A Ruler for Interpreting Diagnostic Test Results

2005 ◽  
Vol 44 (01) ◽  
pp. 124-126 ◽  
Author(s):  
W. Lehmacher ◽  
M. Hellmich
Keyword(s):  
Diagnostic Test ◽  
Likelihood Ratio ◽  
Bayes Rule ◽  
Test Results ◽  
Post Test ◽  
Log Odds ◽  
Additive Equation ◽  
Diagnostic Test Result ◽  
Test Result ◽  
Test Probability

Summary Objectives: Bayes’ rule formalizes how the pre-test probability of having a condition of interest is changed by a diagnostic test result to yield the post-test probability of having the condition. To simplify this calculation a geometric solution in form of a ruler is presented. Methods: Using odds and the likelihood ratio of a test result in favor of having the condition of interest, Bayes’ rule can succinctly be expressed as ”the post-test odds equals the pre-test odds times the likelihood ratio”. Taking logarithms of both sides yields an additive equation. Results: The additive log odds equation can easily be solved geometrically. We propose a ruler made of two scales to be adjusted laterally. A different, widely used solution in form of a nomogram was published by Fagan [2]. Conclusions: Whilst use of the nomogram seems more obvious, the ruler may be easier to operate in clinical practice since no straight edge is needed for precise reading. Moreover, the ruler yields more intuitive results because it shows the change in probability due to a given test result on the same scale.

scholarly journals Accuracy of closed pleural biopsy in the diagnosis of malignant pleural effusion

2017 ◽  
Vol 43 (6) ◽  
pp. 424-430 ◽  
Author(s):  
Renata Báez-Saldaña ◽  
Uriel Rumbo-Nava ◽  
Araceli Escobar-Rojas ◽  
Patricia Castillo-González ◽  
Santiago León-Dueñas ◽  
...  
Keyword(s):  
Pleural Effusion ◽  
Diagnostic Test ◽  
Likelihood Ratio ◽  
Predictive Value ◽  
Definitive Diagnosis ◽  
Accuracy Analysis ◽  
Pleural Biopsy ◽  
Post Test ◽  
Post Test Probability ◽  
Test Probability

ABSTRACT Objective: Previous studies have demonstrated that closed pleural biopsy (CPB) has a sensitivity of less than 60% for diagnosing malignancy. Therefore, controversy has recently emerged regarding the value of CPB as a diagnostic test. Our objective was to assess the accuracy of CPB in diagnosing malignancy in patients with pleural effusion. Methods: This was a prospective 8-year study of individuals who underwent CPB to establish the etiology of pleural effusion. Information on each patient was obtained from anatomopathological reports and medical records. When CPB findings showed malignancy or tuberculosis, the biopsy was considered diagnostic, and that was the definitive diagnosis. In cases in which biopsy histopathological findings were nonspecific, a definitive diagnosis was established on the basis of other diagnostic procedures, such as thoracoscopy, thoracotomy, fiberoptic bronchoscopy, biochemical and cellular measurements in pleural fluid, and/or microbiological tests. The accuracy of CPB was determined with 2 × 2 contingency tables. Results: A total of 1034 biopsies from patients with pleural effusion were studied. Of those, 171 (16.54%) were excluded from the accuracy analysis either because of inadequate samples or insufficient information. The results of the accuracy analysis were as follows: sensitivity, 77%; specificity, 98%; positive predictive value, 99%; negative predictive value, 66%; positive likelihood ratio, 38.5; negative likelihood ratio, 0.23; pre-test probability, 2.13; and post-test probability, 82. Conclusions: CPB is useful in clinical practice as a diagnostic test, because there is an important change from pre-test to post-test probability.

scholarly journals A “Clinician’s Probability Calculator” to convert pre-test to post-test probability of COVID-19 , based on method validation from each laboratory

2020 ◽  
Author(s):  
Zoe Brooks ◽  
Saswati Das ◽  
Tom Pliura
Keyword(s):  
Health Staff ◽  
Test Results ◽  
Likelihood Ratios ◽  
Percent Agreement ◽  
Public Health Staff ◽  
Post Test ◽  
Online Calculator ◽  
Test Result ◽  
Post Test Probability ◽  
Test Probability

During coronavirus pandemic testing and identifying the virus has been a unique and constant challenge for the scientific community. In this paper, we discuss a practical solution to help guide clinicians and public health staff with the interpretation of the probability that a positive, or negative, COVID-19 test result indicates an infected person, based on their clinical estimate of pre-test probability of infection. The LinkedIn survey confirmed that the pre-test probability of COVID-19 increases with patient age, known contact, and severity of symptoms, as well as prevalence of disease in the local population. PPA (Positive Percent Agreement, PPA) and NPA (Negative Percent Agreement, specificity), differ between individual methods. Results vary between laboratories and the manufacturer for the same method. The confidence intervals of results vary with the number of samples tested, often adding a large range of possibilities to the reported test result. The online calculator met the objective.The authors postulated that the clinical pre-test probability of COVID-19 increases relative to local prevalence of disease plus patient age, known contact, and severity of symptoms. We conducted a small survey on LinkedIn to confirm that hypothesis. We examined results of PPA (Positive Percent Agreement, sensitivity) and NPA (Negative Percent Agreement, specificity) from 73 individual laboratory experiments for molecular tests for SARS-CoV-2as reported to the FIND database,(1) and for selected methods in FDA EUA submissions (2,3). We calculated likelihood ratios to convert pre-test to post-test probability of disease, then further calculated the number of true and false results expected in every ten positive or negative test results, plus an estimate that one in ‘x’ test results is true. We designed an online calculator to create graphics and text to fulfill the objective. A positive or negative test result from one laboratory conveys a higher probability for the presence or absence of COVID-19 than the same result from another laboratory, depending on clinical pre-test probability of disease plus proven method PPA and NPA in each laboratory. Likelihood ratios and confidence intervals provide valuable information but are seldom used in clinical settings. We recommend that testing laboratories verify PPA and NPA, and utilize a tool such as the “Clinician’s Probability Calculator” to verify acceptable test performance and create reports to help guide clinicians and public health staff with estimation of post-test probability of COVID-19 .

Drop the Likelihood Ratio

2015 ◽  
Vol 54 (03) ◽  
pp. 283-287 ◽  
Author(s):  
L. Herich ◽  
W. Lehmacher ◽  
M. Hellmich
Keyword(s):  
Diagnostic Test ◽  
Likelihood Ratio ◽  
Intermediate Step ◽  
Logarithmic Scale ◽  
Test Results ◽  
Predictive Values ◽  
Electronic Tool ◽  
Post Test ◽  
Ratio Determination ◽  
Sensitivity Specificity

SummaryObjective: To present a geometric ruler to determine predictive values of binary diagnostic test results from prevalence, sensitivity and specificity without calculation.Methods: On logarithmic scale the relationships between pre-/post-test odds and the likelihood ratio as well as sensitivity, specificity and the likelihood ratio appear as simple linear (additive) equations.Results: Each of these additive equations can be solved geometrically in form of a ruler with three scales. By amalgamation we devise a novel non-electronic tool which omits the intermediate step of likelihood ratio determination.Conclusions: We propose a simple geometric method to aid in interpretation of diagnostic test results for both practical and educational purposes.

scholarly journals Pengaruh Penggunaan Media Gambar Untuk Meningkatkan Hasil Belajar Bahasa Arab Siswa Kelas VII Di Madrasah Tsanawiyah Muhammadiyah 12 Palirangan

2021 ◽  
Vol 7 (1) ◽  
pp. 39-60
Author(s):  
Idzi' Layyinati
Keyword(s):  
Student Learning ◽  
Learning Outcomes ◽  
Human Life ◽  
Student Learning Outcomes ◽  
Arabic Language ◽  
Test Results ◽  
Correlation Test ◽  
Post Test ◽  
The Mean ◽  
Test Result

Education is a necessity for everyone. Educational activities are activities that are very important in human life and cannot be separated from their lives. With education, human needs regarding change and development can be fulfilled. The mean score of the pre-test results was 71.73, while the mean value of the post-test results was 79.61. From these data it can be seen that the pre-test result value is lower than the post-test score, so it can be interpreted that there are differences in student learning outcomes before and after using image media in the learning process. the completeness of the pre-test result value is 46.15%, while the post-test result value is 80.76%. From this data, it can be seen that using image media can affect student learning outcomes. Then from the hypothesis testing using the Product Moment Correlation test and the Paired Sample T-test with the help of SPSS 20 software in the sig (2-tailed) section, it isknown that 0.000 <0.05 The condition is if r count is smaller than r table, then H0 is accepted. and Ha is rejected and vice versa if r count is greater than r table (r count> r table) then H0 is rejected and Ha is accepted. In fact, r count (0.977) is greater than r table (0.404). Thus H0 is rejected and Ha is accepted. As the basis for decision making in the Product Moment Correlation test and decision guidelines based on the probability value, it can be concluded that H0 is rejected and Ha is accepted. This means that image media can affect the improvement of learning outcomes in Arabic language material for class VII at MTs. Muhammadiyah 12Palirangan

scholarly journals Ultrasound diagnosis of molar pregnancy

Ultrasound ◽  
2018 ◽  
Vol 26 (3) ◽  
pp. 153-159 ◽  
Author(s):  
Jackie A. Ross ◽  
Alina Unipan ◽  
Jackie Clarke ◽  
Catherine Magee ◽  
Jemma Johns
Keyword(s):  
Likelihood Ratio ◽  
Gestational Trophoblastic Disease ◽  
Ultrasound Diagnosis ◽  
Histopathological Diagnosis ◽  
Molar Pregnancy ◽  
Diagnostic Challenge ◽  
Trophoblastic Disease ◽  
Post Test ◽  
Post Test Probability ◽  
Test Probability

Introduction The primary aims of this study were to establish what proportion of ultrasonically suspected molar pregnancies were proven on histological examination and what proportion of histologically diagnosed molar pregnancies were identified by ultrasound pre-operatively. The secondary aim was to review the features of these scans to help identify criteria that may improve ultrasound diagnosis. Methods This was a retrospective observational study conducted in the Early Pregnancy Unit at King’s College Hospital London over an 11-year period. Cases of ultrasonically suspected molar pregnancy or other gestational trophoblastic disease were identified and compared with the final histopathological diagnosis. In addition, cases which were diagnosed on histopathology that were not suspected on ultrasound were also examined. In discrepant cases, the images were reviewed unblinded by two senior sonographers. Statistical analysis for likelihood ratio and post-test probabilities was performed. Results One hundred eighty-two women had gestational trophoblastic disease suspected on ultrasound examination (1:360, 0.3%); 106/182 (58.2%, 95% CI 51.0 to 65.2%) had histologically confirmed gestational trophoblastic disease. The likelihood ratio for gestational trophoblastic disease after a positive ultrasound was 607.27, with a post-test probability of 0.628.The sensitivity of ultrasound for gestational trophoblastic disease was 70.7% (95% CI 62.9% to 77.4%) with an estimated specificity of 99.88% (95% CI 99.85% to 99.91%); 102/143 (71.3%, 95% CI 63.4 to 78.1%) molar pregnancies were suspected on pre-op ultrasound; 60/68 (88.2%, 95% CI 78.2 to 94.2%) of complete moles were suspected on pre-op ultrasound, compared with 42/75 (56.0%, 95% CI 44.7 to 66.7%) of partial moles. On retrospective review of the pre-op ultrasound images, there were cases that could have been suspected prior to surgery. Conclusion Detecting molar pregnancy by ultrasound remains a diagnostic challenge, particularly for partial moles. These data suggest that there has been an increase in both the predictive value and the sensitivity of ultrasound over time, with a high LR and post-test probability; however, the diagnostic criteria remain ill-defined and could be improved.

scholarly journals Closing the loop on test results to reduce communication failures: a rapid review of evidence, practice and patient perspectives

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Breanna Wright ◽  
Alyse Lennox ◽  
Mark L. Graber ◽  
Peter Bragge
Keyword(s):  
Diagnostic Test ◽  
Point Of Care ◽  
Patient Perspectives ◽  
Audit And Feedback ◽  
Rapid Review ◽  
Test Results ◽  
Multiple Perspectives ◽  
Communication Breakdown ◽  
Closing The Loop ◽  
Test Result

Abstract Background Communication failures involving test results contribute to issues of patient harm and sentinel events. This article aims to synthesise review evidence, practice insights and patient perspectives addressing problems encountered in the communication of diagnostic test results. Methods The rapid review identified ten systematic reviews and four narrative reviews. Five practitioner interviews identified insights into interventions and implementation, and a citizen panel with 15 participants explored the patient viewpoint. Results The rapid review provided support for the role of technology to ensure effective communication; behavioural interventions such as audit and feedback could be effective in changing clinician behaviour; and point-of-care tests (bedside testing) eliminate the communication breakdown problem altogether. The practice interviews highlighted transparency, and clarifying the lines of responsibility as central to improving test result communication. Enabling better information sharing, implementing adequate planning and utilising technology were also identified in the practice interviews as viable strategies to improve test result communication. The citizen panel highlighted technology as critical to improving communication of test results to both health professionals and patients. Patients also highlighted the importance of having different ways of accessing test results, which is particularly pertinent when ensuring suitability for vulnerable populations. Conclusions This paper draws together multiple perspectives on the problem of failures in diagnostic test results communication to inform appropriate interventions. Across the three studies, technology was identified as the most feasible option for closing the loop on test result communication. However, the importance of clear, consistent communication and more streamlined processes were also key elements that emerged. Review registration The protocol for the rapid review was registered with PROSPERO CRD42018093316.

scholarly journals HIV post-test practices: an online survey examining perceived delivery of HIV test results, post-test discussion and referral in healthcare settings across the WHO European Region

Sexual Health ◽  
2016 ◽  
Vol 13 (3) ◽  
pp. 205 ◽  
Author(s):  
Stephen Bell ◽  
Jordi Casabona ◽  
Nino Tsereteli ◽  
Dorthe Raben ◽  
John de Wit
Keyword(s):  
Hiv Testing ◽  
Positive Test ◽  
European Region ◽  
Hiv Positive ◽  
Test Results ◽  
Negative Test ◽  
Hiv Test ◽  
Post Test ◽  
Test Result ◽  
Hiv Negative

Background The aim of this study was to assess perceptions of health professionals involved in HIV testing policy and practice in national settings across the WHO European Region regarding the delivery of HIV test results, post-test discussion and referral to specialist HIV services as recommended in authoritative guidelines. Methods: An online self-report survey was completed by a convenience sample of 338 respondents (response rate 34.1%) from 55 countries. Respondents worked with non-government organisations (49.4%), health services (32.8%), non-health service government agencies (6.2%) or other organisations (11.5%; e.g. prisons, education and research, international development). Results: Experts’ perceptions indicate that delivery of HIV-positive test results and related post-test discussion in their country generally corresponded to recommendations. However, results pointed to a significant gap perceived by experts between recommendations and the practice of delivering HIV-negative test results. Fewer respondents thought that suitable time is taken to deliver a negative HIV-test result (54.1%) than a positive result (73.1%). Also, fewer respondents thought there was a procedure for referral to specialist treatment, care and support services for people receiving a HIV-negative test result (34.9%) than for people receiving an HIV-positive test result (86.2%). Experts also reported low perceived use of communication technologies (i.e. telephone, email, text messaging, a secure website) for delivering HIV test results. Conclusions: This expert survey offers new insight into perceived HIV post-test practices in almost all national settings across the WHO European Region. The findings provide valuable guidance for future HIV testing guidelines for the WHO European Region.

scholarly journals PENGARUH LATIHAN BERPASANGAN TERHADAP KEMAMPUAN TENDANGAN SABIT PADA PENCAK SILAT SMA NEGERI 15 LUWU

2021 ◽  
Vol 5 (2) ◽  
pp. 101
Author(s):  
Ahmad Ahmad
Keyword(s):  
Data Collection ◽  
Performance Measurement ◽  
Significant Influence ◽  
T Test ◽  
Test Design ◽  
Test Results ◽  
Measurement Instruments ◽  
Sample Number ◽  
Post Test ◽  
Test Result

Based on the pre-test results of students’ sickle kick ability of pencak silat extracurriculer at Sma Negeri 15 Luwu is still relatively low, this study aims to determine the effect of the use of paired exercises in improving sickle kick capability. This study used OneGroup Pre-test - Post-test Design design with a sample number of 15 people. Data collection using a grid of performance measurement instruments skills, as well as dataanalyzed with the help of SPSS 25. Results research shows that paired exercises have an influence on sickle kick capability, this can be seen from the average post-test result of 80.2667 higher than the average pre-test result of 66.4667. And 16,307 t test and ttabel value of 2,145. As such Ha accepted and H0 rejected. This means there is a significant influence of paired exercises toward the students’ ability of sickle kickin the pencak silat extracurriculer at Sma Negeri 15 Luwu.

scholarly journals Pengaruh Pendidikan Kesehatan Dengan Metode Simulasi Pertolongan Pertama (Log Roll) Pada Korban Dengan Indikasi Cedera Tulang Belakang Di Pendidikan Informal Kecamatan Tempuran Magelang

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Akhmad Rifai ◽  
Moh Ilyas
Keyword(s):  
Informal Education ◽  
Test Group ◽  
Skills Training ◽  
Spinal Injuries ◽  
Wilcoxon Test ◽  
Test Results ◽  
Before And After ◽  
Post Test ◽  
Motorcycle Accidents ◽  
Test Result

Background: Prevalence in Indonesian society in 2007 was 7.5%, with several factors causing traffic and crossing sharp/ blunt objects. In 2013 there was an increase in the prevalence of trauma to 8.2%, with the highest order of injuries being down 40.9%, motorcycle accidents (40.6%), trauma due to sharp/blunt objects 7.3%, other land transportation 7, 1% and 2.5% fallout. To equip ordinary students in carrying out the Log roll Skills to help victims with spinal trauma need to do log roll Skills training. In this regard, researchers intend to conduct research on "The Effect of Health Education with First Aid (Log Roll) Simulation Methods on Spinal Injuries in Tempuran Informal Education in Magelang". Methods: This research is experimental research with the PreTest-Post Test Group design approach. through hypothesis testing research. The population of this research was 50 people in the cloud (Ponpes Roudlotuttulab students). Statistical test on paired groups using the nonparametric Wilcoxon test. Result: Based on the Wilcoxon test results, it can be concluded that 50 respondents who log roll training can be drawn in the conclusion that the majority of students have a basic score of 0.001 which means there is a difference that takes place between before and after training. Conclusion: The suggestion put forward in this study is that education and log roll action training for lay people, especially students, continues to be held at other Islamic boarding schools to improve the skills of log roll action skills suspected in victims with spinal injuries.

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