Sampling in Long-Screened Wells: Issues, Misconceptions, and Solutions.

The issues associated with long-screened wells (LSWs) (and open boreholes) at contaminated sites are well documented in the groundwater literature but are still not fully appreciated in practice. As established in seminal and review papers going back over three decades, the interpretation of sampling results from LSWs is challenging in the presence of vertical hydraulic gradients and borehole flow; furthermore, LSWs allow for vertical redistribution of contamination between aquifer layers. Acknowledgment of these issues has led to the development of new technologies and well designs to enable discrete-zone monitoring (DZM), yet LSWs remain common for many reasons, for example, as multipurpose wells, for geophysical logging, and (or) as legacy installations. Despite the literature on LSWs and despite the adoption of DZM at many sites, the use of LSWs persists and the challenges of interpreting sampling results from LSWs remain. In this issue paper, we provide a conceptual overview of the problems posed by LSWs and review existing literature and past work to improve the interpretation of sampling in LSWs. We draw on experience from previous studies at the Hanford Site in eastern WA, USA, and use synthetic examples to illustrate key concepts and challenges for interpretation. A recently published analytical modeling framework is used to develop illustrative synthetic examples and demonstrate a workflow for building scientific intuition to understand issues around interpreting samples from LSWs, which is critical to effective characterization and groundwater remediation at sites with LSWs.

New Horizons in Peripheral Artery Disease.

Peripheral artery disease (PAD) is the lower limb manifestation of systemic atherosclerotic disease. PAD may initially present with symptoms of intermittent claudication, whilst chronic limb-threatening ischaemia (CLTI), the end stage of PAD, presents with rest pain and/or tissue loss. PAD is an age-related condition present in over 10% of those aged ≥65 in high-income countries. Guidelines regarding definition, diagnosis and staging of PAD and CLTI have been updated to reflect the changing patterns and presentations of disease given the increasing prevalence of diabetes. Recent research has changed guidelines on optimal medical therapy, with low-dose anticoagulant plus aspirin recommended in some patients. Recently published randomised trials highlight where bypass-first or endovascular-first approaches may be optimal in infra-inguinal disease. New techniques in endovascular surgery have increased minimally invasive options for ever more complex disease. Increasing recognition has been given to the complexity of patients with CLTI where a high prevalence of both frailty and cognitive impairment are present and a significant burden of multi-morbidity and polypharmacy. Despite advances in minimally invasive revascularisation techniques and reduction in amputation incidence, survival remains poor for many with CLTI. Shared decision-making is essential, and conservative management is often appropriate for older patients. There is emerging evidence of the benefit of specialist geriatric team input in the perioperative management of older patients undergoing surgery for CLTI. Recent UK guidelines now recommend screening for frailty, cognitive impairment and delirium in older vascular surgery patients as well as recommending all vascular surgery services have support and input from specialist geriatrics teams.

Staffing Patterns of Non-ACGME Fellowships with 4-Year Residency Programs: A National Survey.

Introduction: Emergency medicine (EM) is one of few specialties with variable training lengths. Hiring a three-year graduate to continue fellowship training in a department that supports a four-year residency program can lead to conflicts around resident supervision. We sought to understand hiring and clinical supervision, or staffing, patterns of non-Accreditation Council for Graduate Medical Education (ACGME) fellowships hosted at institutions supporting four-year residency programs. Methods: We performed a web-based, cross-sectional survey of non-ACGME fellowship directors (FD) hosted at institutions supporting four-year EM residency programs. We calculated descriptive statistics. Our primary outcome was the proportion of programs with four-year EM residencies that hire non-ACGME fellows graduating from three-year EM residencies. Results: Of 119 eligible FDs, 88 (74%) completed the survey. Seventy FDs (80%) indicated that they hire graduates of three-year residencies. Fifty-six (80%) indicated that three-year graduates supervise residents. Most FDs (74%) indicated no additional requirements exist to supervise residents outside of being hired as faculty. The FDs cited department policy, concerns about quality and length of training, and resident complaints as reasons for not hiring three-year graduates. A majority (10/18, 56%) noted that not hiring fellows from three-year programs negatively impacts recruitment and gives them access to a smaller applicant pool. Conclusion: Most non-ACGME fellowships at institutions with four-year EM programs recruit three-year graduates and allow them to supervise residents. This survey provides programs information on how comparable fellowships recruit and staff their departments, which may inform policies that fit the needs of their learners, the fellowship, and the department.

Experimental and Numerical Study of Radioiodine Sorption and Transport in Hanford Sediments.

Radioiodine (129I) poses a potential risk to human health and the environment at several U.S. Department of Energy sites, including the Hanford Site, located in southeastern Washington State. Experimental studies and numerical modeling were performed to provide a technical basis for field-scale modeling of iodine sorption and transport behavior. The experiments were carried out using six columns of repacked contaminated sediments from the Hanford Site. Although iodate has been determined to be the dominant iodine species at the Hanford Site, the sorption and transport behaviors of different iodine species were investigated in a series of column experiments by first leaching sediments with artificial groundwater (AGW) followed by AGW containing iodate (IO3-), iodide (I-), or organo-iodine (2-iodo-5-methoxyphenol, C7H7IO2). Ferrihydrite amendments were added to the sediments for three of the columns to evaluate the impact of ferrihydrite on 129I attenuation. The results showed that ferrihydrite enhanced the iodate sorption capacity of the sediment and retarded the transport but had little effect on iodide or organo-I, providing a technical basis for developing a ferrihydrite-based remedial strategy for iodate under oxidizing conditions. Data from the column transport experiments were modeled using the linear equilibrium Freundlich isotherm model, the kinetic Langmuir adsorption model, and a distributed rate model. Comparisons of the experimental data and modeling results indicated that sorption was best represented with the distributed rate model with rates and maximum sorption extents varying by iodine species and ferrihydrite treatment. However, the linear Freundlich isotherm (Kd) model was also found to fit the laboratory experimental data relatively well, suggesting that the Kd model could also be used to represent iodine transport at the field scale.

Extracorporeal cardiopulmonary resuscitation-based approach to refractory out-of-hospital cardiac arrest: A focus on organ donation, a secondary analysis of a Prague OHCA randomized study.

BACKGROUND: Refractory out-of-hospital cardiac arrest (OHCA) has a poor outcome. In patients, who cannot be rescued despite using advanced techniques like extracorporeal cardiopulmonary resuscitation (ECPR), organ donation may be considered. This study aims to evaluate, in refractory OHCA, how ECPR versus a standard-based approach allows organ donorship. METHODS: The Prague OHCA trial randomized adults with a witnessed refractory OHCA of presumed cardiac origin to either an ECPR-based or standard approach. Patients who died of brain death or those who died of primary circulatory reasons and were not candidates for cardiac transplantation or durable ventricle assist device were evaluated as potential organ donors by a transplant center. In this post-hoc analysis, the effect on organ donation rates and one-year organ survival in recipients was examined. RESULTS: Out of 256 enrolled patients, 75 (29%) died prehospitally or within 1 hour after admission and 107 (42%) during the hospital stay. From a total of 24 considered donors, 21 and 3 (p = 0.01) were recruited from the ECPR vs standard approach arm, respectively. Fifteen brain-dead and none cardiac-dead subjects were ultimately accepted, 13 from the ECPR and two from the standard strategy group. A total of 36 organs were harvested. The organs were successfully transplanted into 34 recipients. All transplanted organs were fully functional, and none of the recipients died due to graft failure within the one-year period post-transplant. CONCLUSION: The ECPR-based approach in the refractory OHCA trial is associated with increased organ donorship and an excellent outcome of transplanted organs. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01511666. Registered January 19, 2012.

Baseline Factors Associated with Pain Intensity, Pain Catastrophizing, and Pain Interference in Intensive Interdisciplinary Pain Treatment for Youth.

Background: More could be known about baseline factors related to desirable Intensive Interdisciplinary Pain Treatment (IIPT) outcomes. This study examined how baseline characteristics (age, gender, child pain catastrophizing (PCS-C), pain interference, pain intensity, anxiety, depression, paediatric health-related quality of life (PedsQLTM), and parent catastrophizing (PCS-P)) were associated with discharge and 3-month follow-up scores of PCS-C, pain intensity, and pain interference. Methods: PCS-C, pain intensity, and pain interference T-scores were acquired in 45 IIPT patients aged 12-18 at intake (baseline), discharge, and 3-month follow-up. Using available and imputed data, linear mixed models were developed to explore associations between PCS-C, pain intensity, and pain interference aggregated scores at discharge and follow-up with baseline demographics and a priori selected baseline measures of pain, depression, anxiety, and PCS-C/P. Results: PCS-C and pain interference scores decreased over time compared to baseline. Pain intensity did not change significantly. Baseline PCS-C, pain interference, anxiety, depression, and PedsQLTM were associated with discharge/follow-up PCS-C (available and imputed data) and pain interference scores (available data). Only baseline pain intensity was significantly associated with itself at discharge/follow-up. Conclusions: Participants who completed the IIPT program presented with reduced PCS-C and pain interference over time. Interventions that target pre-treatment anxiety and depression may optimize IIPT outcomes.

Avoiding Hospital Admissions and Delayed Transfers of Care by Improved Access to Intermediate Care: A Simulation Study.

OBJECTIVE: The current waiting times for intermediate care in the Netherlands prohibit timely access, leading to unwanted and costly hospital admissions. We propose alternative policies for improvement of intermediate care and estimate the effects on the waiting times, hospitalization, and the number of patient replacements. DESIGN: Simulation study. SETTING AND PARTICIPANTS: For our case study, data were used of older adults who received intermediate care in Amsterdam, the Netherlands, in 2019. For this target group, in- and outflows and patient characteristics were identified. METHODS: A process map of the main pathways into and out of the intermediate care was obtained and a discrete event simulation (DES) was built. We demonstrate the use of our DES for intermediate care by evaluating possible policy changes for a real-life case study in Amsterdam. RESULTS: By means of a sensitivity analysis with the DES, we show that in Amsterdam the waiting times are not a result of a lack in bed capacity but are due to an inefficient triage and application process. Older adults have to wait a median of 1.8 days for admission, leading to hospitalization. If the application process becomes more efficient and evening and weekend admissions are allowed, we find that unwanted hospitalization can be decreased substantially. CONCLUSION AND IMPLICATIONS: In this study, a simulation model is developed for intermediate care that can serve as a basis for policy decisions. Our case study shows that the waiting times for health care facilities are not always solved by increasing bed capacity. This underlines the necessity for a data-driven approach to identify logistic bottlenecks and find the best ways to solve them.

Peripheral artery disease (PAD) in primary care-educational experiences for PAD primary care in England-a mixed-method study.

BACKGROUND: Peripheral artery disease (PAD), the pathophysiologic narrowing of arterial blood vessels of the lower leg due to atherosclerosis, is a highly prevalent disease, with sharp increases in prevalence with age. Primary care is ideally located to identify and manage PAD. OBJECTIVES: This study aims to identify the educational experiences, opinions, and confidence of primary care clinicians (PCCs) regarding PAD. METHOD: This mixed-method study was conducted within primary care in England. An online survey was completed with follow-on semistructured interviews, between January and September 2021, with PCCs, namely GPs, practice nurses, and allied professionals (survey n = 874, interviews n = 50). RESULTS: PCCs report variation in PAD education received, where the content could not often be recalled. Patient-focussed experiential and self-directed learning, formed the largest method to gain PAD education. All PCCs recognized that they have an important role in recognizing PAD yet confidence in recognizing and diagnosing PAD was lacking. PCCs acknowledged that late or missed PAD diagnosis resulted in significant patient morbidity and mortality. Yet many did not recognize PAD as a common disease. CONCLUSION: As "specialist-generalists" with finite resources, education provided to primary care needs to be applicable for the multimorbid patient presentations often seen, utilizing resources available in primary care, with consideration to the time constraints endured.

Interpreting Concentrations Sampled in Long-Screened Wells with Borehole Flow: An Inverse Modeling Approach.

New approaches are needed to assess contaminant mass based on samples from long-screened wells and open boreholes (LSW&OB). The interpretation of concentration samples collected in LSW&OB is complicated in the presence of vertical flow within the well. In the absence of pumping (i.e., ambient conditions), the well provides a conduit for flow to occur between aquifer layers or fractures as a result of head differences. Under pumping conditions, vertical borehole flow may vary with depth depending on far-field heads and hydraulic conductivity; furthermore, if pumping fails to overcome ambient gradients, outflow from the well to the aquifer may occur. Concentration samples thus represent flow-weighted averages of formation concentrations, but the averaging process is commonly unknown or difficult to identify. Recognition of the importance of borehole flow has motivated the use of multi-level wells, packers, and well liners; however, LSW&OB remain common for numerous reasons, including cost, multi-purpose design requirements (e.g., pump-and-treat, water supply), logging, and installation of instrumentation. Here, we present a simple analytical model for flow and transport within a well and interaction with the surrounding aquifer. We formulate an inverse problem to estimate formation concentration based on sampled concentrations and data from flowmeter logs. The approach is demonstrated using synthetic examples. Our results (1) underscore the importance of interpreting sampled concentrations within the context of hydraulic conditions and aquifer/well exchange; (2) demonstrate the value of flowmeter measurements for this purpose; and (3) point to the potential of the new inverse approach to better interpret results from samples collected in LSW&OB.

A new label-free optical imaging method for the lymphatic system enhanced by deep learning.

Our understanding of the lymphatic vascular system lags far behind that of the blood vascular system, limited by available imaging technologies. We present a label-free optical imaging method that visualizes the lymphatic system with high contrast. We developed an orthogonal polarization imaging (OPI) in the shortwave infrared range (SWIR) and imaged both lymph nodes and lymphatic vessels of mice and rats in vivo through intact skin, as well as human mesenteric lymph nodes in colectomy specimens. By integrating SWIR-OPI with U-Net, a deep learning image segmentation algorithm, we automated the lymph node size measurement process. Changes in lymph nodes in response to cancer progression were monitored in two separate mouse cancer models, through which we obtained insights into pre-metastatic niches and correlation between lymph node masses and many important biomarkers. In a human pilot study, we demonstrated the effectiveness of SWIR-OPI to detect human lymph nodes in real time with clinical colectomy specimens. One Sentence Summary: We develop a real-time high contrast optical technique for imaging the lymphatic system, and apply it to anatomical pathology gross examination in a clinical setting, as well as real-time monitoring of tumor microenvironment in animal studies.

Morphology of Polymer Brushes in the Presence of Attractive Nanoparticles: Effects of Temperature.

We study the role of temperature on the structure of pure polymer brushes and their mixture with attractive nanoparticles in flat and cylindrical geometries. It has previously been established that the addition of such nanoparticles causes the polymer brush to collapse and the intensity of the collapse depends on the attraction strength, the nanoparticle diameter, and the grafting density. In this work, we carry out molecular dynamics simulation under good solvent conditions to show how the collapse transition is affected by the temperature, for both plane grafted and inside-cylinder grafted brushes. We first examine the pure brush morphology and verify that the brush height is insensitive to temperature changes in both planar and cylindrical geometries, as expected for a polymer brush in a good solvent. On the other hand, for both system geometries, the brush structure in the presence of attractive nanoparticles is quite responsive to temperature changes. Generally speaking, for a given nanoparticle concentration, increasing the temperature causes the brush height to increase. A brush which contracts when nanoparticles are added eventually swells beyond its pure brush height as the system temperature is increased. The combination of two easily controlled external parameters, namely, concentration of nanoparticles in solution and temperature, allows for sensitive and reversible adjustment of the polymer brush height, a feature which could be exploited in designing smart polymer devices.

A consensus list of ultrasound competencies for graduating emergency medicine residents.

Objectives: Emergency ultrasound (EUS) is a critical component of emergency medicine (EM) resident education. Currently, there is no consensus list of competencies for EUS training, and graduating residents have varying levels of skill and comfort. The objective of this study was to define a widely accepted comprehensive list of EUS competencies for graduating EM residents through a modified Delphi method. Methods: We developed a list of EUS applications through a comprehensive literature search, the American College of Emergency Physicians list of core EUS benchmarks, and the Council of Emergency Medicine Residency-Academy of Emergency Ultrasound consensus document. We assembled a multi-institutional expert panel including 15 faculty members from diverse practice environments and geographical regions. The panel voted on the list of competencies through two rounds of a modified Delphi process using a modified Likert scale (1 = not at all important, 5 = very important) to determine levels of agreement for each application-with revisions occurring between the two rounds. High agreement for consensus was set at >80%. Results: Fifteen of 15 panelists completed the first-round survey (100%) that included 359 topics related to EUS. After the first round, 195 applications achieved high agreement, four applications achieved medium agreement, and 164 applications achieved low agreement. After the discussion, we removed three questions and added 13 questions. Fifteen of 15 panelists completed the second round of the survey (100%) with 209 of the 369 applications achieving consensus. Conclusion: Our final list represents expert opinion on EUS competencies for graduating EM residents. We hope to use this consensus list to implement a more consistent EUS curriculum for graduating EM residents and to standardize EUS training across EM residency programs.

Branched-Chain Amino Acids Are Neuroprotective Against Traumatic Brain Injury and Enhance Rate of Recovery: Prophylactic Role for Contact Sports and Emergent Use.

Branched-chain amino acids (BCAAs) are known to be neurorestorative after traumatic brain injury (TBI). Despite clinically significant improvements in severe TBI patients given BCAAs after TBI, the approach is largely an unrecognized option. Further, TBI continues to be the most common cause of morbidity and mortality in adolescents and adults. To date, no study has evaluated whether BCAAs can be preventive or neuroprotective if taken before a TBI. We hypothesized that if BCAAs were elevated in the circulation before TBI, the brain would readily access the BCAAs and the severity of injury would be reduced. Before TBI induction with a standard weight-drop method, 50 adult mice were randomized into groups that were shams, untreated, and pre-treated, post-treated, or pre- + post-treated with BCAAs. Pre-treated mice received BCAAs through supplemented water and were dosed by oral gavage 45 min before TBI induction. All mice underwent beam walking to assess motor recovery, and the Morris water maze assessed cognitive function post-injury. On post-injury day 14, brains were harvested to assess levels of astrocytes and microglia with glial fibrillary acidic protein (GFAP) and ionized calcium-binding adapter molecule 1 (IBA-1) immunohistochemistry, respectively. Pre-treated and pre- +post-treated mice exhibited significantly better motor recovery and cognitive function than the other groups. The pre- + post-treated group had the best overall memory performance, whereas the pre-treated and post-treated groups only had limited improvements in memory compared to untreated animals. Pre- + post-treated brains had levels of GFAP that were similar to the sham group, whereas the pre-only and post-only groups showed increases. Although trends existed, no meaningful changes in IBA-1 were detected. This is the first study, animal or human, to demonstrate that BCAA are neuroprotective and substantiates their neurorestorative benefits after TBI, most likely through the important roles of BCAAs to glutamate homeostasis.

Effect of diagnostic labelling on management intentions for non-specific low back pain: A randomized scenario-based experiment.

BACKGROUND: Diagnostic labels may influence treatment intentions. We examined the effect of labelling low back pain (LBP) on beliefs about imaging, surgery, second opinion, seriousness, recovery, work, and physical activities. METHODS: Six-arm online randomized experiment with blinded participants with and without LBP. Participants received one of six labels: 'disc bulge', 'degeneration', 'arthritis', 'lumbar sprain', 'non-specific LBP', 'episode of back pain'. The primary outcome was the belief about the need for imaging. RESULTS: A total of 1375 participants (mean [SD] age, 41.7 years [18.4 years]; 748 women [54.4%]) were included. The need for imaging was rated lower with the labels 'episode of back pain' (4.2 [2.9]), 'lumbar sprain' (4.2 [2.9]) and 'non-specific LBP' (4.4 [3.0]) compared to the labels 'arthritis' (6.0 [2.9]), 'degeneration' (5.7 [3.2]) and 'disc bulge' (5.7 [3.1]). The same labels led to higher recovery expectations and lower ratings of need for a second opinion, surgery and perceived seriousness compared to 'disc bulge', 'degeneration' and 'arthritis'. Differences were larger amongst participants with current LBP who had a history of seeking care. No differences were found in beliefs about physical activity and work between the six labels. CONCLUSIONS: 'Episode of back pain', 'lumbar sprain' and 'non-specific LBP' reduced need for imaging, surgery and second opinion compared to 'arthritis', 'degeneration' and 'disc bulge' amongst public and patients with LBP as well as reducing the perceived seriousness of LBP and enhancing recovery expectations. The impact of labels appears most relevant amongst those at risk of poor outcomes (participants with current LBP who had a history of seeking care).

Reduced Waiting Times by Preference-Based Allocation of Patients to Nursing Homes.

OBJECTIVES: The long waiting times for nursing homes can be reduced by applying advanced waiting-line management. In this article, we implement a preference-based allocation model for older adults to nursing homes, evaluate the performance in a simulation setting for 2 case studies, and discuss the implementation in practice. DESIGN: Simulation study. SETTING AND PARTICIPANTS: Older adults requiring somatic nursing home care, from an urban region (Rotterdam) and a rural region (Twente) in the Netherlands. METHODS: Data about nursing homes and capacities for the 2 case studies were identified. A set of preference profiles was defined with aims regarding waiting time preferences and flexibility. Guidelines for implementation of the model in practice were obtained by addressing the tasks of all stakeholders. Thereafter, the simulation was run to compare the current practice with the allocation model based on specified outcome measures about waiting times and preferences. RESULTS: We found that the allocation model decreased the waiting times in both case studies. Compared with the current practice policy, the allocation model reduced the waiting times until placement by at least a factor of 2 (from 166 to 80 days in Rotterdam and 178 to 82 days in Twente). Moreover, more of the older adults ended up in their preferred nursing home and the aims of the distinct preference profiles were satisfied. CONCLUSIONS AND IMPLICATIONS: The results show that the allocation model outperforms commonly used waiting-line policies for nursing homes, while meeting individual preferences to a larger extent. Moreover, the model is easy to implement and of a generic nature and can, therefore, be extended to other settings as well (eg, to allocate older adults to home care or daycare). Finally, this research shows the potential of mathematical models in the care domain for older adults to face the increasing need for cost-effective solutions.

Informing the Alfred Registry for Emergency Care Project: An analysis of presenting complaint documentation in an emergency department.

OBJECTIVE: To assess the feasibility of an ED presenting complaint (PC) tool that categorised all ED PCs into 10 categories. METHODS: A retrospective analysis of 1445 consecutive patient encounters was conducted. The primary outcome was the frequency of use of the 10 PC categories. RESULTS: Of the 1203 patient encounters meeting inclusion criteria, the PC tool was completed by clinicians in 574 (47.7%). When completed, the tool's 10 options were selected for most presentations (72.3%). CONCLUSION: The PC tool captured the majority of presenting complaints in 10 categories. External validation is recommended.

Behavioural drivers influencing emergency department attendance in Victoria during the 2020 COVID-19 pandemic: A mixed methods investigation.

OBJECTIVE: To identify behavioural drivers and barriers that may have contributed to changes in ED attendance during the first 10 months of the coronavirus disease 2019 (COVID-19) pandemic in Victoria. METHODS: We conducted a mixed methods analysis of patients who attended one of eight participating EDs between 1 November 2019 and 31 December 2020. A random sample of patients were chosen after their visit and invited to participate in an online survey assessing behavioural drivers and barriers to attendance. The study timespan was divided into four periods based on local and world events to assess changes in attitudes and behaviours over this period. RESULTS: A total of 5600 patients were invited to complete the survey and 606 (11%) submitted sufficient information for analysis. There were significant differences in participants' attitudes towards healthcare and EDs, levels of concern about contracting and spreading COVID-19 and the influence of mask wearing. Patients expressed more concern about the safety of an ED during the largest outbreak of COVID-19 infections than they did pre-COVID, but this difference was not sustained once community infection numbers dropped. General concerns about hospital attendance were higher after COVID than they were pre-COVID. A total of 27% of patients specifically stated that they had delayed their ED attendance. CONCLUSION: Patients expressed increased concerns around attending ED during the first 10 months of the 2020 COVID-19 pandemic and frequently cited COVID-19 as a reason for delaying their presentation. These factors would be amenable to mitigation via focussed public health messaging.

Association of a longitudinal, preclinical ultrasound curriculum with medical student performance.

INTRODUCTION: Point-of-care ultrasound (US) is used in clinical practice across many specialties. Ultrasound (US) curricula for medical students are increasingly common. Optimal timing, structure, and effect of ultrasound education during medical school remains poorly understood. This study aims to retrospectively determine the association between participation in a preclinical, longitudinal US curriculum and medical student academic performance. METHODS: All first-year medical students at a medical school in the Midwest region of the United States were offered a voluntary longitudinal US curriculum. Participants were selected by random lottery. The curriculum consisted of five three-hour hands on-sessions with matching asynchronous content covering anatomy and pathologic findings. Content was paired with organ system blocks in the standard first year curriculum at our medical school. Exam scores between the participating and non-participating students were compared to evaluate the objective impact of US education on performance in an existing curriculum. We hypothesized that there would be an association between participation in the curriculum and improved medical student performance. Secondary outcomes included shelf exam scores for the surgery, internal medicine, neurology clerkships and USMLE Step 1. A multivariable linear regression model was used to evaluate the association of US curriculum participation with student performance. Scores were adjusted for age, gender, MCAT percentile, and science or engineering degree. RESULTS: 76 of 178 students applied to participate in the curriculum, of which 51 were accepted. US curriculum students were compared to non-participating students (n = 127) from the same class. The US curriculum students performed better in cardiovascular anatomy (mean score 92.1 vs. 88.7, p = 0.048 after adjustment for multiple comparisons). There were no significant differences in cumulative cardiovascular exam scores, or in anatomy and cumulative exam scores for the gastroenterology and neurology blocks. The effect of US curriculum participation on cardiovascular anatomy scores was estimated to be an improvement of 3.48 points (95% CI 0.78-6.18). No significant differences were observed for USMLE Step 1 or clerkship shelf exams. There were no significant differences in either preclinical, clerkship or Step 1 score for the 25 students who applied and were not accepted and the 102 who did not apply. CONCLUSIONS: Participation in a preclinical longitudinal US curriculum was associated with improved exam performance in cardiovascular anatomy but not examination of other cardiovascular system concepts. Neither anatomy or comprehensive exam scores for neurology and gastrointestinal organ system blocks were improved.