Citations

AbstractINTRODUCTIONAs the number of biomarkers used to study Alzheimer's disease (AD) continues to increase, it is important to understand the utility of any given biomarker, as well as what additional information a biomarker provides when compared to others.METHODSWe used hierarchical clustering to group 19 cross‐sectional biomarkers in autosomal dominant AD. Feature selection identified biomarkers that were the strongest predictors of mutation status and estimated years from symptom onset (EYO). Biomarkers identified included clinical assessments, neuroimaging, cerebrospinal fluid amyloid, and tau, and emerging biomarkers of neuronal integrity and inflammation.RESULTSThree primary clusters were identified: neurodegeneration, amyloid/tau, and emerging biomarkers. Feature selection identified amyloid and tau measures as the primary predictors of mutation status and EYO. Emerging biomarkers of neuronal integrity and inflammation were relatively weak predictors.DISCUSSIONThese results provide novel insight into our understanding of the relationships among biomarkers and the staging of biomarkers based on disease progression.

Abstract Background Magnetic Resonance Imaging (MRI) is the mainstay for neurosurgical oncology but not for informing us about glioma biology. An obstacle to developing MR-based glioma biomarkers is the absence of rigorous correlation between MRI features and glioma biology as assessed in multi-regional biopsies, within and across patients. Methods We directly addressed this obstacle by collating a unique cohort of 202 MRI-localized biopsies from 58 patients. We define a low-dimensional transcriptional pseudotime continuum along which heterogeneous high-grade glioma (HGG) samples organize both within and across patients. Results We observe three polarized transcriptional tissue states: infiltrated brain, immune/inflammatory, and proliferative associated with patterns of cohabitation of cellular subpopulations. The states and deconvolved populations show correlation with enhancement status on T1Gd MRI. Moreover, discrete MRI habitats, regions sharing common imaging features, defined as combinations of high or low signal intensity across multiparametric MRI revealed 14 MRI habitats. We order the MRI habitats according to the average pseudotime on the transcriptional continuum. We find that MRI habitats with low pseudotime (associated with early tumor development and diffusely invaded brain tissue) localized at the periphery of the tumor whilst high pseudotime either proliferative or immune/inflammatory states were towards the core of the lesion. We find that composition of MRI habitats are impacted by MGMT status and patient sex. Conclusion This suggests that ongoing aggregation of MRI-localized biopsies may augment our projection of biology onto MRI habitats to support tracking of the evolution of cellular ecologies within and across each patient’s tumor over time. Key Points Trajectory inference of HGG samples reveals a continuum connecting three polarized tissue states reflecting transitions in cellular population ecologies and gene set enrichment Combining multiparametric MRI features into regional MRI habitats reveal clinically-distinct patterns of cell co-habitation and tissue state MGMT methylation status shifts the cellular patterns of cohabitation within MRI habitats Importance of the Study Regional heterogeneity is a defining characteristic of high-grade glioma (HGG). Mapping the transcriptomic biology of multiregionally sampled MRI-localized biopsies from high-grade gliomas onto a low-dimensional space reveals a continuum between three primary tissue states: infiltrated brain, immune/inflammatory, and proliferative. Each state is associated with distinct cell cohabitation ecologies. Transitions between the tissue states coordinate with changes in tumor composition, revealing potential direct connections between tumor biology shifts and their manifestation on clinical imaging.

Genome-wide association studies (GWAS) have identified more than 200 susceptibility loci for breast cancer, but these variants explain less than a fifth of the disease risk. Although gene–environment interactions have been proposed to account for some of the remaining heritability, few studies have empirically assessed this. We obtained genotype and risk factor data from 46,060 cases and 47,929 controls of European ancestry from population-based studies within the Breast Cancer Association Consortium (BCAC). We built gene expression prediction models for 4,864 genes with a significant (P < 0.01) heritable component using the transcriptome and genotype data from the Genotype-Tissue Expression (GTEx) project. We leveraged predicted gene expression information to investigate the interactions between gene-centric genetic variation and 14 established risk factors in association with breast cancer risk, using a mixed-effects score test. After adjusting for number of tests using Bonferroni correction, no interaction remained statistically significant. The strongest interaction observed was between the predicted expression of the C13orf45 gene and age at first full-term pregnancy (PGXE = 4.44 × 10−6). In this transcriptome-informed genome-wide gene–environment interaction study of breast cancer, we found no strong support for the role of gene expression in modifying the associations between established risk factors and breast cancer risk. Our study suggests a limited role of gene–environment interactions in breast cancer risk.

OBJECTIVE Procedural reimbursement for spine surgery has changed drastically over the past 20 years. A comprehensive understanding of these trends is important as major changes in reimbursement models of spine surgery continue to evolve within various spine specialties as well as broader national healthcare policy. In this study the authors evaluated the monetary trends in Medicare reimbursement rates for the 15 most common spinal surgery procedures from 2000 to 2021. METHODS The National Surgery Quality Improvement Project database (2019) was queried to determine the 15 most commonly performed spine surgery procedures. The Current Procedural Terminology (CPT) codes for each of these procedures were obtained from the Physician Fee Schedule Look-Up Tool from the Centers for Medicare and Medicaid Services, and comprehensive reimbursement data for each code were extracted. Changes in Medicare reimbursement rates were calculated and averaged for each procedure as both raw percent changes and percent changes adjusted for inflation to 2021 US dollars (USD) based on the consumer price index (CPI). The adjusted R2 value, the compound annual growth rate (CAGR), and both the average annual and the total percent change in reimbursement were calculated based on these adjusted trends for all included procedures. RESULTS After adjustment for inflation, average reimbursement for all procedures decreased by 33.8% from 2000 to 2021. The greatest mean decrease was seen in anterior cervical arthrodesis (−38.7%), while the smallest mean decrease was in vertebral body excision (−17.1%). From 2000 to 2021, the adjusted reimbursement rate for all included procedures decreased by an average of 1.9% each year, with an average R2 value of 0.69. CONCLUSIONS This is the first study to evaluate monetary trends in Medicare reimbursement for spine surgery procedures. After adjusting for inflation, Medicare reimbursement for the 15 most commonly performed spine procedures has steadily decreased from 2000 to 2021. Increased awareness of these trends and the forces driving them will be critical in the coming years as negotiations regarding reimbursement models continue to unfold. Greater understanding of spine surgery reimbursement among policy makers, hospitals, and surgeons will be important to ensure continued access to quality surgical spine care in the United States.

Objectives: Limited information is available on the prevalence of cardiorespiratory arrest (CA) and its predisposing factors in patients with acute ischemic stroke. We analyzed/evaluated clinical characteristics, risk factors, access to care, and survival in stroke patients who developed a cardiac arrest. Methods: This is a multicenter cohort study including consecutive patients with acute ischemic stroke admitted to regional stroke centers participating in the Registry of the Canadian Stroke Network from July 2003 to March 2008. Patients with DNR order on admission were excluded. CA was defined as cardiac or respiratory arrest within 30 days of admission documented by a physician and identified from resuscitation records. The main outcome measures were the 30-day and 1-year survival among patients with CA vs. no CA. We also assessed the association between medical complications during hospitalization and CA. Results: Overall, 9,019 patients with acute ischemic stroke were included. Cardiac arrest was observed in 352 patients (3.9%). In patients with CA, 30-day survival (17.9% vs. 90.7%, P<0.001) and 1-year survival (4.5% vs. 80.1, p<0.001) were significantly lower. Less than 1% of stroke patients with CA were discharged home (vs. 47.3%; p<0.0001). Other outcome measures are summarized in Table 1. On multivariable analyses, older age, more severe stroke, previous history of myocardial infarction, congestive heart failure, atrial fibrillation, and diabetes were associated with CA. Conclusions: Cardiac arrest affects less than 5% of patients admitted with an acute ischemic stroke and is associated with poor outcomes. Less than 1% of patients were independent or discharged home.

Background: Interruption of OAC is often required for invasive procedures, yet the frequency, management, and outcomes of temporary interruptions (TIs) in community practice are unknown. Methods: We assessed the frequency and reasons for TI in outpatients with AF enrolled in the Outcomes Registry for Better Informed Treatment of AF (ORBIT-AF). Patient characteristics and use of bridging anticoagulants were analyzed. Endpoints included periprocedural adverse events (bleeding, thrombotic, or other) and cause-specific hospitalization within 30 days after TI. Results: Overall 7,372 patients were treated with OAC at baseline; 30% (n=2200) required at least 1 TI during median follow-up of 1 year. Patients requiring TI were similar in age (mean age 74 for both) and CHADS2 scores (mean 2.4 for both) to those not requiring TI. Among 3104 interruptions, the most commonly-identified reasons were for non-cardiac surgery (n=827, 27%), followed by endoscopic procedures (n=551, 18%) and cardiac catheterization (n=308, 10%). Bridging anticoagulants were used in 23% (n=709) of interruptions, including low-molecular weight heparin (n=512) or unfractionated heparin (n=109). Rates of bridging were highest during cardiac surgery (44%), cardiac catheterization (32%), and catheter ablation (33%). Patients with a prior stroke or TIA were significantly more likely to receive bridging (35% vs. 25%, p=0.0003), however there was no difference between patients with CHADS2 score >=2 vs. 0-1 (27% vs. 25%, p=NS). Adverse events during interruption were more common in bridged patients (5.1% vs. 2.9%, p=0.02), including bleeding events (3.6% vs. 1.8%, p=0.02); thrombotic events were uncommon (0.7 [n=4] vs. 0.5% [n=10], p=NS). After interruption, adverse events occurred early in follow-up (Figure), and bridged patients were more likely to experience any adverse event (13% vs. 6.3%, p<0.0001), cardiovascular hospitalization (4.3% vs. 2.3%, p=0.02), and bleeding hospitalization (2.2% vs. 0.7%, p=0.002) within 30 days. Conclusions: Temporary interruptions are common in patients receiving OAC for AF, however, bridging anticoagulation is used in a minority. Bleeding events following TI occurred significantly more often in patients receiving bridging anticoagulation.

Background: Dabigatran is a novel oral anticoagulant approved in October 2010 for thromboprophylaxis in atrial fibrillation (AF), yet patterns of adoption of this novel agent in clinical practice are unknown. Methods: Using the ORBIT-AF Registry, a national outpatient prospective AF registry involving 170 sites, we examined patterns of those switching to dabigatran from warfarin from 2010 to 2012. Results: Of 7,066 patients with AF receiving warfarin at baseline, 511 (7%) were switched to dabigatran during follow-up. Patients switched to dabigatran were younger (median age 73 vs. 76, p<0.0001), more likely to be White (94% vs. 89%, p=0.001), and had better kidney function (median creatinine clearance (CrCl) 77 mL/min vs. 69 mL/min, p<0.0001), but less likely to have a history of anemia, (14% vs. 18%, p=0.009) or history of any cerebrovascular disease (14% vs. 17%, p=0.04) or CAD (22% vs. 34%, p<0.0001) or be followed in an anticoagulation clinic (36% vs. 45%, p<0.0001). Patients switched to dabigatran were more likely to have been recently diagnosed with AF (5.3% vs. 3.0%, p=0.03), and their CHADS 2 scores were significantly lower (p<0.0001). Conclusions: Patients receiving warfarin who were switched to dabigatran were younger, with lower CHADS 2 scores, better kidney function, and less concomitant cardiovascular disease than those not switched. This conservative transition pattern suggests greater physician emphasis on bleeding avoidance than on stroke risk reduction.

Background. Oral anticoagulation therapy (OAC) reduces the risk of thromboembolic events associated with atrial fibrillation (AF), yet a substantial proportion of patients with AF are not prescribed OAC. The frequencies of and factors associated with contraindications to OAC therapy in clinical practice are not well-described. Methods. We used data from the ORBIT-AF study, a national, prospective, outpatient registry of incident and prevalent AF. OAC contraindications were uniformly collected at study enrollment by site personnel. Patient and provider characteristics were compared between participants with documented OAC contraindications at baseline and those without OAC contraindications. Results. From June 2010 to August 2011, 10124 patients ≥18 years old with electrocardiographically documented AF were enrolled at 176 practices. Of these, 1409 (13.9%) had OAC contraindications documented at the baseline visit: prior bleed (26.2%), patient refusal/preference (26.0%), high bleeding risk (22.6%), frequent falls/frailty (16.6%), other (11.9%), need for dual antiplatelet therapy (9.8%), unable to adhere/monitor warfarin (5.7%), comorbid illness (5.0%), prior intracranial hemorrhage (4.7%), allergy (2.3%), occupational risk (0.8%), and pregnancy (0.2%). Compared to patients without contraindications, those with contraindications had higher stroke risk (CHADS2>2) and were older, more likely to be female, more likely to be seen by a cardiologist and less likely to be seen by an electrophysiologist (Table 1). Among those patients with reported contraindications, 28.4% were taking warfarin. Conclusions. Contraindications to OAC therapy among AF patients are common and often due to high bleeding risk. Furthermore, many patients with reported contraindications are taking warfarin, suggesting that many contraindications to warfarin therapy are minor, relative, or temporary.

Introduction: Cerebrovascular disease (CVD) and neuropsychiatric symptoms (NPS) are common in older adults and are independently associated with cognitive impairment. In addition, vascular depression (a late-life depression) is hypothesized to be associated with cerebrovascular pathology. Hypothesis: CVD pathology imaging biomarkers (e.g., white matter hyperintensities (WMH), infarctions) are associated with depression and anxiety, and both (depression/anxiety and CVD imaging biomarkers) are independently associated with mild cognitive impairment (MCI). Methods: This cross-sectional study included 1739 Mayo Clinic Study of Aging participants (≥50 years old) without dementia, with comprehensive cognitive evaluations and available data on the Beck Depression Inventory II (BDI), the Beck Anxiety Inventory (BAI) and imaging CVD biomarkers via FLAIR-MRI (i.e., WMH% of total intracranial volume (TIV) and brain infarctions). We used linear and logistic regression models to examine the associations adjusting for age, sex, education, and apolipoprotein E ε4 status. Results: Participants’ mean age (SD) was 71.11 (10.61) years (53.3% males). Higher WMH% TIV burden was significantly associated with higher BDI (b= 0.082, 95%CI: 0.031, 0.133), p=0.002) and BAI scores (b= 0.088, 95%CI: 0.037, 0.140), p=0.001); the presence of infarctions was also associated with a higher BDI score. Both WMH %TIV burden (OR: 1.20 (95%CI:1.05, 1.38), p=0.008) and BDI score (OR: 1.38 (95%CI:1.21, 1.57), p<0.001) were significantly associated with MCI when included simultaneously in the model. We observed similar associations for CVD biomarkers and BAI score with MCI. Conclusions: CVD imaging biomarkers and NPS, as measured by BDI and BAI scores, could represent two distinct processes associated with cognitive impairment. Studies are ongoing to further examine these associations and delineate how CVD, NPS, and other pathophysiology processes (e.g., Alzheimer’s disease) interact and are associated with cognitive impairment.

Background: Little information exists on clinical characteristics and treatment patterns of patients with atrial fibrillation (AF) following a major bleeding event in clinical practice. Methods: We used data from a large, national outpatient registry, ORBIT-AF (2010 – 2011), to evaluate event characteristics and oral anticoagulation (OAC) management following a major bleeding event. Major bleeds were defined according to ISTH criteria. We compared baseline characteristics among patients who persisted on OAC therapy at the first clinic visit following a major bleed and those in whom OAC was discontinued using chi-squared tests. Results: Of 10135 patients enrolled in ORBIT-AF, n=791 (7.8%) bleeding events occurred during 2 years of follow-up. Among patients who were receiving OA, n=632 (3.5 per 100 person years) experienced a major bleed. Of these, 67.3% experienced a fall in hemoglobin and 46.8% required transfusion of 2 of more units of red blood cells. Critical site bleeding occurred in 150 OAC patients, with the majority of these classified as intracranial bleeding (n= 89), followed by retroperitoneal (n=25) and intraocular (n=17). Fatal bleeds occurred in 37 patients (5.9% of all major bleeds). Nearly one-third of patients (31.0%) discontinued OAC therapy following the major bleeding event. Compared with those who persisted on OAC, patients who discontinued OAC were more likely to have hypertension and CKD. Those who discontinued OAC were more likely to have gastrointestinal or CNS site bleeding compared with those who persisted (Table). Conclusions: One in three patients who experienced a major bleed were no longer optimally anticoagulated after the event. Those who discontinued OAC had a greater comorbidity burden and more likely to have bleeding in a critical site those who persisted on OAC.