A parametric comparison of diagnostic accuracy with three ordinal diagnostic groups

Many medical diagnostic studies involve three ordinal diagnostic groups in which the diagnostic accuracy can be summarized by the volume or partial volume under a Receiver Operating Characteristic (ROC) surface. We study in this paper the statistical comparison of diagnostic accuracy from multiple diagnostic tests when three ordinal diagnostic groups are involved. Under the assumption that the multiple diagnostic tests follow a multivariate normal distribution within each diagnostic group, we provide the asymptotic variance and covariance for the maximum likelihood estimates of the volumes under the ROC surfaces from multiple diagnostic tests and propose statistical tests to test whether the diagnostic accuracy as measured by the volume under the ROC surface is the same for multiple diagnostic tests. We also propose a confidence interval estimate to the difference of two volumes under two ROC surfaces. Our approach depends crucially on the assumptions of normal distributions on diagnostic tests, which might not be robust when such assumptions are violated. Finally, we apply our proposed methodology to a real data set of 118 subjects to compare the diagnostic accuracy of early stage Alzheimer's disease (AD) from multiple neuropsychological tests.     

Diagnostic randomized controlled trials: the final frontier

ABSTRACT: Clinicians, patients, governments, third-party payers, and the public take for granted that diagnostic tests are accurate, safe and effective. However, we may be seriously misled if we are relying on robust study design to ensure accurate, safe, and effective diagnostic tests. Properly conducted, randomized controlled trials are the gold standard for assessing the effectiveness and safety of interventions, yet are rarely conducted in the assessment of diagnostic tests. Instead, diagnostic cohort studies are commonly performed to assess the characteristics of a diagnostic test including sensitivity and specificity. While diagnostic cohort studies can inform us about the relative accuracy of an experimental diagnostic intervention compared to a reference standard, they do not inform us about whether the differences in accuracy are clinically important, or the degree of clinical importance (in other words, the impact on patient outcomes). In this commentary we provide the advantages of the diagnostic randomized controlled trial and suggest a greater awareness and uptake in their conduct. Doing so will better ensure that patients are offered diagnostic procedures that will make a clinical difference.     

长白山劲松林场植物群落的分类和排序

将长白山白河林业局劲松林场的５４块样地用聚类分析法划分成６个植被类群,再用ＰＣ－ＶＴＡＢ程序中经过改进的Ｂｒａｕｎ－Ｂｌａｎｑｕｅｔ学派的植被排表分析法进行综合,产生了鉴别概要表,为各个等级的植被类群筛选出诊断种。此外,还用鉴别种地样地记录进行主成分分析,以验证诊断种的有效性,结果表明,ＰＣ－ＶＴＡＢ中的植被排表分析法是筛选鉴别种的有效方法,而鉴别种以显著地提高植被分析和排序的质量。     

Comparison of cytohistologic techniques in diagnosis of gastroesophageal malignancy

OBJECTIVE: To evaluate the diagnostic performance of various endoscopic cytologic techniques, namely, brushing cytology, touch smear cytology and crush cytology, and comparison with concurrent biopsy results in diagnosis of gastroesophageal malignancy. STUDY DESIGN: This prospective study was conducted on 100 patients, with 78 clinically suspected cases of esophageal malignancy and 22 cases of gastric malignancy. RESULTS: The diagnostic accuracy of touch smear in esophageal malignancy was significantly higher (94.12%) than brushing and crush smears (89.71% each), and endoscopic biopsy had the diagnostic accuracy of 88.24%. The diagnostic accuracy of combined brushing and biopsy was 100%; it was 97.06% for touch smears combined with biopsy. In comparison, the diagnostic accuracy in gastric malignancy was 75% for brushing alone, which was significantly lower than touch smear (87.5%) and endoscopic biopsy (87.5%). The diagnostic yield for crush smear was 81.25%. A combination of touch smears and biopsy had a diagnostic yield of 100%; it was 93.75% for combined brushings and biopsy. CONCLUSION: A combination of cytohistologic techniques resulted in a statistically significant increase in the diagnostic yield of gastroesophageal malignancies and thus cytologic techniques may act as adjunct to biopsy histology to increase the diagnostic efficiency.     

Serologic diagnostics of Legionella infection

Technical approaches to construction of preparations for serologic diagnostics of Legionella infection were presented in the article; antigenic- and immunoglobulin-based diagnostic kits with known characteristics were developed. Immunogenic properties of protein and lypopolysaccharide antigens, which have diagnostic value, were studied; similarity of protein antigens from 7 serogroups of L. pneumophila was demonstrated. Soluble antigen with known composition was obtained and used for the development of antigen-based polymeric kit for diagnostics of Legionella infection. On the basis of hyperimmune sera, immunoglobulin-based polymeric diagnostic kit and array of coagglutinating diagnostic kits for the mentioned 7 serogroups were developed. Antigen-based polymeric diagnostic kit was recommended for licensure.     

基于专利分析的肿瘤基因PCR诊断技术研究

肿瘤目前成为人类健康和生命的重要危胁,肿瘤基因诊断是对肿瘤的各种原癌基因、抑癌基因进行检测,聚合酶链反应(polymerase chain reaction,PCR)技术是目前临床基因诊断应用最广泛的诊断技术,具有普及率高、特异性好、简便快捷等特点。肿瘤基因PCR诊断技术可以用于已知基因突变的检测,快速了解突变状态,有效制定治疗方案,为肿瘤患者带来福音。本研究主要基于专利数据,对肿瘤基因PCR诊断技术进行分析,探讨了全球与中国在肿瘤基因PCR诊断技术领域的发展现状与趋势。在Innography数据库共检索到PCR技术相关专利16,939件,专利家族6,285件。在肿瘤基因PCR诊断技术领域中,荧光定量PCR技术占比较大,约占肿瘤基因PCR诊断技术总量的三分之一。从技术技术生命周期来看,肿瘤基因PCR诊断技术目前仍处在高速发展阶段。美国是肿瘤基因PCR诊断技术的发展领先国家。该技术的主要来源国为美国,全球42.09%的专利来自美国,同时美国也是同族专利的主要分布地区。在肿瘤基因PCR诊断技术领域,排名前15位的顶尖机构中,来自美国的机构有7所。中国在肿瘤基因PCR诊断技术领域起步较晚,但发展迅速,在该技术领域申请的专利数量仅次于美国。中国申请的肿瘤基因PCR诊断技术的专利绝大多数都只在中国进行专利保护,并没有布局全球市场的意愿。     

Usefulness of bile cytology in the diagnostic management of patients with biliary tract obstruction

Eighteen patients with evidence of biliary tract obstruction had a total of 29 satisfactory bile samples submitted for diagnostic cytology during a two-year period. These 29 specimens were reviewed in order to determine if bile cytology is useful in the diagnostic management of patients with obstructive biliary tract disease. Twenty-one of the bile specimens were from patients with malignant biliary stricture, and eight were from patients with benign biliary obstruction. Bile cytology was positive for carcinoma in eight samples from patients with malignant stricture and was inconclusive for malignancy in two. There were no false positives. The diagnostic specificity of bile cytology was 100%, the diagnostic sensitivity was 48%, and the diagnostic accuracy was 62%. When carefully collected and promptly processed, bile proved an excellent specimen for cytologic evaluation and was a valuable adjunct to other diagnostic procedures for the detection of carcinoma causing biliary tract obstruction.     

Comparison of the pick-and-smear and Saccomanno methods for sputum cytologic analysis

The two methods of preparing sputum specimens for cytologic study, the (fresh) pick-and-smear technique and the (blended) Saccomanno technique, were compared using 249 consecutive specimens. Two slides were prepared for each specimen by each technique. Of the specimens, 103 showed squamous metaplasia, carcinoma in situ or carcinoma. A semiquantitative rating system (0 to 4+) was used to determine the number of diagnostic cells for each method for those 103 cases. More diagnostic cells were found on the Saccomanno preparations (217) than on the fresh preparations (154). There were 121 diagnostic cells in the Saccomanno preparations versus 95 diagnostic cells in the fresh preparations from 63 squamous metaplasias; 7 versus 3 for the preparations from 5 carcinomas in situ; 64 versus 42 from 28 squamous cell carcinomas; 3 versus 1 from 1 large cell undiffernomas; and 12 diagnostic cells in Saccomanno preparations versus 5 in fresh preparations from 3 small cell cancers. Twelve squamous metaplasias, two carcinomas in situ, four squamous carcinomas, one adenocarcinoma and one small cell cancer had no diagnostic cells on the fresh preparations; four squamous metaplasias and one squamous carcinoma had no diagnostic cells on the Saccomanno preparations. More diagnostic information and fewer false-negative results were achieved with the Saccomanno technique.     

Rapid Diagnostic Algorithms as a Screening Tool for Tuberculosis: An Assessor Blinded Cross-Sectional Study

Background

A major obstacle to effectively treat and control tuberculosis is the absence of an accurate, rapid, and low-cost diagnostic tool. A new approach for the screening of patients for tuberculosis is the use of rapid diagnostic classification algorithms.

Methods

We tested a previously published diagnostic algorithm based on four biomarkers as a screening tool for tuberculosis in a Central European patient population using an assessor-blinded cross-sectional study design. In addition, we developed an improved diagnostic classification algorithm based on a study population at a tertiary hospital in Vienna, Austria, by supervised computational statistics.

Results

The diagnostic accuracy of the previously published diagnostic algorithm for our patient population consisting of 206 patients was 54% (CI: 47%–61%). An improved model was constructed using inflammation parameters and clinical information. A diagnostic accuracy of 86% (CI: 80%–90%) was demonstrated by 10-fold cross validation. An alternative model relying solely on clinical parameters exhibited a diagnostic accuracy of 85% (CI: 79%–89%).

Conclusion

Here we show that a rapid diagnostic algorithm based on clinical parameters is only slightly improved by inclusion of inflammation markers in our cohort. Our results also emphasize the need for validation of new diagnostic algorithms in different settings and patient populations.     

Surface EMG recordings and pain-related disorders: a diagnostic framework

Surface electromyography provides a very valuable set of information when used diagnostically with pain-related disorders. Unfortunately, most researchers and clinicians limit their investigation to only one level of diagnostic information available concerning the neuromuscular system. This article develops and encourages the clinician/researcher to consider three levels of diagnostic information: emotional, organ-related, and postural aspects. The theoretical background and diagnostic procedures used to investigate each is presented. Differential treatment considerations, given differential diagnostic findings, are discussed.     

Surface EMG recordings and pain-related disorders: A diagnostic framework

Surface electromyography provides a very valuable set of information when used diagnostically with pain-related disorders. Unfortunately, most researchers and clinicians limit their investigation to only one level of diagnostic information available concerning the neuromuscular system. This article develops and encourages the clinician/researcher to consider three levels of diagnostic information: emotional, organ-related, and postural aspects. The theoretical background and diagnostic procedures used to investigate each is presented. Differential treatment considerations, given differential diagnostic findings, are discussed.     

Comparative evaluation of diagnostic preparations

The diagnostic value of preparations is commonly characterized by sensitivity and specificity. But not all these characteristics make it possible to decide unequivocally which of the preparations to be compared is superior to the other one with respect to its diagnostic value. It is proposed that in the choice of a diagnostic preparation its capacity to provide data for exact diagnosis should be considered, i.e. the additional characteristic indicating the spread of the disease under study. As an example, the comparison of the diagnostic value of conventional methods and the polymerase chain reaction in the diagnostics of helicobacteriosis is presented. The described method for the evaluation of the diagnostic value of the preparation is well-grounded, simple and obvious.     

我国兽用诊断试剂产业现状与未来趋势

兽用诊断试剂产业服务于动物疾病防控的技术需求,既是一个独立的产业,也是多学科交叉、技术密集、资金密集型产业。和国际兽用诊断试剂产业相比,我国兽用诊断试剂产业起步晚,底子薄,产品质量差距明显。通过对比和分析兽用诊断试剂产业的国内外现状,提出了我国兽用诊断试剂行业所面临的挑战,指出了未来的发展趋势,以期为我国兽用诊断试剂产业的发展提供有益的参考建议。     

The efficacy of 18F-FDG PET/CT-based diagnostic model in the diagnosis of colorectal cancer regional lymph node metastasis

In order to assess the efficacy of ¹⁸F-FDG PET/CT-based diagnostic model in diagnosing colorectal cancer (CRC) lymph node metastasis (LNM), the ¹⁸F-FDG PET/CT medical records of CRC patients were acquired, and the CRC regional LNM diagnostic model was constructed through the combination of image and grain factors of ¹⁸F-FDG PET/CT. The specific analysis methods include univariate analysis, multivariate analysis, ROC curve analysis, and statistical analysis. The research results showed statistical differences in TNM staging, intestinal obstructions, tumor infiltration, regional lymph node (LN) SUVmax, regional LN minimum dimension, and remote metastasis between the CRC patients in the LNM positive group and the LNM negative group. Through the comparisons between the diagnostic model proposed in the research and other diagnostic methods, it was found that the AUC (95%CI) and sensitivity of the proposed diagnostic model were the highest, the comprehensive diagnostic efficacy of the diagnostic model was optimal. Therefore, it was concluded that the diagnostic model was of significant application values, which provided the basis for subsequent clinical diagnosis of CRC.     

Serological diagnosis of suppurative-septic diseases of staphylococcal etiology

The parallel examination of osteomyelitis patients by means of the passive hemagglutination (PHA) test with the use of antigenic erythrocyte diagnostic agents, prepared on the basis of hydrochloric acid extract from Staphylococcus aureus strain 209P and teichoic acid extract from S. aureus strain Wood 46 has revealed that these diagnostic agents are practically equal in their diagnostic effectiveness. In the examination of endocarditis patients measurement of the total antibody activity in the PHA test with diagnosticum on the basis of strain 209P has proved to be a more sensitive method, whereas in osteomyelitis patients the total IgG activity has been more accurately measured by ELISA. The treatment of sera with 2-mercaptoethanol essentially decreased the diagnostic effectiveness of the PHA test. The study has shown the diagnostic value of not only IgG but also of IgM antibody measurements.     

乳腺浸润性导管癌96例影像诊断体会

目的：探讨全数字化乳腺摄影与彩色多普勒相结合对乳腺癌的诊断价值。方法：搜集经X线摄影及超声检查并经病理证实为乳腺浸润性导管癌的96例进行回顾性分析。结果：96例乳腺癌中,单发病灶83例,多发病灶13例。采用全数字化X线摄影单独诊断乳腺癌80例,诊断符合率83.33%,采用超声单独诊断乳腺癌87例,诊断符合率90.63%。结论：乳腺X线与超声相结合,诊断乳腺癌95例,诊断符合率99.06%,此二种检查综合诊断,可明显提高乳腺癌的诊断符合率,减少漏诊和误诊。     

Regulating whole exome sequencing as a diagnostic test

In the last decade, there has been a flood of new technology in the sequencing arena. The onset of next-generation sequencing (NGS) technology has resulted in the vast increase in genetic diagnostic testing available to the ordering physician. Whole exome sequencing (WES) has become available as a diagnostic test performed in certified clinical laboratories. This has led to increased presence in the diagnostic marketplace, increased consumer awareness, and the question has been raised by various stakeholders to whether there is sufficient stringent regulation of WES and other NGS-based tests. We discuss the various WES services currently available in the marketplace, current regulation of WES as a laboratory developed test, the proposed FDA involvement in its oversight as well as the response of various laboratory groups that provide these diagnostic services. Overall, a rigorous process oversight and assessment of inter-lab reproducibility is strongly warranted for WES as it is used as a diagnostic test, but regulation should be mindful of the excessive administrative burden on academic and smaller diagnostic laboratories.     

How to Determine the Accuracy of an Alternative Diagnostic Test when It Is Actually Better than the Reference Tests: A Re-Evaluation of Diagnostic Tests for Scrub Typhus Using Bayesian LCMs

BackgroundThe indirect immunofluorescence assay (IFA) is considered a reference test for scrub typhus. Recently, the Scrub Typhus Infection Criteria (STIC; a combination of culture, PCR assays and IFA IgM) were proposed as a reference standard for evaluating alternative diagnostic tests. Here, we use Bayesian latent class models (LCMs) to estimate the true accuracy of each diagnostic test, and of STIC, for diagnosing scrub typhus.ConclusionsThe low specificity of STIC was caused by the low specificity of IFA IgM. Neither STIC nor IFA IgM can be used as reference standards against which to evaluate alternative diagnostic tests. Further evaluation of new diagnostic tests should be done with a carefully selected set of diagnostic tests and appropriate statistical models.     

Interpretation of diagnostic testing strategies for production and economic usefulness

Veterinarians providing reproductive services use a variety of diagnostic testing methods, including physical examination, laboratory testing, diagnostic imaging, and performance record evaluation. The diagnostic end point may be a physical diagnosis of pregnancy, attainment of puberty, or adequate quality and quantity of sperm; furthermore, it may be a medical diagnosis of reproductive tract pathology, presence of an infectious pathogen, or abnormal hormonal status. Proper interpretation of test results requires an understanding of how sensitivity and specificity (as measures of test accuracy), and prevalence of the condition, affect the interpretation of an individual result. For many diagnostic questions, the proper use of more than one test, either in series or in parallel, allows veterinarians to optimize their diagnostic accuracy and the economic return for the testing strategy.