scholarly journals Diversity in Typhoid Diagnostic Protocols And Recommendation for Composite Reference Standard

2021 ◽  
Author(s):  
Bernard Igiri ◽  
Stanley Irobekhian Reuben Okoduwa ◽  
Shaibu Ahmed Munirat ◽  
Iquo Bassey Otu-Bassey ◽  
Abdullahi Bashir ◽  
...  
Keyword(s):  
Typhoid Fever ◽  
Diagnostic Accuracy ◽  
Predictive Value ◽  
Reference Standard ◽  
Widal Test ◽  
Average Percentage ◽  
Public Health Burden ◽  
Significant Difference ◽  
Prospective Study Design ◽  
Composite Reference Standard

Typhoid fever is a major public health burden which causes substantial global morbidity and mortality due to lack of decisive diagnostic protocols. The capacity of commonly use diagnostic test to validate the absence of typhoid fever is controversial. This study explores to evaluate new techniques for typhoid diagnosis and proposed a harmonised suitable standardized composite reference to be adopted. Published peer-reviewed articles indexed in PubMed, MEDLINE and Google scholar were reviewed for hospital-based studies. This study reveals new typhoid diagnostic techniques such as proteomics, serology, Rapid Diagnostic tests (RDTs), transcriptomics, genomics, and metabolomics. 34.4% of the studies use prospective study design. The study result establishes that, Widal test has a moderate diagnostic accuracy with average percentage sensitivity (52.9%), specificity (54%), positive predictive value (PPV) (56.8%) as well as negative predictive value (NPV) (55.6%) when compared with 29.4%, 28%, 29.5%, and 27.8% of Typhidot respectively. The findings showed a statistically significant difference on the sensitivity between Widal and Typhidot t (40) = 2.639, p = 0.012 at p<0.05 using independent sample t-test. When there is no perfect reference standard that has an optimal diagnostic accuracy, the need for a harmonised suitable standardized composite reference is essential. Hence, this study recommends that, peripheral blood culture with established sensitivity of 60% and Widal test with average sensitivity of 52.9% be adopted as a consensus composite reference standard for typhoid fever diagnosis in other to improve confidence in prevalence estimates.

scholarly journals Diversity in Typhoid Diagnostic Protocols And Recommendation for Composite Reference Standard

2021 ◽  
Author(s):  
Bernard Igiri ◽  
Stanley Irobekhian Reuben Okoduwa ◽  
Shaibu Ahmed Munirat ◽  
Iquo Bassey Otu-Bassey ◽  
Abdullahi Bashir ◽  
...  
Keyword(s):  
Typhoid Fever ◽  
Diagnostic Accuracy ◽  
Predictive Value ◽  
Reference Standard ◽  
Widal Test ◽  
Average Percentage ◽  
Public Health Burden ◽  
Significant Difference ◽  
Prospective Study Design ◽  
Composite Reference Standard

Typhoid fever is a major public health burden which causes substantial global morbidity and mortality due to lack of decisive diagnostic protocols. The capacity of commonly use diagnostic test to validate the absence of typhoid fever is controversial. This study explores to evaluate new techniques for typhoid diagnosis and proposed a harmonised suitable standardized composite reference to be adopted. Published peer-reviewed articles indexed in PubMed, MEDLINE and Google scholar were reviewed for hospital-based studies. This study reveals new typhoid diagnostic techniques such as proteomics, serology, Rapid Diagnostic tests (RDTs), transcriptomics, genomics, and metabolomics. 34.4% of the studies use prospective study design. The study result establishes that, Widal test has a moderate diagnostic accuracy with average percentage sensitivity (52.9%), specificity (54%), positive predictive value (PPV) (56.8%) as well as negative predictive value (NPV) (55.6%) when compared with 29.4%, 28%, 29.5%, and 27.8% of Typhidot respectively. The findings showed a statistically significant difference on the sensitivity between Widal and Typhidot t (40) = 2.639, p = 0.012 at p<0.05 using independent sample t-test. When there is no perfect reference standard that has an optimal diagnostic accuracy, the need for a harmonised suitable standardized composite reference is essential. Hence, this study recommends that, peripheral blood culture with established sensitivity of 60% and Widal test with average sensitivity of 52.9% be adopted as a consensus composite reference standard for typhoid fever diagnosis in other to improve confidence in prevalence estimates.

scholarly journals Diagnostic accuracy of RT-PCR for detection of SARS-CoV-2 compared to a “composite reference standard” in hospitalized patients

2021 ◽  
Author(s):  
Noah Reich ◽  
Christopher F. Lowe ◽  
David Puddicombe ◽  
Nancy Matic ◽  
Jesse Greiner ◽  
...  
Keyword(s):  
Diagnostic Accuracy ◽  
Predictive Value ◽  
High Sensitivity ◽  
Laboratory Diagnosis ◽  
Hospitalized Patients ◽  
Serological Testing ◽  
Reference Standard ◽  
Diagnostic Reliability ◽  
Radiographic Findings ◽  
Composite Reference Standard

AbstractBackgroundCOVID-19 caused by the novel coronavirus SARS-CoV-2 has caused the greatest public health emergency of our time. Accurate laboratory detection of the virus is critical in order to contain the spread. Although real-time polymerase chain reaction (PCR) has been the cornerstone of laboratory diagnosis, there have been conflicting reports on the diagnostic accuracy of this method.MethodsA retrospective review was performed on all hospitalized patients tested for SARS-CoV-2 (at St. Pauls Hospital in Vancouver, BC) from March 13 – April 12, 2020. Diagnostic accuracy of initial PCR on nasopharyngeal (NP) swabs was determined against a composite reference standard which included a clinical assessment of the likelihood of COVID-19 by medical experts, initial and repeat PCR, and post-hoc serological testing.ResultsA total of 323 patients were included in the study, 33 (10.2%) tested positive and 290 (89.8%) tested negative by initial PCR. Patients testing positive were more likely to exhibit features of cough (66.7% vs 39.3%), shortness of breath (63.6% vs 35.9%), fever (72.7% vs 27.6%), radiographic findings (83.3% vs 39.6%) and severe outcomes including ICU admission (24.2% vs 9.7%) and mortality (21.2% vs 6.2%) compared to patients testing negative. Serology was performed on 90 patients and correlation between serology and PCR was 98.9%. There were 90 patients included in the composite reference standard. Compared to the composite reference standard, initial PCR had sensitivity of 94.7% (95% CI 74.0 to 99.9%), specificity of 100% (95% CI 94.9 to 100%), positive predictive value of 100% (95% CI 81.5 to 100%) and a negative predictive value of 98.6% (95% CI 92.5 to 100%).DiscussionOur study showed high sensitivity of PCR on NP swab specimens when compared to composite reference standard in hospitalized patients. High correlation of PCR with serological testing further increased confidence in the diagnostic reliability of properly collected NP swabs.

Accuracy of Electronic Surveillance of Catheter-Associated Urinary Tract Infection at an Academic Medical Center

2014 ◽  
Vol 35 (06) ◽  
pp. 685-691 ◽  
Author(s):  
H. L. Wald ◽  
B. Bandle ◽  
A. Richard ◽  
S. Min
Keyword(s):  
Urinary Tract ◽  
Diagnostic Accuracy ◽  
Predictive Value ◽  
Medical Center ◽  
Academic Medical Center ◽  
University Hospital ◽  
Reference Standard ◽  
Electronic Surveillance ◽  
Tract Infections ◽  
Sensitivity Specificity

Objective.To develop and validate a methodology for electronic surveillance of catheter-associated urinary tract infections (CAUTIs).Design.Diagnostic accuracy study.Setting.A 425-bed university hospital.Subjects.A total of 1,695 unique inpatient encounters from November 2009 through November 2010 with a high clinical suspicion of CAUTI.Methods.An algorithm was developed to identify incident CAUTIs from electronic health records (EHRs) on the basis of the Centers for Disease Control and Prevention (CDC) surveillance definition. CAUTIs identified by electronic surveillance were compared with the reference standard of manual surveillance by infection preventionists. To determine diagnostic accuracy, we created 2 × 2 tables, one unadjusted and one adjusted for misclassification using chart review and case adjudication. Unadjusted and adjusted test statistics (percent agreement, sensitivity, specificity, positive predictive value [PPV], negative predictive value [NPV], and κ) were calculated.Results.Electronic surveillance identified 64 CAUTIs compared with manual surveillance, which identified 19 CAUTIs for 97% agreement, 79% sensitivity, 97% sensitivity, 23% PPV, 100% NPV, and κ of .33. Compared with the reference standard adjusted for misclassification, which identified 55 CAUTIs, electronic surveillance had 98% agreement, 80% sensitivity, 99% specificity, 69% PPV, 99% NPV, and κ of .71.Conclusion.The electronic surveillance methodology had a high NPV and a low PPV compared with the reference standard, indicating a role of the electronic algorithm in screening data sets to exclude cases. However, the PPV markedly improved compared with the reference standard adjusted for misclassification, suggesting a future role in surveillance with improvements in EHRs.Infect Control Hosp Epidemiol2014;35(6):685–691

scholarly journals Utility of A Single Widal Test in The Diagnosis of Typhoid Fever

2012 ◽  
Vol 35 (2) ◽  
pp. 53-58 ◽  
Author(s):  
ABM Shahidul Alam ◽  
Fahim Ahmed Rupam ◽  
Farhana Chaiti
Keyword(s):  
Blood Culture ◽  
Typhoid Fever ◽  
Predictive Value ◽  
Salmonella Typhi ◽  
Definitive Diagnosis ◽  
Blood Cultures ◽  
Widal Test ◽  
Female Ratio ◽  
The Mean ◽  
Agglutinin Titer

Background & objectives: The clinical diagnosis of typhoid fever is difficult, as the presenting symptoms are often diverse and similar to those observed with other febrile illnesses. The definitive diagnosis of typhoid fever requires the isolation of Salmonella typhi or paratyphi from the patient concerned. Since patients often receive antibiotics prior to a confirmatory diagnosis, there is uncertainty that bacteria can be isolated from the blood cultures. Besides this, the facilities for blood culture are not always available or feasible. All these limitations have made Widal test the most utilized diagnostic test for typhoid fever. Many studies have produced data which had cast serious doubts on the value of the Widal Test and thus reappraisal of the role of a single Widal test is needed.Methods & materials: This study was carried out to determine the changes in clinical pattern of enteric fever. A total of 153 children, aged 0 to 14 years, diagnosed as typhoid fever (either positive blood culture for Salmonella typhi or paratyphi) were induced in the study. Of them, 86 children were with a definitive diagnosis of typhoid or paratyphoid fever as indicated by the isolation of S. typhi or S. paratyphi from the blood and 17 had negative blood culture but were clinically suspected of having typhoid fever. The control group was comprised of 50 children with non-typhoidal fevers The Widal test was carried out using rapid slide agglutination method and its accuracy was assessed by comparing the findings with that obtained through blood culture.Result: The mean age of the patients was 5.2 ± 2.8 years and the youngest and oldest patients were 0.7 and 14 years respectively and male to female ratio was roughly 1:1. Nearly one-quarter (24.6%) of the patients had been suffering from the disease for >10 days and the mean duration of illness was 8.2 ± 3.3 days. Widal Test result showed that an ‘O’ agglutinin titer of cut-off value e”1:40 gave a sensitivity of 87.2%, a specificity of 47.1%, a positive predictive value (PPV) of 89.2% and a negative predictive value (NPV) of 42.1%. The sensitivity and NPV decreased with the increase in titer levels and were 56.9% and 31.5% at cut-off value of e” 1:320, while the specificity and PPV increased with the increase in titer levels from 47.1% and 89.2% respectively at a titer of e”1:40 to 100% at a titer of e” 1:320. The ‘titer behaved in the same way as did the ‘O’ agglutinin titer. Similarly when H’ agglutinin was used the sensitivity and NPV decreased from 65% and 31.7% at a titer of e”1:40 to only 25% and 20% respectively at a titer of > 1:320, while specificity and PPV increased from 76.4% and 81.1% at >1:40 to 94.1% and 95.6% respectively at e” 1:320. When either ‘O’ or ‘H’ antibody titer of e”1:160 was used, a good sensitivity (71%), specificity (70.6%) and PPV (92.4%) resulted, though NPV decreased to 32.4%.Conclusion: The Widal test can be of diagnostic value when blood cultures are not available nor practically feasible.DOI: http://dx.doi.org/10.3329/bjch.v35i2.10377  Bangladesh J Child Health 2011; Vol 35 (2): 53-58

scholarly journals A COMPARATIVE STUDY OF WIDAL TEST WITH BLOOD CULTURE IN THE DIAGNOSIS OF TYPHOID FEVER IN FEBRILE PATIENTS ATTENDING GGH, ANANTHAPURAMU.

2020 ◽  
pp. 40-41
Author(s):  
B.R.Chandra Sekhar ◽  
G. Swarna Latha ◽  
M. Sailaja ◽  
M S Prabhakar
Keyword(s):  
Blood Culture ◽  
Typhoid Fever ◽  
Antibody Titer ◽  
Predictive Value ◽  
Reservoir Host ◽  
World Health ◽  
Human Beings ◽  
Widal Test ◽  
Recent Infection ◽  
Total Prevalence

Introduction Typhoid fever is a systemic prolonged febrile illness caused by certain Salmonella serotypes including Salmonella typhi, S. paratyphi A, S. paratyphi B and S. paratyphi C. 1 Human beings are the only reservoir host for typhoid fever. It is transmitted is by feco-oral contamination of water and food in endemic areas especially by carriers handling food. The World Health Organization (WHO) estimates about 21 million cases of typhoid fever with >600,000 deaths annually. 2 The cases are more likely to be seen because of rapid population growth, increased urbanization, and limited safe water, limited infrastructure and health systems. Aims & Objectives The main aim of this study is to compare the result of Widal test and blood culture in the diagnosis of typhoid fever in febrile patients. Material & Methods: This is a prospective study conducted in the GGH Anantapuramu, for a period of 18 months .i.e. from May 2018 to Oct 2019. Blood samples were collected from 542 febrile patients with symptoms clinically similar to typhoid fever. Blood culture was used to isolate S.typhi and S.paratyphi. Slide agglutination test and tube agglutination tests were used for the determination of antibody titer. An antibody titer of ≥1:80 for anti TO and ≥1:160 for anti TH were taken as a cut of value to indicate recent infection of typhoid fever. Results: A total of the 542 patients were the study population, among which 384 (70.8%) were females, and 158 (29.1%) were males. Widal and blood culture was performed, 11 (2.02%) cases of S. typhi and 5 (0.9%) cases of S. paratyphi were identified using blood culture. The total prevalence of typhoid fever is 2.95%. The specificity, sensitivity, Positive Predictive Value, and Negative Predictive Value of the Widal test with O Ag is 70%, 81.25%, 10.93%, and 96%, respectively, and with H Ag is 40%, 96%, 18.1%, 98.8% respectively.

scholarly journals Three-hour post-ERCP amylase level: a useful indicator for early prediction of post-ERCP pancreatitis

2020 ◽  
Author(s):  
Ze-Hui Lv ◽  
Da-Qing Kou ◽  
Shi-Bin Guo
Keyword(s):  
Confidence Interval ◽  
Diagnostic Accuracy ◽  
Roc Curve ◽  
Predictive Value ◽  
Serum Amylase ◽  
Roc Curves ◽  
Amylase Level ◽  
Early Prediction ◽  
Serum Amylase Level ◽  
Significant Difference

Abstract Background: To evaluate the value of the 3-hour post-ERCP serum amylase level for early prediction of post-ERCP pancreatitis (PEP). Method: A study of 206 patients performed ERCP was analysed. The patients with PEP were recorded. ROC curves were used to statistically analyze the data. Results: PEP occurred in 21 patients (10.19%). The 3-hour post-ERCP pancreatic amylase level was used as the test variable, and the PEP occurrence as the state variable to plot ROC curve. The area under the curve (AUC) was 0.816 , and was statistically significant (P<0.001). The standard error (SE) was 0.0507, the 95% confidence interval (CI) was 0.756-0.866, and the optimal cut-off value was 351U/L (sensitivity 76.19%, specificity 83.24%, positive likelihood ratio 4.55, negative likelihood ratio 0.29, Youden index 59.43%). The ROC curves were plotted for both serum amylase and lipase respectively. The areas under the ROC curves were statistically significant(P<0.001). The area under the ROC curve for the 3-hour post-ERCP lipase was 0.778, the 95% confidence interval was 0.673-0.862, and optimal cut-off value was 1834 U/L. The area under the ROC curve for the 3-hour post-ERCP serum amylase was 0.780, and the 95% confidence interval was 0.676-0.864. The optimal cut-off is 380U/L, and there was no statistically significant difference between the two for diagnostic accuracy. According to gender, there was no statistically significant difference in the diagnostic accuracy. In the male group, 436 U/L serum amylase provided the greatest diagnostic accuracy with sensitivity(SE) of 70.5%, specificity(SP) of 89.2%, positive predictive value (PPV) 87.5%, and negative predictive value (NPV) 78.1%. Whereas, in the female group, 357U/L serum amylase provided the greatest diagnostic accuracy with sensitivity of 76.9%, specificity of 81.2%, positive predictive value of 80.4%, negative predictive value of 77.9%. Conclusions: 1. The 3-hour post-ERCP serum amylase level is a useful measurement for predicting post-ERCP pancreatitis. 2. There was no significant difference between serum amylase and lipase 3-hour post-ERCP for predicting PEP. 3. There was no statistically significant difference between male and female using the 3-hour post-ERCP serum amylase level to predict PEP. For female, the optimal cut-off value was 357 U/L, whereas male 436U/L .

scholarly journals Diagnostic accuracy of GeneXpert MTB/RIF assay for detection of tubercular pleural effusion

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0251618
Author(s):  
Jyoti Jain ◽  
Pooja Jadhao ◽  
Shashank Banait ◽  
Preetam Salunkhe
Keyword(s):  
Pleural Effusion ◽  
Diagnostic Accuracy ◽  
Tertiary Care ◽  
Public Health Problem ◽  
P Value ◽  
Care Hospital ◽  
Reference Standard ◽  
Likelihood Ratios ◽  
Predictive Values ◽  
Composite Reference Standard

India has been engaged in tuberculosis (TB) control activities for over 50 years and yet TB continues to remain India’s important public health problem. The present study was conducted to compare the performance of GeneXpert MTB/RIF (GXpert) assay with composite reference standard in diagnosing cases of tubercular pleural effusion (TPE) and to evaluate the reliability of rifampicin resistance. A cross-sectional study was performed in a Department of Medicine of a rural teaching tertiary care hospital in central India. In all consecutive patients with pleural effusion on chest radiograph presenting to Department of Medicine, GXpert assay and composite reference standard was performed to evaluate the diagnostic accuracy of GXpert assay for detecting TPE in comparison to composite reference standard. Standard formulae were used to calculate the sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV), positive likelihood ratios (LR+) and negative likelihood ratios (LR-). Mc-Nemar’s test was applied to compare variables. All comparisons were two-tailed. We considered the difference to be statistically significant if the P value was less than 0.05. The sensitivity of the GXpert assay in diagnosing TPE was 16.6% among 158 study participants, the specificity was 100% and diagnostic accuracy was 52.5% which was statistically significant (p value < 0.05). It had a PPV of 100% (95%CI: 88.3% - 100%) and a NPV of 47.5% (95%CI: 39.3% - 55.7%). The LR+ and LR-were 23.5 (95%CI: 1.43–38.6) and 0.83 (95%CI: 0.76–0.91) respectively. GXpert assay has a very high specificity in diagnosing TPE but has a low sensitivity. In comparison to composite reference standard Thus its clinical utility is limited when used as a standalone test. A physician’s clinical acumen in combination with routine pleural fluid analysis should be the key factor in the diagnosis of TPE in clinically and radiologically suspected patients, especially in high TB burden countries.

scholarly journals Clinical evaluation of the Xpert MTB/XDR assay for rapid detection of isoniazid, fluoroquinolone, ethionamide and second-line drug resistance: A cross-sectional multicentre diagnostic accuracy study

2021 ◽  
Author(s):  
Adam Penn-Nicholson ◽  
Sophia B Georghiou ◽  
Nelly Ciobanu ◽  
Mubin Kazi ◽  
Manpreet Bhalla ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Diagnostic Accuracy ◽  
Susceptibility Testing ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Foreign Affairs ◽  
Second Line ◽  
Reference Standard ◽  
Composite Reference Standard ◽  
Resistance Detection

Background The WHO End TB Strategy requires universal drug susceptibility testing and treatment of all people with tuberculosis. However, available second-line diagnostic tools are cumbersome and require sophisticated laboratory infrastructure, and ultimately less than half of those with drug-resistant tuberculosis receive appropriate treatment. Xpert MTB/XDR was developed to help overcome these limitations. Methods We assessed the diagnostic accuracy of sputum-based Xpert MTB/XDR for isoniazid, fluoroquinolone, ethionamide and second-line injectable resistance detection in adults with an Xpert MTB/RIF or Ultra Mycobacterium tuberculosis-positive result against a composite reference standard of phenotypic drug-susceptibility testing and whole genome sequencing (NCT03728725). Participants with pulmonary tuberculosis symptoms and ≥1 risk factor for drug resistance were consecutively enrolled between four clinical sites in India, Moldova and South Africa. Findings Between 31 July 2019 and 21 March 2020, we enrolled 710 patients, of which 611 (86.1%) had results from index and composite reference standard tests and were included in analysis. The sensitivity of Xpert MTB/XDR was 94% for isoniazid, 95% for fluoroquinolones, 54% for ethionamide, 73% for amikacin, 86% for kanamycin, and 61% for capreomycin resistance detection. Specificity was 98-100% for all drugs. Performance was equivalent to line-probe assays. The non-determinate rate of Xpert MTB/XDR was 2.96%. Interpretation This first prospective, multicentre clinical study of the Xpert MTB/XDR assay demonstrated high diagnostic test accuracy, meeting target product profile criteria for a next-generation drug susceptibility test. Funding German Federal Ministry of Education and Research through KfW, Dutch Ministry of Foreign Affairs, and Australian Department of Foreign Affairs and Trade.

Tuberculosis diagnostic accuracy of stool Xpert MTB/RIF and urine AlereLAM in vulnerable children

2021 ◽  
pp. 2101116
Author(s):  
Patrick Orikiriza ◽  
Julianna Smith ◽  
Bob Ssekyanzi ◽  
Dan Nyehangane ◽  
Ivan Mugisha Taremwa ◽  
...  
Keyword(s):  
Diagnostic Accuracy ◽  
Sensitivity And Specificity ◽  
Severe Malnutrition ◽  
Hiv Positive ◽  
Age Group ◽  
Reference Standard ◽  
Hiv Status ◽  
Vulnerable Children ◽  
Diagnostic Approaches ◽  
Composite Reference Standard

BackgroundNon-sputum based diagnostic approaches are crucial in children at high risk of disseminated tuberculosis [TB] who cannot expectorate sputum. We evaluated the diagnostic accuracy of Xpert MTB/RIF from stool and urine AlereLipoarabinomannan [LAM] test in this group of children.MethodsHospitalised children with presumptive TB and either age <2 years, HIV-positive or severe malnutrition were enrolled in a diagnostic cohort. At enrolment, we attempted to collect two urine, two stool and two respiratory samples. Urine and stool were tested with AlereLAM and Xpert MTB/RIF, respectively. Respiratory samples were tested with Xpert MTB/RIF and mycobacterial culture. Both a microbiological and a composite clinical reference standard were used.ResultsThe study enrolled 219 children; median age 16.4 months, 72 (32.9%) HIV-positive and 184 (84.4%) severely malnourished. Twelve (5.5%) and 58 (28.5%) children had confirmed and unconfirmed TB respectively. Stool and urine were collected in 219 (100%) and 216 (98.6%) children. Against the microbiological reference standard the sensitivity and specificity (n/N, 95% confidence intervals) of stool Xpert MTB/RIF was 50.0% (6/12, 21.1–78.9) and 99.1% (198/200 96.4–99.9), while that of urine AlereLAM was 50.0% (6/12, 21.1–78.9) and 74.6% (147/197, 67.9–80.5) respectively. Against the composite reference standard sensitivity was reduced to 11.4% (8/70) for stool and 26.2% (17/68) for urine, with no major difference by age group (<2 and >2 years) or HIV status.ConclusionThe Xpert MTB/RIF assay has excellent specificity on stool, but sensitivity is suboptimal. Urine AlereLAM is compromised by poor sensitivity and specificity in children.

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