AAPM WGPE report 394: Simulated error training for the physics plan and chart review

BACKGROUND

Simulated error training is a method to practice error detection in situations where the occurrence of error is low. Such is the case for the physics plan and chart review where a physicist may check several plans before encountering a significant problem. By simulating potentially hazardous errors, physicists can become familiar with how they manifest and learn from mistakes made during a simulated plan review.

PURPOSE

The purpose of this project was to develop a series of training datasets that allows medical physicists and trainees to practice plan and chart reviews in a way that is familiar and accessible, and to provide exposure to the various failure modes (FMs) encountered in clinical scenarios.

METHODS

A series of training datasets have been developed that include a variety of embedded errors based on the risk-assessment performed by American Association of Physicists in Medicine (AAPM) Task Group 275 for the physics plan and chart review. The training datasets comprise documentation, screen shots, and digital content derived from common treatment planning and radiation oncology information systems and are available via the Cloud-based platform ProKnow.

RESULTS

Overall, 20 datasets have been created incorporating various software systems (Mosaiq, ARIA, Eclipse, RayStation, Pinnacle) and delivery techniques. A total of 110 errors representing 50 different FMs were embedded with the 20 datasets. The project was piloted at the 2021 AAPM Annual Meeting in a workshop where participants had the opportunity to review cases and answer survey questions related to errors they detected and their perception of the project's efficacy. In general, attendees detected higher-priority FMs at a higher rate, though no correlation was found between detection rate and the detectability of the FMs. Familiarity with a given system appeared to play a role in detecting errors, specifically when related to missing information at different locations within a given software system. Overall, 96% of respondents either agreed or strongly agreed that the ProKnow portal and training datasets were effective as a training tool, and 75% of respondents agreed or strongly agreed that they planned to use the tool at their local institution.

CONCLUSIONS

The datasets and digital platform provide a standardized and accessible tool for training, performance assessment, and continuing education regarding the physics plan and chart review. Work is ongoing to expand the project to include more modalities, radiation oncology treatment planning and information systems, and FMs based on emerging techniques such as auto-contouring and auto-planning.

Cardiovascular risk reduction in older people with type 2 diabetes mellitus-a comprehensive narrative review

Metabolic targets are controversial in older people with type 2 diabetes due to functional heterogeneity and morbidity burden. Tight blood pressure and metabolic control appears beneficial in fit individuals who are newly diagnosed with type 2 diabetes and have fewer comorbidities. The benefits of low blood pressure and tight metabolic control is attenuated with the development of comorbidities, especially frailty. Guidelines consider frail older people as one category and recommend relaxed targets. However, sarcopenic obese frail individuals may benefit from tight targets and intensification of therapy due to their unfavourable metabolic profile, accelerated diabetes trajectory and high cardiovascular risk. In addition, the early use of sodium glucose transporter-2 inhibitors and glucagon like peptide-1 receptor agonists may be beneficial in this frailty phenotype due to their cardio-renal protection, which is independent of glycaemic control, provided they are able to engage in resistance exercise training to avoid loss of muscle mass. In the anorexic malnourished frail individual, early use of insulin, due to its weight gain and anabolic properties, is appropriate. In this phenotype, targets should be relaxed with deintensification of therapy due to significant weight loss, decelerated diabetes trajectory and increased risk of medication side effects.

Variant allelic frequencies of driver mutations can identify gliomas with potentially false-negative MGMT promoter methylation results

MGMT promoter methylation testing is required for prognosis and predicting temozolomide response in gliomas. Accurate results depend on sufficient tumor cellularity, but histologic estimates of cellularity are subjective. We sought to determine whether driver mutation variant allelic frequency (VAF) could serve as a more objective metric for cellularity and identify possible false-negative MGMT samples. Among 691 adult-type diffuse gliomas, MGMT promoter methylation was assessed by pyrosequencing (N = 445) or DNA methylation array (N = 246); VAFs of TERT and IDH driver mutations were assessed by next generation sequencing. MGMT results were analyzed in relation to VAF. By pyrosequencing, 56% of all gliomas with driver mutation VAF ≥ 0.325 had MGMT promoter methylation, versus only 37% with VAF < 0.325 (p < 0.0001). The mean MGMT promoter pyrosequencing score was 19.3% for samples with VAF VAF ≥ 0.325, versus 12.7% for samples with VAF < 0.325 (p < 0.0001). Optimal VAF cutoffs differed among glioma subtypes (IDH wildtype glioblastoma: 0.12-0.18, IDH mutant astrocytoma: ~0.33, IDH mutant and 1p/19q co-deleted oligodendroglioma: 0.3-0.4). Methylation array was more sensitive for MGMT promoter methylation at lower VAFs than pyrosequencing. Microscopic examination tended to overestimate tumor cellularity when VAF was low. Re-testing low-VAF cases with methylation array and droplet digital PCR (ddPCR) confirmed that a subset of them had originally been false-negative. We conclude that driver mutation VAF is a useful quality assurance metric when evaluating MGMT promoter methylation tests, as it can help identify possible false-negative cases.

Multiorgan MRI findings after hospitalisation with COVID-19 in the UK (C-MORE): a prospective, multicentre, observational cohort study

INTRODUCTION

The multiorgan impact of moderate to severe coronavirus infections in the post-acute phase is still poorly understood. We aimed to evaluate the excess burden of multiorgan abnormalities after hospitalisation with COVID-19, evaluate their determinants, and explore associations with patient-related outcome measures.

METHODS

In a prospective, UK-wide, multicentre MRI follow-up study (C-MORE), adults (aged ≥18 years) discharged from hospital following COVID-19 who were included in Tier 2 of the Post-hospitalisation COVID-19 study (PHOSP-COVID) and contemporary controls with no evidence of previous COVID-19 (SARS-CoV-2 nucleocapsid antibody negative) underwent multiorgan MRI (lungs, heart, brain, liver, and kidneys) with quantitative and qualitative assessment of images and clinical adjudication when relevant. Individuals with end-stage renal failure or contraindications to MRI were excluded. Participants also underwent detailed recording of symptoms, and physiological and biochemical tests. The primary outcome was the excess burden of multiorgan abnormalities (two or more organs) relative to controls, with further adjustments for potential confounders. The C-MORE study is ongoing and is registered with ClinicalTrials.gov, NCT04510025.

FINDINGS

Of 2710 participants in Tier 2 of PHOSP-COVID, 531 were recruited across 13 UK-wide C-MORE sites. After exclusions, 259 C-MORE patients (mean age 57 years [SD 12]; 158 [61%] male and 101 [39%] female) who were discharged from hospital with PCR-confirmed or clinically diagnosed COVID-19 between March 1, 2020, and Nov 1, 2021, and 52 non-COVID-19 controls from the community (mean age 49 years [SD 14]; 30 [58%] male and 22 [42%] female) were included in the analysis. Patients were assessed at a median of 5·0 months (IQR 4·2-6·3) after hospital discharge. Compared with non-COVID-19 controls, patients were older, living with more obesity, and had more comorbidities. Multiorgan abnormalities on MRI were more frequent in patients than in controls (157 [61%] of 259 vs 14 [27%] of 52; p<0·0001) and independently associated with COVID-19 status (odds ratio [OR] 2·9 [95% CI 1·5-5·8]; padjusted=0·0023) after adjusting for relevant confounders. Compared with controls, patients were more likely to have MRI evidence of lung abnormalities (p=0·0001; parenchymal abnormalities), brain abnormalities (p<0·0001; more white matter hyperintensities and regional brain volume reduction), and kidney abnormalities (p=0·014; lower medullary T1 and loss of corticomedullary differentiation), whereas cardiac and liver MRI abnormalities were similar between patients and controls. Patients with multiorgan abnormalities were older (difference in mean age 7 years [95% CI 4-10]; mean age of 59·8 years [SD 11·7] with multiorgan abnormalities vs mean age of 52·8 years [11·9] without multiorgan abnormalities; p<0·0001), more likely to have three or more comorbidities (OR 2·47 [1·32-4·82]; padjusted=0·0059), and more likely to have a more severe acute infection (acute CRP >5mg/L, OR 3·55 [1·23-11·88]; padjusted=0·025) than those without multiorgan abnormalities. Presence of lung MRI abnormalities was associated with a two-fold higher risk of chest tightness, and multiorgan MRI abnormalities were associated with severe and very severe persistent physical and mental health impairment (PHOSP-COVID symptom clusters) after hospitalisation.

INTERPRETATION

After hospitalisation for COVID-19, people are at risk of multiorgan abnormalities in the medium term. Our findings emphasise the need for proactive multidisciplinary care pathways, with the potential for imaging to guide surveillance frequency and therapeutic stratification.

FUNDING

UK Research and Innovation and National Institute for Health Research.

Abstract WP54: Factors Associated With First Year Inpatient And Outpatient Rehabilitation Use Among Acute Ischemic Stroke Patients

Introduction: Stroke is a leading cause of long-term disability in the U.S., and 90% of stroke survivors have residual movement impairment. Inpatient and outpatient rehabilitation is critical for restoring functionality and quality of life among survivors. However, there are few studies evaluating the patterns and predictors of rehabilitation use among stroke survivors.

Methods: This study used 947 tPA-eligibe patients from an observational, prospective, multicenter, clinical trial in the U.S., who had complete 1 year follow-up utilization data, collected quarterly as self-reported surveys. We determined the occurrence and length of stay for inpatient rehabilitation, and occurrence and number of visits for outpatient rehabilitation. Logistic and linear regressions were used to examine predictors associated with these occurrences and intensities.

Results: The majority of rehabilitation use occurred during the first quarter with 19% and 33% of patients using inpatient and outpatient rehabilitation respectively, and rehabilitation use fell considerably over the rest of the year (Table 1). Higher disability at baseline (mRS≥2 and not living at home) reduced rehabilitation use, and higher disability at discharge increased rehabilitation use. Being uninsured reduced rehabilitation use. Other socio-demographic characteristics (such as age, gender and race-ethnicity), baseline comorbidities, and type and timeliness of therapies after stroke did not have an effect on rehabilitation use.

Conclusion: Rehabilitation use is highest during the first 3 months after discharge. Patients with higher discharge disability are more in need of rehabilitation, hence receive it. Patients already disabled at baseline are often excluded, probably due to a combination of rehabilitation entry requirements and perceived lack of potential benefits. Access barriers, such as lack of insurance reduced rehabilitation use suggesting an unmet need among stroke survivors.

Abstract WMP2: Acute Stroke Treatment In Patients With Pre-exiting Disability: A Secondary Analysis Of The BEST-MSU Trial

Background: Few data exists on acute stroke treatment in patients with pre-existing disability (PD) since they are usually excluded from clinical trials.

Methods: A pre-specified subgroup analysis of tPA-eligible patients with PD enrolled in a prospective multicenter trial of Mobile Stroke Units (MSUs) vs standard management by emergency medical services (EMS). All patients had baseline mRS scores. Co-primary outcomes were mean utility-weighted modified Rankin Scale score (uw-mRS) and return to baseline mRS at 90 days. Linear and logistic regression models compared outcomes in patients with vs without PD, and patients with PD treated by MSU vs EMS. Time metrics, safety, quality of life, and health-care utilization were also compared.

Results: Of 1047 patients, 254 had baseline mRS >= 2 (159 MSU, 95 EMS; 31% mRS 2, 52% mRS 3, 17% mRS 4). Compared to patients without disability, patients with PD were older, had higher NIHSS, more comorbidities, less often lived at home, were treated slower, and had less thrombectomy. Patients with PD had worse 90-day uw-mRS (0.39 vs 0.80), higher mortality, more health-care utilization and worse quality of life than patients without PD. However, rates of symptomatic intracranial hemorrhage and final diagnoses of stroke mimics were similar between groups, and 52% of patients with PD returned to their baseline mRS. Patients with PD treated within the first hour had better 90-day uw-mRS than those treated later (0.48 vs 0.36, p=0.01). Comparing patients with PD treated by MSU vs EMS, time from last-known-well to tPA bolus was shorter (82 vs 111 min), and 24% vs 0% were treated in the first hour. Among patients with PD, MSU patients had non-significantly better 90-day uw-mRS (0.41 vs 0.35, p=0.09) and higher rate of returning to baseline mRS (56% vs 44%, p=0.09) than EMS patients. There was no interaction between either time to treatment (p=0.24) or MSU vs EMS group assignment (p= 0.42), 90-day uw-mRS, and PD vs no disability status.

Conclusion: Although outcomes after stroke are less favorable in patients with vs without PD, in a large, controlled trial, we found no interaction between baseline disability and the benefit of MSU treatment. Our data support the earliest treatment of acute stroke patients regardless of premorbid functional status.

Clinical characteristics with inflammation profiling of long COVID and association with 1-year recovery following hospitalisation in the UK: a prospective observational study

BACKGROUND

No effective pharmacological or non-pharmacological interventions exist for patients with long COVID. We aimed to describe recovery 1 year after hospital discharge for COVID-19, identify factors associated with patient-perceived recovery, and identify potential therapeutic targets by describing the underlying inflammatory profiles of the previously described recovery clusters at 5 months after hospital discharge.

METHODS

The Post-hospitalisation COVID-19 study (PHOSP-COVID) is a prospective, longitudinal cohort study recruiting adults (aged ≥18 years) discharged from hospital with COVID-19 across the UK. Recovery was assessed using patient-reported outcome measures, physical performance, and organ function at 5 months and 1 year after hospital discharge, and stratified by both patient-perceived recovery and recovery cluster. Hierarchical logistic regression modelling was performed for patient-perceived recovery at 1 year. Cluster analysis was done using the clustering large applications k-medoids approach using clinical outcomes at 5 months. Inflammatory protein profiling was analysed from plasma at the 5-month visit. This study is registered on the ISRCTN Registry, ISRCTN10980107, and recruitment is ongoing.

FINDINGS

2320 participants discharged from hospital between March 7, 2020, and April 18, 2021, were assessed at 5 months after discharge and 807 (32·7%) participants completed both the 5-month and 1-year visits. 279 (35·6%) of these 807 patients were women and 505 (64·4%) were men, with a mean age of 58·7 (SD 12·5) years, and 224 (27·8%) had received invasive mechanical ventilation (WHO class 7-9). The proportion of patients reporting full recovery was unchanged between 5 months (501 [25·5%] of 1965) and 1 year (232 [28·9%] of 804). Factors associated with being less likely to report full recovery at 1 year were female sex (odds ratio 0·68 [95% CI 0·46-0·99]), obesity (0·50 [0·34-0·74]) and invasive mechanical ventilation (0·42 [0·23-0·76]). Cluster analysis (n=1636) corroborated the previously reported four clusters: very severe, severe, moderate with cognitive impairment, and mild, relating to the severity of physical health, mental health, and cognitive impairment at 5 months. We found increased inflammatory mediators of tissue damage and repair in both the very severe and the moderate with cognitive impairment clusters compared with the mild cluster, including IL-6 concentration, which was increased in both comparisons (n=626 participants). We found a substantial deficit in median EQ-5D-5L utility index from before COVID-19 (retrospective assessment; 0·88 [IQR 0·74-1·00]), at 5 months (0·74 [0·64-0·88]) to 1 year (0·75 [0·62-0·88]), with minimal improvements across all outcome measures at 1 year after discharge in the whole cohort and within each of the four clusters.

INTERPRETATION

The sequelae of a hospital admission with COVID-19 were substantial 1 year after discharge across a range of health domains, with the minority in our cohort feeling fully recovered. Patient-perceived health-related quality of life was reduced at 1 year compared with before hospital admission. Systematic inflammation and obesity are potential treatable traits that warrant further investigation in clinical trials.

FUNDING

UK Research and Innovation and National Institute for Health Research.

Safety, Feasibility, and Merits of Longitudinal Molecular Testing of Multiple Metastatic Sites to Inform mTNBC Patient Treatment in the Intensive Trial of Omics in Cancer

Patients with metastatic triple-negative breast cancer (mTNBC) have poor outcomes. The Intensive Trial of Omics in Cancer (ITOMIC) sought to determine the feasibility and potential efficacy of informing treatment decisions through multiple biopsies of mTNBC deposits longitudinally over time, accompanied by analysis using a distributed network of experts.

In the Intensive Trial of Omics in Cancer (ITOMIC), the feasibility and potential efficacy of informing treatment decisions through omics analysis of multiple biopsies of mTNBC deposits over time was assessed. An ITOMIC Tumor Board (ITB) that comprised experts discussed tumor profile findings and made treatment recommendations to each subject's physician. Study-directed omics analysis revealed that of the 31 enrolled subjects, two were found to have lung cancer, one a carcinoma of unknown primary site that and tumor samples from five subjects showed some receptor-positivity. Several subjects survived well beyond what would be expected for this patient group, supporting the merits of further investigation of this approach.

81 An Audit of Venous Thromboembolism (VTE) Risk Assessment & Prophylaxis Implementation

Introduction

VTE is considered one of the most common preventable causes of death and significant co-morbidity in inpatients and is responsible for approximately 60,000 deaths occur per annum in the UK. The NHS Standard Contract requires all inpatients to undergo a VTE risk assessment, with a 95% patient assessment threshold. In January 2020 we identified that 72% of patients within our trust had a risk assessment completed, and 15% of these were accurate. We subsequently implemented mandatory VTE prescribing training for all junior doctors joining the trust.

Aim

Review the impact of mandatory training module on VTE risk assessment and prescribing, in compliance with NICE Guidelines.

Method

All inpatient medical notes, VTE risk assessments, and VTE prescriptions were reviewed to assess accurate risk assessment completion and subsequent appropriate prophylaxis prescribing. The standards were as set out in the NICE guidelines [NG89]. Paediatric, Obstetric and ITU patients were excluded.

Results

Our VTE risk assessment completion rates increased from 72.1% to 94.2%, and the accuracy of these assessments from 15.4% to 34.5%. Our prescription rate increased from 84.6% to 90.6%, and prescribing accuracy from 41.2% to 79.5%.

Conclusions

By implementing mandatory VTE prophylaxis training for all junior doctors joining a new NHS trust, we can see increased compliance with appropriate risk assessment and prophylaxis prescribing. This will reduce the risk of unnecessary death from VTE in hospital inpatients.

Abstract TP262: Effect Of Prehospital Blood Pressure Fluctuations On Early Neurological Changes In Acute Ischemic Stroke Patients With Large Vessel Occlusion

Introduction: Blood pressure fluctuations in the acute phase of large vessel occlusion (LVO) ischemic stroke are associated with infarct progression and poor outcomes. We evaluated the association of prehospital blood pressure variations on a Mobile Stroke Unit (MSU) with early neurological change.

Methods: Prospectively-derived data were analyzed from tPA-eligible LVO patients treated and transported on the MSU, identified by hyperdense artery on CT or arterial occlusion on CTA. Patients were categorized by change in mean arterial pressure (ΔMAP) of > 10 mm Hg vs Δ MAP < 10 mmHg from arrival of MSU on-scene to arrival to the emergency department (ED). A sub-analysis of patients with ΔMAP > 10 mm Hg compared those whose MAP decreased by > 10 mm Hg vs those whose MAP increased by > 10 mm Hg. The primary outcome was 24-hour change in NIHSS. Groups were compared using Chi-square/Fisher’s exact test for categorical variables and Wilcoxon rank sum test for continuous variables.

Results: A total of 39 tPA-eligible LVO patients were identified, 19 with ΔMAP < 10mm Hg and 20 with ΔMAP > 10mm Hg. Baseline characteristics were comparable between groups including NIHSS (18.0 [11.0, 21.0] vs 20.0 [16.8, 25.8]) (Table 1). A similar percentage from each group received tPA and thrombectomy. Upon presentation to ED, 7/19 (37%) patients with ΔMAP < 10mm Hg had a 30% improvement in NIHSS, compared to 4/20 (20%) patients with ΔMAP >10mm Hg (p=0.417). The 24-hour change in NIHSS was also similar (ΔMAP < 10mm Hg = 7.0 [3.5, 12.0] vs ΔMAP > 10 mm Hg 10.0 [4.0, 16.0], p=0.517). Among patients with ΔMAP of 10mm Hg group, those with MAP decrease by > 10 mm Hg had a 10 point [7.0, 16.0] improvement in NIHSS vs 6.0 [2.5, 15.0] point improvement in those whose MAP increased by > 10 mm Hg (p=0.169).

Conclusion: Though limited by a small sample size, prehospital blood pressure fluctuations in LVO stroke patients on a MSU were not associated with early clinical changes.

Abstract 24: Mobile Stroke Units Associated With Favorable Clinical Outcome In Large Vessel Occlusion Stroke Patients: BEST-MSU Substudy

Introduction: Mobile Stroke Units (MSUs) improve clinical outcome in patients treated with tPA compared to standard management by Emergency Medical Services (EMS), but the impact of MSUs on outcomes in patients with large vessel occlusions (LVOs) having endovascular thrombectomy (EVT) has yet to be determined.

Methods: A pre-specified substudy of tPA-eligible stroke patients with LVOs on CT and/or CTA who were enrolled in the Benefits of Stroke Treatment Using a Mobile Stroke Unit (BEST-MSU), a prospective multicenter controlled trial comparing MSU with standard EMS management, was conducted. The primary outcome was the score on the 90-day utility-weighted modified Rankin Scale (uw-mRS). Secondary outcomes were rate of early neurologic recovery (30% improvement in NIHSS score) at 24 hours and functional independence (mRS 0-1) at 90 days.

Results: A total of 295 patients were included, 169 in the MSU group and 126 in the EMS group. Baseline characteristics were comparable between the groups, with the exception of baseline NIHSS (MSU median 19.0 [IQR 13.0, 23.0] vs EMS 16.0 [11.0, 20.0], p=0.003). 92% MSU vs 87% EMS LVO patients received tPA, and 78% vs 85% went on to have EVT. MSU LVO patients had faster tPA bolus from symptom onset (65.0 min [50.5, 92.0] vs 96.0 [79.3, 130.0], p<0.001), however the two groups had similar onset to groin puncture (169.0 min [133.8, 212.3] vs 162.0 [135.3, 207.0], p=0.77). The mean (±SD) score on the uw-mRS at 90 days was 0.64±0.39 in the MSU group and 0.50±0.40 in the EMS group (mean difference 0.16, 95% CI [0.07, 0.25] after adjustment for age, baseline NIHSS, premorbid functional status, prior stroke/TIA and site; p<0.001). Early neurologic recovery (68% vs 52%; adjusted OR 1.89 95% CI [1.14,3.17]) and functional independence (Figure 1, 42% vs 29%; 2.48 [1.38,4.55]) also favored the MSU group.

Conclusions: In tPA-eligible LVO stroke patients, MSU management was associated with better clinical outcomes compared with standard EMS management.

Cerebrospinal fluid neurofilament light predicts the rate of executive function decline in younger-onset dementia

INTRODUCTION

Determining disease severity and predicting prognosis in younger onset-dementia (YOD) remains challenging. Whether CSF biomarkers neurofilament light (NfL), tau and amyloidβ 42 (Aβ42) can help provide such information has been underexplored.

METHODS

Patients with YOD and CSF analysis were identified. We compared baseline NfL, tau and Aβ42 concentrations with contemporaneous Neuropsychiatry Unit Cognitive Assessment Tool (NUCOG) scores to assess their association with severity of cognitive impairment. Cognitive decline, as measured by longitudinal NUCOG assessment, was correlated against baseline biomarker levels to assess their utility in predicting the rate of cognitive decline.

RESULTS

78 patients with YOD (mean age = 56 years, SD = 8) and CSF analysis were identified. Dementia types included Alzheimer's disease, behavioural variant frontotemporal dementia, dementia not-otherwise-specified and other. Tau was associated with contemporaneous memory dysfunction (r = -0.556, 95% CI:[-0.702,-0.393], p < .001). 21 patients had longitudinal cognitive assessment up to 82 months from CSF sampling. NfL was associated with the rate of executive function decline (r = 0.755, 95% CI:[0.259,0.937], p < .001). Aβ42 was associated with the rate of memory decline (r = -0.582, 95% CI:[-0.855,-0.274], p = .007) and rate of total NUCOG decline (r = -0.515, 95% CI: [-0.809, -0.227], p = .017).

CONCLUSION

CSF tau is related to contemporaneous memory impairment in YOD. NfL and Aβ42 levels are associated with the rate of executive function and memory decline, respectively, and may have a role in prognostication in YOD.

Machine Learning Automated Detection of Large Vessel Occlusion From Mobile Stroke Unit Computed Tomography Angiography

BACKGROUND AND PURPOSE

Prehospital automated large vessel occlusion (LVO) detection in Mobile Stroke Units (MSUs) could accelerate identification and treatment of patients with LVO acute ischemic stroke. Here, we evaluate the performance of a machine learning (ML) model on CT angiograms (CTAs) obtained from 2 MSUs to detect LVO.

METHODS

Patients evaluated on MSUs in Houston and Los Angeles with out-of-hospital CTAs were identified. Anterior circulation LVO was defined as an occlusion of the intracranial internal carotid artery, middle cerebral artery (M1 or M2), or anterior cerebral artery vessels and determined by an expert human reader. A ML model to detect LVO was trained and tested on independent data sets consisting of in-hospital CTAs and then tested on MSU CTA images. Model performance was determined using area under the receiver-operator curve statistics.

RESULTS

Among 68 patients with out-of-hospital MSU CTAs, 40% had an LVO. The most common occlusion location was the middle cerebral artery M1 segment (59%), followed by the internal carotid artery (30%), and middle cerebral artery M2 (11%). Median time from last known well to CTA imaging was 88.0 (interquartile range, 59.5-196.0) minutes. After training on 870 in-hospital CTAs, the ML model performed well in identifying LVO in a separate in-hospital data set of 441 images with area under receiver-operator curve of 0.84 (95% CI, 0.80-0.87). ML algorithm analysis time was under 1 minute. The performance of the ML model on the MSU CTA images was comparable with area under receiver-operator curve 0.80 (95% CI, 0.71-0.89). There was no significant difference in performance between the Houston and Los Angeles MSU CTA cohorts.

CONCLUSIONS

In this study of patients evaluated on MSUs in 2 cities, a ML algorithm was able to accurately and rapidly detect LVO using prehospital CTA acquisitions.

Are medical procedures that induce coughing or involve respiratory suctioning associated with increased generation of aerosols and risk of SARS-CoV-2 infection? A rapid systematic review

BACKGROUND

The risk of transmission of SARS-CoV-2 from aerosols generated by medical procedures is a cause for concern.

AIM

To evaluate the evidence for aerosol production and transmission of respiratory infection associated with procedures that involve airway suctioning or induce coughing/sneezing.

METHODS

The review was informed by PRISMA guidelines. Searches were conducted in PubMed for studies published between January 1st, 2003 and October 6th, 2020. Included studies examined whether nasogastric tube insertion, lung function tests, nasendoscopy, dysphagia assessment, or suctioning for airway clearance result in aerosol generation or transmission of SARS-CoV-2, SARS-CoV, MERS, or influenza. Risk of bias assessment focused on robustness of measurement, control for confounding, and applicability to clinical practice.

FINDINGS

Eighteen primary studies and two systematic reviews were included. Three epidemiological studies found no association between nasogastric tube insertion and acquisition of respiratory infections. One simulation study found low/very low production of aerosols associated with pulmonary lung function tests. Seven simulation studies of endoscopic sinus surgery suggested significant increases in aerosols but findings were inconsistent; two clinical studies found airborne particles associated with the use of microdebriders/drills. Some simulation studies did not use robust measures to detect particles and are difficult to equate to clinical conditions.

CONCLUSION

There was an absence of evidence to suggest that the procedures included in the review were associated with an increased risk of transmission of respiratory infection. In order to better target precautions to mitigate risk, more research is required to determine the characteristics of medical procedures and patients that increase the risk of transmission of SARS-CoV-2.

Abstract P424: Hemorrhage Enlargement in the First Two Hours: A Mobile Stroke Unit Study

Objective: Hematoma enlargement (HE) occurs after spontaneous intracerebral hemorrhage (ICH) but no studies have evaluated the frequency of HE in first 1-2 h after symptom onset. We evaluated HE in the first 2h after onset using a mobile stroke unit (MSU).

Methods: Patients with spontaneous ICH within 4.5h were evaluated on the Houston MSU between 5/2014 and 4/2020. Baseline CT scans from the MSU were compared with scans repeated within 1h [median 67min (IQR 57-82 min]. Significant HE was defined as >6 ml if baseline volume was <20 ml and 30% increase if baseline volume >20 ml. Kruskal-Wallis and Wilcoxon rank sum tests evaluated differences in baseline volumes and HE. Intraclass correlation coefficient (ICC) evaluated agreement between two ICH measurement techniques (ABC/2 vs semi-automated).

Results: 163 patients had baseline CTs, of whom 60 had repeat 1h CTs (table 1). There was no difference between baseline volume and time of CT from symptom onset {<1h vs 1-2h vs >2h median (IQR) = 14 ml (6-28) vs. 16 ml (7-32) vs. 12 ml (4-24), P=0.42)}. There was also no correlation between time from onset and difference in volume between baseline and 1 h repeat imaging. However, 9/60 patients had significant HE from baseline to 1 h repeat imaging; all of these occurred in patients initially imaged within 2 h of onset (6/24 within 1h, 3/20 within 1-2h) (P=0.03) (figure 1). High reliability was seen between the two methods measuring volumes (ICC = 0.84).

Conclusion: Significant HE in the next hour occurs in 25% of ICH patients imaged within the first hour after symptom onset, and 17% imaged between 1-2 hours of onset. These patients would be a target for ultra-early hemostatic intervention.

Abstract P132: Successful Conduct of an Acute Stroke Clinical Trial During COVID

Introduction: Most clinical research stopped during COVID due to possible impact on data quality and personnel safety. We aimed to assess the impact of COVID on study conduct at sites that continued to enroll patients during the pandemic.

Methods: BEST-MSU is an ongoing study of Mobile Stroke Units (MSU) vs standard management of tPA eligible acute stroke patients in the pre-hospital setting. MSU personnel include a vascular neurologist via telemedicine, and a nurse, CT tech, and medics on board using appropriate PPE. During COVID, consent, 90 d mRS and EQ5D could be obtained by phone instead of in person, otherwise management was the same. We compared patient demographics, study metrics, and infection of study personnel during intra- vs pre-COVID eras.

Results: Four of 6 BEST-MSU sites continued to enroll during COVID. There was no difference in intra- (n= 41) vs pre- (n= 763) COVID enrolled tPA eligible patients’ age, sex, race (45% vs 41% Black), ethnicity (23% vs 19% Hispanic), or NIHSS (12 vs 12). MSU alert frequency did not change, but percent of screened patients enrolled and treated with tPA declined to 12% from 23% (p<.001); enrollment correlated with local stay at home and reopening (fig). There was no difference in alert to MSU arrival or arrival to tPA times, but on-scene time was 2 min longer (p=.04). There was no difference in ED door to CT, tPA, or EVT times, hospital LOS, discharge disposition, or 90d mRS or EQ5D accuracy. One MSU nurse tested positive but did not require medical care.

Conclusion: Clinical research in the pre-hospital setting can be carried out accurately and safely during a pandemic. Study enrollment and tPA treatment rates declined, but otherwise there was no difference in patient demographics, deterioration of study processes, or serious infection of study staff.

Abstract 3: Early Recanalization of Large Vessel Occlusions by tPA on the Mobile Stroke Unit

Introduction: The benefit of intravenous tPA in acute ischemic stroke patients with large vessel occlusions (LVOs) is limited but time dependent. We evaluated pre-hospital treatment with tPA on the Mobile Stroke Unit (MSU) to explore the recanalization rate in patients with LVOs and its effect on clinical improvement upon ED arrival.

Methods: Prospectively derived data were analyzed from patients on the Houston MSU who were treated with tPA and had LVOs identified by hyperdense artery on MSU CT or arterial occlusion on MSU CTA. The primary outcome was early recanalization, categorized as resolution of LVO on repeat vascular imaging in the ED or on emergent angiography versus no recanalization. Secondary outcome was change in baseline NIHSS at 24 hours. Differences in NIHSS were evaluated using Wilcoxon rank sum test with continuity correction.

Results: Seventy-one patients received tPA and had proximal LVOs both in the anterior and posterior circulation. Eleven had recanalization on CTA upon ED arrival (15.5%), while 7 had recanalization on emergent angiography (9.9%). The total early recanalization rate with tPA was 25.4%. Forty-seven patients with persistent LVOs on ED arrival (66.2%) underwent endovascular thrombectomy (EVT). Time from symptom onset (last known normal) to tPA bolus did not differ significantly between the early recanalization vs non-early recanalization groups (64.5 minutes [IQR 43.0-78.5] vs 64.0 minutes [52.5-92.0]; p = 0.41). Early recanalization resulted in greater improvement in baseline to ED arrival NIHSS (median NIHSS change 4.0 [0-11.8] vs 0 [0-3.5]; p = 0.01). There were no differences in ED arrival to 24 hour NIHSS between the early recanalization versus non-early recanalization groups irrespective of EVT.

Conclusions: Recanalization by ED arrival occurs in 25% of LVO patients with tPA treatment on a MSU and was associated with early clinical improvement. Subsequent EVT did not “make up” for the clinical benefit of early recanalization.

Abstract PS11-13: Multidimensional molecular profiling of repeated metastatic TNBC biopsies in the intensive trial of omics &lt;ITOMIC&gt; safely guides treatment decisions

Background Metastatic triple negative breast cancer (mTNBC) is an inherently diverse disease and while molecular classification of mTNBC has assisted in treatment decisions, if based on only an initial biopsy, it does not take into account the evolution of metastatic cancer. Characterization of emerging metastases is needed to reveal both new resistance or sensitivity to available therapeutics. The goal of “Intensive Trial of OMics in Cancer (ITOMIC) - Intensive Longitudinal Monitoring in Subjects With Triple-Negative Breast Cancer” (NCT01957514) - was to determine the feasibility of longitudinal collection of patient biopsies that would be subjected to molecular analysis to provide actionable, relevant and timely information to guide treatment decisions.Methods Multiple biopsies were collected longitudinally, including pre- and post-treatment, from 29 mTNBC patients enrolled in the ITOMIC study and subjected to multi-dimensional molecular profiling including WES, WGS, cancer gene panel sequencing, RNA-seq, and proteomics and/or IHC for tumor biomarkers. This information was used to guide iterative, patient- and tumor- individualized treatment recommendations made by a multi-institutional ITOMIC Tumor Board (ITB) and conveyed to each subject’s oncologist.Results Longitudinal biopsy collection was found to be safe. Molecular profiling revealed that 2 of an original 31 enrolled subjects likely had lung cancer rather than mTNBC, supporting the merit of repeated tissue analysis. While the other 29 subjects had all been given a diagnosis of mTNBC before entering the trial, estrogen receptor, progesterone receptor, and/or HER2 were found to be over-expressed in at least one sample for 12 subjects; appearance of receptor positivity suggests targeted therapy may be effective. Tumor evolution in response to the first on-study treatment for most subjects (cisplatin) was revealed by copy number alterations, changes in single nucleotide variants, and insertions/deletions in pre-/post-treatment biopsies. Over the course of the study, the ITB convened 54 times and 39 of 182 recommended treatments were evaluated and accessed through either an existing clinical trial, a single patient IND, approved off label or label indication. While not all ITB treatment recommendations were followed, 24 subjects did receive at least one ITB-recommended drug, frequently as part of a clinical trial. Currently, for 27 subjects (2 withdrew) median survival is ~31 months. There are 4 surviving patients in treatment with a remarkable median survival of &gt;51 months.Conclusion Collection and molecular analysis of multiple biopsies during the course of patient’s disease, shown here to be safe and feasible, provides information vital to appropriate treatment choice and reveals new targets for and resistance to therapy in metastatic TNBC.

Citation Format: Kimberly A Burton, Eric Q Konnick, Sibel Blau, Michael O Dorschner, Julie Gralow, Rahul Parulkar, Elisabeth Mahen, Patricia Spilman, Stephanie Parker, Francis M Senecal, Colin Pritchard, Christopher Szeto, Jing Zhu, Vijayakrishna K Gadi, Stephen C Benz, Shahrooz Rabizadeh, Patrick Soon-Shiong, Carl Anthony Blau. Multidimensional molecular profiling of repeated metastatic TNBC biopsies in the intensive trial of omics &lt;ITOMIC&gt; safely guides treatment decisions [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS11-13.

A multi-institutional assessment of COVID-19-related risk in radiation oncology

PURPOSE

The COVID-19 pandemic has presented challenges to delivering safe and timely care for cancer patients. The oncology community has undertaken substantial workflow adaptations to reduce transmission risk for patients and providers. While various control measureshave been proposed and implemented, little is known about their impact on safety of the radiation oncology workflow and potential for transmission. The objective of this study was to assess potential safety impacts of control measures employed during the COVID-19 pandemic.

METHODS

A multi-institutional study was undertaken to assess the risks of pandemic-associated workflow adaptations using failure mode and effects analysis (FMEA). Failure modes were identified and scored using FMEA formalism. FMEA scores were used to identify highest-risk aspects of the radiation therapy process. The impact of control measures on overall risk was quantified. Agreement among institutions was evaluated.

RESULTS

Thirty three failure modes and 22 control measures were identified. Control measures resulted in risk score reductions for 22 of the failure modes, with the largest reductions from screening of patients and staff, requiring use of masks, and regular cleaning of patient areas. The median risk score for all failure modes was reduced from 280 to 168. There was high institutional agreement for 90.3% of failure modes but only 47% of control measures.

CONCLUSIONS

COVID-related risks are similar across oncology practices in this study. While control measures can reducerisk, their use varied. The effectiveness of control measures on risk may guide selection of the highest-impact workflow adaptions to ensure safe care in oncology.

An absolute risk-guided approach to cardiovascular risk management within a chest pain clinic: the ARCPAC randomized trial

Background

The majority of patients attending chest pain clinics are found not to have a cardiac cause of their symptoms, but have a high burden of cardiovascular risk factors that may be opportunistically addressed. Absolute risk calculators are recommended to guide risk factor management, although it is uncertain to what extent these calculations may assist with patient engagement in risk factor modification.

Purpose

We sought to determine the usefulness of a proactive, absolute risk-based approach, to guide opportunistic cardiovascular risk factor management within a chest pain clinic.

Methods

This was a prospective, open-label, blinded-endpoint study in 192 enhanced risk (estimated 5-year risk ≥8%, based on Australian Absolute Risk Calculator) patients presenting to a tertiary hospital chest pain clinic. Patients were randomized to best practice usual care, or intervention with development of a proactive cardiovascular risk management strategy framed around a discussion of the individual's absolute risk. Patients found to have a cardiac cause of symptoms were excluded as they constitute a secondary prevention population. Primary outcome was 5-year absolute cardiovascular risk score at minimum 12 months follow up. Secondary outcomes were individual modifiable risk factors (lipid profile, blood pressure, smoking status).

Results

192 people entered the study; 100 in the intervention arm and 92 in usual care. There was no statistical difference between the two groups' baseline sociodemographic and clinical variables. The intervention group showed greater reduction in 5-year absolute risk scores (difference −2.77; p&lt;0.001), and more favourable individual risk factors, although only smoking status and LDL cholesterol reached statistical significance (table).

Conclusion

An absolute risk-guided proactive risk factor management strategy employed opportunistically in a chest pain clinic significantly improves 5-year cardiovascular risk scores.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Tasmanian Community Fund

South Africans' understanding of and response to the COVID-19 outbreak: An online survey

BACKGROUND

The COVID-19 outbreak is in an accelerating phase, and South Africa (SA) has had the highest number of documented cases during the early phase of the pandemic in sub-Saharan Africa.

OBJECTIVES

To assess South Africans' understanding of and response to COVID-19 during the first week of the country's lockdown period.

METHODS

An online survey was conducted in SA from 27 March to 2 April 2020. The survey was distributed widely among several websites and social media networks, including on a data-free platform. Descriptive statistics of knowledge, risk perception, access to and trust in information sources, and public and media opinions were calculated. Estimates were benchmarked to the 2019 national adult population estimates.

RESULTS

Of the 55 823 participants, the majority (83.4%) correctly identified the main symptoms of COVID-19. Over 90% had correct knowledge of the incubation period, with lower rates for 18 - 29-year-olds. Knowledge of symptoms and the incubation period varied significantly by population group (p&lt;0.001), dwelling type (p&lt;0.001) and sex (p&lt;0.001). A quarter (24.9%) perceived themselves as at high risk of contracting COVID-19. Risk perception varied by age, population group, employment status and dwelling type (p&lt;0.001). The most prevalent COVID-19 information sources were government sources (72.9%), news websites/apps (56.3%), satellite television (51.6%) and local television (51.4%).

CONCLUSIONS

Understanding knowledge, attitudes and behaviours of people facing the COVID-19 pandemic is crucial for guiding strategic policy. These findings provide public understanding of COVID-19 as the phases of the country-level epidemic progress, and also directly inform communication needs and gaps.

Barriers to the Use of Assistive Technology with Children: A Survey

This article reports on the responses of 120 teachers and habilitative specialists of multiply handicapped blind and deaf-blind children in Massachusetts to a survey on their use of assistive technology. The respondents reported problems in all areas covered by the survey: knowledge of electronic mobility aids and communication devices; the availability, maintenance, and funding of devices; and adequate information about devices. They especially mentioned the need for resources to assess and match students to appropriate devices and to generate more training for themselves.

Strategies for effective physics plan and chart review in radiation therapy: Report of AAPM Task Group 275

BACKGROUND

While the review of radiotherapy treatment plans and charts by a medical physicist is a key component of safe, high-quality care, very few specific recommendations currently exist for this task.

AIMS

The goal of TG-275 is to provide practical, evidence-based recommendations on physics plan and chart review for radiation therapy. While this report is aimed mainly at medical physicists, others may benefit including dosimetrists, radiation therapists, physicians and other professionals interested in quality management.

METHODS

The scope of the report includes photon/electron external beam radiotherapy (EBRT), proton radiotherapy, as well as high-dose rate (HDR) brachytherapy for gynecological applications (currently the highest volume brachytherapy service in most practices). The following review time points are considered: initial review prior to treatment, weekly review, and end-of-treatment review. The Task Group takes a risk-informed approach to developing recommendations. A failure mode and effects analysis was performed to determine the highest-risk aspects of each process. In the case of photon/electron EBRT, a survey of all American Association of Physicists in Medicine (AAPM) members was also conducted to determine current practices. A draft of this report was provided to the full AAPM membership for comment through a 3-week open-comment period, and the report was revised in response to these comments.

RESULTS

The highest-risk failure modes included 112 failure modes in photon/electron EBRT initial review, 55 in weekly and end-of-treatment review, 24 for initial review specific to proton therapy, and 48 in HDR brachytherapy. A 103-question survey on current practices was released to all AAPM members who self-reported as working in the radiation oncology field. The response rate was 33%. The survey data and risk data were used to inform recommendations.

DISCUSSION

Tables of recommended checks are presented and recommendations for best practice are discussed. Suggestions to software vendors are also provided.

CONCLUSIONS

TG-275 provides specific recommendations for physics plan and chart review which should enhance the safety and quality of care for patients receiving radiation treatments.

Feasibility and preliminary effects of a peer-led motivationally-embellished workplace walking intervention: A pilot cluster randomized trial (the START trial)

Walking interventions can be effective in increasing physical activity amongst physically inactive employees. However, despite their promising potential regarding sustainability and scalability, peer-led workplace walking interventions have not been tested. We evaluated a peer-led workplace group walking intervention designed to engage physically inactive employees. A 16-week pilot cluster randomized controlled trial consisted of enhanced (5 worksites; n = 50 participants) and minimal treatment (3 worksites; n = 47) conditions. All participants were provided with a Fitbit Zip and information on health benefits of walking. Enhanced treatment participants had access to a mobile phone app incorporating behavior change techniques, were trained on principles of autonomous motivation, and had a peer leader trained in a motivationally supportive communication style. Feasibility assessments included recruitment and drop-out rates, assessment completion rates, training acceptability (walkers and peer leaders), and intervention acceptability (walkers only). Outcomes assessed included movement-related behaviors (assessed via activPAL devices), cardio-metabolic risk factors, motivation to walk, and well-being, and these measures were taken at baseline and post-intervention. The results supported intervention feasibility. Preliminary efficacy evidence was mixed. Markers of cardio-metabolic risk improved in the enhanced treatment only. Autonomous motivation increased in both conditions. There were no changes in step counts, standing, and sitting time, or well-being. Further fine tuning is needed before a definitive RCT. Australian and New Zealand Clinical Trials Registry: ACTRN12618000807257.

Abstract TP494: Estimated tPA Dosing Weight on a Mobile Stroke Unit: Comparison between Estimated and Hospital-measured Weights

Introduction: The purpose of the Houston Mobile Stroke Unit (MSU) is to expedite stroke care by treating patients in the pre-hospital setting where obtaining a measured body weight, critical for accurate pre-hospital tPA dosing, is challenging and impossible. The paramedic and nurse on the MSU subjectively estimate by assessment (with patient report if possible) the weight for calculating tPA dosing. We aimed to determine the accuracy of the estimated weight method compared to the actual weight of patients treated with tPA on the MSU.

Methods: Data were prospectively collected for MSU tPA-treated patients as part of the BEST-MSU study comparing MSU to standard EMS management. We collected the first-documented hospital-measured weight (bed scale) within 24 hours of hospital arrival, and the estimated weight used on the MSU for treatment. Mean absolute and percent difference in weights were calculated; less than 10% difference in weights was considered acceptable. To compare the estimated and measured weights, we conducted a Wilcoxon signed-rank test. Differences between weights were set as 0 if both weights were above 100kg. Fisher’s exact test was used to explore association between weight difference > 10% and patient outcomes.

Results: Among 337 patients, mean age was 67.8 (15.6) and average measured weight was 81.2 kg (SD 22.3). Median absolute difference in measured versus estimated weight was 2.70 kg (IQR 0.55-7.60), and both weights were significantly different from each other (p value < 0.0001). The average absolute percent difference in weight was 7.04% (SD 9.11%). The absolute mean difference in tPA dosage was 3.49 mg (SD 6.06). Among patients whose estimated and measured weights were not both ≥100 kg, 56 (16.6%) had weight difference >10%. In patients with overestimation of weight by >10%, there were no symptomatic intracerebral hemorrhages. There was no association between weight difference and discharge modified Rankin score (p value = 0.5921).

Conclusion: Weight estimation on a mobile stroke unit can lead to similar tPA dosing for 82% of subjects compared to if dosing were determined based on actual weight. Weight over- or under-estimation had no detected significant impact on tPA outcomes.

Abstract TP284: Mobile Stroke Unit Site Experience in Diagnosis and Management of Extraparenchymal Intracranial Hemorrhage in the Prehospital Setting

Background: Mobile stroke units (MSUs) permit advanced cerebrovascular diagnosis, triage, and treatment to be delivered in the field. While the range of acute cerebral ischemia and intraparenchymal hemorrhage patients encountered by MSUs has been described, the frequency, determinants, and outcomes of patients presenting with extraparenchymal intracranial hemorrhages (subdurals/subarachnoid/epidural) has not been well delineated.

Methods: We analyzed consecutive transports among MSU programs in 3 cites, Los Angeles, Houston and Cleveland from program inception through August 2018 in the two former and through 2015 in the latter. Frequency and demographic, presenting, and treatment features of patients with subdural hematoma (SDH) and subarachnoid hemorrhage (SAH) were quantified.

Results: Among 850 overall transports, extraparenchymal intracranial hemorrhages accounted for 18 (2.1%), and included 11 (1.3%) SDH and 7 (0.8%) SAH. Among the SDH patients, age was mean 70/median 77 (range 28 to 85). Special features of SDH cases included: acute on chronic blood on CT in 36%, seizures in 9%, and isolated head trauma in 9%. Among SAH patients, mean age was 57 (range 41-75). Special features of SDH/SAH cases included accompanying intraparenchymal hemorrhage in 17%. Of the 18 combined SDH/SAH patients (67% women), 4 (22%) required field intubation, 1 (5%) was actively treated in the field with KCentra to reverse anticoagulation, and 5 (28%) were treated in the field with antihypertensives. (See Figure for exemplar cases.)

Conclusions: Extraparenchymal intracranial hemorrhages account for about 1 in 50 cases managed in Mobile Stroke Units. MSU response permits immediate definitive diagnosis by CT imaging, earlier start of indicated medical therapies, and direct routing to neurosurgically-capable stroke centers.

Abstract 32: “Rendezvous System” for Broadening a Mobile Stroke Unit Catchment Area

Purpose: Mobile Stroke Units (MSU) deliver acute stroke treatment on-scene in coordination with Emergency Medical Services (EMS) prior to transport to a stroke center. One criticism is the limited range of a single MSU. The Houston MSU is the only one in the U.S. using a rendezvous system with EMS to expand its range.

Methods: In addition to direct 911 dispatch of our MSU directly to the scene for tPA eligible patients within our “catchment” area (8 miles), we asked more distant EMS units to notify the MSU and also monitored EMS radio communication to identify eligible patients. For these “distant” patients, the MSU meets the EMS unit enroute to the stroke center and treats the patient at that intermediate location (usually a parking lot). The distribution of the distance from MSU base station to site of stroke and time from alert to tPA bolus were compared between patients treated on scene and by rendezvous using Wilcoxon rank sum test.

Results: From August 18, 2014 to July 20, 2018, 290 acute ischemic stroke patients were treated with tPA on our MSU. Of these, 140 (48.3%) were treated on scene by direct 911 dispatch, with a median of 7 miles (IQR 5 miles) from MSU base station. 150 (51.7%) patients were treated by rendezvous. They had their strokes a median of 13 miles from base (IQR 6 miles) (p<0.0001). Time (min) from 911 alert to tPA bolus was 37.6±9.7 with on-scene, and 37.7±12.7 with rendezvous (p=0.89).

Conclusion: A “rendezvous system” significantly expands the range of operations for a MSU in an urban area, doubling the number of patients treated, without incurring delay. This approach might be even more useful in rural areas.

Abstract TP79: Do Early Ischemic Changes Occur on CT Within the First Hour of Acute Ischemic Stroke

Introduction: Early ischemic changes (EIC) on non-contrast computed tomography (NCCT) can appear within 6 hours of last known normal (LKN), and can be quantified using the Alberta Stroke Program Early CT Score (ASPECTS). However, there is lack of data describing when EIC first appear. We leveraged our Mobile Stroke Unit (MSU) to determine the incidence of EIC on NCCT within 1 hour of LKN.

Methods: Prospectively derived data were analyzed from patients on our MSU who were independently adjudicated as tissue plasminogen activator (tPA) eligible, had NCCT within 1 hour of LKN, and had definite strokes based on subsequent testing. EIC, defined as ASPECTS ≤ 7, was measured and correlated to time from LKN, stroke severity (National Institutes of Health Stroke Scale, NIHSS), and presence of large vessel occlusion (LVO) on neuroimaging. All scans were obtained on an 8 slice Ceretom (Neurologica Corp) and graded by a Vascular Neurology fellow, with random scans compared with a Vascular Neurology attending (κ=0.69).

Results: 80 tPA eligible patients with NCCT within 1 hour of LKN were identified. 57 had definite strokes and/or strokes reversed by tPA. Of these, 54 (95%) had NCCT with sufficient diagnostic quality. Mean ASPECTS was 9.2 (median 10, interquartile range (IQR) 9-10) with a mean of 45.3 minutes (median 46, IQR 39-52) from LKN. Average NIHSS was 14.9. EIC (e.g. ASPECTS 6, 6, 7, 7) was identified in 4 patients (7%). There was no association between ASPECTS and time from LKN to CT (p=0.63), stroke severity (p=0.12) or presence of LVO (p= 0.09); the LVO analysis was limited by the small number of EIC patients (n=4).

Conclusions: Based on our experience, EIC may be present but ASPECTS is not < 6 within the first hour after LKN. Close scrutiny of NCCT for EIC within this timeframe may not be necessary for determining eligibility for tPA or endovascular thrombectomy.

Menstrual abnormalities amongst female South African Hajj pilgrims: a cross-sectional study

Introduction: Hajj (pilgrimage), the fifth pillar of Islam, is obligatory for every Muslim, male or female, provided that he/she is physically and financially able to do so, at least once in his/her lifetime. One of the rituals of Hajj requires the absence of menstruation. In the current modern era, many females utilise oral contraception to manipulate their menstrual cycle so that the pilgrim can be menses free during the main rituals of Hajj. However, many such females are at risk of breakthrough bleeding. Very little information has been documented concerning the incidence of menstrual cycle abnormalities amongst female Hajj pilgrims in general and South African pilgrims in particular. This study aims to determine the incidence of menstrual cycle abnormalities amongst South African female Hajj pilgrims and the potential factors that predispose to them.Methods: A cross-sectional descriptive study was conducted amongst South African female pilgrims during the five-day Hajj period. South Africa is usually limited to 5 000 pilgrims annually with a 50:50 gender split. For most of the five days of Hajj, pilgrims, separated by gender, are housed in special tents. Data were collected using an anonymous self-administered questionnaire. The questionnaires were distributed amongst the ladies’ tents in Mina on the last day of Hajj by nursing sisters attached to the South African medical mission. A total of 470 South African female pilgrims participated in the study with 147 excluded as they were either postmenopausal or had had hysterectomies, resulting in a sample size of 323.Results: Of the 318 participants who responded to the question about hormonal menstrual manipulation (HMM), 195 (61%) attempted this and 123 (39%) did not. Of the 308 participants who responded to the question concerning menstrual cycle problems (MCP), 54 (18%) had problems and 254 (82%) did not. Of the 189 participants who attempted HMM and answered the question on MCP, 44/189 (23%) had MCP, whilst 10/108 (9%) of those who did not attempt HMM had MCP. The OR for MCP was 2.97 (CI 1.46–6.04) if HMM was attempted compared with no HMM attempt.Conclusion: Menstrual irregularities occurred more frequently in those who attempt hormonal menstrual manipulation compared with those who do not. Health education on this issue should be integrated into the pre-Hajj classes.

Characterisation of a sub-20 ps temporal resolution pulse dilation photomultiplier tube

A pulse-dilation photomultiplier tube (PD-PMT) with sub-20 ps temporal resolution has been developed for use with γ-ray-sensitive gas Cherenkov detectors at the National Ignition Facility to improve the diagnosis of nuclear fusion burn history and the areal density of the remaining capsule ablator. The pulse-dilation mechanism entails the application of a time-dependent, ramp waveform to a photocathode-mesh structure, introducing a time-dependent photoelectron accelerating potential. The electric field imparts axial velocity dispersion to outgoing photoelectrons. The photoelectron pulse is dilated as it transits a drift region prior to amplification in a microchannel plate and read out with a digital oscilloscope. We report the first measurements with the prototype PD-PMT demonstrating nominal <20 ps FWHM across a 400 ps measurement window and <30 ps FWHM for an extracted charge up to 300 pC. The output peak areas are linear to within 20% over 3 orders of magnitude of input intensity. 3D particle in cell simulations, which included space charge effects, have been carried out to investigate the device temporal magnification, resolution, and linearity.

Effect of the carbon dioxide 10,600-nm laser and topical fluoride gel application on enamel microstructure and microhardness after acid challenge: an in vitro study

The aim of this in-vitro study was to evaluate positive effects of the carbon dioxide laser (CO₂, 10,600 nm) with acidulated phosphate fluoride (APF) gel on enamel acid resistance. Twenty extracted human third molars (40 surfaces) were randomly assigned into four groups: group C, untreated control; group L, CO₂ laser alone group; group F, APF 1.23% fluoride gel; and group FL, APF 1.23% gel and laser. Samples from group L were irradiated with a CO₂ laser for 30s. The parameter settings used were average power, 0.73 W; time on, 100 μs; time off, 40 ms; tip-to-tissue distance, 20 mm; tip diameter 700 μm; and energy density with movements, 5 J/cm². Samples from group F were treated with the APF gel for 4 min, and the gel was washed off with distilled water. The enamel samples from group FL were treated with APF gel for 4 min and then irradiated with the CO₂ laser for 30s without removing the gel. Each enamel sample was placed in 50 ml soft drink (pH = 2.75) for 10 min then rinsed with deionized water and stored in artificial saliva at 37 °C for 1 h. Samples were assessed for Vickers hardness number (VHN) before and after treatments and subjected to SEM analysis. Data were analyzed using a one-way analysis of variance (ANOVA) and Tukey's test (α < 0.05). After the acid challenge, the untreated C group was demineralized to a great extent and the enamel surface was with the lowest mean score of microhardness. The observed VHN in the control (C group) had a mean value of 176.13, the scores in the CO₂ laser group (L group) were with mean value of 238.40, the F group with a mean value of 218.45, and the fluoride-treated and laser-irradiated FL group-with a mean of 268.28 VHN. Paired t test performed to compare groups C, L, F, and FL has shown that group FL has greater resistance to decrease in microhardness of dental enamel (P ≤ 0.05) on exposure to acidic protocol. After the acid challenge, the fluoride-treated and laser-irradiated samples (group FL) showed the least diminution in enamel surface microhardness. The sub-ablative carbon dioxide laser irradiation in combination with fluoride treatment is more effective in protecting enamel surface and resisting demineralization than CO₂ laser irradiation or fluoride alone.

Participant Attitudes Toward an Intensive Trial of Multiple Biopsies, Multidimensional Molecular Analysis, and Reporting of Results in Metastatic Triple-Negative Breast Cancer

Purpose

Multidimensional molecular analysis of tumor tissue intensively over space and time can provide insight into how cancers evolve and escape treatment. Attitudes of participants in such trials have not been assessed. We explored patient views regarding an intensive study incorporating multiple biopsies, multidimensional molecular testing, and drug response predictions that are reported to the oncologist and patient.

Patients and Methods

A structured, self-administered survey was conducted among the first 15 patients enrolled in ITOMIC-001 (Intensive Trial of Omics in Cancer). Patients with metastatic triple-negative breast cancer were accrued at two sites in Washington state. Surveys containing 17 items were administered at enrollment and after the return of results. Surveys explored perceptions regarding risks, personal benefits, benefits to others, uncertainties associated with interpreting complex molecular results, concerns regarding multiple biopsies, and potential loss of confidentiality. At follow-up, three additional unique items explored patient coping.

Results

All participants expressed a strong desire for their experiences to benefit others, and all perceived a higher likelihood of deriving benefit than described during detailed consent discussions. Loss of confidentiality ranked lowest among patient concerns. Despite acknowledging uncertainties and risks inherent in complex molecular testing for clinical reporting, participants wanted access to findings in evaluating treatment choices, even if the best available evidence was weak. Follow-up surveys demonstrated relatively little change in attitudes, although concern about study biopsies generally declined. Study participation helped several patients cope better with their disease.

Conclusion

In advanced breast cancer, these findings demonstrate the feasibility of engaging motivated patients in trials that navigate the uncertainties associated with intensive spatial and longitudinal multidimensional molecular testing for the purpose of advancing precision medicine.

Opportunity for interprofessional collaborative care-findings from a sample of federally qualified health center patients in the Midwest

OBJECTIVES

Federally qualified health centers (FQHCs) frequently serve more socio-economically disadvantaged populations; existing literature suggests that underserved groups are more likely to experience various chronic physical and mental health conditions. FQHC patients may have significant needs for various specialty services that are beyond common FQHC providers. This study examines chronic condition prevalence, healthcare satisfaction, and use of multiprovider services in a Midwest FQHC patient population. We also evaluated the potential of interprofessional collaborative practices in FQHC settings.

STUDY DESIGN

Cross-sectional study.

METHODS

A total of 232 participants were recruited prior to or immediately after their scheduled clinic visit within an FQHC located on the fringes of an urban area. Respondents were invited to complete a brief questionnaire and grant access to their electronic medical records.

RESULTS

Nearly half of participants were covered by Medicaid, private insurance carriers (19.4%), or Medicare (17.7%). The most prevalent chronic conditions included diabetes, depression, anxiety, and chronic pain. Almost half (46.6%) of participants were seen by two or three providers; 20% had 7+ office visits in the last year. While 35.3% reported health dissatisfaction, 30.6% reported health satisfaction. When asked if they were satisfied with their health care, nearly 70% reported satisfaction with health care, while only 4.7% reported healthcare dissatisfaction.

CONCLUSIONS

The authors of this study recommend an interprofessional collaborate healthcare model be explored to address the complex and multifaceted healthcare needs of this population. Future research in this area should prospectively examine the utility of monitoring patient satisfaction in a collaborative practice setting.

Management practices associated with pain in cattle on western Canadian cow-calf operations: A mixed methods study

The implementation of on-farm pain mitigation strategies is dependent on feasibility and importance to producers. Currently, there is a lack of information regarding adoption of management practices associated with pain in cattle within the Canadian beef industry. The objective of this mixed methods study was to describe pain-associated practices implemented on farm and producer perceptions toward pain mitigation strategies. A questionnaire about calving management and calf processing was delivered to 109 cow-calf producers in western Canada. In addition, 15 respondents were purposively selected based on questionnaire responses to participate in individual semistructured, on-farm interviews. The prevalence of pain mitigation strategies used for dystocia and cesarean section by respondents were 46 and 100%, respectively. The majority of operations reported castrating and dehorning calves before 3 mo of age (95 and 89%, respectively). The majority of operations did not use pain mitigation strategies for castration and dehorning (90 and 85%, respectively). Branding was practiced by 57% of respondents, 4% of which used pain mitigation. Thematic content analysis revealed that producers' perception of pain were influenced by what they referred to as "common sense," relatability to cattle, visual evidence of pain, and age of the animal. Factors that influenced participant rationale for the implementation of pain mitigation practices included access to information and resources, age of the animal, benefit to the operation, cost and logistics, market demands, and personal conscience. Overall, management practices were generally in compliance with published Canadian guidelines. Results of this study may provide direction for future policy making, research, and extension efforts to encourage the adoption of pain mitigation strategies.