False-Positive Results in Metagenomic Virus Discovery: A Strong Case for Follow-Up Diagnosis

Background Multiple causes of false-positive chromogranin A (CgA) measurement have been reported that may affect its impact as a surrogate marker of RECIST progression in well-differentiated gastroenteropancreatic neuroendocrine tumors (WDGEPNET). Aims 1) To evaluate the frequency of false-positive CgA results. 2) To prospectively compare CgA variations with RECIST morphological changes in patients without known causes of false-positive CgA measurements. Methods First, the conditions responsible for potentially false-positive CgA measurements were screened in 184 consecutive patients with metastatic WDGEPNET. Secondly, a variation in CgA at a 6-month interval was compared to RECIST results at 6 months in 46 patients. Results Among 184 patients, elevated CgA was found in 130 cases (71%) including 99 patients with at least one cause of a false-positive result. Impaired kidney function as well as medication with proton pump inhibitors were found to be the 2 major causes of false-positive results. The sensitivity and specificity of CgA measurements compared with morphological tumor changes according to the RECIST criteria were 71% and 50%, respectively, at 6 months. Conclusion Routine screening for the causes of false-positive CgA measurements is mandatory in WDGEPNET patients. Our study does not validate the use of CgA as a surrogate marker of tumor progression.

Download Full-text

False positive results in ovarian cancer screening: One year follow-up of psychological status

Psychology and Health ◽

10.1080/08870449408401934 ◽

1994 ◽

Vol 10 (1) ◽

pp. 33-40 ◽

Cited By ~ 27

Author(s):

Jane Wardle ◽

Amanda Pernet ◽

William Collins ◽

Thomas Bourne

Keyword(s):

Ovarian Cancer ◽

Cancer Screening ◽

False Positive ◽

Psychological Status ◽

Ovarian Cancer Screening ◽

One Year ◽

Positive Results

Download Full-text

Home Urine Cultures by the Dip-Strip Method: Results in 289 Cultures

PEDIATRICS ◽

10.1542/peds.58.4.508 ◽

1976 ◽

Vol 58 (4) ◽

pp. 508-512

Author(s):

Jay Y. Gillenwater ◽

Charles H. Gleason ◽

Jacob A. Lohr ◽

Donald Marion

Keyword(s):

False Positive ◽

Urine Specimen ◽

Strip Method ◽

Home Testing ◽

Significant Bacteriuria ◽

Positive Results ◽

Home Administration ◽

At Home

Bacteriuria screening on 289 children was performed by their parents by means of a self-administered dip-strip culture which was inoculated, incubated, and interpreted in the home. Simultaneous pour-plate quantitative cultures and laboratory-tested dip-strip cultures were done on the same urine specimen which had been tested at home. The dip-strip culture was reliable (89%) in detecting significant bacteriuria with home administration and interpretation. Only 1.6% false-positive results occurred in the home testing. The dip-strip home cultures are an effective way for screening or follow-up of patients with bacteriuria.

Download Full-text

FDG-PET for Staging and Follow-up of HIV-Infected Patients with Non Hodgkin Lymphoma and Hodgkin Lymphoma: A Single Center Experience.

Blood ◽

10.1182/blood.v114.22.5014.5014 ◽

2009 ◽

Vol 114 (22) ◽

pp. 5014-5014

Author(s):

Silvia Cantoni ◽

Erika Ravelli ◽

Maria Cristina Moioli ◽

Chiara Rusconi ◽

Vittorio Ruggero Zilioli ◽

...

Keyword(s):

Hiv Infection ◽

Ct Scan ◽

Hodgkin Lymphoma ◽

False Positive ◽

Fdg Pet ◽

False Negative ◽

Hiv Positive ◽

Number Of Patients ◽

Positive Results

Abstract Abstract 5014 Introduction Risk of developing non Hodgkin lymphomas (NHL) is known to be increased among patients (pts) infected by HIV-1 and sporadic non-HIV related cases of Hodgking lymphomas (HL) are also described. HIV-positive pts also feature a virus-related systemic lymphoadenopathy which makes nodal involvement by lymphoma difficult to evaluate using conventional imaging. The role of positron-emission tomography using 18F-fluorodeoxyglucose (FDG-PET) in the staging and evaluation of response to treatment of pts with NHL and HL is well established in immunocompetent pts, while only limited information is available on lymphomas arising in the setting of HIV infection. We report on a retrospective analysis of FDG-PET results in a group of HIV pts with lymphoma, both NHL and HL, followed-up at our hospital. Patients and methods Twelve HIV-positive male pts with a diagnosis of lymphoma (7 high grade and 1 follicular NHL, 4 HL) underwent a total of 22 PET scans. PET results were compared with those obtained by computed tomography (CT). Nine PET were performed at staging, 7 at restaging following chemotherapy, and 6 at follow-up. At diagnosis of lymphoma: median CD4 count was 200 cells/mcL (range 98-451); HIV genome was undetectable in 5/9 pts, in the remaining 4 pts for whom the data was available viral loads ranged from 103 to 1,452,720 copies/mL; 10/12 pts were already receiving HAART, while the remaining 2 pts started treatment upon diagnosis of lymphoma. Results In the majority of cases (17/22 = 77%) results of PET, CT scan and clinical status were concordant, being diagnostic of either lymphoma presence (11/17) or absence (6/17). No false positive results were recorded at follow-up. In 5/22 cases (23%) PET and CT scan were discordant. In 4 cases PET yielded a false negative result; in 2 cases at diagnosis (2 pts with HL) and in 2 cases at follow-up (both in the pt with follicular lymphoma). In the remaining case, a PET-negative CT-positive adenopathy was demonstrated which proved to be reactive in nature at biopsy. Discussion Our results suggest that FDG-PET is useful in the evaluation of lymphoma in the setting of HIV infection, similarly to what has been observed among immunocompetent pts. Although the number of patients is limited, in our experience PET proved to be able to discriminate between reactive and lymphomatous involvement of lymphoid tissue as demonstrated by absence of false positive results in pts evaluated at follow-up. These results need to be confirmed by larger clinical trials. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Immunoscintigraphy with 131I or 111In Labelled OC 125 F(ab')2 Fragments in Patients with Ovarian Carcinoma

The International Journal of Biological Markers ◽

10.1177/172460089000500401 ◽

1990 ◽

Vol 5 (4) ◽

pp. 159-165 ◽

Cited By ~ 2

Author(s):

A. Jiménez-Vicioso ◽

M. Torres ◽

A. Jiménez-Heffernan ◽

M.D. Grana ◽

J.M. Latre ◽

...

Keyword(s):

Ovarian Carcinoma ◽

False Positive ◽

True Positive ◽

Recurrence Analysis ◽

Uterine Myomas ◽

Follicular Cyst ◽

S 100 ◽

B Uptake ◽

Positive Results

To evaluate the clinical usefulness of immunoscintigraphy with OC 125 in ovarian carcinoma, we studied 25 patients suspected of having ovarian carcinoma or in follow-up after surgery. Fourteen patients were studied with 131I-OC 125 F(ab')2 and 11 with 111In-OC 125 F(ab')2. No differences were observed with the use of either radionuclide. Global diagnostic indexes obtained were S = 100%, Sp = 44,5% and A = 81%. The low specificity obtained was remarkable: 5 false positive results in two uterine myomas, one abscess, one follicular cyst and one granulation tissue scar. On the other hand, all lesions of ovarian carcinoma were detected. Analysis of the evolution of tumor/background (T/B) uptake ratios from the first to the second day of exploration revealed a tendency for the ratio to diminish significantly (> 15%) in false positive cases with the exception of the abscess while this did not happen in true positive cases, with the exception of a regional recurrence. Analysis of T/B ratio variations could contribute towards elevating the test's specificity.

Download Full-text

Biliary Brush Cytology Revisited

Acta Cytologica ◽

10.1159/000446149 ◽

2016 ◽

Vol 60 (2) ◽

pp. 167-172 ◽

Cited By ~ 6

Author(s):

Shafqat Mehmood ◽

Asif Loya ◽

Muhammed Aasim Yusuf

Keyword(s):

Cystic Duct ◽

Predictive Value ◽

False Positive ◽

Diagnostic Yield ◽

Biliary Strictures ◽

Brush Cytology ◽

Factors Affecting ◽

Ca 19.9 ◽

Positive Results

Purpose: To evaluate the diagnostic yield of biliary brush cytology and the factors affecting positive results in patients with biliary strictures. Patients and Methods: The medical records of all patients who underwent endoscopic retrograde cholangiopancreatography (ERCP) with biliary brush cytology at our institution from November 2004 to December 2013 were reviewed in this retrospective study. The yield of positive brush cytology and the factors affecting positive yield, such as stricture location, age, gender and preprocedure CA 19.9 level were assessed. The final histopathology, diagnosis obtained by other methods, such as endoscopic ultrasound-guided fine-needle aspiration cytology, CT scan, Tru-Cut biopsy and/or clinical/radiological follow-up were used to identify true- and false-positive/negative results. The brush cytology results were divided into 4 main categories: malignant, benign, atypical cells and inadequate. Results: A total of 1,168 patients underwent ERCP during this 9-year period. Out of these, 142 patients had ERCP and biliary brushings for diagnosis. The mean age of the patients at presentation was 58.7 years (range 23-84 years; 64.8% males). The indication for referral was obstructive jaundice in all patients. Of the 142 patients, 77 (54.2%) had a distal common bile duct (CBD) stricture and 65 (45.8%) had a proximal /complex hilar stricture. The strictures were classified as proximal or distal, based on their relationship with the cystic duct; those below the cystic duct insertion were classified as distal and those above it were considered proximal. The diagnostic yield of brush cytology was 58.5%. The diagnostic yield was higher for proximal than for distal CBD strictures (67 vs. 50%; p = 0.047). It was also higher for females (58 vs. 57.6%; p = 0.94), patients >50 years (60 vs. 50%; p = 0.29) and those with a CA 19.9 level >300 IU/ml (59.4 vs. 55.5%; p = 0.65) but did not reach statistical significance for any of these parameters. Complete follow-up data were available for 96 patients and 46 patients were lost to follow-up. The sensitivity, specificity, positive predictive value and negative predictive value were 65.3, 100, 100 and 27%, respectively. When patients with atypia were included in the group with positive results, the diagnostic yield increased to 65.5% with a diagnostic sensitivity of 68.6%. There were 27 false-negative diagnoses, 10 patients were true-negative and no patients had a false-positive diagnosis. Conclusion: Biliary brush cytology is a safe and simple initial diagnostic procedure in patients with biliary strictures and can be performed at the time of therapeutic ERCP. If performed correctly and then interpreted by a dedicated cytopathologist, it has a good diagnostic yield and sensitivity. We feel that the low rates of success with this technique reported in some earlier studies have led to a feeling that this is not a particularly useful technique. We recommend that this topic should be revisited, and that the technique should be used more often.

Download Full-text

Psychological Effects of False-Positive Results in Cystic Fibrosis Newborn Screening: A Two-Year Follow-Up

The Journal of Pediatrics ◽

10.1016/j.jpeds.2009.12.003 ◽

2010 ◽

Vol 156 (5) ◽

pp. 771-776.e1 ◽

Cited By ~ 21

Author(s):

Julie Beucher ◽

Emmanuelle Leray ◽

Eric Deneuville ◽

Monique Roblin ◽

Isabelle Pin ◽

...

Keyword(s):

Cystic Fibrosis ◽

Newborn Screening ◽

False Positive ◽

Psychological Effects ◽

Positive Results

Download Full-text

Detection of Squamous Cell Carcinoma Antigen with Two Systems in the follow-up of Patients with Cervical Cancer

The International Journal of Biological Markers ◽

10.5301/jbm.5000031 ◽

2013 ◽

Vol 28 (3) ◽

pp. 313-317 ◽

Cited By ~ 3

Author(s):

Maria T. Sandri ◽

Michela Salvatici ◽

Cristian Mauro ◽

Davide Radice ◽

Paola Lentati ◽

...

Keyword(s):

Squamous Cell Carcinoma ◽

Cell Carcinoma ◽

Squamous Cell ◽

False Positive ◽

Laboratory Data ◽

Squamous Cell Carcinoma Antigen ◽

Mean Values ◽

Comparison Of The Results ◽

Positive Results

Since squamous cell carcinoma antigen (SCC-Ag) testing became commercially available on the Architect platform, the previously established method on the Abbott IMx platform has been progressively replaced. Aim of this work was to compare SCC-Ag values obtained with the 2 methods. Clinical and laboratory data of 188 patients for whom SCC-Ag determination was requested, were reviewed. IMx was used to determine the levels of SCC-Ag from June 2007 to May 2009, while the Architect system was used from June 2009 to April 2011. Only patients consistently diagnosed with no evidence of disease, for whom at least 2 determinations with each analyzer were available were used. Comparison of the results obtained with the 2 systems was then performed. Mean values for SCC-Ag were 0.56 ng/mL (Standard Error (SE): 0.08) with the IMx method, and 1.08 ng/mL (SE 0.10) with Architect (p<0.0001). False positive results were found in 4.8% of patients with the IMx method and in 9.5% of patients with Architect (p=0.049). The values of SCC-Ag determined on the Architect platform are higher than those obtained on the IMx, with a higher percentage of false positive results.

Download Full-text

A Cluster of Primary Varicella Cases Among Healthcare Workers With False-Positive Varicella Zoster Virus Titers

Infection Control and Hospital Epidemiology ◽

10.1086/502187 ◽

2003 ◽

Vol 24 (3) ◽

pp. 202-206 ◽

Cited By ~ 26

Author(s):

Amy Behrman ◽

D. Scott Schmid ◽

Anne Crivaro ◽

Barbara Watson

Keyword(s):

Varicella Zoster Virus ◽

False Positive ◽

Healthcare Workers ◽

Screening Program ◽

Varicella Vaccine ◽

Varicella Zoster ◽

Control And Prevention ◽

Serologic Screening ◽

Positive Results

AbstractBackground:Five cases of primary varicella zoster virus (VZV) were diagnosed among hospital healthcare workers (HCWs). All had complied with a pre-employment VZV screening program and had been considered immune.Objectives:To summarize the investigation of VZV among un-immunized HCWs and to provide recommendations for avoiding false-positive serologic tests.Design:Risk of transmission of VZV to susceptible HCWs is minimized through serologic screening. Varicella vaccine is recommended for susceptible HCWs. A commercially available latex bead agglutination assay (LA) is widely used because it is rapid and easy to perform. LA was compared with the whole-cell varicella ELISA standardized in the Centers for Disease Control and Prevention (CDC) National Herpes Laboratory.Setting/Population:Large inner-city, tertiarycare hospital with a diverse employee population.Results:In a year, 5 HCWs presented with laboratory-confirmed primary varicella infection. Four had VZV exposures 2 weeks prior to presentation. All had documented positive VZV titers by LA performed at hire. None were offered VZV vaccination. The original LAs were judged false-positives.Intervention/Follow-Up Investigation:Fifty-three consecutive VZV LA samples from the hospital laboratory were retested at the CDC. Forty-four samples concurred. Of the remaining 9, 4 were positive by hospital LA but negative by CDC IgG ELISA. Four were equivocal by hospital LA but negative by CDC IgG ELISA and LA. One was positive by hospital LA but negative by LA and equivocal by ELISA at the CDC.Conclusion:LA may be prone to false-positive results and inappropriate for screening hospital HCWs.

Download Full-text

False-Positive Xpert MTB/RIF Results in Retested Patients with Previous Tuberculosis: Frequency, Profile, and Prospective Clinical Outcomes

Journal of Clinical Microbiology ◽

10.1128/jcm.01696-17 ◽

2018 ◽

Vol 56 (3) ◽

Cited By ~ 25

Author(s):

Grant Theron ◽

Rouxjeane Venter ◽

Liezel Smith ◽

Aliasgar Esmail ◽

Philippa Randall ◽

...

Keyword(s):

False Positive ◽

Positive Culture ◽

Previous Treatment ◽

Treatment Completion ◽

Diagnostic Dilemma ◽

Negative Results ◽

Previously Treated Patients ◽

Positive Results ◽

Culture Negative

ABSTRACTGlobally, Xpert MTB/RIF (Xpert) is the most widely used PCR test for the diagnosis of tuberculosis (TB). Positive results in previously treated patients, which are due to old DNA or active disease, are a diagnostic dilemma. We prospectively retested sputum from 238 patients, irrespective of current symptoms, who were previously diagnosed to be Xpert positive and treated successfully. Patients who retested as Xpert positive and culture negative were exhaustively investigated (repeat culture, chest radiography, bronchoscopy with bronchoalveolar lavage, long-term clinical follow-up). We evaluated whether the duration since previous treatment completion, mycobacterial burden (the Xpert cycle threshold [CT] value), and reclassification of Xpert-positive results with a very low semiquantitation level to Xpert-negative results reduced the rate of false positivity. A total of 229/238 (96%) of patients were culture negative. Sixteen of 229 (7%) were Xpert positive a median of 11 months (interquartile range, 5 to 19 months) after treatment completion. The specificity was 93% (95% confidence interval [CI], 89 to 96%). Nine of 15 (40%) Xpert-positive, culture-negative patients reverted to Xpert negative after 2 to 3 months (1 patient declined further participation). Patients with false-positive Xpert results had a lower mycobacterial burden than patients with true-positive Xpert results (CT, 28.7 [95% CI, 27.2 to 30.4] versus 17.6 [95% CI, 16.9 to 18.2];P< 0.001), an increased likelihood of a chest radiograph not compatible with active TB (5/15 patients versus 0/5 patients;P= 0.026), and less-viscous sputum (15/16 patients versus 2/5 patients whose sputum was graded as mucoid or less;P= 0.038). All patients who initially retested as Xpert positive and culture negative (“Xpert false positive”) were clinically well without treatment after follow-up. The duration since the previous treatment poorly predicted false-positive results (a duration of ≤2 years identified only 66% of patients with false-positive results). Reclassifying Xpert-positive results with a very low semiquantitation level to Xpert negative improved the specificity (+3% [95% CI, +2 to +5%]) but reduced the sensitivity (−10% [95% CI, −4 to −15%]). Patients with previous TB retested with Xpert can have false-positive results and thus not require treatment. These data inform clinical practice by highlighting the challenges in interpreting Xpert-positive results, underscore the need for culture, and have implications for next-generation ultrasensitive tests.

Download Full-text