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Testing Positive (testing + positive)
Selected AbstractsAssessment of balsam of Peru patch testsCONTACT DERMATITIS, Issue 6 2000Bolli Bjarnason To find an ideal test technique for as low a dose of balsam of Peru (Myroxylon Pereirae) as possible, subjects testing positive to balsam of Peru are re-tested with a 25% concentration of balsam of Peru in petrolatum. Applications are with Finn Chambers® for 6 different application times, and directly by foils for 96 h (4 days (D)). The goals are to confirm which subjects are positive and which are not, and, using that information, to see if it is possible to distinguish between these 2 groups, tested concomitantly at much lower serial dose levels, in terms of perfusion or by visual assessments. 5 different serial doses are applied with strips for 3,96 h (4D) and with foils for 96 h (4D). The Finn Chamber® tests allow a distinction between visually positive and negative subjects supported by perfusion assessments. With the foils, a 24× lower serial dose level than with the 25% test substance is sufficient to distinguish between positive and negative subjects in terms of perfusion values. This approach requires readings up to 9 days. With this test, the visual approach yields only 3 of 10 positive subjects. This study demonstrates that a lower test dose is possible with perfusion assessments compared to visual ones. [source] Gastroesophageal reflux before and after Helicobacter pylori eradication.DISEASES OF THE ESOPHAGUS, Issue 4 2003A prospective study using ambulatory 24-h esophageal pH monitoring SUMMARY, The aim of this study was to assess prevalence of GERD before and after Helicobacter pylori (HP) eradication utilizing 24-h esophageal pH/manometry studies. Helicobacter pylori status was confirmed by the Campylobacter like organism test. Those testing positive underwent 24-h pH/manometry followed by HP eradication therapy and urea breath test. Patients were followed up at 6 months and then at 1 year when they underwent a repeat 24-h pH/manometry. Twenty patients, 10 with non-ulcer dyspepsia (NUD) and 10 with duodenal ulcer (DU) were enrolled, though only 10 patients attended for a repeat 24-h pH/manometry study. The patients were well matched, though patients with NUD had a significantly higher symptom score at entry compared with the DU group (8.5 vs 5.7, P < 0.05). The pH and esophageal manometry data were similar in the two groups. Overall nine patients (45%; DU = 5, NUD = 4) had evidence of GERD prior to HP eradication and it persisted one year after cure of the infection. The reflux disease occurred in the presence of normal LES pressure (mean 15.6 ± 3.3 mmHg). New onset GERD was uncommon after cure of HP infection, occurring in only one patient with NUD. Overall HP eradication had no impact on percentage of time pH < 4 (4.69 ± 3 vs 4.79 ± 3), episodes > 5 min (9.8 ± 16 vs 15.5 ± 25.3) and Johnson DeMeester Score (16.8 ± 7.5 vs 26.8 ± 18). In addition successful cure of HP produced no significant changes in LES pressure (17.9 ± 3.8 mmHg vs 19.3 ± 4.6 mmHg), and other esophageal manometry data. Half of HP-positive patients with NUD and DU have evidence of GERD before HP eradication. This persists after successful cure of the infection. New onset GERD occurs very uncommonly one year after HP eradication. [source] The outcome of a rapid hepatitis B vaccination programme in a methadone treatment clinicADDICTION, Issue 2 2010Parameswaran Ramasamy ABSTRACT Aim Injecting drug users are a high-risk population for hepatitis B (HBV), but are difficult to engage in vaccination programmes. This study examines the completion rates of a HBV vaccination schedule and seroconversion in a group of patients in methadone maintenance treatment. Methods Patients at a public methadone maintenance programme in Sydney, Australia, were screened for viral hepatitis (hepatitis A, B and C) and offered a rapid HBV vaccination schedule (0, 1 and 2 months). Hepatitis B surface antibody (antiHBs) was retested on completion of the vaccination schedule. Results A total of 143 patients [71.3% male, mean age 33.1 (standard deviation ± 8.3)] enrolled in the project. Forty-nine per cent of patients were HAV antibody (Ab) positive, 81.1% hepatitis C virus (HCV) antibody (Ab) positive and 38.9% antiHBs positive. Exposure to multiple hepatitis viruses was common, with 24.5% testing positive for all three viruses. Seventy-three (83%) of the 88 antiHBs negative patients completed the vaccination schedule. Post-vaccination serology indicated a seroconversion rate of 75.4% (55 of 73) of completors, or 62.5% of eligible participants (55 of 88). Conclusion While there was a high rate of completion of the rapid vaccination schedule in this population, a moderate seroconversion rate was achieved. Further work is required to identify an optimal vaccination schedule in opioid substitution patients. [source] A meta-analysis of marijuana, cocaine and opiate toxicology study findings among homicide victimsADDICTION, Issue 7 2009Joseph B. Kuhns ABSTRACT Aim To synthesize the results of marijuana, cocaine and opiate drug toxicology studies of homicide victims and examine variation in results across person and setting characteristics. Methods A meta-analysis of 18 independent studies identified from an extensive review of 239 published articles that met the inclusion criteria of reporting marijuana, cocaine and/or opiate toxicology test results for homicide victims. A total of 28 868 toxicology test results derived from 30 482 homicide victims across five countries were examined. Results On average, 6% of homicide victims tested positive for marijuana, 11% tested positive for cocaine, and 5% tested positive for opiates. The proportion of homicide victims testing positive for illicit drugs has increased over time. Age had a strong curvilinear relationship with toxicology test results, but gender differences were not apparent. Hispanic and African American homicide victims were more likely to test positive for cocaine; Caucasians were most likely to test positive for opiates. Cocaine use appeared to be related to increased risk of death from a firearm and was a greater risk factor for violent victimization in the United States than in Newfoundland and Scandinavia. Conclusion There are relatively few studies of illicit drug toxicology reports from homicide victims that allow for cross-cultural comparisons. This study provides a basis for comparing future local toxicology test results to estimates from existing research. [source] First report of saxitoxin in Finnish lakes and possible associated effects on human healthENVIRONMENTAL TOXICOLOGY, Issue 3 2005Jarkko Rapala Abstract This study is the first report of saxitoxin in cyanobacterial blooms in Finland. Bloom samples (n = 50) were collected from Finnish freshwater sites during summer months of 2002 and 2003. These samples were screened for the presence of paralytic shellfish toxins (PSTs) using the Jellett rapid PSP screening test. Samples testing positive for PSTs (n = 7) were further analyzed with saxiphilin- and voltage-gated sodium channel [3H]-STX,binding radioreceptor assays and liquid chromatography using fluorescence and mass spectrometric analysis. The results indicated that saxitoxin (STX) was the only PST analogue in the samples and that it was present in high concentrations, as much as 1 mg L,1. Microscopic analysis revealed that 95%,100% of the phytoplankton in the positive samples consisted of Anabaena lemmermannii. The trophic status of lakes in which STX-containing blooms were found varied from oligotrophic to hypertrophic. All the lakes had high nitrogen-to-phosphorus ratios. In some instances, samples had been collected from sites where swimmers had reported adverse health effects, and in three such cases, reported adverse health effects were associated with sites from which samples testing positive for STX had been received. Symptoms of fever, eye irritation, abdominal pains, and skin rash were reported in children aged 2,10 years after exposure to the water. These were not the adverse human symptoms typical of STX poisoning; rather, they represented acute effects often reported following recreational exposure to cyanobacterial blooms. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 331,340, 2005 [source] Elevated prevalence of hepatitis C infection in users of United States veterans medical centers,HEPATOLOGY, Issue 1 2005Jason A. Dominitz Several studies suggest veterans have a higher prevalence of hepatitis C virus infection than nonveterans, possibly because of military exposures. The purpose of this study was to estimate the prevalence of anti,hepatitis C antibody and evaluate factors associated with infection among users of Department of Veterans Affairs medical centers. Using a two-staged cluster sample, 1,288 of 3,863 randomly selected veterans completed a survey and underwent home-based phlebotomy for serological testing. Administrative and clinical data were used to correct the prevalence estimate for nonparticipation. The prevalence of anti,hepatitis C antibody among serology participants was 4.0% (95% CI, 2.6%-5.5%). The estimated prevalence in the population of Veterans Affairs medical center users was 5.4% (95% CI, 3.3%-7.5%) after correction for sociodemographic and clinical differences between participants and nonparticipants. Significant predictors of seropositivity included demographic factors, period of military service (e.g., Vietnam era), prior diagnoses, health care use, and lifestyle factors. At least one traditional risk factor (transfusion or intravenous drug use) was reported by 30.2% of all subjects. Among those testing positive for hepatitis C antibody, 78% either had a transfusion or had used injection drugs. Adjusting for injection drug use and nonparticipation, seropositivity was associated with tattoos and incarceration. Military-related exposures were not found to be associated with infection in the adjusted analysis. In conclusion, the prevalence of hepatitis C in these subjects exceeds the estimate from the general US population by more than 2-fold, likely reflecting more exposure to traditional risk factors among these veterans. (HEPATOLOGY 2005;41:88,96.) [source] Comparison of risk factors for invasive squamous cell carcinoma and adenocarcinoma of the cervix: Collaborative reanalysis of individual data on 8,097 women with squamous cell carcinoma and 1,374 women with adenocarcinoma from 12 epidemiological studiesINTERNATIONAL JOURNAL OF CANCER, Issue 4 2007Article first published online: 27 NOV 200 Abstract Squamous cell carcinomas account for about 80% of cancers of the uterine cervix, and the majority of the remainder are adenocarcinomas. There is limited evidence on the extent to which these histological types share a common etiology. The International Collaboration of Epidemiological Studies of Cervical Cancer has brought together and combined individual data on 8,097 women with invasive squamous cell carcinoma, 1,374 women with invasive adenocarcinoma and 26,445 women without cervical cancer (controls) from 12 epidemiological studies. Compared to controls, the relative risk of each histological type of invasive cervical cancer was increased with increasing number of sexual partners, younger age at first intercourse, increasing parity, younger age at first full-term pregnancy and increasing duration of oral contraceptive use. Current smoking was associated with a significantly increased risk of squamous cell carcinoma (RR = 1.50, 95% CI: 1.35,1.66) but not of adenocarcinoma (RR = 0.86 (0.70,1.05)), and the difference between the two histological types was statistically significant (case-case comparison p < 0.001). A history of screening (assessed as having had at least one previous nondiagnostic cervical smear) was associated with a reduced risk of both histological types, but the reduction was significantly greater for squamous cell carcinoma than for adenocarcinoma (RR = 0.46 (0.42,0.50) and 0.68 (0.56,0.82), respectively; case,case comparison, p = 0.002). A positive test for cervical high-risk HPV-DNA was a strong risk factor for each histological type, with 74% of squamous cell carcinomas and 78% of adenocarcinomas testing positive for HPV types 16 or 18. Squamous cell and adenocarcinoma of the cervix share most risk factors, with the exception of smoking. © 2006 Wiley-Liss, Inc. [source] Microbial population profiles of the microflora associated with pre- and postharvest tomatoes contaminated with Salmonella typhimurium or Salmonella montevideoJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2009X Shi Abstract Aims:, To determine the microflora profiles of pre- and postharvest tomatoes contaminated with Salmonella montevideo or S. typhimurium DT104. Methods and Results:,Salmonella montevideo or S. typhimurium was inoculated onto the flowers of tomato plants with the microflora of the subsequent fruit examined using a combination of Source Carbon Utilization and 16S rDNA-PCR profiling. From 16S rDNA profiles it was evident that tomatoes derived from Salmonella inoculated plants harboured a different microbial population compared to nontreated controls. The same result was observed for tomatoes inoculated at postharvest and subsequently stored for 14 days at 15°C. From sequencing analysis it was found that tomatoes derived from Salmonella inoculated plants but testing negative for the enteric pathogen, frequently harboured Enterobacter and Bacillus spp. In contrast, both bacterial types were not found associated with tomatoes testing positive for Salmonella. Conclusions:,Salmonella introduced onto tomatoes at pre- or postharvest alters the composition of the microbial community. The presence of Enterobacter and Bacillus spp negatively affects the persistence of Salmonella on preharvest tomatoes. Significance and Impact of the Study:,Salmonella appears to modify rather than become integrated into the microbial communities associated with tomatoes. Yet, the presence of antagonistic bacteria appears to reduce the persistence of the enteric pathogen. [source] Early-onset and persisting thrombocytopenia in post-cardiac surgery patients is rarely due to heparin-induced thrombocytopenia, even when antibody tests are positiveJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 1 2010S. SELLENG See also Gruel Y, Pouplard C. Post-operative platelet count profile: the most reliable tool for identifying patients with true heparin-induced thrombocypenia after cardiac surgery. This issue, pp 27,29. Summary.,Background:,The high frequency of thrombocytopenia in post-cardiac surgery patients makes it challenging to diagnose heparin-induced thrombocytopenia (HIT). Two platelet count profiles are reported as indicating possible HIT in these patients: profile 1 describes a platelet count fall that begins between postoperative days 5 and 10, whereas profile 2 denotes early-onset thrombocytopenia that persists beyond day 5. Objectives: To examine how these platelet count profiles correlate with antibody status and HIT post-cardiac surgery. Methods: We prospectively screened 581 cardiac surgery patients for heparin-dependent antibodies by platelet factor 4 (PF4),heparin immunoassay and platelet-activation test, and performed daily platelet counts (until day 10) with 30-day follow-up. Results: All three patients with platelet count profile 1 tested positive for platelet-activating anti-PF4,heparin IgG antibodies [odds ratio (OR) 521.7, 95% confidence interval (CI) 3.9,34 000, P = 0.002], and were judged to have HIT. In contrast, none of 25 patients with early-onset and persisting thrombocytopenia (profile 2) was judged to have HIT, including five patients testing positive for platelet-activating anti-PF4,heparin IgG antibodies. In these patients, the frequency of heparin-dependent antibodies did not differ from that in non-thrombocytopenic controls, either for anti-PF4,heparin IgG (OR 1.7, 95% CI 0.7,4.1, P = 0.31) or for platelet-activating antibodies (OR 1.9, 95% CI 0.6,5.7, P = 0.20). Multivariate analysis revealed that type of cardiac surgery, but not HIT antibody status, predicted early-onset and persisting thrombocytopenia. Together, these findings show that HIT was uncommon in this study population [overall frequency, 3/581 (0.5%), 95% CI 0.1,1.5%]. Conclusions: Thrombocytopenia that begins between 5 and 10 days post-cardiac surgery is highly predictive for HIT. In contrast, early-onset and persisting thrombocytopenia is usually caused by non-HIT factors with coinciding heparin-dependent antibody seroconversion. [source] Concurrence of hepatitis B surface antibodies and surface antigen: implications for postvaccination control of health care workersJOURNAL OF VIRAL HEPATITIS, Issue 2 2002H. L. Zaaijer Among 1081 persons testing positive for hepatitis B surface antigen, 106 (10%) tested positive for antibodies to surface antigen (anti-HBs) in the same blood sample. Thirty of these persons were studied in detail: seven tested positive for hepatitis B e-antigen, nine were apparently healthy blood donors, and in 14 chronic infection could be demonstrated in follow-up samples. Frozen samples of 14 persons were available for additional quantitative anti-HBs testing using another anti-HBs assay: three showed no anti-HBs reactivity, seven showed borderline anti-HBs levels (1,5 IU/L), and anti-HBs titres ranged from 23 to 66 IU/L in four HBsAg-positive persons, including an apparently healthy blood donor. Thus, after hepatitis B vaccination of medical personnel, presence of anti-HBs may erroneously suggest immunity, while in fact chronic infection with hepatitis B virus is present. [source] Accuracy of the stool antigen test in the diagnosis of Helicobacter pylori infection before treatment and in patients on omeprazole therapyALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 1 2001G. Manes To evaluate the Helicobacter pylori stool antigen (HpSA) test in the assessment of H. pylori infection and the effect of omeprazole treatment on its accuracy. Methods: Study 1: 140 dyspeptic patients were enrolled in the study and defined as H. pylori positive if histology and rapid urease test, or culture alone were positive. HpSA was performed on all patients and 13C-urea breath test (UBT) on 87. Study 2: 75 patients testing positive using both UBT and HpSA, were given omeprazole 20 mg for 2 weeks (Group A) or omeprazole 40 mg for 2 weeks (Group B), or OAC for 1 week (group C). A Helicobacter pylori stool antigen test was performed on all patients on days 3, 5, 7 and 14 during treatment, and also on days 7 and 14 post-treatment in groups A and B. UBT was performed in groups A and B on days 7 and 14 during treatment, and days 7 and 14 post-treatment. Results: 80/140 patients were H. pylori positive. The sensitivity and specificity of HpSA were 93.8 and 90%, similar to UBT (93.9 and 92.1%). Omeprazole significantly reduced both HpSA and UBT values, resulting in a decreased accuracy. Of 25 patients receiving 20 mg omeprazole, HpSA gave 5 and 6 false negatives after 7 and 14 days treatment respectively, while UBT gave 4 and 7 false negatives after 7 and 14 days treatment. Of 25 patients receiving 40 mg omeprazole, HpSA gave 7 and 9 false negatives after 7 and 14 days of treatment, while UBT gave 8 and 9 false negatives after 7 and 14 days of treatment. Two weeks after stopping omeprazole treatment, the HpSA and UBT were positive in all cases. Conclusions: The Helicobacter pylori stool antigen test is valuable in the assessment of H. pylori infection. Short-term omeprazole treatment decreases the accuracy of both HpSA and UBT in a similar manner. [source] Molecular detection of predation by soil micro-arthropods on nematodesMOLECULAR ECOLOGY, Issue 7 2006D. S. READ Abstract The relative importance of the factors driving change in the population dynamics of nematodes in the soil is almost completely unknown. Top-down control by micro-arthropod predators may have a significant impact on nematode population dynamics. We report experiments showing that mites and Collembola were capable of reducing nematode numbers in the laboratory and were feeding on a targeted nematode species in the field. A PCR-based approach was developed for the detection of predation on three species of slug- and insect-pathogenic nematodes: Phasmarhabditis hermaphrodita, Heterorhabditis megidis and Steinernema feltiae. The collembolan Folsomia candida and the mesostigmatid mite Stratiolaelaps miles were employed as model predators to calibrate post-ingestion prey DNA detection times. Fragments of cytochrome oxidase I (COI) mtDNA were sequenced and species-specific primers were designed, amplifying 154-, 154- and 203-bp fragments for each of the nematode species. Detection times for nematode DNA within the guts of Collembola were longer than in mites, with half-lives (50% of samples testing positive) of 08.75 h and 05.03 h, respectively. F. candida significantly reduced numbers of the nematode H. megidis, with rates of predation of ,0.4 nematode infective juveniles per collembolan per hour over 10 h. Four taxa of field-caught micro-arthropod that had been exposed to the nematode P. hermaphrodita for a period of 12 h were analysed and significant numbers of three taxa tested positive. This is the first application of PCR techniques for the study of nematophagy and the first time these techniques have been used to measure predation on nematodes in the field. [source] Use of Intradermal Dilutional Testing and Skin Prick Testing: Clinical Relevance and Cost EfficiencyTHE LARYNGOSCOPE, Issue 9 2006Dr. Merritt Seshul MD, FAAOA Abstract Objectives/Hypothesis: The objective was to determine the agreement of the positive results from a multiple skin prick test (SPT) device with the ability to determine a definable endpoint through intradermal dilutional testing (IDT) to compare semiquantitatively the degree of positivity of SPT results with quantitative results from IDT and to analyze the cost of immunotherapy based on SPT compared with IDT guided by SPT. Study Design: Retrospective review of clinical data (random accrual). Methods: One hundred thirty-four patients underwent allergy screening using a multiple SPT device. Antigens testing positive by skin prick device were tested using IDT on a separate day. Antigens testing negative by SPT were not evaluated by IDT. Regional allergy testing practice patterns were determined, and a cost analysis using Medicare rates was performed Results: There was good agreement between an antigen testing positive by SPT and the determination of a definable endpoint (93.33%, n = 1,334 antigens). The degree of positivity from the SPT correlated poorly with the final endpoint concentration (r = 0.40, P < .0001). Blended testing techniques were similar in cost when compared with several commonly used allergy testing protocols. Conclusions: Antigens which show reactivity to a multiple SPT device usually have a treatable endpoint that is independent of the degree of positivity of the SPT result. IDT is an important step in the determination of the strongest starting dose of immunotherapy that may be safely administered. Initiating immunotherapy in this manner may potentially create significant health care savings by shortening the time required for a patient to reach their individual maximally tolerated dose. The use of a relatively large screening panel is cost effective and does not increase the average number of antigens treated by immunotherapy. Blended allergy testing techniques that include IDT in their protocol are comparable in cost with commonly used allergy testing protocols. [source] Reducing De Novo Donor-Specific Antibody Levels during Acute Rejection Diminishes Renal Allograft LossAMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2009M. J. Everly The effect of de novo DSA detected at the time of acute cellular rejection (ACR) and the response of DSA levels to rejection therapy on renal allograft survival were analyzed. Kidney transplant patients with acute rejection underwent DSA testing at rejection diagnosis with DSA levels quantified using Luminex single-antigen beads. Fifty-two patients experienced acute rejection with 16 (31%) testing positive for de novo DSA. Median follow-up was 27.0 ± 17.4 months postacute rejection. Univariate analysis of factors influencing allograft survival demonstrated significance for African American race, DGF, cytotoxic PRA >20% (current) and/or >50% (peak), de novo DSA, C4d and repeat transplantation. Multivariate analysis showed only de novo DSA (6.6-fold increased allograft loss risk, p = 0.017) to be significant. Four-year allograft survival was higher with ACR (without DSA) (100%) than mixed acute rejection (ACR with DSA/C4d) (65%) or antibody-mediated rejection (35%) (p < 0.001). Patients with >50% reduction in DSA within 14 days experienced higher allograft survival (p = 0.039). De novo DSAs detected at rejection are associated with reduced allograft survival, but prompt DSA reduction was associated with improved allograft survival. DSA should be considered a potential new end point for rejection therapy. [source] Emergency Department Chlamydia Screening Through Partnership with the Public Health DepartmentACADEMIC EMERGENCY MEDICINE, Issue 11 2009Charlene Babcock Irvin MD Abstract Background:, The emergency department (ED) serves a population that may benefit from numerous screening initiatives but screening in the ED is challenging due to crowding as well as resource and time constraints. One option may be to collect specimens in the ED and then partner with the public health department (PHD) to analyze the specimens off-site and arrange follow-up treatment. Objectives:, The objective was to explore the feasibility of chlamydia screening in females using a partnership model in which the ED is responsible for urine collection and the PHD is responsible for chlamydia testing, notification, and treatment. Methods:, A collaborative partnership-based chlamydia screening project was initiated at a large (90,000 visits/yr), urban, teaching ED from April 2007 to April 2008. Study information sheets were handed out to a convenience sample of eligible female patients and visitors (15,24 yr of age). Those wishing to participate provided a urine sample and follow-up contact information. The information sheet also asked if they had either lower abdominal pain or vaginal discharge (affirmative answer for either was considered symptomatic). Specimens collected in the ED were retrieved by PHD staff for off-site testing. The PHD contacted those participants testing positive using the patient provided contact information and arranged for treatment. Results:, Of the 633 women offered screening, 296 (47%) agreed to testing and provided samples. Of the 296 tested, 38 (12.8%) were positive for chlamydia infection, and 25 (66%) received follow-up and treatment; 13 could not be contacted through information they provided. A higher percentage of symptomatic subjects (23 of 115, or 20%) tested positive for chlamydia than asymptomatic subjects (15 of 181, or 8.3%; p < 0.01). Conclusions:, This study demonstrates the feasibility of an ED,PHD partnership for chlamydia screening in young women. This model can potentially be applied to other initiatives and may improve public health screening without creating significant additional burdens for crowded EDs. [source] Comparison of real-time PCR and conventional hemi-nested PCR for the detection of Bordetella pertussis in nasopharyngeal samplesCLINICAL MICROBIOLOGY AND INFECTION, Issue 7 2003T. P. Anderson We directly compared a conventional hemi-nested PCR assay with a real-time (LightCycler) PCR assay for the detection of Bordetella pertussis in nasopharyngeal samples. Of the 152 samples tested, 49 (32%) were positive by first-round conventional PCR, 56 (37%) were positive by the hemi-nested PCR assay, and 39 (26%) were positive by the real-time assay. All samples testing positive with the real-time assay were also positive by the hemi-nested assay (both first- and second-round PCR), and all culture-positive samples tested positive by both PCR assays. These results suggest that the hemi-nested assay is more sensitive than the real-time assay for detecting B. pertussis. [source] ESTIMATING THE FALSE NEGATIVE FRACTION FOR A MULTIPLE SCREENING TEST FOR BOWEL CANCER WHEN NEGATIVES ARE NOT VERIFIEDAUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS, Issue 4 2004Chris J. Lloyd Summary This paper aims to estimate the false negative fraction of a multiple screening test for bowel cancer, where those who give negative results for six consecutive tests do not have their true disease status verified. A subset of these same individuals is given a further screening test, for the sole purpose of evaluating the accuracy of the primary test. This paper proposes a beta heterogeneity model for the probability of a diseased individual ,testing positive' on any single test, and it examines the consequences of this model for inference on the false negative fraction. The method can be generalized to the case where selection for further testing is informative, though this did not appear to be the case for the bowel-cancer data. [source] | |||||||||||||