Faculty Bibliography

BACKGROUND CONTEXT: Anterior cervical discectomy and fusion (ACDF) is the gold standard surgical intervention for cervical degenerative disc disease (DDD). It has a history of clinical success, but has been associated with degeneration of adjacent levels. Cervical disc arthroplasty (CDA) has been recently introduced as an alternative to ACDF. CDA offers the potential advantage of preserving intersegmental motion and preventing adjacent segment degeneration. Although four FDA sponsored clinical trials and a meta-analysis have demonstrated non-inferiority of CDA compared to ACDF in terms of symptom/function related outcomes, little data is available comparing perioperative outcomes and procedural costs. PURPOSE: The purpose of this study is to compare patient characteristics, perioperative outcomes, and costs of CDA and ACDF. STUDY DESIGN/SETTING: Retrospective review of national data from a large administrative database. PATIENT SAMPLE: Patients undergoing CDA or ACDF between 2005 and 2010. OUTCOME MEASURES: Perioperative complications, length of stay, total costs, mortality. METHODS: The national inpatient sample (NIS) database was queried for patients undergoing ACDF and CDA between 2005 and 2010. Univariate analyses were carried out comparing the two procedures in terms of patient demographics, comorbidities, perioperative complications, length of stay (LOS), total cost of hospitalization, and mortality. Complications rates that were significant on univariate analysis were analyzed via logistic regression models that account for age, gender, and overall comorbidity burden. National estimates of annual total number of procedures were calculated. RESULTS: An estimated 9,910 CDAs and 699,289 ACDFs were performed in the United States between 2005 and 2010. Patients undergoing CDA were on average younger (45.1 versus 51.5, p<.0001) and with less comorbidities (mean Charlson score 0.14 versus 0.29, p<.0001) then those undergoing ACDFs. CDAwas associated with less postoperative dysphagia (0.27% vers!

BACKGROUND CONTEXT: Postoperative venous thromboembolic events (VTEs), which include pulmonary embolisms (PEs) and deep venous thrombosis (DVTs), are important potentially preventable causes of death. Evidence is lacking regarding which patients are at highest risk of developing postoperative VTEs. PURPOSE: This study aims to investigate the patient and procedure determined risk factors for VTE in patients undergoing spinal surgery. STUDY DESIGN/SETTING: Retrospective analysis of a national database. PATIENT SAMPLE: Patients undergoing spinal fusion. OUTCOME MEASURES: Occurrence of postoperative complications, length of stay, total charges, mortality. METHODS: Using the National Inpatient Sample (NIS) database from 2001 through 2010 patients undergoing spinal fusions and occurrence of symptomatic VTE were identified via corresponding ICD-9 procedure and diagnosis codes. Univariate analysis of patient and hospital demographics, comorbidities, and postoperative complications was used to compare the VTE and non-VTE groups. Independent risk factors for VTE were identified via multivariate logistic regression. RESULTS: A total of 755,082 spinal fusion procedures were identified. The NIS dataset contained 2,234 DVTs (0.30%) and 1,870 PEs (0.25%), for a total of 4,104 (0.54%) VTEs in 3,831 patients. Patients who had a VTE were on average older (58.98 years for VTE, 53.53 years for no VTE, p<.01), more often women then men (VTE incidence in women 0.60% , men 0.4%, p<.01), black (white patients .48%, black .78%, p<.01), insured with Medicare or Medicaid (.77% Medicare, .71% Medicaid, .38% private insurance, p<.01), and had a higher comorbidity burden (Charlson index 1.27 versus 0.37, p<.01). Postoperative VTE was associated with longer hospital stays (18.7 days versus 4.09). VTE increased the total hospital costs (>=207,182 versus >=68,029, p<.01). The results of logistic regression models were used to construct a VTE Risk Index comprised of 29 patient and procedure related risk factors for VTE, a score!

BACKGROUND CONTEXT: Spinal fusions have been used to treat a variety of spinal pathologies including deformity, trauma, degenerative disc disease, and spondylolisthesis. Fusions have experienced a remarkable increase in utilization over the past decade. A recent estimate suggests that over 413,000 fusions were performed in the United States in 2008 accounting for >=33.9 billion in total hospital costs. It is essential to critically evaluate surgical outcomes in order to better identify patients who benefit the most from surgical intervention. Significant volumes of clinical evidence are accruing from implementation of electronic medical records and compilation of administrative health care databases. Integration of this substantial empiric evidence into clinical decision-making is instrumental in providing higher quality, evidence based, patient centered care. PURPOSE: This study aims to use a national database to analyze the trends in perioperative complications and mortality for spinal fusion surgery, and build predictive models for complications based on patient characteristics. STUDY DESIGN/SETTING: Retrospective review of national data from a large administrative database. PATIENT SAMPLE: Patients that underwent spinal fusion of any level between 2001 and 2010. OUTCOME MEASURES: Perioperative complications, length of stay, total costs, mortality. METHODS: This study used national inpatient sample (NIS) data spanning 10 years between 2001 and 2010. Patients that underwent spinal fusions were identified using the Clinical Classification Software (CCS). Fusions were further subdivided by cervical, thoracic, or lumbar via corresponding ICD-9 procedure codes. Data on patient comorbidities, primary diagnosis, and postoperative complications was obtained via ICD-9 diagnosis codes and via the CCS categories provided by the AHRQ. National estimates were calculated using weights provided as part of the database. Time trend analysis for average length of stay, total charges, mortality, and comorbidit!

BACKGROUND CONTEXT: Incremental cost utility analysis is critical to the efficient allocation of health care resources; however, little is known regarding the determining factors of the incremental cost-effectiveness (ICER) of surgical versus nonsurgical treatment for ASD. PURPOSE: Quantify the role of baseline HRQOL and readmissions on the ICER of surgical treatment for ASD using regression-based methods to estimate the incremental effect of surgical versus nonsurgical treatment on QALYs. STUDY DESIGN/SETTING: Single-center, retrospective consecutive case series. PATIENT SAMPLE: 239 consecutive primary surgical ASD patients and 113 consecutive non-surgical ASD patients with three-year follow-up data. OUTCOME MEASURES: Payments (expressed in 2010 dollars) to the hospital were collected from administrative data, with QALYs calculated from the SF-6D. Minimum three-year follow-up was required. METHODS: Payments and QALYs were discounted at 3.5% per year. The effect of surgery on QALYs was estimated using a multivariable regression specifying QALYs after three-years as the dependent variable and baseline characteristics, along with an indicator for surgical versus non-surgical treatment, as independent variables. Results were projected through 10- year follow-up, and 95% confidence intervals (CI) were estimated using nonparametric bootstrap methods. RESULTS: Patients were predominantly female (n=297, or 84%) with average age of 48 (range from 18 to 82). Total payments to the hospital averaged $211,529 for surgical treatment, including readmissions. Surgical patients were older (49 vs 45, p=0.002) and reported lower baseline HRQOL (0.61 vs 0.71, p=0.00) than nonsurgical patients. Controlling for baseline HRQOL, diagnosis, age, and gender, surgical treatment was estimated to increase QALYs by 0.12 (p=0.00) over three-year followup period. Projected through 10-year follow-up, the ICER for a patient with average baseline HRQOL was estimated to be $578,740 (95% CI: $328,000 to >=1.1 mm), reducing $220,9!

BACKGROUND CONTEXT: Incremental cost-utility analysis is critical to the efficient allocation of health care resources; however, the incremental cost-effectiveness ratio (ICER) of surgery for adult spinal deformity (ASD) has eluded the literature due in part to inherent self selection into surgical treatment. PURPOSE: Using observed preoperative HRQOL outcomes for patients who later underwent surgery, the study builds a statistical model to predict future HRQOL as if surgical treatment where never pursued. The analysis compares predicted QALYs to observed postoperative QALYs and forms the resulting ICER. STUDY DESIGN/SETTING: Single-center, retrospective analysis of consecutive patients undergoing primary surgery for ASD. PATIENT SAMPLE: 239 consecutive patients undergoing primary surgical treatment for ASD with three-year follow-up data, out of 278 patients eligible for three-year follow-up. OUTCOME MEASURES: Payments (expressed in 2010 dollars) to the hospital were collected from administrative data, with QALYs calculated from the SF-6D. Minimum three-year follow-up was required. METHODS: Payments and QALYs were discounted at 3.5% per year. Regression analysis was used to predict hypothetical QALYs without surgery based on preoperative longitudinal data for 141 crossover surgical patients with similar diagnosis, baseline HRQOL, age, and gender compared to the study cohort. Results were projected through 10-year follow-up, and the cost-effectiveness acceptability curve (CEAC) was estimated using nonparametric bootstrap methods. RESULTS: Patients were predominantly female (n=203, 85%) with average age of 49 (range 18 to 82). With discounting, total payments to the hospital averaged $211,529, including readmissions, with average QALYs of 1.9 at three-year follow-up. Average QALYs without surgery were predicted to be 1.5 after three years. At three and five-year follow-up, the ICER was $570,000 and $278,000, respectively. Projecting through 10-year follow-up, the ICER was $105,600. Through projec!

BACKGROUND CONTEXT: Vertebral compression fractures (VCFs) secondary to low bone mass are responsible for almost 130,000 inpatient admissions and 133,500 emergency department visits annually, totaling over >=5 billion of direct inpatient costs. Although most VCFs heal within a few months with conservative therapy, a significant portion fail to improve with conservative treatment and require long-term care, conservative treatment or both. Fractures that fail conservative therapy are treated with vertebral augmentation procedures such as vertebroplasty (VP) and kyphoplasty (KP). Two large randomized clinical trials published in 2009 questioned the efficacy of VP in treatment of VAPs. PURPOSE: This study aims to investigate trends in utilization of VP and KP between 2005 and 2010 in order to capture the impact of the 2009 literature on utilization of VAPs. The study also compares patient characteristics and perioperative outcomes between VP and KP to further delineate the risks of each procedure. STUDY DESIGN/SETTING: Retrospective analysis of national utilization rates, clinical outcomes, patient demographics and patient comorbidities using a large national inpatient database. PATIENT SAMPLE: A total of 63,459 inpatient admissions from 46 states and over 1,000 different hospitals were included in the analysis. OUTCOME MEASURES: Length of stay, total direct cost, mortality, postoperative complications. METHODS: Data were obtained from the National Inpatient Sample (NIS) database for the period between 2005 and 2010. Patients undergoing VP and KP were identified via ICD-9 procedure codes. Patients under 40 years of age were excluded from the study. National utilization trends were estimated using weights supplied as part of the NIS. A series of univariate and multivariate analyses were used to compare patient characteristics, clinical outcomes, cost and length of stay between VP and KP. RESULTS: A total of 225,259 inpatient KPs and 81,790 inpatient VPs were identified in the database. Out of those !

BACKGROUND CONTEXT: Previous studies have shown improved outcomes associated with higher volume surgeons and hospitals. Revision adult spinal deformity surgery (RASDS) is a particularly high-risk intervention. We aimed to assess complication rates in RASDS by surgeon and hospital operative volume for this entity. PURPOSE: We aimed to assess complication rates in RASDS by surgeon and hospital operative volume for this entity. STUDY DESIGN/SETTING: Analysis of National Inpatient Sample. PATIENT SAMPLE: Adult spinal deformity revision surgery patients, age>50, with in-hospital stays including a spine arthrodesis for a diagnosis of scoliosis from 2003-2009. OUTCOME MEASURES: Complications, mortality, length of stay and hospital charges. METHODS: The 2003-2009 National Inpatient Sample was queried using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for patients age>50 with in-hospital stays including a spine arthrodesis for a diagnosis of scoliosis. Annual surgeon and hospital identifiers were used to allocate records into volume quartiles by number of surgeries performed in that year. Hospitals and surgeons were assigned to a quartile based on the annual volume of ASDS cases. In 2003, hospitals with <=5 procedures and surgeons with<2 were assigned to the first quartile (low-volume), whereas hospitals with >=30 and surgeons with >=11 procedures were assigned to the fourth quartile (high-volume). In 2009, the first quartile included hospitals <=10, and surgeons <=3, and the fourth quartile included hospitals >=44 and surgeons >=18. The primary endpoint was morbidity during the hospital stay. One-way analysis of variance was used to assess continuous measures, chi-square for categorical measures. RESULTS: A total of 9,321 (8774 primaries and 247 revisions) patients in the NIS database met our inclusion criteria. High volume hospitals had a greater mean number of cases annually (58/yr high volume vs 4.7/yr low volume, p<0.001). Mean hospital charges at!

BACKGROUND CONTEXT: Spine surgery may be associated with substantial blood loss necessitating transfusions. Blood loss-associated morbidity can be due to direct risks, such as hypotension and organ damage, or as result of blood transfusions. The antifibrinolytics tranexamic acid (TXA) and epsilon aminocaproic acid (EACA) are lysine analogues which inhibit activation of plasminogen and have been shown to reduce surgical blood loss. PURPOSE: The purpose of the meta-analysis is to consolidate findings of randomized controlled trials (RCTs) investigating the effects of these drugs on bleeding in spine surgery. STUDY DESIGN/SETTING: Meta-analysis. PATIENT SAMPLE: RCTs investigating effectiveness of intravenous TXA or EACA in reducing blood loss in spine surgery, compared to placebo. OUTCOME MEASURES: Outcome measures included intraoperative blood loss, total blood loss (TBL), transfusion rates and incidences of thromboembolism (TE), pulmonary embolism (PE) and myocardial infarction (MI). METHODS: MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Google Scholar were used to identify RCTs published before January 2013 that examined the effectiveness of intravenous TXA or EACA on reduction of blood loss and transfusions in spine surgery, compared to a placebo. Meta-analysis was performed using RevMan 5. Spine surgeries where blood loss was relatively small (<200ml) were excluded. Weighted mean difference was used to summarize findings across the trials for continuous outcomes. Dichotomous data were expressed as risk ratio with 95% confidence intervals (CI). Statistical significance was set at p<0.05. RESULTS: Eight RCTs were included for TXA (476 total patients) and two for EACA (218 total patients).TXA reduced intraoperative blood loss by an average of 398 ml ([-485, -311], p<0.05) and TBL by 431 ml ([-587, -275], p<0.05). TXA led to a reduction in the proportion of patients receiving a blood transfusion, RR 0.71 ([0.55, 0.92], p<0.05), relative to placebo. EACA reduced intraoperati!

BACKGROUND CONTEXT: The importance of the sagittal plane in adult spinal deformity (ASD) has been well demonstrated in the literature. Established measures of sagittal balance such as the sagittal vertical axis (SVA), T1 spinopelvic inclination (T1SPi), and the pelvic tilt (PT) can be modified by postural compensation, including pelvic retroversion and knee flexion, and by factors affecting patient positioning as in the use of patient assistive devices and patient support in standing. We introduce the T1 pelvic angle (TPA), a novel radiographic measure of sagittal alignment, which is less dependent on postural factors. The TPA is the angle of a line from the center of T1 to the femoral heads (FH) and a line from the FH to the center of the S1 endplate. PURPOSE: To investigate the relationship of the TPA and other established radiographic measures of sagittal alignment and to correlate these parameters with clinical measures of disability. STUDY DESIGN/SETTING: Multicenter, prospective database. PATIENT SAMPLE: Consecutive case series. OUTCOME MEASURES: Oswestry Disability Index (ODI), Scoliosis Research Society (SRS)-22, and Short-Form (SF)-36 Physical Component Score (PCS). METHODS: Multicenter, prospective, analysis of consecutive ASD patients. Inclusion criteria: ASD, age>18, and any of the following: scoliosis Cobb angle greater than 20degree, SVA greater than = cm, thoracic kyphosis greater than 60degree, and PT greater than 25 deg. Clinical measures of disability included ODI, SRS and SF36. RESULTS: 559 consecutive ASD patients (mean age 52.5) were enrolled. TPA correlated most strongly with SVA (r=0.837) and PI-LL (r=0.889) and PT (0.933). Categorizing the patients by increasing TPA(<10; 10-20; 20-30; >30) revealed a significant and progressive worsening in HRQOL (all p< 0.001). T1PA and SVA correlated strongly with ODI (0.435, 0.457), SF36 PCS (-0.440, -0.465) and SRS (-0.304, -0.360). Utilizing a linear regression analysis, the threshold for TPA of 19.8 was found to correspond to a sev!

BACKGROUND CONTEXT: Adolescent idiopathic scoliosis (AIS) is a complex multi-plane deformity of the spine that involves a lateral component in the coronal plane in addition to a rotational component affecting all three planes. AIS occurs in otherwise healthy children at or around puberty. The natural history of scoliosis varies significantly depending on curve pattern and pathogenesis. Potential sequelae of untreated AIS include curve progression, back pain, cardiopulmonary problems and psychosocial concerns. Optimal treatment of AIS must weigh the benefits and effectiveness of the intervention against its potential risks. This study aims to better define the risks associated with surgical intervention in AIS patients by comparing the perioperative complications of primary and revision spinal fusions in this population. PURPOSE: The goal of this study is to investigate the rates of perioperative complications of primary and revision spinal fusions for AIS. STUDY DESIGN/SETTING: Retrospective review of national data from a large administrative database. PATIENT SAMPLE: Patients between 10 and 18 years of age with diagnosis of idiopathic scoliosis undergoing primary or revision spinal fusions. OUTCOME MEASURES: Perioperative complications, length of stay, total costs, mortality. METHODS: The national inpatient sample (NIS) database was queried for patients undergoing spinal fusion for AIS between 2001 and 2010. Patients with AIS were identified as those between 10 and 18 years of age with a diagnosis of idiopathic scoliosis as identified with ICD-9 codes. Univariate and multivariate analyses were carried out comparing primary and revision fusions in terms of perioperative complications, length of stay (LOS), total cost of hospitalization and mortality. National estimates of annual total number of procedures were calculated. RESULTS: A total of 48,403 fusions were performed for AIS between 2001 and 2010. Of those fusions 1.3% (630) were revisions. Revision fusions were associated with a higher rat!