Error‐corrected estimation of a diagnostic accuracy index of a biomarker against a continuous gold standard

ABSTRACT Background: Conventionally Pleural effusions are suspected by history of pleuritis, evaluated by physical signs and multiple view radiography. Trans-thoracic pleural aspiration is done and aspirated pleural fluid is considered the gold-standard for pleural effusion. Chest sonography has the advantage of having high diagnostic efficacy over radiography for the detection of pleural effusion. Furthermore, ultrasonography is free from radiation hazards, inexpensive, readily available and feasible for use in ICU, pregnant and pediatric patients. This study aims to explore the diagnostic accuracy of trans-thoracic ultrasonography for pleural fluid detection, which is free of such disadvantages. The objective is to determine the diagnostic efficacy of trans-thoracic ultrasound for detecting pleural effusion and also to assess its suitability for being a non-invasive gold-standard. Subject and Methods: This retrospective study of 4597 cases was conducted at pulmonology OPD-Gulab Devi Teaching Hospital, Lahore from November 2016 to July 2018. Adult patients with clinical features suggesting pleural effusions were included while those where no suspicion of pleural effusion, patients < 14 years and pregnant ladies were excluded. Patients were subjected to chest x-ray PA and Lateral views and chest ultrasonography was done by a senior qualified radiologist in OPD. Ultrasound-guided pleural aspiration was done in OPD & fluid was sent for analysis. At least 10ml aspirated fluid was considered as diagnostic for pleural effusion. Patient files containing history, physical examination, x-ray reports, ultrasound reports, pleural aspiration notes and informed consent were retrieved, reviewed and findings were recorded in the preformed proforma. Results were tabulated and conclusion was drawn by statistical analysis. Results: Out of 4597 cases, 4498 pleural effusion were manifested on CXR and only 2547(56.62%) pleural effusions were proved by ultrasound while 2050 (45.57%) cases were reported as no Pleural effusion. Chest sonography demonstrated sensitivity, specificity, PPV, NPV and diagnostic accuracy 100 % each. Conclusions: Trans-thoracic ultrasonography revealed an excellent efficacy that is why it can be considered as non-invasive gold standard for the detection of pleural effusion.

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AB1086 POWER DOPPLER AND SPECTRAL DOPPLER ULTRASOUND IN SUSPECTED ACTIVE SACROILIITIS: A COMPARISON WITH MAGNETIC RESONANCE IMAGING AS GOLD STANDARD

Annals of the Rheumatic Diseases ◽

10.1136/annrheumdis-2020-eular.2281 ◽

2020 ◽

Vol 79 (Suppl 1) ◽

pp. 1832.1-1832

Author(s):

P. Falsetti ◽

E. Conticini ◽

C. Baldi ◽

M. Bardelli ◽

S. Gentileschi ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Diagnostic Accuracy ◽

Doppler Ultrasound ◽

Gold Standard ◽

Clinical Characteristics ◽

Power Doppler ◽

Resonance Imaging ◽

Asas Criteria ◽

Spectral Doppler

Background:SIJ involvement is a characteristic feature of Spondylarthritis (SpA). Magnetic Resonance imaging (MRI) has been included in the new Assessment of SpA International Society (ASAS) criteria for the classification of Axial SpA. Gray scale US, Color Doppler ultrasound (CDUS), contrast-enhanced CDUS, and spectral Doppler (SD) US has been used in few works to evaluate the inflammatory activity of the SIJ with not conclusive results. Power Doppler ultrasound (PDUS) was not yet applied to the study of SIJ with active SI.Objectives:The aim of this work was to study with PDUS and SD US the SIJ of patients with suspected active SI, to describe inflammatory flows with spectral wave analysis (SWA) in duplex Doppler US, and to correlate US data with clinical characteristics and the presence of bone marrow edema (BME) in MRI.Methods:22 patients (18 females and 4 males, mean age 35 years) with new onset of inflammatory back pain (IBP), were included. Every patient underwent an US examination in prone position. The sonographers were blinded to the clinical data of the patient. A Esaote Twice US machine, equipped with a convex multifrequency 1-8 MHz probe, was used, with standardized parameters: 1-5 MHz for gray scale, 1.9-2.3 MHz frequency for Doppler with Pulse Repetition Frequency (PRF) of 1.0 KHz and a color gain just under the artifact limit. SIJ was located as the hypoechoic triangle delimited between the sacrum and iliac bone, and the posterior SI ligament as the upper margin. The first sacral foramen was always localized to avoid measurement of the normal pre-sacral arteries. The PDUS was applied, and if any signals were detected in the SIJ, they were scored with a 3-points scale: 0= absence of signals, 1= isolate vessels, 2= more than one vessel. The signals were also classified as intra-articular or peri-articular. The same vessels were also evaluated using quantitative SD calculating the Resistive Index (RI=peak of systolic flow- end diastolic flow/peak systolic flow), ranging between 0 and 1. Every patient underwent MRI of SIJ within the same week, before treatment. A statistical analysis was performed, estimating the sensitivity and specificity against the gold standard (presence of BME in the same SIJ according to ASAS criteria). The Spearman rank not-parametric test was applied to correlate the presence and grading of BME with PDUS grading and RI. A regression analysis was applied between PDUS results and clinical characteristics.Results:In 14/22 SIJ MRI revealed BME. In 13 of them, PDUS confirmed abnormal hypervascularisation in the intrarticular portion of SI, and in 3 in the periarticular site too. Two SIJ showed hypervascularisation at PD with no BME in MRI. A significant correlation was demonstrated between positivity and grading of PD and presence of BME in MRI (p=0.0005). SD analysis demonstrated low Resistance Index (RI) values in 14 SIJ (mean 0.57). An inverse correlation was demonstrated between RI and grading of BME in MRI (r= -0,6229, p= 0,044). The diagnostic accuracy of SD for detection of active SI varied on the basis of RI cut-off value. The best values of sensitivity (62,5%) and specificity (61,5%) were obtained with a RI cut-off values of 0.60. A multiple regression model demonstrated a significant relationship between PDUS signals and ASDAS (p=0.0382), but not with inflammatory reactants.Conclusion:PDUS and SD US of SIJ can be useful as first imaging assessment in suspected active SI, demonstrating a good diagnostic accuracy compared with MRI. Intra-articular low RI values (<0.60) on SD indicate active SI with good accuracy. Moreover, PDUS signals into the SIJ correlate with clinical symptoms but not with inflammation reactants.Figure 1.Doppler US in SI.Right SIJ with a Doppler signal along the posterior SIJ ligament, and another Doppler signal into the joint, where SD analysis gave a RI of 0,62.Disclosure of Interests:None declared

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Diagnostic accuracy of Instantaneous Wave-Free Ratio (iFR) for the assessment of myocardial ischaemia: a comparison with non-invasive stress imaging

European Heart Journal ◽

10.1093/ehjci/ehaa946.1369 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

L Stazzoni ◽

L Tessandori ◽

P Spontoni ◽

M Angelillis ◽

C Giannini ◽

...

Keyword(s):

Diagnostic Accuracy ◽

Myocardial Ischaemia ◽

Gold Standard ◽

Coronary Revascularization ◽

Stress Test ◽

Invasive Coronary Angiography ◽

Coronary Syndrome ◽

Non Invasive ◽

Coronary Stenoses ◽

Epicardial Stenosis

Abstract Background Instantaneous Wave-Free Ratio (iFR) allows for the assessment of the haemodynamic effects of epicardial coronary stenoses without the need for hyperaemia; iFR is currently recommended as a means to evaluate myocardial ischaemia. Purpose To assess the diagnostic accuracy of iFR with respect to the identification of coronary epicardial stenoses causing ischemia. Therefore, we combined anatomical (% stenosis at invasive coronary angiography, ICA) and functional (non-invasive imaging stress test, NIST) information to obtain a “gold standard” for the identification of stenoses causing ischaemia. Methods We enrolled 71 patients (52 male, 19 female; age mean 68.4±8.1 years) with chronic coronary syndrome or low-risk acute coronary syndrome without ST segment elevation who had at least a NIST and who had at least one vessel with a 50%-85% stenosis at ICA. iFR was measured in all coronary arteries with stenosis >50% and categorised according to the 0.89 threshold for ischaemia. Results iFR was assessed in 122 vessels. In a per-vessel analysis, in 56.7% ischaemia was present both at iFR and NIST, in 21.3% ischaemia was absent in both, while in 23.0% ischaemia was found at NIST but not confirmed by iFR. The overall accuracy of iFR with respect to NIST was 90.1%. However, when considering as the “gold standard” for coronary disease causing ischaemia the contemporary presence of an epicardial stenosis >70% at ICA and a positive NIST, the diagnostic accuracy of iFR greatly improved. The sensibility, specificity, PPV, NPV and accuracy were 96.5%, 75.0%, 73.3%, 96.7% and 84.4%, respectively. In case of discordance between NIST and iFR, revascularization was based on iFR. At a mean follow-up of 23±18 months, the composite endpoint of MACE (major adverse cardiac events, defined as the composite of all-cause death, nonfatal MI and unplanned coronary revascularization) occurred in 16.4%, while death/MI occurred in 11.9%. Stratification according to the per-patient concordance between iFR and NIST showed no significant differences in rates of MACE (p=0.50) and death/MI (p=0.20). Stratification based on iFR showed a higher death/MI rate in iFR-positive patients (11.9% vs. 0%, p=0.047) and a trend to higher MACE rate (11.9% vs. 4.47% p=0.14), Conclusions The diagnostic accuracy of iFR is low when compared with NIST as the reference for myocardial ischaemia, but it is very high when compared with the combined presence of epicardial stenosis and positive NIST. Therefore, iFR can accurately guide the decision to treat or defer revascularization of intermediate coronary stenoses, being most useful in patients with multivessel CAD and when non-invasive functional data are lacking or discordant with anatomy. Funding Acknowledgement Type of funding source: None

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Limited Diagnostic Capacities of Two Commercial Assays for the Detection of Leptospira Immunoglobulin M Antibodies in Laos

Clinical and Vaccine Immunology ◽

10.1128/cvi.00219-06 ◽

2006 ◽

Vol 13 (10) ◽

pp. 1166-1169 ◽

Cited By ~ 33

Author(s):

Stuart D. Blacksell ◽

Lee Smythe ◽

Rattanaphone Phetsouvanh ◽

Michael Dohnt ◽

Rudy Hartskeerl ◽

...

Keyword(s):

Diagnostic Accuracy ◽

Immunosorbent Assay ◽

Gold Standard ◽

Agglutination Test ◽

Immunoglobulin M ◽

Microscopic Agglutination Test ◽

Enzyme Linked Immunosorbent Assay ◽

Diagnostic Utility

ABSTRACT The diagnostic utility of immunochromatographic (Leptotek) and enzyme-linked immunosorbent assay (ELISA; Panbio) tests for the detection of Leptospira immunoglobulin M antibodies was assessed in febrile adults admitted in Vientiane, Laos. Both tests demonstrated poor diagnostic accuracy using admission serum (Leptotek sensitivity of 47.3% and specificity of 75.5%: ELISA sensitivity of 60.9% and specificity of 65.6%) compared to the Leptospira “gold standard” microscopic agglutination test.

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Comparison of Diagnostic Accuracy of Magnetic Resonance Spectroscopy with Conventional Magnetic Resonance Imaging for Brain Tumors and Correlation with Histopathology as Gold Standard

10.53350/pjmhs211594009 ◽

2021 ◽

Vol 15 (9) ◽

pp. 4009-4011

Author(s):

Saulat Sarfraz ◽

Mahwish Farzana

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Magnetic Resonance Spectroscopy ◽

Brain Tumors ◽

Diagnostic Accuracy ◽

Gold Standard ◽

Age Groups ◽

Resonance Spectroscopy ◽

Resonance Imaging ◽

Conventional Mri

Background: In spite of recent advances in the use of diagnostic imaging modalities none of them has a hundred percent accuracy. So, misdiagnosis still occurs. Many trials are being done to evaluate the accuracy of these tools individually or in combination. The most useful investigation is MRI which broadly gives information of lesion as well its relationship with surrounding structures. While magnetic resonance spectroscopy further characterizes the lesion into benign or malignant. So this study is bit superior giving more details. By enlarge histopathology is gold standard for ultimate diagnosis. However these radiological investigations are extremely important for preoperative planning as well management of the lesion. In this study we compare the diagnostic accuracy of Magnetic Resonance Spectroscopy (MRS) with conventional MRI (Magnetic Resonance Imaging) sequences for diagnosis of brain tumors keeping histopathology as gold standard. Methods: The study was performed in 150 clinically suspected cases which were referred to Radiology Department from OPD, Indoor, Emergency and private sources from outside the hospital. Results: Majority 85(56.7%) were adult males and 65(43.3%) were adult females. The study was divided into two major age groups. There were 33cases (22%) with average age 20-35 years. The other age group 36-50 years had 40(26.7%) Majority of the cases 77(51.3%) were of average >50 years of age. The higher age groups showed a female dominance. Histopathology of 100(66.7%) cases confirmed positive and 50(33.3%) negative for MR Spectroscopy. On comparison of conventional MRI with contrast, and Histopathology it was observed that the sensitivity of MRI was 74.0% and the specificity 82.0%.The positive and negative predictive values gave a lower accuracy rate of 76.6%. Conclusion: The conclusion of our study is that MRS is a rigorous, non-invasive, safe and convenient imaging modality for the evaluation of brain tumors as compared to MRI. Keywords: Brain tumors, MRI, MRS, Histopathology

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Diagnostic Accuracy of HRCT Chest in Detection of Covid-19 Infection Taking PCR as Gold Standard

10.53350/pjmhs211561679 ◽

2021 ◽

Vol 15 (6) ◽

pp. 1679-1681

Author(s):

Afaque Ali ◽

Majid Shaikh ◽

Ahsanullah . ◽

Adeel Ahmed ◽

Abid Ali Sahito ◽

...

Keyword(s):

Computed Tomography ◽

High Resolution ◽

Diagnostic Accuracy ◽

Predictive Value ◽

Gold Standard ◽

Cross Sectional Study ◽

Radiology Department ◽

High Resolution Computed Tomography ◽

Cross Sectional ◽

Head Of Department

Objective: To determine the diagnostic accuracy of High-resolution computed tomography (HRCT) chest in detection of covid-19 infection taking PCR as gold standard. Study Design: Cross-sectional study Setting: Radiology department of Tabba Hospital, Karachi. Duration: From March 2019 to September 2020 Material and Methods: All the clinically suspected patients of covid-19, of any age, both genders and those referred to radiology for High-resolution computed tomography (HRCT) chest to detect the covid-19 infection were included. After two days, patients’ PCR reports were collected from the ward, after taking informed consent and permission from head of department. The diagnostic accuracy of HRCT was established with respect to sensitivity, PPV, NPV, and specificity by taking PCR as gold standard. All the information was collected via study proforma. Results: Total 70 patients suspected for COVID-19 were studied, and the patients’ mean age was 58.23±9.52 years. Males were in majority 54(77.1%). As per HRCT findings, COVID-19 infection was positive in 46 patients, however, 48 patients were detected positive for COVID-19 infection as per PCR findings. In the detection of COVID-19 infection, HRCT chest showed sensitivity of 91%, specificity of 90%, PPV of 83%, NPV of 84% and diagnostic accuracy of 94%; by taking PCR as gold standard. Conclusion: High-resolution computed tomography (HRCT) is a reliable diagnostic approach in promptly detecting the COVID-19; with 91% sensitivity, 90% specificity, 83% positive predictive value, 84% negative predictive value and 94% diagnostic accuracy. Keywords: Accuracy, HRCT, COVID-19

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Accuracy of MRI in the Differential Diagnosis of Wilms Tumor

10.53350/pjmhs211582057 ◽

2021 ◽

Vol 15 (8) ◽

pp. 2057-2059

Author(s):

Maham Ashraf ◽

Aysha Anjum ◽

Eisha Tahir ◽

Amber Goraya ◽

Rabia Aqeel

Keyword(s):

Differential Diagnosis ◽

Diagnostic Accuracy ◽

Gold Standard ◽

Wilms Tumor ◽

Correct Diagnosis ◽

Renal Tumors ◽

Common Finding ◽

Predictive Values ◽

Female Ratio ◽

Male Predominance

Background & Objective: Renal tumors are a common finding in diagnostic imaging; these lesions usually are solid or cystic, benign or malignant, and the correct diagnosis may be difficult. The current study aims at to determine the diagnostic accuracy of magnetic resonance imaging for the diagnosis of Wilms tumor taking histopathology as gold standard. Methodology: This cross-sectional study was carried at the Department of Radiology, The Children’s Hospital & Institute of Child Health Lahore over 6 months from March 2019 to September 2019. The study involved 125 children of both genders aged between 2 years to 14 years presenting with a neoplastic mass in the retroperitoneum on ultrasound abdomen during initial workup. These children were assessed on MRI for the diagnosis of Wilms tumor. Later the diagnosis was confirmed on histopathology which was taken as gold standard and the diagnosis of MRI was judged accordingly as true/false and positive/negative. A written informed consent was obtained from every patient. Results: The mean age of the children was 5.8±3.9 years having a male predominance with male to female ratio of 1.8:1. Wilms tumor was suspected in 13 (10.4%) children on MRI. The diagnosis of Wilms tumor was confirmed in 13 (10.4%) children on histopathology. MRI was found to be 76.9% sensitive, 97.3% specific and 95.2% accurate with positive and negative predictive values of 76.9% and 97.3% respectively. Conclusion: In the present study, MRI was found to be 95.2% accurate in the differential diagnosis of Wilms tumor in children presenting with retroperitoneal mass which along with its non-invasive and radiation free nature advocates the preferred use of MRI in the diagnostic evaluation of such children in future oncologic practice. Keywords: Retroperitoneal Tumor, Wilms Tumor, MRI, Diagnostic Accuracy

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Diagnostic Accuracy of Multislice Contrast CT scan in Detection of Squamous cell Carcinoma of Oral cavity, in clinically suspected Patients

10.53350/pjmhs211582500 ◽

2021 ◽

Vol 15 (8) ◽

pp. 2500-2501

Author(s):

Aliya Khan ◽

Abid Ali Sahito ◽

Mahreen Shaikh ◽

Humera Jabeen ◽

Humaira Ashraf ◽

...

Keyword(s):

Computed Tomography ◽

Squamous Cell Carcinoma ◽

Oral Cavity ◽

Diagnostic Accuracy ◽

Cell Carcinoma ◽

Squamous Cell ◽

Gold Standard ◽

Multislice Computed Tomography ◽

Multislice Ct ◽

Sensitivity Specificity

Objective: To evaluate the diagnostic accuracy of multislice computed tomography (CT) in detection of squamous cell carcinoma (SCC) of oral cavity in clinically suspected patients taking histopathology as gold standard. Material and Methods: This cross-sectional study has been conducted at Radiology department of Civil Hospital Karachi from 8th September 2018 to March 2019. All the cases having suspected oral squamous cell carcinoma and either of gender were included. Patients underwent computed tomography by using multislice scanner. Then patients undergone biopsy sampling and patients were labeled as positive or negative for squamous cell carcinoma of oral cavity on MDCT and histopathology. Sensitivity, specificity, and diagnostic accuracy of multislice CT for squamous cell carcinoma of oral cavity were measured taking histopathology as gold standard. Results: Total 168 cases were studied and out of them males were 76.8% and females were 23.2%. Mean gutka addiction history was 11.52±5.21 years. Mean lesion size on CT scan was 2.44±1.43 cm. In our study, 35.1% patients were diagnosed positive by multislice computed tomography and 43.5% through histopathology. Sensitivity, Specificity, PPV, NPV and accuracy were 86.4%, 79.8%, 69.9%, 91.6%, and 82.1% respectively. Conclusion: Multislice CT observed to be the effective diagnostic tool for the detection of SCC of oral cavity. Keywords: Multislice Computed Tomography, cancer, Oral Cavity

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Could a low-cost audio-visual link be useful in rheumatology?

Journal of Telemedicine and Telecare ◽

10.1258/1357633001934078 ◽

2000 ◽

Vol 6 (1_suppl) ◽

pp. 35-37 ◽

Cited By ~ 9

Author(s):

L E Graham ◽

S Mcgimpsey ◽

S Wright ◽

G Mcclean ◽

J Carser ◽

...

Keyword(s):

Diagnostic Accuracy ◽

Gold Standard ◽

Junior Doctor ◽

Low Cost ◽

Clinical Signs ◽

Final Diagnosis ◽

Provisional Diagnosis ◽

Face To Face ◽

Significant Difference ◽

Small Joint

We have investigated prospectively the diagnostic accuracy, specialist satisfaction and patient–specialist rapport of a low-cost audio-visual link between a junior doctor with a patient and a consultant rheumatologist. Using a telephone link and subsequently a video-phone link, 20 patients, with various rheumatological problems, were presented by a junior doctor to the consultant rheumatologist for provisional diagnosis. All patients were then seen face to face by the consultant, when a final diagnosis was made. An independent consultant rheumatologist made a ‘gold standard’ diagnosis. Thirty-five per cent of diagnoses were made correctly over the telephone and 40% over the video-phone – there was no significant difference in the diagnostic accuracy between these two methods of communication. Rapport over the video-phone was universally poor. Where it was important, clinical signs could not be visualized over the video-phone and in more than 85% of cases small joint swellings could not be seen clearly.

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