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Anthony L. Asher, Matthew J. McGirt and Zoher Ghogawala

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Anthony L. Asher, Paul C. McCormick and Douglas Kondziolka

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Walter A. Hall, Edward Rustamzadeh and Anthony L. Asher

The poor prognosis associated with the current management of malignant gliomas has led investigators to develop alternative treatments such as targeted toxin therapy. The optimal method for administering these agents is under development but appears to be convection-enhanced delivery (CED).

The direct intratumoral infusion of targeted toxins was first performed in nude mouse flank tumor models of human malignant glioma. After the demonstration of in vivo efficacy, these potent cytotoxic compounds were tested in Phase I and Phase II clinical trials.

Using a high-flow microinfusion technique, volumes of up to 180 ml were infused by CED through catheters placed directly into brain tumors. Minor systemic toxicity was seen in the form of hepatic enzyme elevation. Neural toxicity manifested as seizure activity and hemiparesis resulted from peritumoral edema that followed the completion of the infusion. Peritumoral toxicity was believed to be more related to the concentration of the infused immunotoxin than to the infusion volume. In approximately half of patients treated with CED a stable disease course, a partial response, or a complete response was demonstrated in some clinical trials.

Targeted toxin therapy has clinical efficacy in patients with malignant gliomas. Convection-enhanced delivery appears to represent an effective method for administering these agents in patients with malignant brain tumors.

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Scott L. Parker, Anthony L. Asher, Saniya S. Godil, Clinton J. Devin and Matthew J. McGirt

OBJECT

The health care landscape is rapidly shifting to incentivize quality of care rather than quantity of care. Quality and outcomes registry platforms lie at the center of all emerging evidence-driven reform models and will be used to inform decision makers in health care delivery. Obtaining real-world registry outcomes data from patients 12 months after spine surgery remains a challenge. The authors set out to determine whether 3-month patient-reported outcomes accurately predict 12-month outcomes and, hence, whether 3-month measurement systems suffice to identify effective versus noneffective spine care.

METHODS

All patients undergoing lumbar spine surgery for degenerative disease at a single medical institution over a 2-year period were enrolled in a prospective longitudinal registry. Patient-reported outcome instruments (numeric rating scale [NRS], Oswestry Disability Index [ODI], 12-Item Short Form Health Survey [SF-12], EQ-5D, and the Zung Self-Rating Depression Scale) were recorded prospectively at baseline and at 3 months and 12 months after surgery. Linear regression was performed to determine the independent association of 3- and 12-month outcome. Receiver operating characteristic (ROC) curve analysis was performed to determine whether improvement in general health state (EQ-5D) and disability (ODI) at 3 months accurately predicted improvement and achievement of minimum clinical important difference (MCID) at 12 months.

RESULTS

A total of 593 patients undergoing elective lumbar surgery were included in the study. There was a significant correlation between 3-month and 12-month EQ-5D (r = 0.71; p < 0.0001) and ODI (r = 0.70; p < 0.0001); however, the authors observed a sizable discrepancy in achievement of a clinically significant improvement (MCID) threshold at 3 versus 12 months on an individual patient level. For postoperative disability (ODI), 11.5% of patients who achieved an MCID threshold at 3 months dropped below this threshold at 12 months; 10.5% of patients who did not meet the MCID threshold at 3 months continued to improve and ultimately surpassed the MCID threshold at 12 months. For ODI, achieving MCID at 3 months accurately predicted 12-month MCID with only 62.6% specificity and 86.8% sensitivity. For postoperative health utility (EQ-5D), 8.5% of patients lost an MCID threshold improvement from 3 months to 12 months, while 4.0% gained the MCID threshold between 3 and 12 months postoperatively. For EQ-5D (quality-adjusted life years), achieving MCID at 3 months accurately predicted 12-month MCID with only 87.7% specificity and 87.2% sensitivity.

CONCLUSIONS

In a prospective registry, patient-reported measures of treatment effectiveness obtained at 3 months correlated with 12-month measures overall in aggregate, but did not reliably predict 12-month outcome at the patient level. Many patients who do not benefit from surgery by 3 months do so by 12 months, and, conversely, many patients reporting meaningful improvement by 3 months report loss of benefit at 12 months. Prospective longitudinal spine outcomes registries need to span at least 12 months to identify effective versus noneffective patient care.

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Matthew J. McGirt, Saniya S. Godil, Anthony L. Asher, Scott L. Parker and Clinton J. Devin

OBJECT

In an era of escalating health care cost and universal pressure of improving efficiency and cost of care, ambulatory surgery centers (ASCs) have emerged as lower cost options for many surgical therapies. Anterior cervical discectomy and fusion (ACDF) is one of the most prevalent spine surgeries performed and is rapidly increasing with an expanding aging population. While ASCs offer cost advantages for ACDF, there is a scarcity of evidence that ASCs allow for equivalent quality and thus superior health care value. Therefore, the authors analyzed a nationwide, prospective quality improvement registry (National Surgical Quality Improvement Program [NSQIP]) to compare the quality of ACDF surgery performed in the outpatient ASC versus the inpatient hospital setting.

METHODS

Patients undergoing ACDF (2005-2011) were identified from the NSQIP database based on the primary Current Procedural Terminology codes. Patients were divided into 2 cohorts (outpatient vs inpatient) based on the acute care setting documented in the NSQIP database. All 30-day surgical morbidity and mortality rates were compared between the 2 groups. Propensity score matching and multivariate logistic regression analysis were used to adjust for confounding factors and to identify the independent association of outpatient ACDF with perioperative outcomes and morbidity.

RESULTS

A total of 7288 ACDF cases were identified (inpatient = 6120, outpatient = 1168). Unadjusted rates of major morbidity (0.94% vs 4.5%, p < 0.001) and return to the operating room (OR) within 30 days (0.3% vs 2.0%, p < 0.001) were significantly lower in outpatient versus inpatient ACDF. After propensity matching 1442 cases (inpatient = 650, outpatient = 792) based on baseline 32 covariates, rates of major morbidity (1.4% vs 3.1%, p = 0.03), and return to the OR (0.34% vs 1.4%, p = 0.04) remained significantly lower after outpatient ACDF. Adjusted comparison using multivariate logistic regression demonstrated that ACDF performed in the outpatient setting had 58% lower odds of having a major morbidity and 80% lower odds of return to the OR within 30 days.

CONCLUSIONS

An analysis of a nationwide, prospective quality improvement registry representing more than 250 hospitals demonstrates that 1- to 2-level ACDF can be safely performed in the outpatient ambulatory surgery setting in patients who are appropriate candidates. In an effort to decrease cost of care, surgeons can safely consider performing ACDF in an ASC environment.

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Scott L. Parker, Ahilan Sivaganesan, Silky Chotai, Matthew J. McGirt, Anthony L. Asher and Clinton J. Devin

OBJECTIVE

Hospital readmissions lead to a significant increase in the total cost of care in patients undergoing elective spine surgery. Understanding factors associated with an increased risk of postoperative readmission could facilitate a reduction in such occurrences. The aims of this study were to develop and validate a predictive model for 90-day hospital readmission following elective spine surgery.

METHODS

All patients undergoing elective spine surgery for degenerative disease were enrolled in a prospective longitudinal registry. All 90-day readmissions were prospectively recorded. For predictive modeling, all covariates were selected by choosing those variables that were significantly associated with readmission and by incorporating other relevant variables based on clinical intuition and the Akaike information criterion. Eighty percent of the sample was randomly selected for model development and 20% for model validation. Multiple logistic regression analysis was performed with Bayesian model averaging (BMA) to model the odds of 90-day readmission. Goodness of fit was assessed via the C-statistic, that is, the area under the receiver operating characteristic curve (AUC), using the training data set. Discrimination (predictive performance) was assessed using the C-statistic, as applied to the 20% validation data set.

RESULTS

A total of 2803 consecutive patients were enrolled in the registry, and their data were analyzed for this study. Of this cohort, 227 (8.1%) patients were readmitted to the hospital (for any cause) within 90 days postoperatively. Variables significantly associated with an increased risk of readmission were as follows (OR [95% CI]): lumbar surgery 1.8 [1.1–2.8], government-issued insurance 2.0 [1.4–3.0], hypertension 2.1 [1.4–3.3], prior myocardial infarction 2.2 [1.2–3.8], diabetes 2.5 [1.7–3.7], and coagulation disorder 3.1 [1.6–5.8]. These variables, in addition to others determined a priori to be clinically relevant, comprised 32 inputs in the predictive model constructed using BMA. The AUC value for the training data set was 0.77 for model development and 0.76 for model validation.

CONCLUSIONS

Identification of high-risk patients is feasible with the novel predictive model presented herein. Appropriate allocation of resources to reduce the postoperative incidence of readmission may reduce the readmission rate and the associated health care costs.

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Tim Adamson, Saniya S. Godil, Melissa Mehrlich, Stephen Mendenhall, Anthony L. Asher and Matthew J. McGirt

OBJECTIVE

In an era of escalating health care costs and pressure to improve efficiency and cost of care, ambulatory surgery centers (ASCs) have emerged as lower-cost options for many surgical therapies. Anterior cervical discectomy and fusion (ACDF) is one of the most prevalent spine surgeries performed, and the frequency of its performance is rapidly increasing as the aging population grows. Although ASCs offer significant cost advantages over hospital-based surgical centers, concern over the safety of outpatient ACDF has slowed its adoption. The authors intended to 1) determine the safety of the first 1000 consecutive ACDF surgeries performed in their outpatient ASC, and 2) compare the safety of these outpatient ACDFs with that of consecutive ACDFs performed during the same time period in the hospital setting.

METHODS

A total of 1000 consecutive patients who underwent ACDF in an ACS (outpatient ACDF) and 484 consecutive patients who underwent ACDF at Vanderbilt University Hospital (inpatient ACDF) from 2006 to 2013 were included in this retrospective study of patients' medical records. Data were collected on patient demographics, comorbidities, operative details, and perioperative and 90-day morbidity. Perioperative morbidity and hospital readmission were compared between the outpatient and inpatient ACDF groups.

RESULTS

Of the first 1000 outpatient ACDF cases performed in the authors' ASC, 629 (62.9%) were 1-level and 365 (36.5%) were 2-level ACDFs. Mean patient age was 49.5 ± 8.6, and 484 (48.4%) were males. All patients were observed postoperatively at the ASC postanesthesia care unit (PACU) for 4 hours before being discharged home. Eight patients (0.8%) were transferred from the surgery center to the hospital postoperatively (for pain control [n = 3], chest pain and electrocardiogram changes [n = 2], intraoperative CSF leak [n = 1], postoperative hematoma [n = 1], and profound postoperative weakness and surgical reexploration [n = 1]). No perioperative deaths occurred. The 30-day hospital readmission rate was 2.2%. All 90-day surgical morbidity was similar between outpatient and inpatient cohorts for both 1-level and 2-level ACDFs.

CONCLUSIONS

An analysis of 1000 consecutive patients who underwent ACDF in an outpatient setting demonstrates that surgical complications occur at a low rate (1%) and can be appropriately diagnosed and managed in a 4-hour ASC PACU window. Comparison with an inpatient ACDF surgery cohort demonstrated similar results, highlighting that ACDF can be safely performed in the outpatient ambulatory surgery setting without compromising surgical safety. In an effort to decrease costs of care, surgeons can safely perform 1- and 2-level ACDFs in an ASC environment.

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Charles H. Crawford III, Steven D. Glassman, Praveen V. Mummaneni, John J. Knightly and Anthony L. Asher

OBJECTIVE

The relief of leg symptoms by surgical decompression for lumbar stenosis is well supported by the literature. Less is known about the effect on back pain. Some surgeons believe that the relief of back pain should not be an expected outcome of decompression and that substantial back pain may be a contraindication to decompression only; therefore, stabilization may be recommended for patients with substantial preoperative back pain even in the absence of well-accepted indications for stabilization such as spondylolisthesis, scoliosis, or sagittal malalignment. The purpose of this study is to determine if patients with lumbar stenosis and substantial back pain—in the absence of spondylolisthesis, scoliosis, or sagittal malalignment—can obtain significant improvement after decompression without fusion or stabilization.

METHODS

Analysis of the National Neurosurgery Quality and Outcomes Database (N2QOD) identified 726 patients with lumbar stenosis (without spondylolisthesis or scoliosis) and a baseline back pain score ≥ 5 of 10 who underwent surgical decompression only. No patient was reported to have significant spondylolisthesis, scoliosis, or sagittal malalignment. Standard demographic and surgical variables were collected, as well as patient outcomes including back and leg pain scores, Oswestry Disability Index (ODI), and EuroQoL 5D (EQ-5D) at baseline and 3 and 12 months postoperatively.

RESULTS

The mean age of the cohort was 65.6 years, and 407 (56%) patients were male. The mean body mass index was 30.2 kg/m2, and 40% of patients had 2-level decompression, 29% had 3-level decompression, 24% had 1-level decompression, and 6% had 4-level decompression. The mean estimated blood loss was 130 ml. The mean operative time was 100.85 minutes. The vast majority of discharges (88%) were routine home discharges. At 3 and 12 months postoperatively, there were significant improvements from baseline for back pain (7.62 to 3.19 to 3.66), leg pain (7.23 to 2.85 to 3.07), EQ-5D (0.55 to 0.76 to 0.75), and ODI (49.11 to 27.20 to 26.38).

CONCLUSIONS

Through the 1st postoperative year, patients with lumbar stenosis—without spondylolisthesis, scoliosis, or sagittal malalignment—and clinically significant back pain improved after decompression-only surgery.