Urea breath test for Helicobacter pylori infection in adult dyspeptic patients: A meta-analysis of diagnostic test accuracy

BACKGROUND Helicobacter pylori(H.pylori)infection has been well-established as a significant risk factor for several gastrointestinal disorders.The urea breath test(UBT)has emerged as a leading non-invasive method for detecting H.pylori.Despite numerous studies confirming its substantial accuracy,the reliability of UBT results is often compromised by inherent limitations.These findings underscore the need for a rigorous statistical synthesis to clarify and reconcile the diagnostic accuracy of the UBT for the diagnosis of H.pylori infection.AIM To determine and compare the diagnostic accuracy of 13C-UBT and 14C-UBT for H.pylori infection in adult patients with dyspepsia.METHODS We conducted an independent search of the PubMed/MEDLINE,EMBASE,and Cochrane Central databases until April 2022.Our search included diagnostic accuracy studies that evaluated at least one of the index tests(^(13)C-UBT or ^(14)C-UBT)against a reference standard.We used the QUADAS-2 tool to assess the methodo-logical quality of the studies.We utilized the bivariate random-effects model to calculate sensitivity,specificity,positive and negative test likelihood ratios(LR+and LR-),as well as the diagnostic odds ratio(DOR),and their 95%confidence intervals.We conducted subgroup analyses based on urea dosing,time after urea administration,and assessment technique.To investigate a possible threshold effect,we conducted Spearman correlation analysis,and we generated summary receiver operating characteristic(SROC)curves to assess heterogeneity.Finally,we visually inspected a funnel plot and used Egger’s test to evaluate publication bias.endorsing both as reliable diagnostic tools in clinical practice.CONCLUSION In summary,our study has demonstrated that ^(13)C-UBT has been found to outperform the ^(14)C-UBT,making it the preferred diagnostic approach.Additionally,our results emphasize the significance of carefully considering urea dosage,assessment timing,and measurement techniques for both tests to enhance diagnostic precision.Nevertheless,it is crucial for researchers and clinicians to evaluate the strengths and limitations of our findings before implementing them in practice.

Diagnostic accuracy of the tongue blade test combined with clinical signs to detect maxillary and mandibular fractures in the emergency department

BACKGROUND: To evaluate the diagnostic accuracy of clinical signs combined with the tongue blade test(TBT) to detect maxillary and mandibular fractures.METHODS: A cross-sectional study enrolled patients with maxillary and mandibular injuries in the emergency department. Physical examination and the TBT were performed, followed by radiological imaging(facial X-ray or computed tomography [CT]). The diagnostic accuracy was calculated for individuals and a combination of clinical findings at predicting maxillary and mandibular fractures.RESULTS: A total of 98 patients were identified, of whom 31.6% had maxillary fractures and9.2% had mandibular fractures. The combination of malocclusion, tenderness on palpation and swelling with positive TBT had 100% specificity to detect maxillary and mandibular fractures. In the absence of malocclusion, the combination of tenderness on palpation and swelling with positive TBT produced a specificity of 97.8% for maxillary fracture and a specificity of 96.2% for mandibular fracture. A clinical decision tool consisting of malocclusion, tenderness on palpation, swelling and TBT revealed a specificity of 100% and a positive predictive value of 100%.CONCLUSION: The clinical decision tool is potentially useful to rule out mandibular fractures,thus preventing unnecessary radiation exposure.

Evaluation of urea breath test as a diagnostic tool for Helicobacter pylori infection in adult dyspeptic patients

In this editorial,we discuss the article in the World Journal of Gastroenterology.The article conducts a meta-analysis of the diagnostic accuracy of the urea breath test(UBT),a non-invasive method for detecting Helicobacter pylori(H.pylori)infection in humans.It is based on radionuclide-labeled urea.Various methods,both invasive and non-invasive,are available for diagnosing H.pylori infection,inclu-ding endoscopy with biopsy,serology for immunoglobulin titers,stool antigen analysis,and UBT.Several guidelines recommend UBTs as the primary choice for diagnosing H.pylori infection and for reexamining after eradication therapy.It is used to be the first choice non-invasive test due to their high accuracy,specificity,rapid results,and simplicity.Moreover,its performance remains unaffected by the distribution of H.pylori in the stomach,allowing a high flow of patients to be tested.Despite its widespread use,the performance characteristics of UBT have been inconsistently described and remain incompletely defined.There are two UBTs available with Food and Drug Administration approval:The 13C and 14C tests.Both tests are affordable and can provide real-time results.Physicians may prefer the 13C test because it is non-radioactive,compared to 14C which uses a radioactive isotope,especially in young children and pregnant women.Although there was heterogeneity among the studies regarding the diagnostic accuracy of both UBTs,13C-UBT consistently outperforms the 14C-UBT.This makes the 13C-UBT the preferred diagnostic approach.Furthermore,the provided findings of the meta-analysis emphasize the significance of precise considerations when choosing urea dosage,assessment timing,and measurement techniques for both the 13C-UBT and 14C-UBT,to enhance diagnostic precision.

The Accuracy Levels of Vehicle Detectors Commonly Used in Korea Based on the Results of Quality Certification Test

The Ministry of Land, Infrastructure and Transport of Korea introduced the ITS system performance evaluation about six and a half years ago. The main purpose is to make sure that accurate and reliable real-time traffic data are collected from the ITS system installed. There are three types of performance evaluations, which are Quality Certification Test, Pre-Delivery Test and Periodic Check in Operation. In this paper the accuracy levels of vehicle detectors commonly used in Korea are analyzed based on the results of quality certification tests conducted during 2008-2012. The test items consist of volume, speed and occupancy. The analysis shows that loop detectors have the best levels of accuracy in all three test items and their levels of accuracy have been steady. Video image detectors do not have so good levels of accuracy as loop detectors, but the levels of accuracy have improved as time passes. Radar detectors do not have good levels of accuracy. However, their levels of accuracy have improved as time passes. The last vehicle detectors, geomagnetism detectors have the worst accuracy in the occupancy item.

Impact of Typical Steady-state Conditions and Transient Conditions on Flow Ripple and Its Test Accuracy for Axial Piston Pump

The current research about the flow ripple of axial piston pump mainly focuses on the effect of the structure of parts on the flow ripple. Therein, the structure of parts are usually designed and optimized at rated working conditions. However, the pump usually has to work in large-scale and time-variant working conditions. Therefore, the flow ripple characteristics of pump and analysis for its test accuracy with respect to variant steady-state conditions and transient conditions in a wide range of operating parameters are focused in this paper. First, a simulation model has been constructed, which takes the kinematics of oil film within friction pairs into account for higher accuracy. Afterwards, a test bed which adopts Secondary Source Method is built to verify the model. The simulation and tests results show that the angular position of the piston, corresponding to the position where the peak flow ripple is produced, varies with the different pressure. The pulsating amplitude and pulsation rate of flow ripple increase with the rise of pressure and the variation rate of pressure. For the pump working at a constant speed, the flow pulsation rate decreases dramatically with the increasing speed when the speed is less than 27.78% of the maximum speed, subsequently presents a small decrease tendency with the speed further increasing. With the rise of the variation rate of speed, the pulsating amplitude and pulsation rate of flow ripple increase. As the swash plate angle augments, the pulsating amplitude of flow ripple increases, nevertheless the flow pulsation rate decreases. In contrast with the effect of the variation of pressure, the test accuracy of flow ripple is more sensitive to the variation of speed. It makes the test accuracy above 96.20% available for the pulsating amplitude of pressure deviating within a range of ~6% from the mean pressure. However, with a variation of speed deviating within a range of ±2% from the mean speed, the attainable test accuracy of flow ripple is above 93.07%. The model constructed in this research proposes a method to determine the flow ripple characteristics of pump and its attainable test accuracy under the large-scale and time-variant working conditions. Meanwhile, a discussion about the variation of flow ripple and its obtainable test accuracy with the conditions of the pump working in wide operating ranges is given as well.

High-risk symptoms and quantitative faecal immunochemical test accuracy: Systematic review and meta-analysis

BACKGROUND The quantitative faecal immunochemical test for haemoglobin(FIT) has been revealed to be highly accurate for colorectal cancer(CRC) detection not only in a screening setting, but also in the assessment of patients presenting lower bowel symptoms. Therefore, the National Institute for Health and Care Excellence has recommended the adoption of FIT in primary care to guide referral for suspected CRC in low-risk symptomatic patients using a 10 μg Hb/g faeces threshold.Nevertheless, it is unknown whether FIT′s accuracy remains stable throughout the broad spectrum of possible symptoms.AIM To perform a systematic review and meta-analysis to assess FIT accuracy for CRC detection in different clinical settings.METHODS A systematic literature search was performed using MEDLINE and EMBASE databases from inception to May 2018 to conduct a meta-analysis of prospective studies including symptomatic patients that evaluated the diagnostic accuracy of quantitative FIT for CRC detection. Studies were classified on the basis of brand,threshold of faecal haemoglobin concentration for a positive test result,percentage of reported symptoms(solely symptomatic, mixed cohorts) and CRC prevalence(< 2.5%, ≥ 2.5%) to limit heterogeneity and perform subgroup analysis to assess the influence of clinical spectrum on FIT′s accuracy to detect CRC.RESULTS Fifteen cohorts including 13073 patients(CRC prevalence 0.4% to 16.8%) were identified. Pooled estimates of sensitivity for studies using OC-Sensor at 10 μg Hb/g faeces threshold(n = 10400) was 89.6% [95% confidence interval(CI): 82.7%to 94.0%). However, pooled estimates of sensitivity for studies formed solely by symptomatic patients(n = 4035) and mixed cohorts(n = 6365) were 94.1%(95%CI: 90.0% to 96.6%) and 85.5%(95%CI: 76.5% to 91.4%) respectively(P <0.01), while there were no statistically significant differences between pooled sensitivity of studies with CRC prevalence < 2.5%(84.9%, 95%CI: 73.4% to 92.0%)and ≥ 2.5%(91.7%, 95%CI: 83.3% to 96.1%)(P = 0.25). At the same threshold, OCSensor? sensitivity to rule out any significant colonic lesion was 78.6%(95%CI:75.6% to 81.4%). We found substantial heterogeneity especially when assessing specificity.CONCLUSION The results of this meta-analysis confirm that, regardless of CRC prevalence,quantitative FIT is highly sensitive for CRC detection. However, FIT ability to rule out CRC is higher in studies solely including symptomatic patients.

New fecal test for non-invasive Helicobacter pylori detection:A diagnostic accuracy study

AIM To assess the diagnostic accuracy of a new fecal test for detecting Helicobacter pylori(H. pylori), using ^(13)Curea breath test as the reference standard, and explore bacterial antibiotic resistance. METHODS We conducted a prospective two-center diagnostic test accuracy study. We enrolled consecutive people≥ 18 years without previous diagnosis of H. pylori infection, referred for dyspepsia between February and October 2017. At enrollment, all participants underwent 13 C-urea breath test. Participants aged over 50 years were scheduled to undergo upper endoscopy with histology. Participants collected stool samples 1-3 d after enrollment for a new fecal investigation(THD fecal test). The detection of bacterial 23 S rRNA subunit gene indicated H. pylori infection. We also used the index diagnostic test to examine mutations conferring resistance to clarithromycin and levofloxacin. Independent investigators analyzed index test and reference test standard results blinded to the other test findings. We estimated sensitivity, specificity, positive(PPV) and negative(NPV) predictive value, diagnostic accuracy, positive and negative likelihood ratio(LR), together with 95% confidence intervals(CI).RESULTS We enrolled 294 consecutive participants(age: Median 37.0 years, IQR: 29.0-46.0 years; men: 39.8%). Ninetyfive(32.3%) participants had a positive ^(13)C-urea breath test. Twenty-three(7.8%) participants underwent upper endoscopy with histology, with a full concordance between ^(13)C-urea breath test and histology in detecting H. pylori infection. Four(1.4%) out of the 294 participants withdrew from the study after the enrollment visit and did not undergo THD fecal testing. In the 290 participants who completed the study, the THD fecal test sensitivity was 90.2%(CI: 84.2%-96.3%), specificity 98.5%(CI:96.8%-100%), PPV 96.5%(CI: 92.6%-100%), NPV 95.6%(CI: 92.8%-98.4%), accuracy 95.9%(CI: 93.6%-98.2%), positive LR 59.5(CI: 19.3-183.4), negative LR 0.10(CI: 0.05-0.18). Out of 83 infected participants identified with the THD fecal test, 34(41.0%) had bacterial genotypic changes consistent with antibiotic-resistant H. pylori infection. Of these, 27(32.5%) had bacterial strains resistant to clarithromycin, 3(3.6%) to levofloxacin, and 4(4.8%) to both antibiotics. CONCLUSION The THD fecal test has high performance for the non-invasive diagnosis of H. pylori infection while additionally enabling the assessment of bacterial antibiotic resistances.

Test measurements for accuracy of absolute and relative GPS positioning

The paper, after the introduction, briefly outlines the principles of both absolute and relative GPS positioning. It deals with factors and error resources affecting the accuracy of these surveying procedures. It reviews the geodetic determination of a reference point and a base line used for the test measurements. The study describes the completed test measurements, and on the basis of results, it draws the conclusions for the accuracy of the investigated surveying methods. Finally, considering these accuracy measures, their possible application in mine surveying is also mentioned very shortly.

Test Accuracy of CT-Scan for the Detection of Malignant Liver Mass

Background: Detection of malignant liver mass is very important for the treatment modalities. Objective: The purpose of the present study was to establish the usefulness of CT scan in the diagnosis of malignant hepatic mass. Methodology: This cross sectional study was carried out in the Department of Radiology and Imaging at Mymensingh Medical College Hospital (MMCH), Mymensingh, Banghabandhu Sheikh Mujib Medical University (BSMMU), Dhaka and Dhaka Medical College Hospital (DMCH), Dhaka during the period of 1st January 2006 to 31st December 2007. Patients admitted in the Department of Medicine and Department of Hepatobiliary of MMCH, BSMMU, and DMCH with the clinical diagnosis of fever, abdominal pain, anorexia, nausea/vomiting, loss of appetite, jaundice, weight loss and ascites were selected as study population. CT scan and histopathology were performed to all the patients. Result: A total number of 50 patients were recruited for this study. Mean age of all patients was 51.28 ± 14 years with a range of 17 year to 78 years. Among all patients 28 had multiple lesion, of them 71.4% was malignant and 28.6% was benign. On the other side 22 patients had solitary lesion, of them 36.4% was malignant and 63.6% was benign

猕猴桃便携式无损检测仪影响因素及其精度校准分析

为探究产地、成熟度对便携式可溶性固形物无损检测精度的影响,以同一品种3个产地的猕猴桃为试材,分别采用便携式无损检测仪和常规有损检测仪对其可溶性固形物含量进行测定和比较,并运用人工神经网络对其进行分析。结果表明,在使用便携式无损检测仪对猕猴桃可溶性固形物检测时,3个产地的无损检测R2分别为0.26、0.52、0.61,成熟度会对其检测精度造成一定影响,但在不同产地间没有稳定、统一的规律;基于人工神经网络学习、建模产生的随机预测值可将R2提高5%~49%。因此,可利用预测值来作为中间校准程序,以辅助提高便携式无损检测精度。

试验台约束对滑动轴承动特性识别精度的影响

在滑动轴承的动特性测试中,试验台参数对动特性测试精度有重要的影响。以某倒置式轴承动特性试验台为研究对象,基于轴承动力学正反问题,提出滑动轴承动特性系数识别精度的仿真评估方法,分析不同激振频率时试验台约束参数对轴承动特性系数识别精度的影响规律,并对激振频率和约束参数的取值范围进行优选。结果表明:在较低激振频率的条件下,当约束刚度和约束阻尼取值较小时,动特性系数的识别精度受测试误差的影响不大,随着约束刚度和约束阻尼取值增大到一定值,动特性系数的识别精度受测试误差的影响迅速增大。针对研究的试验台,选择激振频率在30~300 Hz之间,选择试验台约束刚度小于试验轴承刚度的0.3%,试验台约束阻尼小于试验轴承阻尼的7%时,能够保证较好的轴承动特性系数的测试精度。

导弹命中精度的序贯截尾概率圆检验方法

针对圆概率偏差检验难以直接计算的问题,提出序贯截尾概率圆检验方法,以目标点为中心,绘制两个同心圆,其中小圆以内区域为接受域,大圆以外区域为拒绝域,中间区域为继续试验域,在此基础上定义了序贯检验的基本决策规则,给出了双方风险及平均试验次数计算模型,提出了两种不同的决策阈值优化计算模型,通过求解优化问题确定接受域及拒绝域半径。利用数值仿真分析了两种不同决策阈值计算方法下检验方案中的各类参数,其中以平均试验次数最小为优化目标的计算模型具有更好的工程实用性。

基于磁流变液的薄壁零件铣削技术研究

针对弱刚度、复杂形状的零件在切削夹紧过程中难夹持、易变形的问题,提出了基于磁流变液(MRF)的变刚度柔性辅助支承方法,以获得理想的加工质量。利用磁流变效应的快速、可逆及可控等特性,通过结构设计和磁路仿真,研制了用于薄壁曲面零件加工的磁流变自适应柔性辅助支承装置;建立了以加工形变最小为目标函数的优化模型,对该装置支承单元的数量和位置分布进行优化设计;搭建了铣削试验平台,通过对铣削信号进行测试分析,验证布局优化和励磁电流对加工质量的影响。结果表明,布局优化后的磁流变辅助支承装置随着电流的增加,可以有效地提高系统刚度,减小切削振动响应,改善加工质量。

化学发光免疫测定甲状腺功能在生化检验中的准确度分析

目的系统分析化学发光免疫测定甲状腺功能在生化检验中的准确度。方法选取2021年2月—2022年2月湖北省公安县人民医院收治的45例疑似甲状腺疾病患者作为研究对象,以最终的病理诊断结果作为金标准,分别对45例疑似甲状腺疾病患者开展放射免疫分析法与化学发光免疫法进行检测,对比两种检查方法准确度、敏感度、特异度。结果化学发光免疫法的敏感度、准确度分别为97.50%、95.56%,高于放射免疫分析法的75.00%、73.33%,差异有统计学意义(χ^(2)=8.538、8.459,P均<0.05);化学发光免疫法的特异度为80%,高于放射免疫分析法的60.00%,差异无统计学意义(χ^(2)=0.476,P>0.05)。结论化学发光免疫法检测甲状腺疾病患者的敏感度、特异度、准确度均较高,可为临床医生诊断与治疗甲状腺疾病提供良好的新思路。

牛3种妊娠相关糖蛋白可视早孕试剂盒检测效果比较

旨在确定牛妊娠相关糖蛋白(PAGs)可视早孕试剂盒与超声检查的差异、检测准确性的判断标准,并比较牛3种PAGs可视早孕试剂盒的检测效果。采用酶联免疫吸附试验法检测牛的“未孕(特异性)”和“怀孕(灵敏性)”,并将检测结果与超声检查相比较,以此判断牛PAGs的检测准确性及检测效果。结果显示,3种PAGs试剂盒的检测结果与超声检查不存在显著性差别,可以用作商业化检测。该类试剂盒的灵敏性与超声检查的一致性高于93%,但不能达到100%,原因在于PAGs存在一定的半衰期,灵敏性只能作为牛PAGs检测准确性的参考依据,不能作为最终判断依据。而3种试剂盒的检测特异性与超声检查的一致性均可达100%,该类试剂盒可以作为准确性最终判断依据。3种试剂盒中,试剂盒2、3可以在人工输精后第27天达到100%,比试剂盒1提前4 d。

放电等离子体粒子云网格蒙特卡罗模拟的分层级验证方法

当前,科学计算的验证主要针对基于确定性偏微分方程组的网格离散方法。放电等离子体的粒子云网格PIC方法作为一种粒子-网格耦合的仿真手段,其验证方法具有显著不同的特点:第一,PIC仿真除了在时间和空间上进行离散,还需要对粒子数权重进行离散;第二,离散粒子的相空间分布函数是否适合作为验证研究的观测量;第三,粒子-网格耦合过程中的电场插值和电荷分配会影响PIC仿真的全局收敛精度。另外,当PIC方法与蒙特卡罗(MC)方法耦合时,离散误差和随机误差通常叠加在一起,理查德森外推需要结合系综平均进行。提出了一种分层级验证的方法。首先对单粒子轨道、电磁场求解、二体粒子碰撞进行收敛精度阶测试;然后采用空间电荷限制流、气体的傅里叶流动等具有精确解的经典物理模型分别对集成PIC、MC模块进行离散误差评估;最后采用放电物理过程对程序功能进行基准校验。

飞机载荷校准试验主动约束技术

在研究以往飞机载荷校准试验支持和约束方式的基础上,结合某型飞机结构特点,提出一种载荷校准主动约束方法。对主动约束方法和传统的起落架方法飞机载荷校准进行受力分析,建立了2种约束方法的理论模型;设计2种约束方法的机翼载荷校准对比试验,并提出主动约束载荷校准试验实施流程;结合某型飞机机翼载荷校准试验和飞行试验对主动约束方法进行了验证。结果表明:与传统的起落架约束方法相比,主动约束方法能有效解决有起落架布置的翼身整体结构机翼根部载荷测量难题,并将机翼载荷校准试验量级提高41%,机翼载荷模型误差可控制在3%以内。

一种R-test球头球心检测装置结构优化设计方法

基于数控系统绕刀具中心旋转(Rotation tool center point,RTCP)功能,R-test装置被用于多轴联动数控机床的联动精度检测与标定。该仪器通过三个直线位移传感器测量安装于主轴的球头球心空间位置,从而可测量机床多轴联动时的刀具中心点位置误差。在分析测量原理的基础上,提出最大测量空间和测量敏感度的两个用于评价测量性能的指标及相应的数值算法,得到一种R-test装置结构优化设计方法。在选择通用球头芯棒与长度计的情况下,通过约束分析得到测量杆安装圆直径、测量杆与基准面夹角两个关键尺寸的设计区间,利用蒙特卡罗法搜索得到这两个关键尺寸的最优解,完成结构优化设计。仿真表明,优化设计得到的R-test测量装置具有最佳的测量敏感度,可测区域大于半径为4 mm的球体,能满足实际测量精度和测量空间需要。

分步精超角接触球轴承外圈沟道工艺试验研究

为提高角接触球轴承外圈沟道精超的加工精度及加工效率,基于沟道表面在精超加工过程中的变化特点,对轴承外圈的精超加工部分进行深入研究,细分为粗精超、精超两步,采用正交试验法来对每一步加工参数进行优化,将优化得出的结果和常规的一步精超试验结果作对比分析,试验结果表明:相较于常规的一步精超,采用分步精超能够将轴承超精加工精度提高10.42%,并且超精加工时间减少2s,说明分步精超的加工精度及加工效率均要高于常规的一步精超。

建筑钢结构焊缝无损检测技术

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