Comprehensive Training Model for Procedural Guidance of Transcatheter Mitral Valve Edge-to-Edge Repair: Divide and Conquer Approach.

Transcatheter edge-to-edge repair (TEER) of the mitral valve is a complex procedure requiring continuous image guidance with 2-dimensional and 3-dimensional transesophageal echocardiography. In this context, the role of the echocardiographer is of paramount importance. Training in interventional echocardiography for procedures such as TEER requires comprehending the complicated workflow of the hybrid operating room and advanced imaging skills that go beyond traditional echocardiography training to guide the procedure. Despite TEER being more commonly performed, the training structure for interventional echocardiographers is lagging, with many practitioners not having any formal training in image guidance for this procedure. In this context, novel training strategies must be developed to increase exposure and aid training. In this review, the authors present a step-wise approach to training for image guidance during TEER of the mitral valve. The authors have deconstructed this complex procedure into modular components and have incremental stages of training based on different steps of the procedure. At each step, trainees must demonstrate proficiency before advancing to the next step, thus ensuring a more structured approach to attaining proficiency in this complex procedure.

Overview of the Interatrial Septum: Review of Cardiac Nomenclature for Transseptal Puncture.

Transseptal puncture is an increasingly common procedure undertaken to gain access to the left side of the heart during structural heart disease interventions. Precision guidance during this procedure is paramount to ensure success and patient safety. As such, multimodality imaging, such as echocardiography, fluoroscopy, and fusion imaging, is routinely used to guide safe transseptal puncture. Despite the use of multimodal imaging, there is currently no uniform nomenclature of cardiac anatomy between the various imaging modes and proceduralists, and echocardiographers tend to use imaging modality-specific terminology when communicating among the various imaging modes. This variability in nomenclature among imaging modes stems from differing anatomic descriptions of cardiac anatomy. Given the required level of precision in performing transseptal puncture, a clearer understanding of the basis of cardiac anatomic nomenclature is required by both echocardiographers as well as proceduralists; enhanced understanding can help facilitate communication across specialties and possibly improve communication and safety. In this review, the authors highlight the variation in cardiac anatomy nomenclature among various imaging modes.

Accuracy of Stereovision-Updated Versus Preoperative CT-Based Image Guidance in Multilevel Lumbar Pedicle Screw Placement: A Cadaveric Swine Study.

Change in vertebral position between preoperative imaging and the surgical procedure reduces the accuracy of image-guided spinal surgery, requiring repeated imaging and surgical field registration, a process that takes time and exposes patients to additional radiation. We developed a handheld, camera-based, deformable registration system (intraoperative stereovision, iSV) to register the surgical field automatically and compensate for spinal motion during surgery without further radiation exposure. Methods: We measured motion-induced errors in image-guided lumbar pedicle screw placement in 6 whole-pig cadavers using state-of-the-art commercial spine navigation (StealthStation; Medtronic) and iSV registration that compensates for intraoperative vertebral motion. We induced spinal motion by using preoperative computed tomography (pCT) of the lumbar spine performed in the supine position with accentuated lordosis and performing surgery with the animal in the prone position. StealthStation registration of pCT occurred using metallic fiducial markers implanted in each vertebra, and iSV data were acquired to perform a deformable registration between pCT and the surgical field. Sixty-eight pedicle screws were placed in 6 whole-pig cadavers using iSV and StealthStation registrations in random order of vertebral level, relying only on image guidance without invoking the surgeon's judgment. The position of each pedicle screw was assessed with post-procedure CT and confirmed via anatomical dissection. Registration errors were assessed on the basis of implanted fiducials. Results: The frequency and severity of pedicle screw perforation were lower for iSV registration compared with StealthStation (97% versus 68% with Grade 0 medial perforation for iSV and StealthStation, respectively). Severe perforation occurred only with StealthStation (18% versus 0% for iSV). The overall time required for iSV registration (computational efficiency) was ∼10 to 15 minutes and was comparable with StealthStation registration (∼10 min). The mean target registration error was smaller for iSV relative to StealthStation (2.81 ± 0.91 versus 8.37 ± 1.76 mm). Conclusions: Pedicle screw placement was more accurate with iSV registration compared with state-of-the-art commercial navigation based on preoperative CT when alignment of the spine changed during surgery. Clinical Relevance: The iSV system compensated for intervertebral motion, which obviated the need for repeated vertebral registration while providing efficient, accurate, radiation-free navigation during open spinal surgery.

A Sequential Approach for Echocardiographic Guidance of Transseptal Puncture: The PITLOC Protocol.

With advancements in technology and progress in interventional procedures, left-sided structural heart disease (SHD) interventions have become part of everyday clinical practice. One of the most important steps for a successful left-sided structural heart intervention is the transseptal puncture (TSP). Appropriate transesophageal echocardiographic (TEE) guidance of TSP requires extensive supervised hands-on experience prior to attaining proficiency. Whereas some TEE skills are acquired during cardiac anesthesia fellowships, continuous procedural guidance during SHD interventions requires substantial hands-on experience. Several studies have emphasized the value of advanced training in imaging for SHD interventions; however, the pathways and advanced training to ensure proficiency in interventional echocardiography have not yet been clearly established. In an effort to achieve a uniform and consistent approach to TSP imaging that is homogeneous and complementary to the component steps of the TSP procedure from an interventional point-of-view, the authors have developed a protocol for providing image guidance for TSP - the PITLOC protocol (Practice, Identification of septal puncture needle, Tracking of needle tip, Localization of needle tip in fossa ovalis, Optimizing septal indentation, and, finally, Crossing the interatrial septum under direct vision). This protocol aims to standarize image guidance for TSP while complementing the the steps of the procedure as performed and described by interventionalists.

A level-wise spine registration framework to account for large pose changes.

PURPOSES: Accurate and efficient spine registration is crucial to success of spine image guidance. However, changes in spine pose cause intervertebral motion that can lead to significant registration errors. In this study, we develop a geometrical rectification technique via nonlinear principal component analysis (NLPCA) to achieve level-wise vertebral registration that is robust to large changes in spine pose. METHODS: We used explanted porcine spines and live pigs to develop and test our technique. Each sample was scanned with preoperative CT (pCT) in an initial pose and rescanned with intraoperative stereovision (iSV) in a different surgical posture. Patient registration rectified arbitrary spinal postures in pCT and iSV into a common, neutral pose through a parameterized moving-frame approach. Topologically encoded depth projection 2D images were then generated to establish invertible point-to-pixel correspondences. Level-wise point correspondences between pCT and iSV vertebral surfaces were generated via 2D image registration. Finally, closed-form vertebral level-wise rigid registration was obtained by directly mapping 3D surface point pairs. Implanted mini-screws were used as fiducial markers to measure registration accuracy. RESULTS: In seven explanted porcine spines and two live animal surgeries (maximum in-spine pose change of 87.5 mm and 32.7 degrees averaged from all spines), average target registration errors (TRE) of 1.70 ± 0.15 mm and 1.85 ± 0.16 mm were achieved, respectively. The automated spine rectification took 3-5 min, followed by an additional 30 secs for depth image projection and level-wise registration. CONCLUSIONS: Accuracy and efficiency of the proposed level-wise spine registration support its application in human open spine surgeries. The registration framework, itself, may also be applicable to other intraoperative imaging modalities such as ultrasound and MRI, which may expand utility of the approach in spine registration in general.

Anesthesia Considerations in Neurological Emergencies.

Airway obstruction and respiratory failure are common complications of neurological emergencies. Anesthesia is often employed for airway management, surgical and endovascular interventions or in the intensive care units in patients with altered mental status or those requiring burst suppression. This article provides a summary of the unique airway management and anesthesia considerations and controversies for neurologic emergencies in general, as well as for specific commonly encountered conditions: elevated intracranial pressure, neuromuscular respiratory failure, acute ischemic stroke, and acute cervical spinal cord injury.

Hand-Held Stereovision System for Image Updating in Open Spine Surgery.

BACKGROUND: Image guidance in open spinal surgery is compromised by changes in spinal alignment between preoperative images and surgical positioning. We evaluated registration of stereo-views of the surgical field to compensate for vertebral alignment changes. OBJECTIVE: To assess accuracy and efficiency of an optically tracked hand-held stereovision (HHS) system to acquire images of the exposed spine during surgery. METHODS: Standard midline posterior approach exposed L1 to L6 in 6 cadaver porcine spines. Fiducial markers were placed on each vertebra as "ground truth" locations. Spines were positioned supine with accentuated lordosis, and preoperative computed tomography (pCT) was acquired. Spines were re-positioned in a neutral prone posture, and locations of fiducials were acquired with a tracked stylus. Intraoperative stereovision (iSV) images were acquired and 3-dimensional (3D) surfaces of the exposed spine were reconstructed. HHS accuracy was assessed in terms of distances between reconstructed fiducial marker locations and their tracked counterparts. Level-wise registrations aligned pCT with iSV to account for changes in spine posture. Accuracy of updated computed tomography (uCT) was assessed using fiducial markers and other landmarks. RESULTS: Acquisition time for each image pair was <1 s. Mean reconstruction time was <1 s for each image pair using batch processing, and mean accuracy was 1.2 ± 0.6 mm across 6 cases. Mean errors of uCT were 3.1 ± 0.7 and 2.0 ± 0.5 mm on the dorsal and ventral sides, respectively. CONCLUSION: Results suggest that a portable HHS system offers potential to acquire accurate image data from the surgical field to facilitate surgical navigation during open spine surgery.

Measuring protein biomarker concentrations using antibody tagged magnetic nanoparticles.

Under physiological conditions biomarker concentrations tend to rise and fall over time e.g. for inflammation. Ex vivo measurements provide a snapshot in time of biomarker concentrations, which is useful, but limited. Approaching real time monitoring of biomarker concentration(s) using a wearable, implantable or injectable in vivo sensor is therefore an appealing target. As an early step towards developing an in vivo biomarker sensor, antibody (AB) tagged magnetic nanoparticles (NPs) are used here to demonstrate the in vitro measurement of ~5 distinct biomarkers with high specificity and sensitivity. In previous work, aptamers were used to target a given biomarker in vitro and generate magnetic clusters that exhibit a characteristic rotational signature quite different from free NPs. Here the method is expanded to detect a much wider range of biomarkers using polyclonal ABs attached to the surface of the NPs. Commercial ABs exist for a wide range of targets allowing accurate and specific concentration measurements for most significant biomarkers. We show sufficient detection sensitivity, using an in-house spectrometer to measure the rotational signatures of the NPs, to assess physiological concentrations of hormones, cytokines and other signaling molecules. Detection limits for biomarkers drawn mainly from pain and inflammation targets were: 10 pM for mouse Granzyme B (mGZM-B), 40 pM for mouse interferon-gamma (mIFN-γ), 7 pM for mouse interleukin-6 (mIL-6), 40 pM for rat interleukin-6 (rIL-6), 40 pM for mouse vascular endothelial growth factor (mVEGF) and 250 pM for rat calcitonin gene related peptide (rCGRP). Much lower detection limits are certainly possible using improved spectrometers and nanoparticles.

The Spectrum of Pediatric Cardiac Procedures and Their Outcomes: A Six-month Report from the Largest Cardiac Facility in Sindh, Pakistan.

Introduction Congenital heart disease (CHD) is the most common birth defect globally, with low-to-middle income Asian countries registering the highest incidence. Every year, 60,000 babies are born with varying severity of CHD in Pakistan. But the country has only three pediatric intensive care units (PICU) fully dedicated to child cardiac surgery patients. The focus of this study is to analyze the spectrum of pediatric cardiac surgical procedures performed for the management of CHD and their outcomes in a cardiac PICU in Pakistan. Methods In this analysis, all surgical records of children admitted to the PICU of National Institute of Cardiovascular Diseases (NICVD), Karachi, from October 2018 to March 2019 were included. It is a 14-bed, state-of-the-art cardiac PICU, which provides high-quality care to critical post-surgical patients. Results The surgical records of 537 patients were extracted for the purpose of our study, which accounted for 89.5 of post-operative patients admitted in the PICU per month and three per day. Tetralogy of Fallot (TOF) was the most commonly treated anomaly (n = 161; 29.9%) in the facility, followed by ventricular septal defect (n = 107; 19.9%). The overall mortality rate was 5.4% (n = 29), out of which 27.5% (n = 8) were TOF-related. Conclusions There is a very high burden of patients on the cardiac PICUs in low-to-middle income Asian countries. Despite the lack of resources, the high- quality care provided by pediatric cardiac critical-care specialists at these PICUs has ensured favorable outcomes and a mortality rate as low as that in any of the developed countries.

Incidence of Aortic Regurgitation in Association with Type of Ventricular Septal Defects and its Immediate and Intermediate Outcome after Surgical Closure.

Introduction Ventricular septal defect (VSD) is one of the more common congenital heart defects, and aortic regurgitation (AR) is its major complication if it remains unrepaired. We aim to determine the AR incidence in various types of VSD, its immediate and intermediate six to 12-month post-VSD repair outcomes of AR. Methods We conducted a retrospective review of medical records of all children aged 18 years or younger who were diagnosed with single VSD at our institution from 2016 to 2018. VSD was classified according to its location and relation to the tricuspid annulus and semilunar valve. AR severity grading was done according to the American Society of Echocardiography, and vena contracta width (VC) was taken as the main parameter for severity. We defined trivial-to-mild AR as VC width less than 0.3 cm, moderate AR was 0.3-0.6 cm VC width, and severe AR was VC width of more than 0.6 cm. Immediate and intermediate outcomes of surgical closure, such as residual VSD and AR, were observed. Results One hundred ninety patients with isolated single VSD were included in the study. Of those, 114 patients had perimembranous VSD (60.0%), 64 patients had muscular VSD (33.7%), and 12 patients had supracristal VSD (6.3%). The median age of our study cohort was six months, with a male to female ratio of 1.3:1. Aortic valve prolapse (28.9%; n = 55) and AR (23.2%; n = 44) were the most common findings on echocardiographic evaluation of VSD patients. Most cases of VSD with AR had trivial-to-mild AR, (68.2%; n = 30). AR was most commonly seen in supracristal VSD (83.3%; n = 10) followed by perimembranous VSD (28.9%; n = 33). VSD closed spontaneously in 34 patients (17.9%) and 98 patients (51.6%) patients underwent surgery. Residual VSD after surgical closure was present in 57.1% (56) and 17.3% (17) of the patients immediate postoperatively and six- to 12-month postoperative follow-up, respectively. Similarly, residual AR after surgical closure of VSD was present in 32.7% (32) and 15.3% (15) of the patients immediate postoperatively and six- to 12-month postoperative follow-up, respectively. Conclusion The incidence of AR with VSD was very high in our study; AR was most commonly associated with supracristal VSD. After surgical repair, mild AR decreased with time. Early corrective surgery of VSD can prevent this complication and help improve outcomes.

Trends in Lumbar Fusion Procedure Rates and Associated Hospital Costs for Degenerative Spinal Diseases in the United States, 2004 to 2015.

STUDY DESIGN: Analysis of National Inpatient Sample (NIS), 2004 to 2015. OBJECTIVE: Describe recent trends in US rates of lumbar fusion procedures and associated costs, by surgical indication. SUMMARY OF BACKGROUND DATA: Spinal fusion is appropriate for spinal deformity and instability, but evidence of effectiveness is limited for primary disc herniation and spinal stenosis without instability. It remains controversial for treatment of axial pain secondary to degenerative disc disease. There are potential non-instability, non-deformity indications for fusion surgery, including but not limited to severe foraminal stenosis and third-time disc herniation. METHODS: Elective lumber fusion trends were reported using Poisson regression, grouped by indication as degenerative scoliosis, degenerative spondylolisthesis, spinal stenosis, disc herniation, and disc degeneration. Generalize linear regression was used to estimate trends in hospital costs, adjusted for age, sex, indication, comorbidity, and inflation. RESULTS: Volume of elective lumbar fusion increased 62.3% (or 32.1% per 100,000 US adults), from 122,679 cases (60.4 per 100,000) in 2004 to 199,140 (79.8 per 100,000) in 2015. Increases were greatest among age 65 or older, increasing 138.7% by volume (73.2% by rate), from 98.3 per 100,000 (95% confidence interval [CI] 97.2, 99.3) in 2004 to 170.3 (95% CI 169.2, 171.5) in 2015. Although the largest increases were for spondylolisthesis (+47,390 operations, 111%) and scoliosis (+16,129 operations, 186.6%), disc degeneration, herniation, and stenosis combined to accounted for 42.3% of total elective lumbar fusions in 2015. Aggregate hospital costs increased 177% during these 12 years, exceeding $10 billion in 2015, and averaging more than $50,000 per admission. CONCLUSION: While the prevalence of spinal pathologies is not known, the rate of elective lumbar fusion surgery in the United States increased most for spondylolisthesis and scoliosis, indications with relatively good evidence of effectiveness. The proportion of fusions coded for indications with less evidence of effectiveness has slightly decreased in the most recent years. LEVEL OF EVIDENCE: 3.

Understanding the value of minimally invasive procedures for the treatment of lumbar spinal stenosis: the case of interspinous spacer devices.

BACKGROUND CONTEXT: Minimally invasive lumbar spinal stenosis procedures have uncertain long-term value. PURPOSE: This study sought to characterize factors affecting the long-term cost-effectiveness of such procedures using interspinous spacer devices ("spacers") relative to decompression surgery as a case study. STUDY DESIGN: Model-based cost-effectiveness analysis. PATIENT SAMPLE: The Medicare Provider Analysis and Review database for the years 2005-2009 was used to model a group of 65-year-old patients with spinal stenosis who had no previous spine surgery and no contraindications to decompression surgery. OUTCOME MEASURES: Costs, quality-adjusted life years (QALYs), and cost per QALY gained were the outcome measures. METHODS: A Markov model tracked health utility and costs over 10 years for a 65-year-old cohort under three care strategies: conservative care, spacer surgery, and decompression surgery. Incremental cost-effectiveness ratios (ICER) reported as cost per QALY gained included direct medical costsfor surgery. Medicare claims data were used to estimate complication rates, reoperation, and related costs within 3 years. Utilities and long-term reoperation rates for decompression were derived frompublished studies. Spacer failure requiring reoperation beyond 3 years and post-spacer health utilities are uncertain and were evaluated through sensitivity analyses. In the base-case, the spacer failure rate was held constant for years 4-10 (cumulative failure: 47%). In a "worst-case" analysis, the 10-year cumulative reoperation rate was increased steeply (to 90%). Threshold analyses were performed to determine the impact of failure and post-spacer health utility on the cost-effectiveness of spacer surgery. RESULTS: The spacer strategy had an ICER of $89,500/QALY gained under base-case assumptions, and remained under $100,000 as long as the 10-year cumulative probability of reoperation did not exceed 54%. Under worst-case assumptions, the spacer ICER was $482,000/QALY and fell below $100,000 only if post-spacer utility was 0.01 greater than post-decompression utility or the cost of spacer surgery was $1,600 less than the cost of decompression surgery. CONCLUSIONS: Spacers may provide a reasonably cost-effective initial treatment option for patients with lumbar spinal stenosis. Their value is expected to improve if procedure costs are lower in outpatient settings where these procedures are increasingly being performed. Decision analysis is useful for characterizing the long-term cost-effectiveness potential for minimally invasive spinal stenosis treatments and highlights the importance of complication rates and prospective health utility assessment.

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.

Use of Stereovision for Intraoperative Coregistration of a Spinal Surgical Field: A Human Feasibility Study.

BACKGROUND: The use of image guidance during spinal surgery has been limited by several anatomic factors such as intervertebral segment motion and ineffective spine immobilization. In its current form, the surgical field is coregistered with a preoperative computed tomography (CT), often obtained in a different spinal confirmation, or with intraoperative cross-sectional imaging. Stereovision offers an alternative method of registration. OBJECTIVE: To demonstrate the feasibility of stereovision-mediated coregistration of a human spinal surgical field using a proof-of-principle study, and to provide preliminary assessments of the technique's accuracy. METHODS: A total of 9 subjects undergoing image-guided pedicle screw placement also underwent stereovision-mediated coregistration with preoperative CT imaging. Stereoscopic images were acquired using a tracked, calibrated stereoscopic camera system mounted on an operating microscope. Images were processed, reconstructed, and segmented in a semi-automated manner. A multistart registration of the reconstructed spinal surface with preoperative CT was performed. Registration accuracy, measured as surface-to-surface distance error, was compared between stereovision registration and a standard registration. RESULTS: The mean surface reconstruction error of the stereovision-acquired surface was 2.20 ± 0.89 mm. Intraoperative coregistration with stereovision was performed with a mean error of 1.48 ± 0.35 mm compared to 2.03 ± 0.28 mm using a standard point-based registration method. The average computational time for registration with stereovision was 95 ± 46 s (range 33-184 s) vs 10to 20 min for standard point-based registration. CONCLUSION: Semi-automated registration of a spinal surgical field using stereovision is possible with accuracy that is at least comparable to current landmark-based techniques.

Validation of Using Claims Data to Measure Safety of Lumbar Fusion Surgery.

STUDY DESIGN: Retrospective analysis of patients undergoing elective lumbar fusion operations, comparing rates of repeat spine surgery based on method of ascertainment. OBJECTIVE: We report the accuracy of a claims-based approach for reporting repeat surgery compared with medical records abstraction as the "gold standard." SUMMARY OF BACKGROUND DATA: Previous studies have reported the validity of a claims-based algorithm for grouping patients by surgical indication and classifying operative features, but their accuracy in measuring surgical quality indicators has not been widely examined. METHODS: We identified a subset of patients undergoing elective lumbar fusion operations at a single institution from 1996 to 2011, excluding those with spinal fracture, spinal cord injury, or cancer. From the medical record we abstracted the incidence of repeat spine operation or rehospitalization at 1 year. We cross-classified each event record with its corresponding value derived from claims. The sensitivity and specificity of the claims-based approach were calculated for reoperation within 30, 90, and 365 days, and all-cause hospital readmission within 30 days. RESULTS: Medical records linked to claims data were obtained for 520 patients undergoing elective lumbar fusion. Reoperation rates based on chart review were 1.0%, 1.3%, 3.6%, compared with 0.8%, 1.7%, and 3.8% based on the final claims methods at 30, 90, and 365 days, respectively. The claims-based algorithm had sensitivities of 80.0%, 100%, and 94.1% and specificities of 100%, 99.6%, 99.2% for repeat surgery within 30, 90, and 365 days, respectively. The sensitivity for all-cause readmission was 50%. CONCLUSION: Health care quality improvement efforts often rely on administrative data to report surgical safety. We found that claims-based ascertainment of safety at a single institution was very accurate. However, accuracy depended on careful attention to the timing of outcomes, as well as the definitions and coding of repeat surgery, including how orthopedic device removal codes are classified. LEVEL OF EVIDENCE: 3.

Bone Morphogenetic Protein Use and Cancer Risk Among Patients Undergoing Lumbar Arthrodesis: A Case-Cohort Study Using the SEER-Medicare Database.

BACKGROUND: Recombinant bone morphogenetic proteins (BMPs) are growth factors utilized in lumbar arthrodeses. Limited data from randomized trials suggest that BMP may increase cancer risk. We sought to evaluate cancer risk and mortality following the use of BMP in lumbar arthrodesis. METHODS: Within the linked Surveillance, Epidemiology, and End Results (SEER) Program-Medicare cohort, we conducted a case-cohort study of 7,278 individuals who were ≥65 years of age and had undergone a lumbar arthrodesis from 2004 to 2011. Of these patients, 3,627 were individuals in a 5% random subcohort of Medicare enrollees in SEER areas including 191 who developed cancer, and there were 3,651 individuals outside the subcohort who developed cancer. Weighted Cox proportional-hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) for cancer on the basis of exposure to BMP. RESULTS: In the SEER-Medicare subcohort, 30.7% of individuals who underwent a lumbar arthrodesis received BMP. BMP was not associated with overall cancer risk in univariate analyses (HR, 0.92 [95% CI, 0.82 to 1.02]) or after adjustment for demographic characteristics, comorbidities, hospital size, history of cancer, and calendar year (adjusted HR, 0.94 [95% CI, 0.84 to 1.05]). Individual cancer types were also not significantly elevated (p > 0.05 for all) in BMP users compared with nonusers. In addition, BMP use was not associated with a new cancer in people who had cancer prior to undergoing lumbar arthrodesis (adjusted HR, 1.04 [95% CI, 0.71 to 1.52]) or with mortality after a cancer diagnosis (adjusted HR, 1.05 [95% CI, 0.93 to 1.19]). CONCLUSIONS: In a large population of elderly U.S. adults undergoing lumbar arthrodesis, BMP use was not associated with cancer risk or mortality. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.