Understanding the Impact of Obesity on Short-term Outcomes and In-hospital Costs After Instrumented Spinal Fusion

Low Body Mass Index Patients Undergoing an Anterior Lumbar Fusion May Have an Increased Risk of Perioperative Complications

BACKGROUND

Previous research has shown that underweight patients may be at a greater risk of experiencing postsurgical complications. The purpose of this study was to investigate the association between body mass index (BMI) and postoperative complications following single-level anterior lumbar fusion (ALF).

METHODS

All single-level elective ALF procedures performed between 2010 and 2020 were identified in the PearlDiver Mariner Database. Patients were separated into 6 groups based on the World Health Organization BMI classifications. Differences in postsurgical complications (ie, deep vein thrombosis, pulmonary embolism, surgical site infection, hardware malfunction, wound dehiscence, and blood transfusion) among BMI categories were assessed using a χ2 contingency test.

RESULTS

Results indicated that underweight patients (BMI <20) were at a significantly greater risk of developing deep vein thromboses, experiencing hardware malfunction, and requiring blood transfusion compared with any other BMI classification (P < 0.001). Results also demonstrated that underweight individuals had similar risks of developing surgical site infection and wound dehiscence compared with patients classified as having obesity class III.

CONCLUSION

Underweight patients may be at a greater risk than currently believed of experiencing postoperative complications following single-level ALF procedures.

CLINICAL RELEVANCE

Patients with a BMI of 20 or less should be carefully evaluated prior to surgical intervention to ensure they are optimized for surgery.

LEVEL OF EVIDENCE: 3

Risk factors for incisional complications after lumbar internal fixation via posterior midline approach: A case-control study of 455 consecutive cases

To analyse the clinical data of patients who developed incisional complications and those who did not develop incisional complications after lumbar internal fixation, and investigate the risk factors for incisional complications in patients after lumbar internal fixation with posterior midline incision. A standardised data collection form was used to collect the clinical data of patients who were admitted and underwent lumbar internal fixation in our hospital from July 2018 to July 2021. Patients who experienced any one of the incisional complications, such as incision exudates, swelling, blisters, bruising, superficial/deep incisional infections, poor healing and scarring, after surgery were included in the incisional complication group, and patients who did not develop the above-mentioned incisional complications were included in the control group. Univariate logistic regression analysis was first performed to identify potential risk factors, significant factors from univariate analysis were then included in multivariable logistic regression analysis to identify independent risk factors for incisional complications after lumbar spine surgery. Among 455 patients included in the study, postoperative incision complications occurred in 82 patients, with an incidence rate of 18.02%. Multivariate regression analysis identified seven independent risk factors for incisional complications: age, body mass index, preoperative albumin level, hypertension, diabetes mellitus, operation time and local anaesthetic infiltration at the incision site after surgery. Our findings documented that age, body mass index, preoperative albumin level, hypertension, diabetes mellitus, operation time, and postoperative local anaesthetic infiltration at the incision site were risk factors for incisional complications after lumbar internal fixation with posterior median incision. Awareness of these risk factors can enable surgeons to develop a more appropriate perioperative management plan for patients undergoing lumbar internal fixation, thus helping them recover faster.

"Satellite pedicle screws" - A novel technique of pedicle screw insertion in obese patients undergoing lumbar fusion

The presence of thick sub-cutaneous fat and bulky paraspinal musculature mandates extensive surgical dissection in obese patients undergoing open Transforaminal lumbar interbody fusion surgery. Securing a 'converging' pedicle screw trajectory becomes difficult by the counterforces of the erector spinae muscles and thick sub-cutaneous fat in obese patients, especially at the L5-S1 level. We describe the use of a limited standard posterior midline exposure and a separate, far lateral 'satellite' incision to insert pedicle screws in an optimal trajectory in obese patients. Through proper pre-operative planning of the axial and sagittal MRI, the appropriate entry site is determined which is executed intra-operatively to insert pedicle screws freehand. Through a single 1.5 cm incision, both L5-S1 screws were inserted. Fourteen obese patients (mean BMI was 30.5 ± 1.1) received 56 satellite pedicle screws for TLIF at L5-S1 level. The mean age was 48.3 ± 9.7 years. The mean blood loss was 244.8 ± 114 ml and the mean operative time was 126.7 ± 82.8 min. In all patients, the screws were inserted as per pre-operative planning without any difficulties. All wounds healed well without wound complications. There were no screw related complications, and in the antero-posterior and lateral radiographs, there were no screw breaches. Satellite free-hand pedicle screws are safe and easily reproducible. They enable limited dissection of the main surgical wound and well-medialised converging pedicle screws in obese patients.

Impact of body mass index on outcomes after lumbar spine surgery

The impact of body mass index (BMI) on outcomes after lumbar spine surgery is currently unknown. Previous studies have reported conflicting evidence for patients with high BMI, while little research has been conducted on outcomes for underweight patients. This study aims to examine the impact of BMI on outcomes after lumbar spine surgery. This prospective cohort study enrolled 5622 patients; of which, 194, 5027, and 401 were in the low (< 18.5 kg/m²), normal (18.5-30), and high (≥ 30) BMI groups, respectively. Pain was assessed via the numerical pain rating scale (NPRS) for the lower back, buttock, leg, and plantar area. Quality of life was assessed via the EuroQol 5 Dimension (EQ-5D) and Oswestry Disability Index (ODI). Inverse probability weighting with propensity scores was used to adjust patient demographics and clinical characteristics between the groups. After adjustment, the 1-year postoperative scores differed significantly between groups in terms of leg pain. The proportion of patients who achieved a 50% decrease in postoperative NPRS score for leg pain was also significantly different. Obese patients reported less improvement in leg pain after lumbar spine surgery. The outcomes of patients with low BMI were not inferior to those of patients with normal BMI.

Body Mass Index and Risk of Complications After Posterior Lumbar Spine Fusion: A Matched Cohort Analysis Investigating Underweight and Obese Patients

OBJECTIVE

Previous studies have demonstrated that obesity is associated with increased complications after lumbar fusion. However, there are little published data on the effect of being underweight on lumbar fusion outcomes. The purpose of this study was to elucidate the effect of being underweight versus obese on outcomes after lumbar spinal fusion.

METHODS

Lumbar spinal fusion patients were identified through the PearlDiver Mariner database between 2010 and 2020. Study groups were created using International Classification of Diseases codes to identify preoperative body mass index (BMI) category as morbid obesity (BMI > 40), obesity (BMI 30 to 40), normal BMI (BMI 20 to 30), and underweight (BMI < 20) cohorts. Complications that occurred within 1 year postoperatively in this study and matched control groups were then isolated. Statistical analyses were conducted using the Pearson chi square method.

RESULTS

A total of 62,616 patients were identified in this analysis. This included 1,258 underweight patients (4.0%), 17,996 obese patients (57.5%), and 12,054 morbidly obese patients (38.5%). The number of patients to experience any postoperative complication was 766 (60.9%), 9,440 (52.4%), and 6,982 (57.9%) for the underweight, obese, and morbidly obese cohorts, respectively. Underweight patients showed an increased likelihood of complications related to instrumentation (odds ratio [OR] 1.85, P = 0.0237), revision fusion (OR 1.34, P = 0.04061), pulmonary complications (OR 1.43, P < 0.001), and sepsis (OR 1.91, P < 0.001). Obese patients with BMI 30 to 40 showed increased odds of the following complications: hemorrhages and hematomas (OR 1.20, P = 0.02634), surgical site complications (OR 1.27, P < 0.001), thromboembolism (OR 1.78, P < 0.001), and urinary complications (OR 1.08, P < 0.001). Morbidly obese patients with BMI > 40 showed increased odds of all complications analyzed in this study.

CONCLUSION

This investigation indicates that both underweight and obese patients are at elevated risk of complications after lumbar fusion. Similar to obese patients, underweight patients may benefit from preoperative optimization by nutrition counseling to avoid potential complications.

LEVEL OF EVIDENCE

III.

Leveraging machine learning to ascertain the implications of preoperative body mass index on surgical outcomes for 282 patients with preoperative obesity and lumbar spondylolisthesis in the Quality Outcomes Database

OBJECTIVE

Prior studies have revealed that a body mass index (BMI) ≥ 30 is associated with worse outcomes following surgical intervention in grade 1 lumbar spondylolisthesis. Using a machine learning approach, this study aimed to leverage the prospective Quality Outcomes Database (QOD) to identify a BMI threshold for patients undergoing surgical intervention for grade 1 lumbar spondylolisthesis and thus reliably identify optimal surgical candidates among obese patients.

METHODS

Patients with grade 1 lumbar spondylolisthesis and preoperative BMI ≥ 30 from the prospectively collected QOD lumbar spondylolisthesis module were included in this study. A 12-month composite outcome was generated by performing principal components analysis and k-means clustering on four validated measures of surgical outcomes in patients with spondylolisthesis. Random forests were generated to determine the most important preoperative patient characteristics in predicting the composite outcome. Recursive partitioning was used to extract a BMI threshold associated with optimal outcomes.

RESULTS

The average BMI was 35.7, with 282 (46.4%) of the 608 patients from the QOD data set having a BMI ≥ 30. Principal components analysis revealed that the first principal component accounted for 99.2% of the variance in the four outcome measures. Two clusters were identified corresponding to patients with suboptimal outcomes (severe back pain, increased disability, impaired quality of life, and low satisfaction) and to those with optimal outcomes. Recursive partitioning established a BMI threshold of 37.5 after pruning via cross-validation.

CONCLUSIONS

In this multicenter study, the authors found that a BMI ≤ 37.5 was associated with improved patient outcomes following surgical intervention. These findings may help augment predictive analytics to deliver precision medicine and improve prehabilitation strategies.

Clinical Outcomes of Bariatric Surgery Before Spinal Fusion: A Systematic Review

INTRODUCTION

Morbidly obese patients are at increased risk for intraoperative and postoperative complications following spinal fusion. Preoperative weight loss can improve clinical outcomes. The present systematic literature review is aimed to evaluate the hypothesis that bariatric surgery before spinal fusion surgery is associated with higher rates of complications and revisions.

METHODS

Three databases were queried for literature pertaining to bariatric surgery prior to spinal fusion. A 2-author screening process was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Methodologic index for non-randomized studies criteria was used to objectively assess the methodologic quality of the studies reviewed. Retrospective cohort studies in which the patients underwent bariatric surgery were included.

RESULTS

Four retrospective cohort studies consisting of a total of 180,090 patients were included. Length of stay was significantly shorter for the bariatric surgery (BS) group patients than the control (C) groups patients (P = 0.009). There were no significant differences in 1-year mortality rate (P = 1.0), readmission rate (P = 0.86), overall postoperative complications (P = 0.83), and postoperative infections (P = 0.97) between the BS and C groups.

CONCLUSIONS

There were no consistent differences in rates of postoperative complications, infections, hospital readmission, and mortality between obese patients with bariatric surgery prior to spinal fusion and control group patients. The present study does not support the hypothesis that bariatric surgery before spinal fusion contributes to a higher rate of postoperative complications in patients undergoing spinal fusion.

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.

Complications of Spine Surgery in "Super Obese" Patients

STUDY DESIGN

Retrospective chart review with matched control.

OBJECTIVE

To evaluate the indications and complications of spine surgery on super obese patients.

METHODS

A retrospective review assessed super obese patients undergoing spine surgery at a level-1 trauma and spine referral center from 2012 to 2016. Outcomes were compared to age-matched controls with body mass index (BMI) <50 kg/m². The control group was further subdivided into patients with BMI <30 kg/m² (normal) and BMI between 30 and 50 kg/m² (obese).

RESULTS

Sixty-three super obese patients undergoing 86 surgeries were identified. Sixty patients (78 surgeries) were in the control group. Age and number of elective versus nonelective cases were not significantly different. Mean BMI of the super obese group was 55 kg/m² (range 50-77 kg/m²) versus 29 kg/m² in the controls (range 20-49 kg/m²). Fifty-two percent of surgeries were elective, and the most common indication was degenerative disease (39%). Compared with controls, super obese patients had a higher complication rate (30% [n = 19] vs 10% [N = 6], P = .0055) but similar 30-day mortality rate (5% vs 5%), a finding that was upheld when comparing super obese with each of the control group stratifications (BMI 30-50 and BMI <30 kg/m²). The most common complication among super obese patients was wound dehiscence/infection (n = 8, 13%); 2 patients' surgeries were aborted. Complication rates for elective surgery were 21% (n = 7) for super obese patients and 4% (n = 1) for controls (P = .121); complication rates for nonelective procedures were 40% (n = 12) and 14% (n = 5), respectively (P = .023).

CONCLUSION

The complication rate of spine surgery in super obese patients (BMI ≥ 50 kg/m²) is significantly higher than other patients, particularly for nonelective cases.

Impact of Obesity on Complications and Surgical Outcomes of Adult Degenerative Scoliosis with Long- Segment Spinal Fusion

INTRODUCTION

The relationship between obesity and outcome of spine surgery has been controversial. The impact of obesity on surgical outcomes of patients undergoing long- segment (6 vertebrae or more) spinal fusion have not been studied. This study was designed to define the influence of obesity on the outcomes of patients undergoing long-segment spinal fusion.

METHODS AND MATERIALS

A retrospective study of patients undergoing long-segment (6 vertebrae or more) spinal fusion was realized. Patients were divided into non-obese group and obese group. Variables such as blood loss, operative time, length of stay, complications, reoperation rates, and clinical outcome were compared between the two groups.

RESULTS

Thirty-four non-obese patients (BMI: 26.43 ± 0.87) and 27 obese ones (BMI: 35.35 ± 1.81) were recruited. Number of fused levels in non-obese group was not significantly different from obese group (9.06±0.57 vertebrae vs 8.85±0.68 vertebrae, p=0.65). There was no significant difference between non-obese group and obese group in the blood loss during surgery (p= 0.12), the operating time (p=0.46) and the length of hospitalization (p=0.64). Similarly, no significant difference was found in surgical complications (p= 0.76) and medical complications (p=0.82) between the two groups. The rate of ambulatory improvement is similar between non-obese group and obese group (p=0.64).

CONCLUSION

Our study showed that there was no relationship between obesity and adverse surgical outcomes in ADS surgery with long-segment (6 vertebrae or more) spinal fusion.

Obesity in Patients Undergoing Lumbar Degenerative Surgery-A Retrospective Cohort Study of Postoperative Outcomes

STUDY DESIGN

Retrospective cohort studying using a national, administrative database.

OBJECTIVE

The aim of this study was to determine the postoperative complications and quality outcomes of patients with and without obesity undergoing surgical management for lumbar degenerative disease (LDD).

SUMMARY OF BACKGROUND DATA

Obesity is a global epidemic that negatively impacts health outcomes. Characterizing the effect of obesity on LDD surgery is important given the growing elderly obese population.

METHODS

This study identified patients with who underwent surgery for LDD between 2007 and 2016. Patients were stratified based on whether the patient had a concurrent diagnosis of obesity at time of surgery. Propensity score matching (PSM) was then utilized to mitigate intergroup differences between patients with and without obesity. Patients who underwent three or more levels surgical correction, were under the age of 18 years, or those with any previous history of trauma or tumor were excluded from this study. Baseline comorbidities, postoperative complication rates, and reoperation rates were determined.

RESULTS

A total of 67,215 patients underwent primary lumbar degenerative surgery, of which 22,405 (33%) were obese. After propensity score matching, baseline covariates of the two cohorts were similar. The complication rate was 8.3% in the nonobese cohort and 10.4% in the obese cohort (P < 0.0001). Patients with obesity also had longer lengths of stay (2.7 days vs. 2.4 days, P < 0.05), and higher rates of reoperation and readmission at all time-points through the study follow-up period to their nonobese counterparts (P < 0.05). Including payments after discharge, lumbar degenerative surgery in patients with obesity was associated with higher payments throughout the 2-year follow-up period ($68,061 vs. $59,068 P < 0.05).

CONCLUSION

Patients with a diagnosis of obesity at time of LDD surgery are at a higher risk for postoperative complications, reoperation, and readmission.Level of Evidence: 4.

Trends in Weight and Body Mass Index after Spinal Surgery for Degenerative Disease

BACKGROUND

Currently, 37% of adults in the United States are obese, and 34% are overweight. Obesity poses a particularly complex challenge in spinal surgery management, whereby risk of adverse surgical outcomes increases with increased body mass index (BMI). When patients are counseled to reduce weight to levels associated with acceptable surgical risks, patients often respond that their spinal problems prohibit the exercise needed to lose the required weight and counter that surgery will allow for increased activity and thereby facilitate weight loss. A retrospective study of a US Veterans Affairs (USVA) nationwide patient database was undertaken.

METHODS

A request was made of the USVA Corporate Data Warehouse for data on all patients undergoing elective spine surgery for degenerative conditions over a 10-year period.

RESULTS

The mean preoperative age of 65 667 patients identified was 59 years. The mean preoperative weight was 91.8 kg, and BMI was 29.2. Before surgery, 26 772 patients had a BMI of >30. After surgery, 12 564 (46.9%) lost at least 2.3 kg, 9450 (35.3%) gained at least 2.3 kg, and 4758 (17.8%) were unchanged. After surgery, 4853 (18.1%) lost at least 11.3 kg and 1360 (5.1%) lost at least 22.7 kg. At a mean of 1.9 years after index surgery, mean postoperative weight was 92.5 kg, and BMI was 29.4. Of the 65 667 patients, 23 125 (35.2%) patients lost at least 2.3 kg, 27 571 (42.0%) gained at least 2.3 kg, and 14 971 (23.0%) remained within 2.3 kg of their preoperative weight.

CONCLUSION

The study results will aid in counseling patients regarding realistic expectations about weight loss after spinal surgery.

LEVEL OF EVIDENCE

4.

CLINICAL RELEVANCE

This evidence will allow for realistic patient counseling regarding the likelihood of weight loss after elective spinal surgery.

Minimally invasive posterior lumbar surgery in the morbidly obese, obese and non-obese populations: A single institution retrospective review

BACKGROUND

There is a paucity of information regarding outcomes in minimally invasive surgical (MIS) approaches to posterior lumbar surgery in morbidly obese patients. We seek to determine if there are differences in operative variables and early complication rates in morbidly obese patients undergoing MIS posterior lumbar surgery compared to obese and non-obese patients.

METHODS

A single institution retrospective review of patients undergoing MIS posterior lumbar surgery (decompression and/or fusion) between 2013 and 2016 was performed. Morbidly obese patients (BMI ≥ 40) were compared to obese (BMI 30-39.9) and non-obese (BMI < 30) cohorts. Postoperative complication rates and perioperative variables including estimated blood loss, operative time, and outcome measures including length of stay (LOS), in-hospital complications, readmission, and disposition were assessed.

RESULTS

47 morbidly obese, 135 obese and 224 non-obese patients underwent posterior MIS instrumented fusion. 59 morbidly obese, 182 obese and 314 non-obese patients underwent posterior MIS decompression. The morbidly obese group experienced a greater rate of deep vein thrombosis and had an increased hospital LOS (p < 0.05). Morbidly obese patients who underwent MIS decompression experienced increased postoperative complications (p < 0.01), and increased LOS (p < 0.0001) compared to obese and non-obese patients. There were no differences in revision rates, readmissions, and other complications including surgical site infection. Morbid obesity was an independent predictor of overall complications and increased LOS on multivariate analysis.

CONCLUSION

Morbidly obese patients undergoing posterior MIS fusion had a higher rate of complications and increased LOS. While weight loss should be encouraged, complication rates remains acceptably low in morbidly obese patients and MIS posterior lumbar surgery should still be offered.

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.

Independent Association of Obesity and Nonroutine Discharge Disposition After Elective Anterior Cervical Discectomy and Fusion for Cervical Spondylotic Myelopathy

OBJECTIVE

The prevalence of obesity continues to rise in the United States at a disparaging rate. Although previous studies have attempted to identify the influence obesity has on short-term outcomes following elective spine surgery, few studies have assessed the impact on discharge disposition following anterior cervical discectomy and fusion (ACDF) for cervical spondylotic myelopathy (CSM). The aim of this study was to determine whether obesity impacts the hospital management, cost, and discharge disposition after elective ACDF for adult CSM.

METHODS

The National Inpatient Sample database was queried using the International Classification of Diseases, 10th revision, Clinical Modification, coding system to identify all (≥18 years) patients with a primary diagnosis of CSM undergoing an elective ACDF for the years 2016 and 2017. Discharge weights were used to estimate national demographics, Elixhauser comorbidities, complications, length of stay, total cost of admission, and discharge disposition.

RESULTS

There were 17,385 patients included in the study, of whom 3035 (17.4%) had obesity (no obesity: 14,350; obesity: 3035). The cohort with obesity had a significantly greater proportion of patients with 3 or more comorbidities compared with the cohort with no obesity (no obesity: 28.1% vs. obesity: 43.5%, P < 0.001). The overall complication rates were greater in the cohort with obesity (no obesity: 10.3% vs. obesity: 14.3%, P = 0.003). On average, the cohort with obesity incurred a total cost of admission $1154 greater than the cost of the cohort with no obesity (no obesity: $19,732 ± 11,605 vs. obesity: $20,886 ± 10,883, P = 0.034) and a significantly greater proportion of nonroutine discharges (no obesity: 16.6% vs. obesity: 24.2%, P < 0.001). In multivariate regression analysis, obesity, age, race, health care coverage, hospital bed size, region, comorbidity, and complication rates all were independently associated with nonroutine discharge disposition.

CONCLUSIONS

Our study demonstrates that obesity is an independent predictor for nonroutine discharge disposition following elective anterior cervical discectomy and fusion for cervical spondylotic myelopathy.

Predicting High-Value Care Outcomes After Surgery for Skull Base Meningiomas

BACKGROUND

Although various predictors of adverse postoperative outcomes among patients with meningioma have been established, research has yet to develop a method for consolidating these findings to allow for predictions of adverse health care outcomes for patients diagnosed with skull base meningiomas. The objective of the present study was to develop 3 predictive algorithms that can be used to estimate an individual patient's probability of extended length of stay (LOS) in hospital, experiencing a nonroutine discharge disposition, or incurring high hospital charges after surgical resection of a skull base meningioma.

METHODS

The present study used data from patients who underwent surgical resection for skull base meningiomas at a single academic institution between 2017 and 2019. Multivariate logistic regression analysis was used to predict extended LOS, nonroutine discharge, and high hospital charges, and 2000 bootstrapped samples were used to calculate an optimism-corrected C-statistic. The Hosmer-Lemeshow test was used to assess model calibration, and P < 0.05 was considered statistically significant.

RESULTS

A total of 245 patients were included in our analysis. Our cohort was mostly female (77.6%) and white (62.4%). Our models predicting extended LOS, nonroutine discharge, and high hospital charges had optimism-corrected C-statistics of 0.768, 0.784, and 0.783, respectively. All models showed adequate calibration (P>0.05), and were deployed via an open-access, online calculator: https://neurooncsurgery3.shinyapps.io/high_value_skull_base_calc/.

CONCLUSIONS

After external validation, our predictive models have the potential to aid clinicians in providing patients with individualized risk estimation for health care outcomes after meningioma surgery.

Influence of dynamic preoperative body mass index changes on patient-reported outcomes after surgery for degenerative lumbar spine disease

Psychological factors demonstrably and often massively influence outcomes of degenerative spine surgery, and one could hypothesize that preoperative weight loss may correlate with motivation and lifestyle adjustment, thus leading to potentially enhanced outcomes. We aimed to evaluate the effect of preoperative weight loss or gain, respectively, on patient-reported outcomes after lumbar spine surgery. Weight loss was defined as a BMI decrease of ≤ − 0.5 kg/m² over a period of at least 1 month, and weight gain as a BMI increase of ≥ 0.5 kg/m² in the same time period, respectively. The primary endpoint was set as the achievement of the minimum clinically important difference (MCID) in the ODI at 1 or 2 years postoperatively. A total of 154 patients were included. Weight loss (odds ratio (OR): 1.18, 95% confidence interval (CI): 0.52 to 2.80) and weight gain (OR: 1.03, 95% CI: 0.43 to 2.55) showed no significant influence on MCID achievement for ODI compared to a stable BMI. The same results were observed when analysing long-term NRS-BP and NRS-LP. Regression analysis showed no correlation between BMI change and PROM change scores for any of the three PROMs. Adjustment for age and gender did not alter results. Our findings suggest that both preoperative weight loss and weight gain may have no measurable effect on long-term postoperative outcome compared to a stable BMI. Weight loss preoperatively—as a potential surrogate sign of patient motivation and lifestyle change—may thus not influence postoperative outcomes.

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.

Complexities of spine surgery in obese patient populations: a narrative review

The obese population is particularly challenging to the spine surgeon in all phases of care. A narrative literature review was performed to review difficulties in spine surgery on the obese patient population and techniques for mitigation. We specifically aimed to assess several topics with regard to this population: patient selection and preoperative care; intraoperative and surgical techniques; and postoperative care, outcomes, and complications. The literature review demonstrated that obese patients are at increased surgical risk with spine surgery due to a variety of factors at all stages of intervention. Preoperatively, obese patients have worse outcomes with physical therapy and present technical difficulties for injections. Transport to a hospital, imaging, resuscitation, and intubation are all challenged by increased body habitus. Intraoperatively, obese patients have increased operative times, blood loss, surgical site infections, and nerve palsies. Patient positioning and intraoperative imaging may be limited. Surgery itself may be technically challenging due to body habitus and minimally invasive techniques are becoming more prevalent in this population. Postoperatively, several studies demonstrate that obese patients have inferior outcomes compared with nonobese counterparts. Patient selection is a key for elective interventions, and appropriate infrastructure aids in the ultimate outcomes for both elective and nonelective surgical treatments. Overall, obese patients present several challenges to the spine surgeon, and certain precautions can be undertaken preoperatively, intraoperatively, and postoperatively to mitigate the associated risks to optimize outcomes.

Rapid Bodyweight Reduction before Lumbar Fusion Surgery Increased Postoperative Complications

Study Design

Retrospective cohort study.

Purpose

To determine the effects of massive weight loss on perioperative complications after lumbar fusion surgery (LFS).

Overview of Literature

Patients who are obese are more likely to experience low back pain, which would require LFS. Nonetheless, they have a higher risk of perioperative complication development compared with individuals who are not obese.

Methods

Patients who underwent LFS at hospitals that participated in the National Surgical Quality Improvement Program database within the United States between 2005 and 2015. Outcomes included 30-day medical complications, surgical complications, and length of stay (LOS). We analyzed a total of 39,742 patients with the use of the International Classification of Disease, ninth revision codes. The patients were categorized in the following two groups: group 1, individuals with a history of massive weight loss within 6 months before LFS, and group 2, individuals without a history of massive weight loss before surgery. Massive weight loss was defined as loss of 10% of total body weight. Patients with a history of malignancy or chronic disease were excluded from the study. Patients in each group were randomly matched based on age, gender, sex, smoking status, and body mass index. Paired two-tailed Student t-tests were used to compare the outcomes.

Results

Of the 39,742 patients identified, 129 (0.32%) met the criteria for inclusion in the weight loss group (WL group) and were successfully matched to individuals in the non-weight loss group (non-WL group). Compared with the non-WL group, the WL group had a significantly longer LOS (9.7 vs. 4.0 days, p<0.05), higher surgical site infections (SSIs) (8.0 vs. 3.0, p<0.05), increased number of blood transfusions (40.0 vs. 20.0, p<0.05), and greater deep vein thrombosis (DVTs) (5.0 and 0.00, p<0.05).

Conclusions

On a nationwide scale, rapid weight loss before LFS is associated with a higher rate of postoperative complications, including SSI and DVTs, longer average LOS, and more frequent blood transfusions.

Dose-Response Meta-Analysis of the Impact of Body Mass Index on Mortality in the Intensive Care Unit

INTRODUCTION

Both low and high body mass index (BMI) are associated with mortality in the intensive care unit (ICU). Although many studies have been done to determine the relationship between BMI and risk of mortality in the ICU, their results were inconsistent. This study aimed to conduct a dose-response meta-analysis of published observational studies to assess the effect of BMI on the risk of mortality in patients admitted to the ICU.

METHODS

PubMed, Scopus, and Google Scholar were searched to identify articles up to May 2019. A total of 31 relevant articles, with 238,961 patients and a follow-up period of 1 month to 11 years, were analyzed.

RESULTS

Linear analysis showed a 0.6% decrease in mortality rate per unit (kg/m² ) increase in BMI (odds ratio: 0.99; 95% CI, 0.98-0.99). In addition, nonlinear analysis showed a decrease in risk of mortality for a BMI of 35 (P < .001) and then increased the risk of mortality with a BMI > 35 (P < .001).

CONCLUSION

This dose-response meta-analysis revealed that a BMI ≤ 35 can be a protective agent against mortality, but a BMI > 35 is a life-threatening factor in patients admitted to the ICU.

Anterior lumbar interbody fusion in a lateral decubitus position: technique and outcomes in obese patients

Background

Multilevel lumbar interbody fusion (LIF) surgery in obese patients is problematic, with positioning and anaesthetic risks during posterior approaches, vascular and visceral complications during anterior approaches, and lack of access to L5/S1 during lateral approaches. Modified anterior LIF (ALIF) via an anterolateral retroperitoneal approach in the lateral decubitus position permits access to L3/4, L4/5, and L5/S1 levels without patient repositioning. This study reports our initial experience with this lateral ALIF in obese patients and describes modifications of existing lateral and anterior techniques.

Methods

We retrospectively analysed a prospectively maintained registry including the first 30 consecutive patients who underwent lateral ALIF. In all patients, supine ALIF was relatively contraindicated because of obesity or previous abdominal surgery. All patients had a body mass index (BMI) ≥30 kg/m². Fusion was assessed by high-definition computed tomography. Patient-reported outcomes included visual analogue scale pain scores, Oswestry Disability Index (ODI), and 36-Item Short-Form Survey (SF-36) physical and mental component scores (PCS and MCS). All patients underwent ≥2 years follow-up.

Results

At last follow-up (mean, 35.0 months) mean back pain improved 64%, leg pain improved 67%, ODI improved 54%, and PCS and MCS both improved 37% (P<0.05 versus preoperative for all). Mean BMI was unchanged postoperatively (P=0.83). Complications occurred in 7 (23%) patients: dysesthesia [2], retroperitoneal hematoma [2], radiculopathy [1], and subsidence [2]. Solid interbody fusion occurred in 19 (63%) patients at 12 months postoperatively and in 26 (87%) patients at 24 months.

Conclusions

Lateral ALIF enables L5/S1 anterior fusion in obese patients and permits multilevel fusion using a single position. Satisfactory clinical outcomes and complication rates are achieved despite unchanged BMI and 87% radiological fusion rates. Lateral ALIF appears to be a reasonable alternative to posterior, lateral, and supine-position anterior approaches for L3/4, L4/5, and L5/S1 interbody fusions.

The Use of Patient-Reported Outcome Measurement Information System Physical Function to Predict Outcomes Based on Body Mass Index Following Minimally Invasive Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

Retrospective.

OBJECTIVE

To determine clinical outcomes in obese patients compared with non-obese patients utilizing Patient-Reported Outcome Measurement Information System Physical Function (PROMIS PF) following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).

SUMMARY OF BACKGROUND DATA

Although obesity is a risk factor for poor outcomes after spinal fusion, there has not been a study to evaluate clinical outcomes of obese patients utilizing the PROMIS PF survey.

METHODS

Patients undergoing MIS TLIF were stratified into three cohorts: non-obese (body mass index [BMI] ≤ 29.9 kg/m), obese I (BMI = 30.0-34.9 kg/m), and obese II-III (BMI ≥ 35.0 kg/m). Demographic and perioperative characteristics were compared using chi-squared analysis and linear regression. Change in PROMIS PF scores was calculated using paired t tests. Differences in PROMIS PF scores at each postoperative timepoint and changes in PROMIS PF from baseline were compared using linear regression.

RESULTS

One hundred eighty-six patients were included: 101 were non-obese, 41 were classified as obese I, and 44 were classified as obese II-III. Obese patients were more likely to be diabetic. Otherwise, no significant differences in demographic and perioperative characteristics were identified. Patients with higher BMIs reported significantly lower PROMIS PF scores at preoperative and all postoperative timepoints. However, patients experienced similar improvements through 6-month follow-up in PROMIS PF scores regardless of BMI. For the non-obese cohort, the change in the postoperative PROMIS PF score from baseline was significant at every postoperative timepoint. However, for the obese I and obese II-III cohorts, the change in the PROMIS PF score from baseline was significant at the 3-month and 6-month timepoints, but not at the 6-week timepoint.

CONCLUSION

Patients with higher BMI had lower preoperative PROMIS PF scores and experienced similar improvement in PROMIS PF scores in the postoperative period. This study established that PROMIS PF may be utilized to evaluate the recovery of obese patients following MIS TLIF.

LEVEL OF EVIDENCE

3.

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.

Thoracolumbar Fusion in Extreme Obesity: Complications and Patient-Reported Outcomes

Background

Extreme obesity (class III) is defined by the Centers for Disease Control as a body mass index (BMI) value ≥40. Recent studies suggest that obese patients have poor outcomes after thoracolumbar spinal fusions. The objective of this study was to analyze 30-day adverse events and patient-reported outcomes (PROs) for this population.

Patients and Methods

A retrospective chart review of spinal fusion surgeries performed at a single institution from 2006 to 2016 was executed. All patients had a preoperative BMI ≥40. Patient characteristics, including age, sex, BMI, American Society of Anesthesiologists (ASA) score, Charlson Comorbidity Index (CCI), and others, were collected. Thirty-day adverse events (complications, readmissions, reoperations, and mortality) and PROs (Oswestry Disability Index [ODI] and visual analog scale [VAS]) were recorded.

Results

Fifty-six patients were identified, including 30 men (54%). Mean age was 55.7 years (range, 31-74 years). Mean BMI was 44.2 (range, 40.0-54.7). Mean ASA was 2.7 (range, 2-3), and mean CCI was 1.1 (range, 0-6). Mean number of fused levels was 2.3 (range, 1-14). Mean length of stay was 4.4 ± 2.1 days. Mean number of complications was 0.7 ± 1.1, with 30.4% of patients having had at least 1 complication. The 30-day all-cause readmission rate was 5.4%, and 30-day reoperation rate was 3.6%. For 30 patients (54%) with 1-year PROs, mean preoperative ODI was 65.2 ± 11.1, and mean preoperative VAS was 6.6 ± 1.6. Mean ODI change was -19.9 ± 20.1 (P < .001), and mean VAS change was -2.6 ± 2.3 (P < .001). A total of 15 patients (50%) achieved the minimum clinically important difference in ODI (12.8), with a mean follow-up of 18.9 months.

Conclusions

Patients with extreme obesity who undergo thoracolumbar fusion have acceptable 30-day adverse events and potentially can achieve significant improvement in pain and disability.

Obese Patients Benefit, but do not Fare as Well as Nonobese Patients, Following Lumbar Spondylolisthesis Surgery: An Analysis of the Quality Outcomes Database

BACKGROUND

Given recent differing findings following 2 randomized clinical trials on degenerative lumbar spondylolisthesis (DLS) surgery, there is a need to better define how subsets of patients fare following surgery.

OBJECTIVE

To investigate the impact of obesity on patient-reported outcomes (PROs) following DLS surgery.

METHODS

A total of 12 high-enrolling sites were queried, and we found 797 patients undergoing surgery for grade 1 DLS. For univariate comparisons, patients were stratified by BMI ≥ 30 kg/m2 (obese) and &lt; 30 kg/m2 (nonobese). Baseline, 3-mo, and 12-mo follow-up parameters were collected. PROs included the North American Spine Society satisfaction questionnaire, numeric rating scale (NRS) back pain, NRS leg pain, Oswestry Disability Index (ODI), and EuroQoL-5D (EQ-5D) Questionnaire.

RESULTS

We identified 382 obese (47.9%) and 415 nonobese patients (52.1%). At baseline, obese patients had worse NRS back pain, NRS leg pain, ODI, and EQ-5D scores (P &lt; .001, P = .01, P &lt; .001, and P = .02, respectively). Both cohorts improved significantly for back and leg pain, ODI, and EQ-5D at 12 mo (P &lt; .001). At 12 mo, similar proportions of obese and nonobese patients responded that surgery met their expectations (62.6% vs 67.4%, P = .24). In multivariate analyses, BMI was independently associated with worse NRS leg pain and EQ-5D at 12 mo (P = .01 and P &lt; .01, respectively) despite adjusting for baseline differences.

CONCLUSION

Obesity is associated with inferior leg pain and quality of life—but similar back pain, disability, and satisfaction—12 mo postoperatively. However, obese patients achieve significant improvements in all PRO metrics at 12 mo.

Body mass index predicts risk of complications in lumbar spine surgery based on surgical invasiveness

BACKGROUND CONTEXT

Obesity as a comorbidity in spine pathology may increase the risk of complications following surgical treatment. The body mass index (BMI) threshold at which obesity becomes clinically relevant, and the exact nature of that effect, remains poorly understood.

PURPOSE

Identify the BMI that independently predicts risk of postoperative complications following lumbar spine surgery.

STUDY DESIGN/SETTING

Retrospective review of the National Surgery Quality Improvement Program (NSQIP) years 2011-2013.

PATIENT SAMPLE

A total of 31,763 patients were undergoing arthrodesis, discectomy, laminectomy, laminoplasty, corpectomy, or osteotomy of the lumbar spine.

OUTCOME MEASURES

Complication rates.

METHODS

The patient sample was categorized preoperatively by BMI according to the World Health Organization stratification: underweight (BMI <18.5), normal overweight (BMI 20.0-29.9), obesity class 1 (BMI 30.0-34.9), 2 (BMI 35.0-39.9), and 3 (BMI≥40). Patients were dichotomized based on their position above or below the 75th surgical invasiveness index (SII) percentile cutoff into low-SII and high-SII. Differences in complication rates in BMI groups were analyzed by Bonferroni analysis of variance (ANOVA) method. Multivariate binary logistic regression evaluated relationship between BMI and complication categories in all patients and in high-SII and low-SII surgeries.

RESULTS

Controlling for baseline difference in SII, Charlson Comorbidity Index (CCI) score, diabetes, hypertension, and smoking, complications significantly increased at a BMI of 35 kg/m². The odds ratios for any complication (odds ratio [OR] [95% confidence interval {CI}]; obesity 2: 1.218 [1.020-1.455]; obesity 3: 1.742 [1.439-2.110]), infection (obesity 2: 1.335 [1.110-1.605]; obesity 3: 1.685 [1.372-2.069]), and surgical complication (obesity 2: 1.622 [1.250-2.104]; obesity 3: 2.798 [2.154-3.634]) were significantly higher in obesity classes 2 and 3 relative to the normal-overweight cohort (all p<.05).

CONCLUSION

There is a significant increase in complications, specifically infection and surgical complications, in patients with BMI≥35 following lumbar spine surgery, with that rate further increasing with BMI≥40.

Risk Factors for Readmissions Following Anterior Lumbar Interbody Fusion

STUDY DESIGN

Retrospective study of prospectively collected data.

OBJECTIVE

To analyze the incidence and risk factors for readmissions following anterior lumbar interbody fusion.

SUMMARY OF BACKGROUND DATA

No study has yet reported readmission rates for a specific lumbar surgical approach. There is evidence to indicate differences in perioperative complication rates between anterior versus posterior lumbar interbody fusion techniques, which may translate into differences in readmission rates.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program is a large multicenter clinical registry that prospectively collects preoperative risk factors, intraoperative variables, and 30-day postoperative morbidity and mortality outcomes from about 400 hospitals nationwide. Current Procedural Terminology codes were used to query the database for adults who underwent anterior lumbar interbody fusion. Patients were separated into groups of those with and without 30-day readmissions. Univariate analysis and multivariate logistic regression were used to analyze the effect of different risk factors on 30-day readmissions.

RESULTS

Multivariate analysis showed that morbid obesity (odds ratio 15.6, P = 0.002) and alcohol use (odds ratio 16.9, P = 0.004) independently predicted unplanned 30-day readmission. Sex, pulmonary comorbidity, cardiac comorbidity, and steroid use were not found to be significant independent predictors of unplanned 30-day readmission in anterior lumbar interbody fusion.

CONCLUSION

Adult patients undergoing anterior lumbar interbody fusion who were morbidly obese and had history of alcohol use are at increased risk for 30-day readmissions. Future studies should look to directly compare readmission rates and risk factors between alternative lumbar interbody surgical approaches with longer follow-up and more clinical and radiological parameters investigated.

LEVEL OF EVIDENCE

3.

Is Body Mass Index a Risk Factor for Revision Procedures After Minimally Invasive Transforaminal Lumbar Interbody Fusion?

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine if an association exists between body mass index (BMI) and the rate of revision surgery after single-level minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).

SUMMARY OF BACKGROUND DATA

MIS TLIF is an effective treatment for lumbar degenerative disease. Previous studies in the orthopedic literature have associated increased BMI with increased postoperative complications and need for revision. Few studies have evaluated the association between BMI and the risk for revision after minimally invasive spinal procedures.

MATERIALS AND METHODS

A surgical registry of patients who underwent a single-level MIS TLIF for degenerative pathology between 2005 and 2014 was reviewed. Patients were stratified based on BMI category: normal weight (BMI<25), overweight (BMI, 25-29.9), obese I (BMI, 30-34.9), and obese II-III (BMI≥35). BMI category was tested for association with demographic and procedural characteristics using 1-way analysis of variance (ANOVA) for continuous variables, and χ analysis or the Fisher exact test for categorical variables. BMI category was tested for association with undergoing a revision fusion procedure within 2 years after MIS TLIF using multivariate Cox proportional hazards survival analysis modeling.

RESULTS

In total, 274 patients were analyzed; of these, 52 (18.98%) were normal weight, 101 (36.86%) were overweight, 62 (22.63%) were obese I, and 59 (21.53%) were obese II-III. On multivariate Cox proportional hazards survival analysis modeling, BMI category was not associated with undergoing a revision procedure within 2 years after MIS TLIF (P=0.599). On multivariate analysis, younger age (P=0.004) was associated with increased risk of undergoing a revision after MIS TLIF.

CONCLUSIONS

The results of this study suggest that increasing BMI is not a risk factor for undergoing a revision procedure after MIS TLIF. As such, patients with high BMI should be counseled regarding having similar rates of needing a revision procedure after MIS TLIF as those with lower BMI.

LEVEL OF EVIDENCE

Level IV.

Physician-Specific Variability in Spine Fusion Patients

BACKGROUND

It is often assumed that each surgeon's patient population is similar to that of his or her peers. Differences in patient characteristics naturally may lead to diverse outcomes. To date, the variability of individual surgeons' patient populations has not been adequately characterized. The purpose of this study is to describe the variation in physician-specific patient characteristics among surgeons performing spine fusion surgery at a large, urban academic medical center.

METHODS

We analyzed administrative data from a single institution for spine fusion surgery from 2009 to 2013. There were 6585 primary and 362 revision cases of spine fusion performed within this time period. Variability between surgeons and their respective patient populations was compared using descriptive statistics.

RESULTS

The mean annual percentage of primary fusion patients with diabetes mellitus ranged from 0 to 16.17% (mean ± SD, 7.79% ± 3.96%) but constituted anywhere from 0 to 41.58% (mean ± SD, 8.15% ± 12.09%) of revision fusions. The mean annual percentage of primary fusion patients who were obese ranged from 0 to 9% (mean ± SD, 2.95% ± 2.7%), and 0 to 25% in revision cases (mean ± SD, 3.43% ± 6.43%). The annual mean percentage of patients with American Society of Anesthesiologists (ASA) scores greater than 3 ranged from 8.8% to 44.43% (mean ± SD, 20.42% ± 8.85%) in primary fusions and 0 to 100% (mean ± SD, 32.79% ± 23.47%) in revision fusions.

CONCLUSION

There was a large amount of variability among surgeons' patient populations when looking at characteristics such as obesity, diabetes, and ASA scores >3. These factors have been shown to impact patient outcomes. The variability in the patient populations of individual surgeons' practices even within the same medical center must be taken into account when evaluating physician specific outcomes and quality of care.

Diabetes and morbid obesity are associated with higher reoperation rates following microvascular decompression surgery: An ACS-NSQIP analysis

Background:

Microvascular decompression (MVD) is the preferred treatment for refractory trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia. Despite its high rate of success, MVD carries risk of complications. In this study, we examine outcomes following MVD and identify risk factors associated with adverse outcomes.

Methods:

A review of the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was performed with CPT code 61458 queried between 2007 and 2014. Demographics, preoperative comorbidities, and 30-day outcomes were analyzed. Univariate and multivariate regression analyses were performed to identify predictors of reoperation and adverse events.

Results:

Five hundred and six craniotomies were studied. Nineteen (5.5%) instances of 30-day readmission were reported, with 14 (2.8%) patients returning to the operating room. No instances of death or hemorrhage requiring operation were reported. Morbid obesity (body mass index >40) (P = 0.030) and diabetes (P = 0.017) were associated with risk of reoperation. Age, operative time, and indication for surgery were not associated with significant differences in adverse events.

Conclusions:

MVD is a common and effective procedure with a relatively safe profile and low 30-day risk of reoperation. Advanced age is not associated with worse outcomes. Obesity and diabetes, however, are associated with increased risk of reoperation and may warrant additional precautions.

Cost Variation of Anterior Cervical Fusions in Elderly Medicare Beneficiaries

STUDY DESIGN

Retrospective database review.

OBJECTIVE

To determine how demographics and comorbid diagnoses influence hospital costs during admission for anterior cervical fusions (ACFs) in the elderly Medicare population.

SUMMARY OF BACKGROUND DATA

Elective ACFs to treat degenerative cervical pathology are extremely common within the elderly population. Although it is well known that every patient has a significantly different medical profile that guides treatment and postoperative care, little information is available regarding how hospital costs vary from patient to patient.

METHODS

Medicare records from the PearlDiver database (2011-2012) were retrospectively queried to select all 65- to 84-year-old patients who underwent primary, 1 to 2 level ACF (International Classification of Diseases, Ninth Revision, Clinical Modification: 81.02) for either cervical spondylosis or cervical disc disease. All patients with corpectomies, posterior cervical fusions, and all other same-day spine fusion surgeries were excluded. The primary outcome of this study was Medicare reimbursement from the full inpatient stay as associated with the selected International Classification of Diseases, Ninth Revision procedure code. The relative contributions of year, age, sex, region, myelopathy diagnosis, and various comorbidities to the total cost were determined with both univariate statistics and multivariate analysis. For all analyses, P < 0.001 was determined to be significant.

RESULTS

In total, 21,853 patients were selected for analysis. The average reimbursement for the full cohort was $13,648 ± $7306. On multivariate analysis, advanced age ($1083), diagnosis of myelopathy ($2150), diabetes mellitus ($1019), obesity ($651), congestive heart failure ($1523), chronic kidney disease ($1962), and chronic pulmonary disease ($489) were all factors that increased costs. Of note, sex, smoking history, and prior liver disease were not associated with changes in cost.

CONCLUSION

Medicare reimbursements provide a value means by which determinants of cost can be elucidated. Although multiple comorbidities, older age, and myelopathy diagnosis could be theorized to contribute to increased costs, there is still some uncertainty regarding their relative costs. These data are informative to practicing physicians as health care as a whole transitions to a more value-based approach.

LEVEL OF EVIDENCE

4.

Prophylactic use of intraoperative vancomycin powder and postoperative infection: an analysis of microbiological patterns in 1200 consecutive surgical cases

OBJECTIVE Wound infections following spinal surgery for deformity place a high toll on patients, providers, and the health care system. The prophylactic application of intraoperative vancomycin powder has been shown to lower the infection risk after thoracolumbar decompression and fusion for deformity correction. The purpose of this study was to assess the microbiological patterns of postoperative surgical site infections (SSIs) after prophylactic use of vancomycin powder in adult patients undergoing spinal deformity surgery. METHODS All cases involving adult patients who underwent spinal deformity reconstruction at Duke University Medical Center between 2011 and 2013 with a minimum of 3 months of clinical follow-up were retrospectively reviewed. In all cases included in the study, crystalline vancomycin powder was applied to the surgical bed for infection prophylaxis. Baseline characteristics, operative details, rates of wound infection, and microbiological data for each case were gathered by direct medical record review. RESULTS A total of 1200 consecutive spine operations were performed for deformity between 2011 and 2013. Review of the associated records demonstrated 34 cases of SSI, yielding an SSI rate of 2.83%. The patients' mean age (± SD) was 62.08 ± 14.76 years. The patients' mean body mass index was 30.86 ± 7.15 kg/m², and 29.41% had a history of diabetes. The average dose of vancomycin powder was 1.41 ± 2.77 g (range 1-7 g). Subfascial drains were placed in 88% of patients. All SSIs occurred within 30 days of surgery, with deep wound infections accounting for 50%. In 74% of the SSIs cultures were positive, with about half the organisms being gram negative, such as Citrobacter freundii, Proteus mirabilis, Morganella morgani, and Pseudomonas aeruginosa. There were no adverse clinical outcomes related to the local application of vancomycin. CONCLUSIONS Our study suggests that in the setting of prophylactic vancomycin powder use, the preponderance of SSIs are caused by gram-negative organisms or are polymicrobial. Further randomized control trials of prophylactic adjunctive measures are warranted to help guide the choice of empirical antibiotic therapy while awaiting culture data.

Use of Allogenic Mesenchymal Cellular Bone Matrix in Anterior and Posterior Cervical Spinal Fusion: A Case Series of 21 Patients

Study Design

Retrospective case series.

Purpose

To report our early experience using allogenic mesenchymal cellular bone matrix (CBM) products in cervical spine fusion.

Overview of Literature

Multi-level cervical fusions have historically yielded lower fusion rates than single level fusions, especially in patients with high risk medical comorbidities. At this time, significant literature in cervical fusion outcomes with this cellular allograft technology is lacking.

Methods

Twenty-one patients underwent either multilevel (3 or 4 level) anterior cervical discectomy and fusion, anterior cervical corpectomy and fusion, or posterior cervical fusion. ViviGen (DePuy Synthes Spine, Raynham, MA, USA), an allogenic bone matrix product, was used in addition to standard instrumentation. Radiographic evaluation was performed at 2 weeks, 12 weeks, 24 weeks and 1 year postoperative. Visual analog scale (VAS) and neck disability index (NDI) scores along with return to work and leisure activity were recorded.

Results

At 6 months postoperative, all patients had radiographic evidence of bone fusion regardless of age or medical comorbidities. All patients reported subjective improvement with a mean decrease in VAS from 8.3 to 1.5 and a mean decrease in NDI from 40.3% to 6.0% at 1 year. All patients also returned to work and/or regular leisure activity within 3 months.

Conclusions

Twenty-one patients undergoing high-risk anterior and posterior cervical spine fusion, with the use of a commercially available mesenchymal CBM product, went on to radiographic fusion and all had improvement in subjective outcomes. While further effort and research is needed to validate its widespread use, this study shows favorable use of CBM in cervical fusion for high-risk cases.

More risks and complications for elective spine surgery in morbidly obese patients

Background:

The vast majority of studies emphasize the greater morbidity/mortality for elective spine surgery in morbidly obese patients.

Methods:

This review focuses on the increased morbidity/mortality of performing elective spinal operations in morbidly obese patients. There are two definitions of morbid obesity; a body mass index (BMI) of equal to or greater than 35 plus two major comorbid factors (e.g., hypertension, diabetes, etc.) or a BMI (morbidly obese III) of =≥40 kg/m².

Results:

For patients undergoing spinal surgery, morbid obesity increases perioperative morbidity/mortality for various reasons. The quality of preoperative and intraoperative imaging is often compromised potentially leading to mistaken preoperative diagnoses, and wrong level surgery. Resultant major technical surgical limitations include poor/inadequate operative exposure, and the risk of suboptimal placement of instrumentation There is also increased exposure to major perioperative complications such as deep venous thrombosis, pulmonary embolism, infection, pneumonia, cardiac complications, blindness in the prone position, brachial and lumbar plexus injuries, increased anesthetic risks (e.g., even using awake intubation/awake positioning), and postoperative wound seromas/hematomas.

Conclusions:

Most of the spinal literature documents the marked increased perioperative morbidity/mortality for morbidly obese patients undergoing elective spine surgery. If elective surgery is warranted in these patients, the risks and timing of surgical intervention should include consideration of major preoperative weight loss strategies including bariatric procedures to optimize outcomes.

Body habitus, serum albumin, and the outcomes after craniotomy for tumor: a National Surgical Quality Improvement Program analysis

OBJECTIVE

Although there is a growing body of research highlighting the negative impact of obesity and malnutrition on surgical outcomes, few studies have evaluated these parameters in patients undergoing intracranial surgery. The goal of this study was to use a national registry to evaluate the association of body mass index (BMI) and hypoalbuminemia with 30-day outcomes after craniotomy for tumor.

METHODS

Adult patients who underwent craniotomy for tumor were extracted from the prospective National Surgical Quality Improvement Program registry. Patients were stratified by body habitus according to the WHO classification, as well as by preoperative hypoalbuminemia (< 3.5 g/dl). Multivariable logistic regression evaluated the association of body habitus and hypoalbuminemia with 30-day mortality, complications, and discharge disposition. Covariates included patient age, sex, race or ethnicity, tumor histology, American Society of Anesthesiology class, preoperative functional status, comorbidities (including hypertension and diabetes mellitus), and additional preoperative laboratory values.

RESULTS

Among the 11,510 patients included, 28.7% were classified as normal weight (BMI 18.5–24.9 kg/m2), 1.9% as underweight (BMI < 18.5 kg/m2), 33.4% as overweight (BMI 25.0–29.9 kg/m2), 19.1% as Class I obese (BMI 30.0–34.9 kg/m2), 8.3% as Class II obese (BMI 35.0–39.9 kg/m2), 5.5% as Class III obese (BMI ≥ 40.0 kg/m2), and 3.1% had missing BMI data. In multivariable regression models, body habitus was not associated with differential odds of mortality, postoperative stroke or coma, or a nonroutine hospital discharge. However, the adjusted odds of a major complication were significantly higher for Class I obese (OR 1.28, 99% CI 1.01–1.62; p = 0.008), Class II obese (OR 1.53, 99% CI 1.13–2.07; p < 0.001), and Class III obese (OR 1.67, 99% CI 1.19–2.36; p < 0.001) patients compared with those of normal weight; a dose-dependent effect was seen, with increased effect size with greater adiposity. The higher odds of major complications was primarily due to significantly increased odds of a venous thromboembolism in overweight and obese patients, as well as of a surgical site infection in those with Class II or III obesity. Additionally, 41.0% of patients had an albumin level ≥ 3.5 g/dl, 9.6% had hypoalbuminemia, and 49.4% had a missing albumin value. Hypoalbuminemia was associated with significantly higher odds of mortality (OR 1.91, 95% CI 1.41–2.60; p < 0.001) or a nonroutine hospital discharge (OR 1.46, 95% CI 1.21–1.76; p < 0.001).

CONCLUSIONS

In this National Surgical Quality Improvement Program analysis evaluating patients who underwent craniotomy for tumor, body habitus was not associated with differential mortality or neurological complications. However, obese patients had increased odds of a major perioperative complication, primarily due to higher rates of venous thromboembolic events and surgical site infections. Preoperative hypoalbuminemia was associated with increased odds of mortality and a nonroutine hospital discharge, suggesting that serum albumin may have utility in stratifying risk preoperatively in patients undergoing craniotomy.

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.

Bariatric bypasses contribute to loss of bone mineral density but reduce axial back pain in morbidly obese patients considering spine surgery

Background:

Many spine surgeons recommend stringent weight loss, including bariatric bypass procedures, prior to “elective” spine surgery (should not be for axial back pain alone) in morbidly obese patients (defined by a body mass index (BMI) of >40 mg/kg² or >35 mg/kg² with two or more major comorbidities) to reduce their greater risk for major perioperative complications. Although bypasses typically lead to marked weight reduction and even reduced axial back pain, they also promote unrecognized and often insufficiently treated vitamin D deficiency and loss of bone mineral density.

Methods:

Morbidly obese patients who are under consideration for “elective” spine operations (other than for back pain alone) are often told to lose weight. Some choose to undergo bariatric bypass procedures, but are unaware of the potential risks/complications of these procedures.

Results:

Within the first 2 years following most bariatric bypass procedures, patients experience not only marked loss of weight and muscle mass, but also significant vitamin D deficiency and loss of bone mineral density, increasing their susceptibility to fractures. Nevertheless, some patients also experience a sufficient reduction of axial back pain to avoid spinal surgery.

Conclusions:

Morbidly obese patients under consideration for “elective” spine surgery may undergo bariatric bypass procedures that lead to a significant reduction of vitamin D levels and loss of bone mineral density. However, potential benefits may include a sufficient reduction of axial back pain to avoid surgery in a select subset of patients altogether.

Impact of Obesity on Complications and 30-Day Readmission Rates After Cranial Surgery: A Single-Institutional Study of 224 Consecutive Craniotomy/Craniectomy Procedures

BACKGROUND

The prevalence of obesity is increasing at a disparaging rate in the United States. Although previous studies have associated obesity with increased surgical complications and readmission rates, the impact of obesity on surgical outcomes after cranial surgery remains understudied. The aim of this study is to assess the effect of obesity on complication and 30-day readmission rates after cranial surgery.

METHODS

The medical records of 224 consecutive patients (nonobese, n = 164; obese, n = 60) undergoing either craniotomy or craniectomy at a major academic institution in 2011 were reviewed. Preoperative body mass index equal to or greater than 30 kg/m² was classified as obese. The primary outcome investigated in this study was the rate of intraoperative and postoperative complications and 30-day readmissions after craniectomy/craniotomy.

RESULTS

Baseline patient characteristics and comorbidities were similar between the cohorts. The mean body mass indexes for both cohorts were significantly different (nonobese, 22.8 ± 4.2 kg/m² vs. obese, 45.1 ± 15.9 kg/m²; P < 0.0001). Most patients underwent tumor excision in both cohorts (nonobese, 64.0% vs. obese, 66.7%; P = 0.75). Compared with the nonobese cohort, the obese cohort had significantly higher estimated blood loss (nonobese, 209.9 ± 201.3 mL vs. obese, 284.9 ± 250.0 mL; P = 0.04), but similar length of operation (nonobese, 187.3 ± 89.4 minutes vs. obese, 209.6 ± 100.5; P = 0.14). Length of hospital stay and rate of postoperative complications were similar between both cohorts. Obese patients had increased rate of 30-day readmission, but this was not statistically significant (nonobese, 3.1% vs. obese, 6.7%; P = 0.25).

CONCLUSIONS

Our study suggests that obesity may not have a significant impact on surgical outcomes after cranial surgery.

Morbid Obesity and Lumbar Fusion in Patients Older Than 65 Years: Complications, Readmissions, Costs, and Length of Stay

STUDY DESIGN

Retrospective database review.

OBJECTIVE

The aim of this study was to determine how both morbid obesity (body mass index [BMI] ≥40) and obesity (BMI 30-39.9) modify 90-day complication rates and 30-day readmission rates following 1- to 2-level, primary, lumbar spinal fusion surgery for degenerative pathology in an elderly population.

SUMMARY OF BACKGROUND DATA

In the United States, both obese and elderly patients are known to have increased risk of complication, yet both demographics are increasingly undergoing elective lumbar spine surgery.

METHODS

Medicare data from 2005 to 2012 were queried for patients who underwent primary 1- to 2-level posterolateral lumbar fusion for degenerative pathology. Elderly patients undergoing elective surgery were selected and separated into three cohorts: morbidly obese (BMI ≥40; n = 2594), obese (BMI ≥30, < 40] (n = 5534), and nonobese controls (n = 48,210). Each pathologic cohort was matched to a unique subcohort from the control population. Ninety-day medical and surgical complication rates, 30-day readmission rates, length of stay (LOS), and hospital costs were then compared.

RESULTS

Both morbidly obese and obese patients had significantly higher odds of experiencing any one major medical complication (odds ratio [OR] 1.79; P < 0.0001 and OR 1.32; P < 0.0001, respectively). Wound infection (OR 3.71; P < 0.0001 and OR 2.22; P < 0.0001) and dehiscence (OR 3.80; P < 0.0001 and OR 2.59; P < 0.0001) rates were increased in morbidly obese and obese patients, respectively. Thirty-day readmissions, length of stay, and in-hospital costs were increased, with patients with morbid obesity incurring charges almost $8000 greater than controls.

CONCLUSION

Patients with both obesity and morbid obesity are at significantly increased risk of major medical complications, wound complications, and 30-day readmissions. Additionally, both groups of patients have significantly increased LOS and hospital costs. Both obese and morbidly obese patients should be appropriately counseled of these risks and must be carefully selected to reduce postoperative morbidity.

LEVEL OF EVIDENCE

3.

The impact of body habitus on outcomes after aneurysmal subarachnoid hemorrhage: a Nationwide Inpatient Sample analysis

OBJECTIVE Although the prevalence of obesity is increasing rapidly both nationally and internationally, few studies have analyzed outcomes among obese patients undergoing cranial neurosurgery. The goal of this study, which used a nationwide data set, was to evaluate the association of both obesity and morbid obesity with treatment outcomes among patients with aneurysmal subarachnoid hemorrhage (SAH); in addition, the authors sought to analyze how postoperative complications for obese patients with SAH differ by the treatment modality used for aneurysm repair. METHODS Clinical data for adult patients with SAH who underwent microsurgical or endovascular aneurysm repair were extracted from the Nationwide Inpatient Sample (NIS). The body habitus of patients was classified as nonobese (body mass index [BMI] < 30 kg/m²), obese (BMI ≥ 30 kg/m² and ≤ 40 kg/m²), or morbidly obese (BMI > 40 kg/m²). Multivariable logistic regression analyzed the association of body habitus with in-hospital mortality rate, complications, discharge disposition, and poor outcome as defined by the composite NIS-SAH outcome measure. Covariates included patient demographics, comorbidities (including hypertension and diabetes), health insurance status, the NIS-SAH severity scale, treatment modality used for aneurysm repair, and hospital characteristics. RESULTS In total, data from 18,281 patients were included in this study; the prevalence of morbid obesity increased from 0.8% in 2002 to 3.5% in 2011. Obese and morbidly obese patients were significantly younger and had a greater number of comorbidities than nonobese patients (p < 0.001). Mortality rates for obese (11.5%) and morbidly obese patients (10.5%) did not significantly differ from those for nonobese patients (13.5%); likewise, no differences in neurological complications or poor outcome were observed among these 3 groups. Morbid obesity was associated with significantly increased odds of several medical complications, including venous thromboembolic (OR 1.52, 95% CI 1.01-2.30, p = 0.046) and renal (OR 1.64, 95% CI: 1.11-2.43, p = 0.01) complications and infections (OR 1.34, 95% CI 1.08-1.67, p = 0.009, attributable to greater odds of urinary tract and surgical site infections). Moreover, morbidly obese patients had higher odds of a nonroutine hospital discharge (OR 1.33, 95% CI 1.03-1.71, p = 0.03). Patients with milder obesity had decreased odds of some medical complications, including cardiac, pulmonary, and infectious complications, primarily among patients who had undergone coil embolization. CONCLUSIONS In this study involving a nationwide administrative database, milder obesity was not significantly associated with increased mortality rates, neurological complications, or poor outcomes after SAH. Morbid obesity, however, was associated with increased odds of venous thromboembolic, renal, and infectious complications, as well as of a nonroutine hospital discharge. Notably, milder obesity was associated with decreased odds of some medical complications, primarily in patients treated with coiling.

The Effects of Obesity on Spine Surgery: A Systematic Review of the Literature

Study Design Literature review. Objective The aim of this literature review is to examine the effects of obesity on postoperative complications and functional outcomes after spine surgery. Methods A review of the relevant literature examining the effects of obesity and spine surgery was conducted using PubMed, Google Scholar, and Cochrane databases. Results Obesity contributes to disk degeneration and low back pain and potentially increases the risk of developing operative pathology. Obese patients undergoing spine surgery have a higher risk of developing postoperative complications, particularly surgical site infection and venous thromboembolism. Though functional outcomes in this population may not mirror the general population, the treatment effect associated with surgery is at least equivalent if not better in obese individuals. This reduction is primarily due to worse outcomes associated with nonoperative treatment in the obese population. Conclusion Obese individuals represent a unique patient population with respect to nonoperative treatment, postoperative complication rates, and functional outcomes. However, given the equivalent or greater treatment effect of surgery, this comorbidity should not prohibit obese patients from undergoing operative intervention. Future investigations in this area should attempt to develop strategies to minimize complications and improve outcomes in obese individuals and also examine the role of controlled weight loss preoperatively to mitigate these risks.