Evaluation of the performance of two commercial SARS-CoV-2 neutralizing antibody test kits / 中华微生物学和免疫学杂志

Objective:To evaluate the performance of two commercial EIA kits for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralizing antibodies.Methods:Two commercial SARS-CoV-2 neutralizing antibody ELISA test kits (A and B) were used to detect serum panel consists of the following sera: 44 collected before vaccination, 120 collected one month after vaccination and 64 collected six months after recovery from convalescent patients of COVID-19. In the meantime, the above samples were also taken for live virus micro-neutralization test (micro-NT) indicated as the 50% neutralization antibody titer (NT 50). The consistency of qualitative and quantitative results between the two commercial kits and live virus neutralization test was analyzed. Results:Taking the micro-NT results as the standard, the positive coincidence rates of A and B kits were 97.40% and 100.00%, respectively; the negative coincidence rates were 97.30% and 95.95%, respectively; the Youden indices were 0.95 and 0.96, respectively. Furthermore, quantitative analysis indicated that the correlation coefficients between A and B kits and micro-NT results were 0.24 ( P<0.05) and 0.52 ( P<0.000 1) for samples collected after vaccination, respectively; while the correlation coefficients were 0.81 ( P<0.000 1) and 0.89 ( P<0.000 1) for convalescent serum samples, respectively. Conclusions:The results obtained by the two commercial neutralizing antibody detection kits were in good agreement with the qualitative results of micro-NT. The neutralizing antibody titers in convalescent serum samples detected by the two kits showed a stronger correlation with the micro-NT results.

Nuevo índice de desempeño global de una prueba diagnóstica: el índice T / New global performance index of a diagnostic test: the T index

Introducción. En el presente artículo se propone un nuevo índice de desempeño global de una prueba diagnóstica: el índice T, que corresponde a la proporción de aciertos (Pa) menos la proporción de error (Pe) dividido entre la proporción de aciertos (Pa). Métodos. Describir los fundamentos teóricos y prácticos del índice T. Comparar el índice T frente al índice de Youden para poder establecer si dos o más modalidades diagnósticas difieren en su capacidad de discriminar, correctamente, entre los individuos verdaderamente enfermos de los sanos. Comparar el índice T frente al índice de Youden para poder establecer si el índice T puede ser utilizado para escoger "el mejor punto de corte" cuando la prueba diagnóstica de interés expresa sus resultados en forma cuantitativa continua.Resultados. Comparado frente al índice de Youden, el índice T permite distinguir entre las pruebas diagnósticas con alto desempeño diagnóstico de aquellas con pobre desempeño diagnóstico. Además, el índice T, de manera confiable, permite escoger "el mejor punto de corte" cuando una prueba diagnóstica utiliza una variable cuantitativa continua para expresar sus resultados.Conclusiones. Al contrastar los resultados del índice T versusel índice de Youden y los resultados del índice T versus la curva COR, podemos afirmar que el índice T es un índice exacto y eficiente.

Introduction. In this article, a new global performance index of a diagnostic test is proposed: the T Index, which corresponds to the proportion of the hit ratio (Hr) minus the error ratio (Er) divided by the hit ratio (Hr).Methods. To describe the theoretical and practical foundations of the T index; to compare the T index against the Youden index in order to establish whether two or more diagnostic modalities differ in their ability to correctly discriminate between truly ill and healthy individuals; and to compare the T index with the Youden index in order to establish whether the T index can be used to choose the "best cut-off point" when the diagnostic test of interest expresses its results in a continuous quantitative way.Results. Compared with the Youden index, the T index allows us to differentiate between diagnostic tests with high diagnostic performance and those with poor diagnostic performance. In addition, the T index, reliably, allows choosing "the best cut-off point" when a diagnostic test uses a continuous quantitative variable to express its results.Conclusions. By contrasting the results of the T index versus the Youden index and the results of the T index versus the COR curve, we can affirm that the T index is an accurate and efficient index.

Selection and optimization of nutritional risk screening tools for esophageal cancer patients in China

Improvement of liver fibrosis diagnostic models based on Youden index / 上海交通大学学报（医学版）

Objective: By using Youden index, to improve the performance of the hepatic fibrosis diagnostic models, and to solve the problem of unbalanced diagnostic sensitivity when there is a big difference in the sample size of two groups. Methods: Two hepatitis B virus (HBV) datasets available on GitHub were selected, including 482 HBV infected subjects recruited from Shuguang Hospital in affiliation with Shanghai University of Traditional Chinese Medicine (train set) and 86 HBV infected subjects from Xiamen Hospital of Traditional Chinese Medicine (validation set). By using the two datasets, linear discriminant analysis model, random forest model, gradient boosting model and decision tree model were established, based on four clinical parameters (age, glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, and platelet count) of patients, for the diagnosis of early and advanced hepatic fibrosis as well as the diagnosis of hepatic fibrosis and cirrhosis. Youden index was used to adjust the threshold value and the classification result of each diagnostic model. The diagnostic performances of each machine learning model and fibrosis index based on the 4 factor (FIB-4) were evaluated by accuracy, the area under the receiver operating characteristic curve (AUC) and sensitivity. Results: The intergroup sensitivity imbalance occurred in all machine learning models. After using Youden index, the difference of intergroup sensitivity was greatly reduced, and the total accuracy and AUC values of machine learning models were generally higher than those of FIB-4 index. Conclusion:The improved diagnostic models based on Youden index can reduce the difference of intergroup sensitivity and improve the comprehensive performance of the diagnostic models of hepatic fibrosis.

Optimal Starting Age for Colorectal Cancer Screening in an Era of Increased Metabolic Unhealthiness: A Nationwide Korean Cross-Sectional Study

BACKGROUND/AIMS: The association between metabolic syndrome and colorectal cancer (CRC) has been suggested as one of causes for the increasing incidence of CRC, particularly in younger age groups. The present study examined whether the current age threshold (50 years) for CRC screening in Korea requires modification when considering increased metabolic syndrome. METHODS: We analyzed data from the National Health Insurance Corporation database, which covers ~97% of the population in Korea. CRC risk was evaluated with stratification based on age and the presence/absence of relevant metabolic syndrome components (diabetes, dyslipidemia, and hypertension). RESULTS: A total of 51,612,316 subjects enrolled during 2014 to 2015 were analyzed. Among them, 19.3% had diabetes, hypertension, dyslipidemia, or some combination thereof. This population had a higher incidence of CRC than did those without these conditions, and this was more prominent in subjects < 40 years of age. The optimal cutoff age for detecting CRC, based on the highest Youden index, was 45 years among individuals without diabetes, dyslipidemia, and hypertension. Individuals with at least one of these components of metabolic syndrome had the highest Youden index at 62 years old, but the value was only 0.2. Resetting the cutoff age from 50 years to 45 years achieved a 6% increase in sensitivity for CRC detection among the total population. CONCLUSIONS: Starting CRC screening earlier, namely, at 45 rather than at 50 years of age, may improve secondary prevention of CRC in Korea.

Effect evaluation of three ELISA kits in detection of paragonimiasis / 中国血吸虫病防治杂志

Objective To evaluate the effects of 3 kinds of ELISA reagents on the detection of human paragonimiasis. Meth?ods A total of 45 serum samples from patients with paragonimiasis,218 serum samples from patients with other parasitic dis?eases as well as 80 serum samples from healthy people were detected by GD?ELISA(IgG antigen ELISA detection reagent),ES?ELISA(using excretory/secretory(ES)products of Paragonimus westermani),and sAg?ELISA(using semi?purified antigen (sAg)of P. westermani),respectively. The effects of the 3 reagents were evaluated and compared. Results The sensitivities of GD?ELISA,ES?ELISA,and sAg?ELISA were 95.6%(95%CI:89.6%~100.0%),93.3%(95%CI:86.0%~100.0%)and 86.7%(95%CI:76.8%~96.6%),respectively;the specificities of the above three reagents were 88.6%(95%CI:85.0%~92.2%),88.9%(95%CI:85.3%~92.5%)and 99.0%(95%CI:97.9%~100.0%),respectively,and the Youden indexes of them were 0.84,0.82 and 0.86,respectively. Conclusion sAg?ELISA is more suitable than GD?ELISA and ES?ELISA for clin?ical sample tests in paragonimiasis endemic areas in China.

A Comparison between Asia-Pacific Region Criteria and Entropy Model Criteria about Body Mass Index of Elderly Females Using Morbidity of Chronic Disease / 대한지역사회영양학회지

OBJECTIVES: This study was conducted to propose the need of re-establishing the criteria of the body weight classification in the elderly. We compared the Asia-Pacific Region Criteria (APR-C) with Entropy Model Criteria (ENT-C) using Morbidity rate of chronic diseases which correlates significantly with Body Mass Index (BMI). METHODS: Subjects were 886 elderly female participating in the 2007-2009 Korea National Health and Nutrition Examination Survey (KNHANES). We compared APR-C with those of ENT-C using Receiver Operating Characteristics (ROC) curve and logistic regression analysis. RESULTS: In the case of the morbidity of hypertension, the results were as follows: Where it was in the T-off point of APR-C, sensitivity was 67.5%, specificity was 43.1%, and Youden's index was 10.6. While in the cut-off point of ENT-C, it was 56.7%, 56.6%, and 13.3 respectively. In the case of the morbidity of diabetes, the results were as follows: In the cut-off point of APR-C, Youden's index was 14.2. While in the cut-off point of ENT-C, it was 17.2 respectively. The Area Under the ROC Curve (AUC) of the subjects who had more than 2 diseases among hypertension, diabetes, and dyslipidemia was 0.615 (95% CI: 0.578-0.652). Compared to the normal group, the odds ratio of the hypertension group which will belong to the overweight or obesity was 1.79 (95% CI: 1.30-2.47) in the APR-C, and 2.04 (95% CI: 1.49-2.80) in the ENT-C (p > 0.001). CONCLUSIONS: We conclude that the optimal cut-off point of BMI to distinguish between normal weight and overweight was 24 kg/m2 (ENT-C) rather than 23 kg/m2 (APR-C).