Diagnostic Accuracy of Chest Computed Tomography Scans for Suspected Patients With COVID-19: Receiver Operating Characteristic Curve Analysis

BACKGROUND: Computed tomography (CT) scans are increasingly available in clinical care globally. They enable a rapid and detailed assessment of tissue and organ involvement in disease processes that are relevant to diagnosis and management, particularly in the context of the COVID-19 pandemic. OBJECTIVE: The aim of this paper is to identify differences in the CT scan findings of patients who were COVID-19 positive (confirmed via nucleic acid testing) to patients who were confirmed COVID-19 negative. METHODS: A retrospective cohort study was proposed to compare patient clinical characteristics and CT scan findings in suspected COVID-19 cases. A multivariable logistic model with LASSO (least absolute shrinkage and selection operator) selection for variables was used to identify the good predictors from all available predictors. The area under the curve (AUC) with 95% CI was calculated for each of the selected predictors and the combined selected key predictors based on receiver operating characteristic curve analysis. RESULTS: A total of 94 (56%) patients were confirmed positive for COVID-19 from the suspected 167 patients. We found that elderly people were more likely to be infected with COVID-19. Among the 94 confirmed positive patients, 2 (2%) patients were admitted to an intensive care unit. No patients died during the study period. We found that the presence, distribution, and location of CT lesions were associated with the presence of COVID-19. White blood cell count, cough, and a travel history to Wuhan were also the top predictors for COVID-19. The overall AUC of these selected predictors is 0.97 (95% CI 0.93-1.00). CONCLUSIONS: Taken together with nucleic acid testing, we found that CT scans can allow for the rapid diagnosis of COVID-19. This study suggests that chest CT scans should be more broadly adopted along with nucleic acid testing in the initial assessment of suspected COVID-19 cases, especially for patients with nonspecific symptoms

Development and Validation of a Questionnaire to Assess Awareness and Knowledge of Nonalcoholic Fatty Liver Disease, a Liver Cancer Etiological Factor, among Chinese Young Adults

PURPOSE: Despite the increasing prevalence of nonalcoholic fatty liver disease (NAFLD), a liver cancer etiological factor, among Chinese young adults (CYA), there is a lack of valid, reliable, ready-to-use survey instruments for assessing awareness and knowledge of NAFLD in this population. The aims of this study were to develop, validate, and assess the reliability of a web-based, self-administered questionnaire evaluating awareness and knowledge of NAFLD among CYA. METHODS: Based on review of relevant literature, a draft questionnaire was initially developed. Face and content validity of the questionnaire was evaluated by an expert panel of seven gastroenterologists. The construct validity was tested through item analysis based on item response theory. Reliability assessment included test-retest for stability and test for internal consistency. Two pilot tests were conducted among 60 randomly selected students at Lanzhou University, China, through WeChat App. RESULTS: The content validity and clarity indexes were both greater than 0.85. Face validity was established by concluding that questions had no issue with feasibility, readability, clarity of wording, clarity of layout, and style. Response rates for two pilot tests were 96.7% (58 out of 60) and 98.3% (59 out of 60), respectively. Results testing the construct validity showed estimated amount of information obtained by the test between -3 and +3 range of ability was 97.57%. The test-retest reliability (Pearson\u27s r) was 0.62. The internal consistency (KR20) was 0.92. CONCLUSIONS: This newly developed questionnaire is a reliable and valid instrument for assessing awareness and knowledge of NAFLD among this sample from CYA

Initial experience with an electron FLASH research extension (FLEX) for the Clinac system

Purpose: Radiotherapy delivered at ultra-high-dose-rates (≥40 Gy/s), that is, FLASH, has the potential to effectively widen the therapeutic window and considerably improve the care of cancer patients. The underlying mechanism of the FLASH effect is not well understood, and commercial systems capable of delivering such dose rates are scarce. The purpose of this study was to perform the initial acceptance and commissioning tests of an electron FLASH research product for preclinical studies. Methods: A linear accelerator (Clinac 23EX) was modified to include a nonclinical FLASH research extension (the Clinac-FLEX system) by Varian, a Siemens Healthineers company (Palo Alto, CA) capable of delivering a 16 MeV electron beam with FLASH and conventional dose rates. The acceptance, commissioning, and dosimetric characterization of the FLEX system was performed using radiochromic film, optically stimulated luminescent dosimeters, and a plane-parallel ionization chamber. A radiation survey was conducted for which the shielding of the pre-existing vault was deemed sufficient. Results: The Clinac-FLEX system is capable of delivering a 16 MeV electron FLASH beam of approximately 1 Gy/pulse at isocenter and reached amaximum dose rate \u3e3.8 Gy/pulse near the upper accessory mount on the linac gantry. The percent depth dose curves of the 16 MeV FLASH and conventional modes for the 10 × 10 cm2 applicator agreed within 0.5 mm at a range of 50% of the maximum dose. Their respective profiles agreed well in terms of flatness but deviated for field sizes \u3e10 × 10 cm2. The output stability of the FLASH system exhibited a dose deviation of \u3c1%.Preliminary cell studies showed that the FLASH dose rate (180 Gy/s) had much less impact on the cell morphology of 76N breast normal cells compared to the non-FLASH dose rate (18 Gy/s), which induced large-size cells. Conclusion: Our studies characterized the non-clinical Clinac-FLEX system as a viable solution to conduct FLASH research that could substantially increase access to ultra-high-dose-rate capabilities for scientists

Supplemental material for Joint modelling for organ transplantation outcomes for patients with diabetes and the end-stage renal disease

<p>Supplemental material for Joint modelling for organ transplantation outcomes for patients with diabetes and the end-stage renal disease by Jianghu(James) Dong, Shijia Wang, Liangliang Wang, Jagbir Gill and Jiguo Cao in Statistical Methods in Medical Research</p