associated to increased odds of readmission. This should be considered during planning of postoperative observation and care.

Invasiveness has no influence on the rate of incidental durotomies in surgery for multisegmental lumbar spinal canal stenosis (≥ 3 levels) with and without fusion. Analysis from the German Spine Registry data (DWG-Register)

BACKGROUND

Nowadays, perioperative complications as dural tear (DT) with subsequent neurological deficits are documented in independent registers. However, the relationship of these complications with the grade of invasiveness (≥3 levels) is still unclear. We attempted to evaluate perioperative complications, particularly DT with subsequent neurological deficits, between patients undergoing laminotomy and decompression and decompression and fusion in ≥3 levels.

METHODS

Retrospective analysis of the data pool of the DWG register based on cases described by 10 clinics between January 2012 and December 2016 was performed. Surgically treated LSS in ≥3 segments were divided into decompression with or without instrumentation and fusion. Cases with intraoperative DT in both subgroups were analysed for risk factor occurrence. The Surgical Invasive Index (SII) was used.

RESULTS

DT occurred in 102/941 (10.8%) patients. Difference in DT between groups was non- significant. The likelihood of DT increased by 2.12-fold with previous spinal surgery at the same level and by 1.9-fold for BMI 30-34 and >35 in comparison with BMI 26-29, respectively. Postoperative deep wound infection was increased by 2.39-fold after DT than without. Significance in outcomes between patients with/without DT was not found. The invasiveness index explained 48% of the variation in blood loss and 51% of the variation in surgery duration.

CONCLUSIONS

The rate of incidental DT during decompression for LSS with and without fusion in ≥3 levels was associated with BMI and previous surgery at the same spinal level. Invasivness (SII) is valid rather for variables proper to surgery such as bledding and Op-time but no with incidence for DT and subsequent CSF-leackage.

The Role of Potentially Modifiable Factors in a Standard Work Protocol to Decrease Complications in Adult Spinal Deformity Surgery: A Systematic Review, Part 1

STUDY DESIGN

Structured Literature Review.

OBJECTIVES

We sought to evaluate the peer-reviewed literature for potentially modifiable patient and surgical factors that could be incorporated into a Standard Work protocol to decrease complications in adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

Lean Methodology uses Standard Work to improve efficiency and decrease waste and error. ASD is known to have a high surgical complication rate. Several patient and surgical potentially modifiable factors have been suggested to affect complications, including preoperative hemoglobin, bone density, body mass index (BMI), age-appropriate realignment, preoperative albumin/prealbumin, and smoking status. We sought to evaluate the literature for evidence supporting these factors to include in a Standard Work protocol to decrease complications.

METHODS

Each of these six factors was developed into an appropriate clinical question that included the patient population, surgical intervention, a comparison group, and outcomes measure (PICO question). A comprehensive literature search was then performed. The authors reviewed abstracts and analyzed data from included studies. From 456 initial citations with abstract, 173 articles underwent full-text review. The best available evidence for clinical questions regarding the influence of these factors was provided by 93 included studies.

RESULTS

We found fair evidence supporting a low preoperative hemoglobin level associated with increased transfusion rates and decreased BMD and increased BMI associated with increased complication rates. Fair evidence supported low albumin/prealbumin associated with increased complications. There was fair evidence associating smoking exposure to increased reoperations, but conflicting evidence associating it with increased complications. There was no evidence in the literature evaluating age-appropriate realignment and complications.

CONCLUSION

Preoperative hemoglobin, bone density, body mass index, preoperative albumin/prealbumin, and smoking status all are potentially modifiable risk factors that are associated with increased complications in the adult spine surgery population. Developing a Standard Work Protocol for patient evaluation and optimization should include these factors.

LEVEL OF EVIDENCE

Level II.

Suboptimal Age-Adjusted Lumbo-Pelvic Mismatch Predicts Negative Cervical-Thoracic Compensation in Obese Patients

Background

Given the paucity of literature regarding compensatory mechanisms used by obese patients with sagittal malalignment, it is necessary to gain a better understanding of the effects of obesity on compensation after comparing the degree of malalignment to age-adjusted ideals. This study aims to compare baseline alignment of obese and nonobese patients using age-adjusted spino-pelvic alignment parameters, describing associated spinal changes.

Methods

Patients ≥ 18 years with full-body stereoradiographs were propensity-score matched for sex, baseline pelvic incidence (PI), and categorized as nonobese (body mass index < 30kg/m²) or obese (body mass index ≥ 30). Age-adjusted ideals were calculated for sagittal vertical axis, spino-pelvic mismatch (PI-LL), pelvic tilt, and T1 pelvic angle using established formulas. Patients were stratified as meeting alignment ideals, being above ideal, or being below. Spinal alignment parameters included C0-C2, C2-C7, C2-T3, cervical thoracic pelvic angle, cervical sagittal vertical axis SVA, thoracic kyphosis, T1 pelvic angle, T1 slope, sagittal vertical axis, lumbar lordosis (LL), PI, PI-LL, pelvic tilt. Lower-extremity parameters included sacrofemoral angle, knee flexion (KA), ankle flexion (AA), pelvic shift (PS), and global sagittal angle (GSA). Independent t tests compared parameters between cohorts.

Results

Included: 800 obese, 800 nonobese patients. Both groups recruited lower-extremity compensation: sacrofemoral angle (P = .004), KA, AA, PS, GSA (all P < .001). Obese patients meeting age-adjusted PI-LL had greater lower-extremity compensation than nonobese patients: lower sacrofemoral angle (P = .002), higher KA (P = .008), PS (P = .002), and GSA (P = .02). Obese patients with PI-LL mismatch higher than age-adjusted ideal recruited greater lower-extremity compensation than nonobese patients: higher KA, AA, PS, GSA (all P < .001). Obese patients showed compensation through the cervical spine: increased C0-C2, C2-C7, C2-T3, and cervical sagittal vertical axis (all P < .001), high T1 pelvic angle (P < .001), cervical thoracic pelvic angle (P = .03), and T1 slope (P < .001), with increased thoracic kyphosis (P = .015) and decreased LL (P < .001) compared to nonobese patients with PI-LL larger than age-adjusted ideal.

Conclusions

Regardless of malalignment severity, obese patients recruited lower-limb compensation more than nonobese patients. Obese patients with PI-LL mismatch larger than age-adjusted ideal also develop upper-cervical and cervicothoracic compensation for malalignment.

Level of Evidence

III.

Clinical Relevance

Clinical evaluation should extend to the cervical spine in obese patients not meeting age-adjusted sagittal alignment ideals.

Reporting Methodology of Neurosurgical Studies Utilizing the American College of Surgeons-National Surgical Quality Improvement Program Database: A Systematic Review and Critical Appraisal

BACKGROUND

Use of large databases such as the American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) has become increasingly common in neurosurgical research.

OBJECTIVE

To perform a critical appraisal and evaluation of the methodological reporting for studies in neurosurgical literature that utilize the ACS-NSQIP database.

METHODS

We queried Ovid MEDLINE, EMBASE, and PubMed databases for all neurosurgical studies utilizing the ACS-NSQIP. We assessed each study according to number of criteria fulfilled with respect to Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement, REporting of studies Conducted using Observational Routinely-collected Health Data (RECORD) Statement, and Journal of American Medical Association–Surgical Section (JAMA-Surgery) Checklist. A separate analysis was conducted among papers published in core and noncore journals in neurosurgery according to Bradford's law.

RESULTS

A total of 117 studies were included. Median (interquartile range [IQR]) scores for number of fulfilled criteria for STROBE Statement, RECORD Statement, and JAMA-Surgery Checklist were 20 (IQR:19-21), 9 (IQR:8-9), and 6 (IQR:5-6), respectively. For STROBE Statement, RECORD Statement, and JAMA-Surgery Checklist, item 9 (potential sources of bias), item 13 (supplemental information), and item 9 (missing data/sensitivity analysis) had the highest number of studies with no fulfillment among all studies (56, 68, 50%), respectively. When comparing core journals vs noncore journals, no significant difference was found (STROBE, P = .94; RECORD, P = .24; JAMA-Surgery checklist, P = .60).

CONCLUSION

While we observed an overall satisfactory reporting of methodology, most studies lacked mention of potential sources of bias, data cleaning methods, supplemental information, and external validity. Given the pervasive role of national databases and registries for research and health care policy, the surgical community needs to ensure the credibility and quality of such studies that ultimately aim to improve the value of surgical care delivery to patients.

Effect of Obesity on the Development, Management, and Outcomes of Spinal Disorders

Obesity is a major public health issue in the United States, and rates of obesity continue to increase across the population. The association of obesity with degenerative spinal pathology underlies the observation that a substantial number of patients undergoing spine surgery are either overweight or obese. Obesity is a notable independent risk factor for both surgical and medical complications in the perioperative period and an important consideration in preoperative planning, intraoperative strategies, and postoperative management. Despite these increased risks, surgery in obese patients for a variety of degenerative conditions results in improvement in outcomes. Although obese patients may undergo gains that are absolutely lower than their nonobese counterparts, they still experience a positive treatment effect with surgery appropriate for their condition. An evidence-based approach to both preoperative and perioperative management of patients with obesity is not well established. The purpose of this article is to review the effect of obesity on the development, management, and outcomes of patients with spinal disorders and to provide data that may guide an evidence-based approach to care in this expanding patient population.

The degree of invasiveness has no influence on the rate of incidental durotomies in surgery for lumbar spinal canal stenosis: data from the German spine registry

BACKGROUND

Risk factors for incidental durotomies are good documented by some authors who consider the degree of invasiveness as a direct risk factor on this serious complication. We compared the rate of incidental durotomies and its dependence from the degree of invasiveness.

METHODS

The German Spine Registry could document 6016 surgeries for lumbar spinal canal stenosis, N.=2539 microsurgical decompression, and N.=2371 open decompression with stabilization.

RESULTS

Both groups were identical concerning age and sex of patients, mean age: 77.1±1.60; females: 58%; males: 32%. There were 410 incidental durotomies, group 1: 209 (8.23%); group 2: 201 (8.47%). This difference is statistically not relevant (P=0,75). A surgical therapy is documented in 345 (84%) cases, suture with/without fibrin glue: group 1=162 and group 2=183. Fifty-nine patients had a persistent fistula that needed treatment with a lumbar drain, group 1: N.=30; and group 2: N.=29.

CONCLUSIONS

The groups decompression vs. decompression plus fusion are statistically comparable. Although the stabilization with instrumentation is a more invasive procedure with longer operation times, trauma tissue and blood loss - in comparison with microsurgical decompression - showed no difference in the rate of incidental durotomies.

Systematic Changes in the National Surgical Quality Improvement Program Database Over the Years Can Affect Comorbidity Indices Such as the Modified Frailty Index and Modified Charlson Comorbidity Index for Lumbar Fusion Studies

STUDY DESIGN

Retrospective cohort study of prospectively collected data.

OBJECTIVE

The aim of this study was to investigate the influence of changes in the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database over the years on the calculation of the modified Frailty Index (mFI) and the modified Charlson Comorbidity Index (mCCI) for posterior lumbar fusion studies.

SUMMARY OF BACKGROUND DATA

Multiple studies have utilized the mFI and/or mCCI and showed them to be predictors of adverse postoperative outcomes. However, changes in the NSQIP database have resulted in definition changes and/or missing data for many of the variables included in these indices. No studies have assessed the influence of different methods of treating missing values when calculating these indices on such studies.

METHODS

Elective posterior lumbar fusions were identified in NSQIP from 2005 to 2014. The mFI was calculated for each patient using three methods: treating conditions for which data was missing as not present, dropping patients with missing values, and normalizing by dividing the raw score by the number of variables collected. The mCCI was calculated by the first two of these methods. Mean American Society of Anesthesiologists (ASA) scores used for comparison.

RESULTS

In total, 19,755 patients were identified. Mean ASA score increased between 2005 and 2014 from 2.27 to 2.50 (+10.1%). For each of the methods of data handling noted above, mean mFI over the years studied increased by 33.3%, could not be calculated, and increased by 183.3%, respectively. Mean mCCI increased by 31.2% and could not be calculated respectively.

CONCLUSION

Systematic changes in the NSQIP database have resulted in missing data for many of the variables included in the mFI and the mCCI and may affect studies utilizing these indices. These changes can be understood in the context of ASA trends, and raise questions regarding the use of these indices with data available in later NSQIP years.

LEVEL OF EVIDENCE

3.

Incidence of early postoperative complications requiring surgical revision for recurrent lumbar disc herniation after spinal surgery: a retrospective observational study of 9,310 patients from the German Spine Register

Background

The recurrence rate in lumbar disc herniations (LDH) has been reported between 5 and 25%. There are only few data about this phenomenon that occurs within days of the initial operation. We analyse early recurrent LDH by analysis of data from the German Spine register.

Methods

Data from patients undergoing disc herniation surgery in the lumbar region were extracted from the German Spine Registry between 1st January 2012 and 31st December 2016. Patients with early recurrent LDH within days of initial surgery were separately analysed.

Results

A total of 9310 surgeries for LDH were documented in the German Spine Register. From these patients 115 (1.2%) presented an early recurrent disc surgeries within days of the initial surgery. The mean age was 70 ± 2.50 years. Most affected segment was L4/5 (47 cases, 41%), followed by L3/4 (45 cases, 39%). The most of our patients showed a normal or overweight Body Mass Index. Surgery for early recurrent LDH was associated with a high rate of incidental durotomies (20 cases, 17.6%). In 3 cases (2.6%) therapy with a lumbar drain was necessary.

Conclusions

The rate of early recurrent LDH within days of surgery is 1.2%. Age seems to be an important factor in early recurrent LDH while obesity does not. The data of the German Spine Register seems to have a reliable data collection system that can perform multicentre data analysis. The databases from this Register could be used in the future for various purposes, such as the evaluation of multicentre surgical techniques, results in patients with various surgical procedures and basic research in spine surgery.

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

STUDY DESIGN

Retrospective review.

OBJECTIVE

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

SUMMARY OF BACKGROUND DATA

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

3.

Inaccuracies in ICD Coding for Obesity Would Be Expected to Bias Administrative Database Spine Studies Toward Overestimating the Impact of Obesity on Perioperative Adverse Outcomes

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine if International Classification of Diseases (ICD) coding for obesity is biased toward certain subgroups and how potential bias may influence the outcomes of database research in spine.

SUMMARY OF BACKGROUND DATA

There has been increased use of national databases using administrative data in the spine surgery literature. Past research demonstrates that sensitivity of ICD codes for obesity is poor, but it is unknown if such inaccuracies are systematically biased and if they may bias studies utilizing such data.

METHODS

Patients who underwent elective posterior lumbar fusion, 2013 to 2016, at a large academic hospital were identified. All ICD codes assigned to the encounter were obtained. Body mass index (BMI) was calculated based on height and weight. The sensitivity of ICD coding for obesity was calculated. Sensitivity was compared for subgroups defined by demographic, comorbidity, intraoperative, and postoperative factors. The association of obesity (as defined by BMI≥30 and ICD coding) with 30-day postoperative adverse events was tested with multivariate regression.

RESULTS

The study included 796 patients. The overall sensitivity of ICD coding for obesity was 42.5%. The sensitivity of ICD coding for obesity was significantly higher in patients with greater BMI, diabetes, American Society of Anesthesiologists class≥III, increased length of stay, venous thromboembolism, any adverse event, and major adverse event. Multivariate analysis for determining outcomes of increased risk with obesity as defined by ICD coding included venous thromboembolism, major adverse events, and any adverse events. However, multivariate analysis for determining outcomes of increased risk with obesity defined by BMI did not yield any positive associations.

CONCLUSION

ICD codes for obesity are more commonly assigned to patients with other comorbidities or postoperative complications. Further, use of such nonrandomly assigned ICD codes for obesity has the potential to skew studies to suggest greater associated adverse events than calculated BMI would demonstrate.

LEVEL OF EVIDENCE

3.

The temporal expression of adipokines during spinal fusion

BACKGROUND CONTEXT

Adipokines are secreted by white adipose tissue and have been associated with fracture healing. Our goal was to report the temporal expression of adipokines during spinal fusion in an established rabbit model.

PURPOSE

Our goal was to report the temporal expression of adipokines during spinal fusion in an established rabbit model.

STUDY DESIGN

The study design included a laboratory animal model.

METHODS

New Zealand white rabbits were assigned to either sham surgery (n=2), unilateral posterior spinal fusion (n=14), or bilateral posterior spinal fusion (n=14). Rabbits were euthanized 1-6 and 10 weeks out from surgery. Fusion was evaluated by radiographs, manual palpation, and histology. Reverse transcription-polymerase chain reaction on the bone fusion mass catalogued the gene expression of leptin, adiponectin, resistin, and vascular endothelial growth factor (VEGF) at each time point. Results were normalized to the internal control gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (2^ΔCt), and control bone sites (2^ΔΔCt). Quantitative data were analyzed by two-factor analysis of variance (p<.05).

RESULTS

Manual palpation scores, radiograph scores, and histologic findings showed progression of boney fusion over time (p<.0003). The frequency of fusion by palpation after 4 weeks was 68.75%. Leptin expression in decortication and bone graft sites peaked at 5 weeks after the fusion procedure (p=.0143), adiponectin expression was greatest 1 week after surgery (p<.001), VEGF expression peaked at 4 weeks just after initial increases in leptin expression (p<.001), and resistin decreased precipitously 1 week after the fusion procedure (p<.001).

CONCLUSIONS

Leptin expression is likely associated with the maturation phase of bone fusion. Adiponectin and resistin may play a role early on during the fusion process. Our results suggest that leptin expression may be upstream of VEGF expression during spinal fusion, and both appear to play an important role in bone spinal fusion.

Predictors for Patient Discharge Destination After Elective Anterior Cervical Discectomy and Fusion

STUDY DESIGN

Retrospective study of prospectively collected data.

OBJECTIVE

To identify risk factors for nonhome patient discharge after elective anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

ACDF is one of the most performed spinal procedures and this is expected to increase in the coming years. To effectively deal with an increasing patient volume, identifying variables associated with patient discharge destination can expedite placement applications and subsequently reduce hospital length of stay.

METHODS

The 2011 to 2014 ACS-NSQIP database was queried using Current Procedural Terminology (CPT) codes 22551 or 22554. Patients were divided into two cohorts based on discharge destination. Bivariate and multivariate logistic regression analyses were employed to identify predictors for patient discharge destination and extended hospital length of stay.

RESULTS

A total of 14,602 patients met the inclusion criteria for the study of which 498 (3.4%) had nonhome discharge. Multivariate logistic regression found that Hispanic versus Black race/ethnicity (odds ratio, OR =0.21, 0.05-0.91, P =0.037), American Indian or Alaska Native, Asian, Native Hawaiian or Pacific Islander versus Black race/ethnicity (OR = 0.52, 0.34-0.80, p-value = 0.003), White versus Black race/ethnicity (OR = 0.55, 0.42-0.71), elderly age ≥65 years (OR = 3.32, 2.72-4.06), obesity (OR = 0.77, 0.63-0.93, P = 0.008), diabetes (OR = 1.32, 1.06-1.65, P = 0.013), independent versus partially/totally dependent functional status (OR = 0.11, 0.08-0.15), operation time ≥4 hours (OR = 2.46, 1.87-3.25), cardiac comorbidity (OR = 1.38, 1.10-1.72, P = 0.005), and ASA Class ≥3 (OR = 2.57, 2.05-3.20) were predictive factors in patient discharge to a facility other than home. In addition, multivariate logistic regression analysis also found nonhome discharge to be the most predictive variable in prolonged hospital length of stay.

CONCLUSION

Several predictive factors were identified in patient discharge to a facility other than home, many being preoperative variables. Identification of these factors can expedite patient discharge applications and potentially can reduce hospital stay, thereby reducing the risk of hospital acquired conditions and minimizing health care costs.

LEVEL OF EVIDENCE

3.

Nutritional Status as an Adjunct Risk Factor for Early Postoperative Complications Following Posterior Cervical Fusion

STUDY DESIGN

Retrospective study on prospectively collected data.

OBJECTIVE

The aim of this study was to study the impact of nutritional status, as measured by serum albumin level, on patient outcomes following posterior cervical fusion (PCF) surgery.

SUMMARY OF BACKGROUND DATA

Malnutrition is a potential modifiable risk factor that has garnered an increasing amount of attention within orthopedics in recent years. There is evidence to suggest the role of nutritional status in lumbar and ACDF surgery, yet the data for PCF are still lacking.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) was queried by current procedure terminology (CPT) from 2010 to 2014. Bivariate analyses were performed to compare the preoperative characteristics between those with normal albumin and hypoalbuminemia. Postoperative complications and outcomes were similarly analyzed for those with and without low albumin levels. Stepwise multivariate logistic regression models were employed to determine whether hypoalbuminemia was an independent risk factor for short-term patient outcomes and complications.

RESULTS

There were 1573 cases with measured albumin levels (42.4%). The mean (standard deviation) serum albumin level was 3.9 (0.6). Among these patients, 265 (16.8%) cases had hypoalbuminemia. The adjusted analyses demonstrated that patients with hypoalbuminemia had a significantly higher risk for length of stay >5 days (odds ratio [OR] = 3.8; 95% confidence interval [CI] = 2.8-5.1; P < 0.0001). In addition, hypoalbuminemia was an independent risk factor for any complications (OR = 2.7; 95% CI = 1.9-3.7; P < 0.0001), pulmonary complications (OR = 2.3; 95% CI = 1.2-4.5; P = 0.010), intra/postoperative blood transfusions (OR = 3.2; 95% CI = 2.1-4.9; P < 0.0001), sepsis (OR = 4.0; 95% CI = 1.7-9.2; P = 0.001), and venous thromboemoblism (OR = 3.6; 95% CI = 1.5-8.5; P = 0.004).

CONCLUSION

These findings implicate that a baseline serum albumin <3.5 g/dL may serve as a valuable prognostic measure for the development of several complications following PCF surgery.

LEVEL OF EVIDENCE

3.

Predictors of complications and readmission following spinal stereotactic radiosurgery

AIM

to identify preoperative factors associated with morbidity/mortality, hospital length of stay (LOS), 30-day readmission and operation rates following spinal stereotactic radiosurgery (SRS) for spinal tumors.

METHODS

The American College of Surgeons National Quality Improvement Program was queried from 2012 to 2014 to identify patients undergoing SRS for spinal tumors. Logistic regression was performed to identify predictors.

RESULTS

2714 patients were identified; 6.8% had major morbidity or mortality, 6.9% were readmitted within 30 days and 4.3% had a subsequent operation within 30 days. Age, BMI and American Society of Anesthesiologist (ASA) class were predictive of LOS. Major morbidity was predicted by age >80, BMI >35, high ASA, pretreatment functional dependence and baseline comorbidities. Predictors of operation within 30 days included preoperative steroid use, renal failure, BMI >35 and if the treatment was nonelective.

DISCUSSION

4-7% of patients undergoing SRS for spinal tumors have morbidity following the procedure. Factors predictive of morbidity, LOS, and subsequent operation included age, BMI, baseline comorbidities and functional status.

CONCLUSION

Identification of preoperative patient-specific factors that are predictive of post-treatment outcome will aid in patient selection and patient counseling leading to greater patient satisfaction and hospital efficiency.

Hospital-Acquired Conditions in Adult Spinal Deformity Surgery: Predictors for Hospital-Acquired Conditions and Other 30-Day Postoperative Outcomes

STUDY DESIGN

A retrospective study of prospectively collected data.

OBJECTIVE

The aim of this study was to identify risk factors in developing hospital-acquired conditions (HACs) and association of HACs with other 30-day complications in the adult spinal deformity (ASD) population.

SUMMARY OF BACKGROUND DATA

HACs are subject to a nonpayment policy by the Center for Medicare and Medicaid Services and provide an incentive for medical institutions to improve patient safety. HACs in the ASD population may further exacerbate the already high rates of postoperative morbidity and mortality.

METHODS

The 2010 to 2014 ACS-NSQIP database was queried using Current Procedural Terminology (CPT) codes for adults who had fusion for spinal deformity. Patients were divided into two cohorts on the basis of the development of an HAC, as defined as a case of surgical site infection, urinary tract infection, or venous thromboembolism. Univariate and multivariate logistic regression analyses were employed to determine predictors for HACs and association of HACs with other 30-day postoperative outcomes.

RESULTS

Five thousand eight hundred nineteen patients met the inclusion criteria for the study of whom 313 (5.4%) had an HAC. Multivariate logistic regression analysis revealed that age 61 to 70 versus ≤50 years [odds ratio (OR) = 1.58, 1.10-2.27, P = 0.013], 71 to 80 versus ≤50 years (OR = 1.94, 1.31-2.87, P = 0.001), and >80 versus ≤50 years (OR = 2.30, 1.21-4.37, P = 0.011), dependent/partially dependent versus independent functional status (OR = 1.74, 1.13-2.68, P = 0.011), combined versus anterior surgical approach (OR = 2.46, 1.43-4.24, P = 0.001), and posterior versus anterior surgical approach (OR = 1.64, 1.19-2.25, P = 0.002), osteotomies (OR = 1.61, 1.22-2.13, P = 0.001), steroid use (OR = 2.19, 1.39-3.45, P = 0.001), obesity (OR = 1.38, 1.09-1.74, P = 0.007), and operation time ≥4 hours (OR = 2.42, 1.82-3.21, P < 0.001) were predictive factors in developing an HAC.

CONCLUSION

Several modifiable and nonmodifiable factors (age, functional status, surgical approach, utilization of osteotomies, steroid use, obesity, and operation time ≥4 hours) were associated with developing an HAC. HACs were also risk factors for other postoperative complications.

LEVEL OF EVIDENCE

3.

Associations between Obesity and Spinal Diseases: A Medical Expenditure Panel Study Analysis

Background: The link between body weight status and spinal diseases has been suggested by a number of cross-sectional and cohort studies with a limited range of patient populations. No population-representative samples have been used to examine the link between obesity and spinal diseases. The present study is based on a nationally representative sample drawn from the Medical Expenditure Panel Survey. Methods: Using the cross-sectional sample of the 2014 Medical Expenditure Panel Study, we built four weighted logistic regression analyses of the associations between body weight status and the following four spinal diseases: low back pain, spondylosis, other cervical disorders and intervertebral disc disorder (IDD). Each respondent's body weight status was used as the key independent variable with three categories: normal/underweight, overweight, and obese. We controlled for marital status, gender, age, smoking status, household income, health insurance coverage, educational attainment and the use of health services for other major categories of diseases. Results: A total sample of 23,048 respondents was used in our analysis. Overweight and obese respondents, as compared to normal/underweight respondents, were more likely to develop lower back problems (Overweight: logged odds = 0.218, p < 0.01; Obese: logged odds = 0.395, p < 0.001) and IDD (Overweight: logged odds = 0.441, p < 0.05; Obese: logged odds = 0.528, p < 0.001). The associations between bodyweight status and spondylitis were statistically insignificant (Overweight: logged odds = 0.281, p = 0.442; Obese: logged odds = 0.680, p = 0.104). The associations between body weight status and other cervical disorders (Overweight: logged odds = -0.116, p = 0.304; Obese: logged odds = -0.160, p = 0.865) were statistically insignificant. Conclusions: As the first study using a national sample to study bodyweight and spinal diseases, our paper supports the hypothesis that obesity adds to the burden of low back pain and IDD. Longitudinal and interventional studies are needed to understand the specific mechanisms behind these positive associations.

Risk factors for dural tears: a study of elective spine surgery. Neurol Res 2016;39:97-106. [PMID: 27908218 DOI: 10.1080/01616412.2016.1261236]

OBJECTIVE

This study moves beyond previous cohort studies and benchmark data by studying a population of elective spine surgery from a multicenter registry in an effort to validate, disprove, and/or identify novel risk factors for dural tears.

METHODS

A retrospective cohort analysis queried a multicenter registry for patients with degenerative spinal diagnoses undergoing elective spinal surgery from 2010-2014. Multivariable logistic regression analysis interrogated for independent risk factors of dural tears.

RESULTS

Of 104,930 patients, a dural tear requiring repair occurred in 0.6% of cases. On adjusted analysis, the following factors were independently associated with increased likelihood of a dural tear: ankylosing spondylitis vs. intervertebral disc disorders, greater than two levels, combined surgical approach and posterior approach vs. anterior approach, decompression only vs. fusion and decompression, age groups 85+, 75-84 and 65-74 vs. <65, obesity (BMI ≥30), corticosteroid use and preoperative platelet count <150,000.

CONCLUSIONS

This multicenter study identifies novel risk factors for dural tears in the elective spine surgery population, including corticosteroids, thrombocytopenia, and ankylosing spondylitis. The results of this analysis provide further information for surgeons to use both in operative planning and in preoperative counseling when discussing the risk of dural tears.

Thirty-day readmission and reoperation after surgery for spinal tumors: a National Surgical Quality Improvement Program analysis

OBJECTIVE

The goal of this study was to use a large national registry to evaluate the 30-day cumulative incidence and predictors of adverse events, readmissions, and reoperations after surgery for primary and secondary spinal tumors.

METHODS

Data from adult patients who underwent surgery for spinal tumors (2011–2014) were extracted from the prospective National Surgical Quality Improvement Program (NSQIP) registry. Multivariable logistic regression was used to evaluate predictors of reoperation, readmission, and major complications (death, neurological, cardiopulmonary, venous thromboembolism [VTE], surgical site infection [SSI], and sepsis). Variables screened included patient age, sex, tumor location, American Society of Anesthesiologists (ASA) physical classification, preoperative functional status, comorbidities, preoperative laboratory values, case urgency, and operative time. Additional variables that were evaluated when analyzing readmission included complications during the surgical hospitalization, hospital length of stay (LOS), and discharge disposition.

RESULTS

Among the 2207 patients evaluated, 51.4% had extradural tumors, 36.4% had intradural extramedullary tumors, and 12.3% had intramedullary tumors. By spinal level, 20.7% were cervical lesions, 47.4% were thoracic lesions, 29.1% were lumbar lesions, and 2.8% were sacral lesions. Readmission occurred in 10.2% of patients at a median of 18 days (interquartile range [IQR] 12–23 days); the most common reasons for readmission were SSIs (23.7%), systemic infections (17.8%), VTE (12.7%), and CNS complications (11.9%). Predictors of readmission were comorbidities (dyspnea, hypertension, and anemia), disseminated cancer, preoperative steroid use, and an extended hospitalization. Reoperation occurred in 5.3% of patients at a median of 13 days (IQR 8–20 days) postoperatively and was associated with preoperative steroid use and ASA Class 4–5 designation. Major complications occurred in 14.4% of patients: the most common complications and their median time to occurrence were VTE (4.5%) at 9 days (IQR 4–19 days) postoperatively, SSIs (3.6%) at 18 days (IQR 14–25 days), and sepsis (2.9%) at 13 days (IQR 7–21 days). Predictors of major complications included dependent functional status, emergency case status, male sex, comorbidities (dyspnea, bleeding disorders, preoperative systemic inflammatory response syndrome, preoperative leukocytosis), and ASA Class 3–5 designation (p < 0.05). The median hospital LOS was 5 days (IQR 3–9 days), the 30-day mortality rate was 3.3%, and the median time to death was 20 days (IQR 12.5–26 days).

CONCLUSIONS

In this NSQIP analysis, 10.2% of patients undergoing surgery for spinal tumors were readmitted within 30 days, 5.3% underwent a reoperation, and 14.4% experienced a major complication. The most common complications were SSIs, systemic infections, and VTE, which often occurred late (after discharge from the surgical hospitalization). Patients were primarily readmitted for new complications that developed following discharge rather than exacerbation of complications from the surgical hospital stay. The strongest predictors of adverse events were comorbidities, preoperative steroid use, and higher ASA classification. These models can be used by surgeons to risk-stratify patients preoperatively and identify those who may benefit from increased surveillance following hospital discharge.