Evaluation of the Clinical and Radiographic Degenerative Spondylolisthesis (CARDS) classification system as a guide to surgical technique selection.

BACKGROUND CONTEXT: The role of fusion in degenerative spondylolisthesis (DS) is controversial. The Clinical and Radiographic Degenerative Spondylolisthesis (CARDS) classification system was developed to assist surgeons in surgical technique selection based on individual patient characteristics. This system has not been clinically validated as a guide to surgical technique selection. PURPOSE: The purpose of this study was to determine if outcomes vary with different surgical techniques across the CARDS categories. STUDY DESIGN/SETTING: Prospective cohort study performed at one Swiss and one American spine center. PATIENT SAMPLE: Five hundred eight patients with DS undergoing surgical treatment. OUTCOME MEASURES: Core Outcomes Measure Index (COMI) at 3 months and 12 months postoperatively. METHODS: Patients undergoing surgery for DS were enrolled at 2 institutions and classified according to the CARDS system using dynamic radiographs. The Core Outcome Measure Index (COMI) was completed preoperatively, and 3 and 12 months postoperatively. Surgical technique was classified as uninstrumented (decompression alone or decompression with uninstrumented fusion) or instrumented (decompression with pedicle screw instrumentation with or without interbody fusion). Unadjusted analyses and mixed effect models compared COMI scores between the two surgery technique groups (uninstrumented vs instrumented), stratified by CARDS category over time. Reoperation rates were also compared between the surgery technique groups stratified by CARDS category. Partial funding was given through NASS grant for clinical research. RESULTS: Five hundred five out of 508 patients enrolled in the study had sufficient data to be classified according to CARDS. Seven percent were classified as CARDS A, 28% as CARDS B, 48% as CARDS C, and 17% as CARDS D (CARDS A most "stable," CARDS D least "stable"). One hundred and thirty-three patients (26%) underwent decompression alone, 30 (6%) underwent decompression and uninstrumented fusion, 42 (8%) underwent decompression and posterolateral instrumented fusion, and 303 (60%) underwent decompression with posterolateral and interbody instrumented fusion. Patients in the least "stable" categories tended to be less likely to be treated with an uninstrumented technique (CARDS D 19% vs 32% for the other categories, p=.10). There were no significant differences in 3 or 12-month COMI scores between surgical technique groups stratified by CARDS category in the unadjusted or adjusted analyses. In the unadjusted analyses, there was a trend towards less improvement in 12-month COMI change score in the CARDS D patients in the uninstrumented group compared to the instrumented group (-2.7 vs -4.1, p=.10). Reoperation rates were not significantly different between the surgical technique groups stratified by CARDS category. CONCLUSIONS: In general, outcomes for uninstrumented and instrumented surgical techniques were similar across the CARDS categories. Surgeons likely took factors included in CARDS into account during surgical technique selection. This resulted in a low number of CARDS D (n=15) patients being treated with uninstrumented techniques, which limited the statistical power of this analysis. As such, this study does not validate CARDS as a useful classification system for surgical technique selection in DS.

Probabilistic Description of Streamflow and Active Length Regimes in Rivers.

In spite of the prevalence of temporary rivers over a wide range of climatic conditions, they represent a relatively understudied fraction of the global river network. Here, we exploit a well-established hydrological model and a derived distribution approach to develop a coupled probabilistic description for the dynamics of the catchment discharge and the corresponding active network length. Analytical expressions for the flow duration curve (FDC) and the stream length duration curve (SLDC) were derived and used to provide a consistent classification of streamflow and active length regimes in temporary rivers. Two distinct streamflow regimes (persistent and erratic) and three different types of active length regimes (ephemeral, perennial, and ephemeral de facto) were identified depending on the value of two dimensionless parameters. These key parameters, which are related to the underlying streamflow fluctuations and the sensitivity of active length to changes in the catchment discharge (here quantified by the scaling exponent b), originate seven different behavioral classes characterized by contrasting shapes of the underlying SLDCs and FDCs. The analytical model was tested using data gathered in three study catchments located in Italy and USA, with satisfactory model performances in most cases. Our analytical and empirical results show the existence of a structural relationship between streamflow and active length regimes, which is chiefly modulated by the scaling exponent b. The proposed framework represents a promising tool for the coupled analysis of discharge and river network length dynamics in temporary streams.

Keys to diagnosis and management of spinal epidural abscesses: 9 years of institutional experience.

OBJECTIVE: Spinal epidural abscesses (SEA's) are a challenge to diagnose, particularly if there are non-contiguous (skip) lesions. There is also limited data to predict which patients can be treated with antibiotics alone and which require surgery. We sought to assess which demographics, clinical and laboratory findings can guide both diagnosis and management of SEA's. METHODS: All patients with SEA (ICD9 324.1, ICD10 G06.1) between April 2011-May 2019 at a single tertiary center were included. A retrospective EMR review was completed. Patient and disease characteristics were compared using appropriate statistical tests. RESULTS: 108 patients underwent initial surgical treatment versus 105 that were treated medically initially; 22 (21 %) of those failed medical management. Patients who failed medical management had significantly higher CRP, longer symptom duration, and had higher rates of concurrent non-spinal infections. 9% of patients had skip lesions. Patients with skip lesions had significantly higher WBC, ESR, as well as higher rates of bacteremia and concurrent non-spinal infections. Demographic characteristics and proportion with IVDU, smoking, malignancy, and immunosuppression were similar among the three treatment groups. CONCLUSIONS: 21 % of SEA patients failed initial medical management; they had significantly greater CRP, longer symptom duration, more commonly had neurologic deficits, and concurrent non-spinal infections. 9% of patients had skip lesions; they had significantly higher WBC, ESR, rates of bacteremia and infections outside the spine. These variables may guide diagnostic imaging, and identify those at risk of failing of medical management, and therefore require more involved clinical evaluation, and consideration for surgical intervention.

Patient-Reported Allergies, a Marker of Preoperative Pain and Disability in Elective Spine Surgery.

STUDY DESIGN: Retrospective review. OBJECTIVE: Previous literature demonstrates mixed results regarding the relationship between patient-reported allergies and pain, function, and satisfaction scores. The objective of this study was to investigate the correlation between patient-reported allergies and preoperative Oswestry Disability Index (ODI), Neck Disability Index (NDI), and Patient-Reported Outcomes Measurement System (PROMIS) scores. METHODS: All patients undergoing elective cervical, lumbar procedures between May 2017 and October 2018 were included. Baseline demographic information was recorded, as well as all reported allergies or adverse reactions. Preoperative PROMIS, ODI, and NDI scores were recorded. Hierarchical multiple linear regressions were used to assess the relationship between total number of allergies and the preoperative pain and function scores. RESULTS: A total of 570 patients were included (476 lumbar, 94 cervical). The mean number of allergies reported was 1.89 ± 2.32. The mean preoperative ODI and NDI scores were 46.39 ± 17.67 and 43.47 ± 16.51, respectively. The mean preoperative PROMIS Physical Health and PROMIS Mental Health scores were 37.21 ± 6.54 and 43.89 ± 9.26, respectively. Hierarchical multiple linear regression showed that total number of reported allergies shared a statistically significant negative relationship with all of the following scores: ODI (B = 0.83, P = .02), NDI (B = 1.45, P = .02), PROMIS Physical Health (B = -0.29, P = .013), and PROMIS Mental Health (B = -0.38, P = .024). CONCLUSIONS: Patient-reported allergies share a statistically significant negative relationship with preoperative pain and function scores; as patients have increasing total number of allergies, the ODI/NDI scores become worse (increase) and the PROMIS scores become worse (decrease).

Preoperative Behavioral Health, Opioid, and Antidepressant Utilization and 2-year Costs After Spinal Fusion-Revelations From Cluster Analysis.

STUDY DESIGN: Retrospective administrative claims database analysis. OBJECTIVE: Identify distinct presurgery health care resource utilization (HCRU) patterns among posterior lumbar spinal fusion patients and quantify their association with postsurgery costs. SUMMARY OF BACKGROUND DATA: Presurgical HCRU may be predictive of postsurgical economic outcomes and help health care providers to identify patients who may benefit from innovation in care pathways and/or surgical approach. METHODS: Privately insured patients who received one- to two-level posterior lumbar spinal fusion between 2007 and 2016 were identified from a claims database. Agglomerative hierarchical clustering (HC), an unsupervised machine learning technique, was used to cluster patients by presurgery HCRU across 90 resource categories. A generalized linear model was used to compare 2-year postoperative costs across clusters controlling for age, levels fused, spinal diagnosis, posterolateral/interbody approach, and Elixhauser Comorbidity Index. RESULTS: Among 18,770 patients, 56.1% were female, mean age was 51.3, 79.4% had one-level fusion, and 89.6% had inpatient surgery. Three patient clusters were identified: Clust1 (n = 13,987 [74.5%]), Clust2 (n = 4270 [22.7%]), Clust3 (n = 513 [2.7%]). The largest between-cluster differences were found in mean days supplied for antidepressants (Clust1: 97.1 days, Clust2: 175.2 days, Clust3: 287.1 days), opioids (Clust1: 76.7 days, Clust2: 166.9 days, Clust3: 129.7 days), and anticonvulsants (Clust1: 35.1 days, Clust2: 67.8 days, Clust3: 98.7 days). For mean medical visits, the largest between-cluster differences were for behavioral health (Clust1: 0.14, Clust2: 0.88, Clust3: 16.3) and nonthoracolumbar office visits (Clust1: 7.8, Clust2: 13.4, Clust3: 13.8). Mean (95% confidence interval) adjusted 2-year all-cause postoperative costs were lower for Clust1 ($34,048 [$33,265-$34,84]) versus both Clust2 ($52,505 [$50,306-$54,800]) and Clust3 ($48,452 [$43,007-$54,790]), P < 0.0001. CONCLUSION: Distinct presurgery HCRU clusters were characterized by greater utilization of antidepressants, opioids, and behavioral health services and these clusters were associated with significantly higher 2-year postsurgical costs. LEVEL OF EVIDENCE: 3.

Reducing Radiation and Lowering Costs With a Standardized Care Pathway for Nonoperative Thoracolumbar Fractures.

STUDY DESIGN: Retrospective observational study. OBJECTIVE: There is marked variation in the management of nonoperative thoracolumbar (TL) compression and burst fractures. This was a quality improvement study designed to establish a standardized care pathway for TL fractures treated with bracing, and to then evaluate differences in radiographs, length of stay (LOS), and cost before and after the pathway. METHODS: A standardized pathway was established for management of nonoperative TL burst and compression fractures (AOSpine classification type A1-A4 fractures). Bracing, radiographs, costs, complications, and LOS before and after pathway adoption were analyzed. Differences between the neurosurgery and orthopedic spine services were compared. RESULTS: Between 2012 and 2015, 406 nonoperative burst and compression TL fractures were identified. A total of 183 (45.1%) were braced, 60.6% with a custom-made thoracolumbosacral orthosis (TLSO) and 39.4% with an off-the-shelf TLSO. The number of radiographs significantly reduced after initiation of the pathway (3.23 vs 2.63, P = .010). A total of 98.6% of braces were custom-made before the pathway; 69.6% were off-the-shelf after the pathway. The total cost for braced patients after pathway adoption decreased from $10 462.36 to $8928.58 (P = .078). Brace-associated costs were significantly less for off-the-shelf TSLO versus custom TLSO ($1352.41 vs $3719.53, respectively, P < .001). The mean LOS and complication rate did not change significantly following pathway adoption. The orthopedic spine service braced less frequently than the neurosurgery service (40.7% vs 52.2%, P = .023). CONCLUSIONS: Standardized care pathways can reduce cost and radiation exposure without increasing complication rates in nonoperative management of thoracolumbar compression and burst fractures.

A 5-Year Review of Hospital Costs and Reimbursement in the Surgical Management of Degenerative Spondylolisthesis.

BACKGROUND: To evaluate charges, expenses, reimbursement, and hospital margins with noninstrumented posterolateral fusion in situ (PLF), posterolateral fusion with pedicle screws (PPS), and PPS with interbody device (PLIF) in degenerative spondylolisthesis with spinal stenosis. METHODS: A retrospective chart review was performed from 2010 to 2014 based on ICD-9 diagnoses of degenerative spondylolisthesis with spinal stenosis in patients undergoing single-level fusions. All charges, expenses, reimbursement, and margins were obtained through financial auditing. A multivariate linear regression model was used to compare demographics, charges, etc. A 1-way analysis of variance with Tukey post hoc analysis was used to analyze reimbursements and margins based upon insurances. RESULTS: Two hundred thirty-three patients met inclusion criteria. The overall charges and expenses for PLF were significantly less compared to both types of instrumented fusions (P < .0001). Medicare and private insurance were the most common insurance types; Medicare and private insurance mean reimbursements for PLF were $36,903 and $47,086, respectively; for PPS, $37,450 and $53,851, and for PLIF $40,171 and $51,640. Hospital margins for PPS and PLIF in Medicaid patients were negative (-$3,702 and -$6,456). Hospital margins were largest for both worker's compensation and private insurance patients in all fusion groups. Hospital margins with Medicare for PLF, PPS, and PLIF were $24,347, $19,205, and $23,046, respectively. Hospital margins for private insurance for PLF, PPS, and PLIF were $37,569, $36,834, and $33,134, respectively. CONCLUSIONS: As more instrumentation is used, the more it costs both the hospital and the insurance companies; hospital margins did not increase correspondingly. CLINICAL RELEVANCE: Improved understanding of related costs and margins associated with lumbar fusions to help transition to more cost effective spine centers.

Quantifying spatiotemporal variation in headwater stream length using flow intermittency sensors.

Scientists and policymakers increasingly recognize that headwater regions contain numerous temporary streams that expand and contract in length, but accurately mapping and modeling dynamic stream networks remain a challenge. Flow intermittency sensors offer a relatively new approach to characterize wet stream length dynamics at high spatial and temporal resolutions. We installed 51 flow intermittency sensors at an average spacing of 40 m along the stream network of a high-relief, headwater catchment (33 ha) in the Valley and Ridge of southwest Virginia. The sensors recorded the presence or absence of water every 15 min for 10 months. Calculations of the wet network proportion from sensor data aligned with those from field measurements, confirming the efficacy of flow intermittency sensors. The fine temporal scale of the sensor data showed hysteresis in wet stream length: the wet network proportion was up to 50% greater on the rising limb of storm events than on the falling limb for dry antecedent conditions, at times with a delay of several hours between the maximum wet proportion and peak runoff at the catchment outlet. Less stream length hysteresis was evident for larger storms with higher event and antecedent precipitation that resulted in peak runoff > 15 mm/day. To assess spatial controls on stream wetting and drying, we performed a correlation analysis between flow duration at the sensor locations and common topographic metrics used in stream network modeling. Topography did not fully explain spatial variation in flow duration along the stream network. However, entrenched valleys had longer periods of flow on the rising limbs of events than unconfined reaches. In addition, large upslope contributing areas corresponded to higher flow duration on falling limbs. Future applications that explore the magnitude and drivers of stream length variability may provide further insights into solute and runoff generation processes in headwater regions.

Selecting Residents for Predetermined Factors Identified and Thought to be Important for Work Performance and Satisfaction: A Methodology.

OBJECTIVE: The medical profession seeks to hire and train individuals who consistently meet and/or exceed both job and cultural expectations. Resident selection is often not structured to meet this goal. The objective of this quality improvement project was to evaluate a classic unscripted interview process (OI) in conjunction with a structured, scripted interview process (SI) developed using an established hiring methodology from industry not yet utilized in health care. Qualitative questions we sought to answer: (1) Can SI be practically applied to the selection of residents? (2) Is there a significant difference in the relative position of applicants between the OI and SI rank lists? (3) Qualitatively, does SI help the evaluation/discussion of the affective domain? METHODS: Design: Prospective qualitative comparison of OI versus SI. SETTING: Dartmouth Hitchcock Medical Center, Lebanon, NH. PARTICIPANTS: Applicants were assessed by OI and SI. SI factors were selected based on a job profile. Interview scripts were created from validated behavioral and attitudinal questions. Online assessments assessed 2 important attributes - adaptability and values. Rank lists were compared for relative rank position of applicants. Feedback from faculty was obtained. RESULTS: Fifty-two applicants. Critical attributes were self-management, integrator-synthesizer, versatility, communication, and achievement. Absolute mean difference in rank/applicant was 9.8 (standard deviation 8.9, Range 0-36) positions. Comparing the top 20 candidates of each rank list, 40% of those applicants were only on one list. Faculty felt that applicants were given a greater opportunity to show "who they are." CONCLUSIONS: In conjunction with OI, an industry proven methodology was practically applied to define and select for high performance for the authors' specific institution. Comparing OI and SI resulted in substantial differences in rank lists. This initiative seemed to provide a structure to evaluate values and motivations that are inherently difficult to assess. Faculty felt SI in conjunction with OI gave a greater chance for applicants to show "who they are."

Early Effects of Medicare's Bundled Payment for Care Improvement Program for Lumbar Fusion.

STUDY DESIGN: Retrospective analysis of Medicare claims linked to hospital participation in the Center for Medicare and Medicaid Innovation's episode-based Bundled Payment for Care Improvement (BPCI) program for lumbar fusion. OBJECTIVE: To describe the early effects of BPCI participation for lumbar fusion on 90-day reimbursement, procedure volume, reoperation, and readmission. SUMMARY OF BACKGROUND DATA: Initiated on January 1, 2013, BPCI's voluntary bundle payment program provides a predetermined payment for services related to a Diagnosis-Related Group-defined "triggering event" over a defined time period. As an alternative to fee-for-service, these reforms shift the financial risk of care on to hospitals. METHODS: We identified fee-for-service beneficiaries over age 65 undergoing a lumbar fusion in 2012 or 2013, corresponding to the years before and after BPCI initiation. Hospitals were grouped based on program participation status as nonparticipants, preparatory, or risk-bearing. Generalized estimating equation models adjusting for patient age, sex, race, comorbidity, and hospital size were used to compare changes in episode costs, procedure volume, and safety indicators based on hospital BPCI participation. RESULTS: We included 89,605 beneficiaries undergoing lumbar fusion, including 36% seen by a preparatory hospital and 7% from a risk-bearing hospital. The mean age of the cohort was 73.4 years, with 59% women, 92% White, and 22% with a Charlson Comorbidity Index of 2 or more. Participant hospitals had greater procedure volume, bed size, and total discharges. Relative to nonparticipants, risk-bearing hospitals had a slightly increased fusion procedure volume from 2012 to 2013 (3.4% increase vs. 1.6% decrease, P = 0.119), did not reduce 90-day episode of care costs (0.4% decrease vs. 2.9% decrease, P = 0.044), increased 90-day readmission rate (+2.7% vs. -10.7%, P = 0.043), and increased repeat surgery rates (+30.6% vs. +7.1% points, P = 0.043). CONCLUSION: These early, unintended trends suggest an imperative for continued monitoring of BPCI in lumbar fusion. LEVEL OF EVIDENCE: 3.

Incremental Hospital Cost and Length-of-stay Associated With Treating Adverse Events Among Medicare Beneficiaries Undergoing Cervical Spinal Fusion During Fiscal Year 2013 and 2014.

STUDY DESIGN: A retrospective study. OBJECTIVE: To report the incremental hospital resources consumed with treating adverse events experienced by Medicare beneficiaries undergoing a two or three vertebrae level cervical spinal fusion. SUMMARY OF BACKGROUND DATA: Hospitals are increasingly at financial risk for patients experiencing adverse events due "pay for performance." Little is known about incremental resources consumed when treating patients who experienced an adverse event after cervical spinal fusions. METHODS: Fiscal years 2013 and 2014 Medicare Provider Analysis and Review file was used to identify 86,265 beneficiaries who underwent 2 or 3 vertebrae level cervical spinal fusion. International Classification of Diseases 9th Clinical Modification diagnostic and procedure codes were used to identify 10 adverse events. This study estimated both the observed and risk-adjusted incremental hospital resources consumed (cost [2014 US $] and length-of-stay) in treating beneficiaries experiencing each adverse event. RESULTS: Overall, 6.2% of beneficiaries undergoing cervical spinal fusion experienced at least one of the study's adverse events. Beneficiaries experiencing any complication consumed significantly more hospital resources (incremental cost of $28,638) and had longer length-of-stay (incremental stays of 9.1 days). After adjusting for patient demographics and comorbid conditions, incremental cost of treating adverse events ranged from $42,358 (infection) to $10,100 (dural tear). CONCLUSION: Adverse events frequently occur and add substantially to the hospital costs of patients undergoing cervical spinal fusion. Shared decision-making instruments should clearly provide these risk estimates to the patient before surgical consideration. Investment in activities that have been shown to reduce specific adverse events is warranted, and this study may allow health systems to prioritize performance improvement areas. LEVEL OF EVIDENCE: 3.

Predicting the Incremental Hospital Cost of Adverse Events Among Medicare Beneficiaries in the Comprehensive Joint Replacement Program During Fiscal Year 2014.

BACKGROUND: The Medicare program's Comprehensive Care for Joint Replacement (CJR) payment model places hospitals at financial risk for the treatment cost of Medicare beneficiaries (MBs) undergoing lower extremity joint replacement (LEJR). METHODS: This study uses Medicare Provider Analysis and Review File and identified 674,777 MBs with LEJR procedure during fiscal year 2014. Adverse events (death, acute myocardial infarction, pneumonia, sepsis or shock, surgical site bleeding, pulmonary embolism, mechanical complications, and periprosthetic joint infection) were studied. Multivariable regressions were modeled to estimate the incremental hospital cost of treating each adverse event. RESULTS: The risk-adjusted estimated hospital cost of treating adverse events varied from a high of $29,061 (MBs experiencing hip fracture and joint infection) to a low of $6308 (MBs without hip fracture that experienced pulmonary embolism). CONCLUSION: Avoidance of adverse events in the LEJR hospitalization will play an important role in managing episode hospital costs in the Comprehensive Care for Joint Replacement program.

Invasiveness Index as a Predictor of Surgical Site Infection after Spinal Fusion, Revision Fusion, or Laminectomy.

OBJECTIVE To evaluate invasiveness index as a potential predictor of spine surgical site infection (SSI) after spinal fusion, revision fusion, or laminectomy. DESIGN Retrospective cohort study. SETTING Single, large, academic medical center. PATIENTS Adults undergoing spinal fusion, revision fusion, or laminectomy. METHODS Data were obtained from electronic hospital databases; cases of SSI were extracted from the infection control database using National Healthcare Safety Network (NHSN) definitions. For each case, an invasiveness index, determined by surgical approach, procedure, and number of spine levels treated, was calculated using current procedural terminology (CPT) billing codes. Statistical analyses were performed using univariate and multivariate logistic regression models. RESULTS In total, 3,143 patients met inclusion criteria, and 43 of these developed SSI. Multivariate regression showed that advanced age (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.005-1.05, for each year of life) and invasiveness index (medium invasiveness index OR, 5.36; 95% CI, 1.92-14.96; high invasiveness index OR, 14.1; 95% CI, 4.38-45.43) were significant predictors of infection. In subgroup analyses of spinal fusion patients, morbid obesity (OR, 2.542; 95% CI, 1.08-5.99), trauma (OR, 2.41; 95% CI, 1.05-5.55), and invasiveness index (medium invasiveness index OR, 5.39; 95% CI, 1.56-18.61; high invasiveness index OR, 13.44; 95% CI, 3.28-55.01) were significant predictors of SSI. Models containing invasiveness index were compared to NHSN models and demonstrated similar performance. CONCLUSIONS Invasiveness index is a predictor of SSI after spinal fusion and performs similarly to NHSN models. Invasiveness index shows promise as a potential risk stratification tool that is easily calculated and is available preoperatively. Infect Control Hosp Epidemiol 2016:1-7.

Incremental Hospital Cost and Length-of-Stay Associated With Treating Adverse Events Among Medicare Beneficiaries Undergoing Lumbar Spinal Fusion During Fiscal Year 2013.

STUDY DESIGN: A retrospective study. OBJECTIVES: To report the incremental hospital resource consumption associated with treating selected adverse events experienced by Medicare beneficiaries undergoing a two- or three-level lumbar spinal fusion. SUMMARY OF BACKGROUND DATA: Hospitals are increasingly at financial risk for the incremental resources consumed in treating patients experiencing adverse events because of public and private third-party payers' efforts to base hospital reimbursement on "pay for performance" measures. However, little is known about average incremental resources consumed in treating patients experiencing adverse events following lumbar spinal fusions. METHODS: The 2013 fiscal year Medicare Provider Analysis and Review file was used to identify 83,658 Medicare beneficiaries who underwent two- or three vertebrae-level lumbar spinal fusion. International Classification of Diseases-9th-Clinical Modification diagnostic and procedure codes were used to identify the frequencies of nine adverse events. This study estimated both the observed and risk-adjusted incremental hospital resources consumed (cost and length of stay [LOS]) in treating Medicare beneficiaries experiencing each adverse event. RESULTS: Overall, 17.7% of Medicare beneficiaries undergoing lumbar spinal fusion experienced at least one of the study's adverse events. Medicare beneficiaries experiencing any complication consumed significantly more hospital resources (incremental cost of $8911) and had longer LOS (incremental stays of 5.7 days). After adjusting for patient demographics and comorbid conditions, incremental cost of treating adverse events ranged from a high of $32,049 (infection) to a low of $9976 (transfusion). CONCLUSION: Adverse events frequently occur and add substantially to the hospital resource costs of patients undergoing spinal fusion. Shared decision-making instruments should clearly provide these risk estimates to the patient before surgical consideration. Investment in activities that have been shown to reduce specific adverse events is warranted, and this project may allow health systems to prioritize performance improvement areas. LEVEL OF EVIDENCE: 3.

The Incremental Hospital Cost and Length-of-Stay Associated With Treating Adverse Events Among Medicare Beneficiaries Undergoing THA During Fiscal Year 2013.

This paper estimates the incremental hospital resource consumption associated with treating selected adverse events experienced by Medicare beneficiaries (MBs) undergoing total hip arthroplasty (THA). This retrospective study, using the Medicare Provider Analysis and Review file, identified 174,167 MBs who underwent THA in 2013. Overall, 20.16% of MB undergoing THA experienced at least one adverse event. MB experiencing any adverse event consumed significantly higher hospital cost ($3429) and had longer length of stays (1.0 day). The risk-adjusted incremental cost of treating adverse events ranged from a high of $27,116 (pneumonia) to a low of $2626 (hemorrhage or post-operative shock requiring transfusion). Most major adverse events occurred infrequently, however when adverse events occurred, they add substantially to the hospital resource costs of treating MB.

Defining Avoidable and Unavoidable Complications in Spine Surgery: A Survey-based Study of Spine Fellowship Directors.

STUDY DESIGN: A cross-sectional survey of orthopedic spine surgery fellowship directors in the United States. OBJECTIVE: The aim of this study was to investigate whether consensus exists with respect to spine-related adverse events and certain hospital-acquired conditions (HACs) or "never events." SUMMARY OF BACKGROUND DATA: As part of a broad effort to improve health care outcomes, providers are no longer reimbursed for HACs, which are deemed avoidable. Although some HACs are unquestionably preventable with proper quality control measures, research suggests that even scrupulous adherence to evidence-based guidelines cannot eliminate others. METHODS: Surveys were distributed via email and post. Participants rated 27 HACs and selected spine-specific events on an ordinal scale. Interobserver reliability was assessed among all 46 spine directors (respondents) using the intraclass correlation coefficient (ICC), based on a two-way random effects model, assuming that the participants were a representative population sample of spine surgeons. Multivariable linear regression analyses were performed on each of the 27 complications to identify potential demographic factors that could be associated with variation among respondents in their ratings of "avoidable" to "unavoidable." RESULTS: Forty-six fellowship directors responded, of whom 98% were orthopedic spine surgeons. The majority (80.4%) of respondents had greater than 10 years' experience as a spine surgeon, and 66.7% had an annual surgical volume >201 cases. The multivariable linear regression analyses found that demographic factors were not predictive of the directors' ratings. The complications thought to be completely avoidable (median scores 1) included "Incompatible blood," "Retained foreign object," and "Wrong level surgery." The HAC considered least avoidable was "Site infection with risk factors" (median score 8). Among 17 spine-specific complications, "L4-L5 disc re-herniation within 3 months" (median score 9) was considered least avoidable. CONCLUSION: This survey suggests that orthopedic spine surgeons consider most "never events" neither avoidable nor unavoidable. There is strong consensus only about the HACs resulting from obvious medical error. LEVEL OF EVIDENCE: 4.

Validation of an administrative coding algorithm for classifying surgical indication and operative features of spine surgery.

STUDY DESIGN: Retrospective review of medical records and administrative data. OBJECTIVE: Validate a claims-based algorithm for classifying surgical indication and operative features in lumbar surgery. SUMMARY OF BACKGROUND DATA: Administrative data are valuable to study rates, safety, outcomes, and costs in spine surgery. Previous research evaluates outcomes by procedure, not indications and operative features. One previous study validated a coding algorithm for classifying surgical indication. Few studies examined claims data for classifying patients by operative features. METHODS: Patients undergoing lumbar decompression or fusion at a single institution in 2009 for back pain, herniated disc, stenosis, spondylolisthesis, or scoliosis were included. Sensitivity and specificity of a claims-based algorithm for indication and operative features were examined versus medical record abstraction. RESULTS: A total of 477 patients, including 246 (52%) undergoing fusion and 231 (48%) undergoing decompression were included in this study. Sensitivity of the claims-based coding algorithm for classifying the indication for the procedure was 71.9% for degenerative disc disease, 81.9% for disc herniation, 32.7% for spinal stenosis, 90.4% for degenerative spondylolisthesis, and 93.8% for scoliosis. Specificity was 87.9% for degenerative disc, 85.6% for disc herniation, 90.7% for spinal stenosis, 95.0% for degenerative spondylolisthesis, and 97.3% for scoliosis. Sensitivity and specificity of claims data for identifying the type of procedure for fusion cases was 97.6% and 99.1%, respectively. Sensitivity of claims data for characterizing key operative features was 81.7%, 96.4%, and 53.0% for use of instrumentation, combined (anterior and posterior) surgical approach, and 3 or more disc levels fused, respectively. Specificity was 57.1% for instrumentation, 94.5% for combined approaches, and 71.9% for 3 or more disc levels fused. CONCLUSION: Claims data accurately reflected certain diagnoses and type of procedures, but were less accurate at characterizing operative features other than the surgical approach. This study highlights both the potential and current limitations of claims-based analysis for spine surgery.

The effect of high obesity on outcomes of treatment for lumbar spinal conditions: subgroup analysis of the spine patient outcomes research trial.

STUDY DESIGN: Spine Patient Outcomes Research Trial subgroup analysis. OBJECTIVE: To evaluate the effect of high obesity on management of lumbar spinal stenosis, degenerative spondylolisthesis (DS), and intervertebral disc herniation (IDH). SUMMARY OF BACKGROUND DATA: Prior Spine Patient Outcomes Research Trial analyses compared nonobese and obese patients. This study compares nonobese patients (body mass index<30 kg/m) with those with class I obesity (body mass index=30-35 kg/m) and class II/III high obesity (body mass index≥35 kg/m). METHODS: For spinal stenosis, 250 of 634 nonobese patients, 104 of 167 obese patients, and 59 of 94 highly obese patients underwent surgery. For DS, 233 of 376 nonobese patients, 90 of 129 obese patients, and 66 of 96 highly obese patients underwent surgery. For IDH, 542 of 854 nonobese patients, 151 of 207 obese patients, and 94 of 129 highly obese patients underwent surgery. Outcomes included Short Form-36, Oswestry Disability Index, stenosis/sciatica bothersomeness index, low back pain bothersomeness index, operative events, complications, and reoperations. Operative and nonoperative outcomes were compared by change from baseline at each follow-up interval using a mixed effects longitudinal regression model. An as-treated analysis was performed because of crossover between surgical and nonoperative groups. RESULTS: Highly obese patients had increased comorbidities. Baseline Short Form-36 physical function scores were lowest for highly obese patients. For spinal stenosis, surgical treatment effect and difference in operative events among groups were not significantly different.For DS, greatest treatment effect for the highly obese group was found in most primary outcome measures, and is attributable to the significantly poorer nonoperative outcomes. Operative times and wound infection rates were greatest for highly obese patients.For IDH, highly obese patients experienced less improvement postoperatively compared with obese and nonobese patients. However, nonoperative treatment for highly obese patients was even worse, resulting in greater treatment effect in almost all measures. Operative time was greatest for highly obese patients. Blood loss and length of stay was greater for both obese cohorts. CONCLUSION: Highly obese patients with DS experienced longer operative times and increased infection. Operative time was greatest for highly obese patients with IDH. DS and IDH saw greater surgical treatment effect for highly obese patients due to poor outcomes of nonsurgical management. LEVEL OF EVIDENCE: 3.

Isotopic signals of summer denitrification in a northern hardwood forested catchment.

Despite decades of measurements, the nitrogen balance of temperate forest catchments remains poorly understood. Atmospheric nitrogen deposition often greatly exceeds streamwater nitrogen losses; the fate of the remaining nitrogen is highly uncertain. Gaseous losses of nitrogen to denitrification are especially poorly documented and are often ignored. Here, we provide isotopic evidence (δ(15)NNO3 and δ(18)ONO3) from shallow groundwater at the Hubbard Brook Experimental Forest indicating extensive denitrification during midsummer, when transient, perched patches of saturation developed in hillslopes, with poor hydrological connectivity to the stream, while streamwater showed no isotopic evidence of denitrification. During small rain events, precipitation directly contributed up to 34% of streamwater nitrate, which was otherwise produced by nitrification. Together, these measurements reveal the importance of denitrification in hydrologically disconnected patches of shallow groundwater during midsummer as largely overlooked control points for nitrogen loss from temperate forest catchments.