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PubMed1985

The sensitivity, specificity, and predictive value of traditional clinical evaluation of peripheral arterial disease: results from noninvasive testing in a defined population.

In a companion article we have reported the prevalence, in an older, defined population, of traditional assessments (intermittent claudication and abnormal pulse examination) of peripheral arterial disease (PAD) as compared with the results of highly accurate noninvasive testing. In this article we report the sensitivity, specificity, and positive and negative predictive values for claudication and abnormal pulses for the diagnosis of large-vessel and small-vessel PAD as determined by noninvasive testing. Claudication and abnormal pulses were completely unrelated to isolated small-vessel PAD. In contrast, both claudication and abnormal pulses were significantly correlated with large-vessel PAD. Claudication and an abnormal femoral pulse showed a high specificity and positive predictive value but a low sensitivity for large-vessel PAD. Conversely, an abnormal dorsalis pedis pulse showed a good sensitivity but low specificity and positive predictive value. The best single discriminator was an abnormal posterior tibial pulse, which had high sensitivity, specificity, and positive predictive value. Various combinations of claudication and pulse abnormalities revealed a good sensitivity for broader criteria but at the expense of specificity, whereas stricter criteria had a good specificity and positive predictive value but a poor sensitivity. No combination was superior to an abnormal posterior tibial pulse alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Validity testing of commercial urine cocaine metabolite assays: II. Sensitivity, specificity, accuracy, and confirmation by gas chromatography/mass spectrometry.

A comprehensive validity assessment study was performed on eight commercial urine assays for detection of cocaine use. Sensitivity, specificity, and accuracy of each assay were evaluated by analyzing, in random order and under blind conditions, specimens spiked with known drug concentrations and clinical specimens obtained from human subjects after intravenous cocaine use. Commercial assay results were compared with gas chromatography/mass spectrometry (GC/MS) assay of the same specimens for benzoylecgonine. All of the assays examined were determined to have utility in screening for cocaine use, with the exception of the KDI Quik Test, which was not a reliable test for detection of cocaine use. Major differences in sensitivity, specificity, and confirmation rate by GC/MS were noted among the assays, differences which should be taken into consideration when implementing a urine screening test for cocaine use or interpreting test results involving use of these assays.

Adult↗
PubMed1986

[Bone marrow scintigraphy using radiocolloids in bone metastases. Sensitivity, specificity, reliability and indications].

The sensitivity and specificity of bone marrow scintigraphy in demonstrating skeletal metastases was examined in 40 patients with focal metastases. Radiology and MDP scintigraphy were used as reference methods. Sensitivity depends on the region of the skeleton. False negatives are the rule in parts of the skeleton containing little bone marrow. In relation to the entire bone marrow content, sensitivity is 0.64. The high proportion of false negatives (36%) in the presence of confirmed metastases and the incomplete demonstration of the bone marrow makes marrow scintigraphy unsuitable as a screening method. Occasionally lesions confined to the marrow can be demonstrated when radiographs and bone scintigrams are still negative. In advanced cases, marrow scintigraphy can demonstrate the extent of destruction of the bone marrow. Demonstration of displacement or of an 'empty bone' is evidence of invasion of the bone marrow in patients with tumours. In patients with reduced haematopoiesis of unknown origin or unidentified diffuse skeletal uptake, bone marrow scintigraphy may provide valuable information.

Adult↗
PubMed1993

Sensitivity, specificity and predictive value of blood cultures from cattle clinically suspected of bacterial endocarditis.

This study investigated the number of blood culture-positive cattle among 215 animals clinically suspected of having bacterial endocarditis. For animals that were necropsied, the sensitivity, specificity and predictive value of the diagnosis of endocarditis were calculated on the basis of the isolation of the causative bacteria from blood. Furthermore, it was investigated whether the glutaraldehyde coagulation time, total leucocyte count, per cent neutrophil granulocytes, pulse rate and duration of disease could help to discriminate endocarditis from other diseases. Among 138 animals necropsied the sensitivity, specificity and predictive value of blood cultivation were 70.7 per cent, 93.8 per cent and 89.1 per cent, respectively. None of the other measurements could be used to discriminate between endocarditis and non-endocarditis cases.

Animals↗
PubMed2004

[Modelling sensitivity, specificity and predictive values of hematuria testing using reagent sticks in the diagnosis of Schistosoma haematobium infection].

Since its recognition as an effective tool to identify Schistosoma haematobium infection, haematuria detection has been used in several large scale control programs. However, large variations in performance between age groups, gender, prevalence and areas were observed. Correlation between the degree of haematuria and the intensity of infection and between intensity of infection with age and/or gender could partly explained these variations. Other factors, such as the circadian cycles and day-to-day variations of haematuria and egg excretion, a concomitant presence of blood in urine for another reason than schistosomiasis and the intrinsic characteristics of the reagents strips also contribute to the observed variations. This study assessed the influence of age, gender and intensity of infection taken together on the performance of the diagnostic test by fitting logistic regression models. During a socio-economic study of schistosomiasis, carried out between 1989 and 1991 in a rice-growing area located in Mali, West Africa, haematuria was detected by reagent strips among 2,873 six-year-old and more subjects randomly chosen from 14 villages. The "gold standard" of infection was provided by the parasite egg counts. Laboratory quality controls were implemented. Observed sensitivities, specificities, positive and negative predictive values were calculated by the standard two-by-two tables. The influence of age, gender, intensity of infection, measured in a continuous scale, on these parameters were studied by fitting two logistic models. The first one modelled sensitivity and specificity The second one modelled predictive values. Goodness-of-fit tests were performed. Large variations in the observed values of sensitivities, specificities and predictive values by age and gender were observed. The best fitted model for sensitivity and specificity included infection status, age, gender, intensity and an age by gender interaction. For the predictive values, the best model included haematuria, age, and an haematuria by age interaction. Given the large variations in the performances across the covariates strata defined by cross-tabulation of the age/gender and intensity categories, this modelling approach provided a more realistic appraisal of the performances than using overall values obtained from a general two- by-two table. It allowed to assess the effect of the covariates of interest on the performances of the test and provided an adjustment of the performances on these covariates. The best fitted model was able to provide estimates of sensitivity for each age/gender stratum as a function of the intensity of infection, which could not be done by using the two-by-two table approach. A decrease in sensitivity adjusted for intensity of infection above 10 years of age among males is discussed. This modelling approach also uses all the information available and not only the data from the stratum of interest.

Adolescent↗
PubMed1987

Allergen-specific leukocyte adherence inhibition (LAI) assay: sensitivity, specificity and mechanism.

An allergen-specific tube leukocyte adherence inhibition (LAI) assay has been developed in order to study the mechanism by which leukocytes lose their normal property of adherence to glass. Peripheral blood leukocytes (PBL) from 27 individuals allergic to Dermatophagoides farinae (DF), 10 with seasonal rhinitis not induced by DF and 49 non-allergic healthy volunteers were challenged in vitro with DF and a non-relevant allergen, Artemisia vulgaris (AV) and then assayed for the ability to adhere to glass tubes. Challenge by DF, but not by AV, resulted in loss of adherence by PBL from patients allergic to DF, but not in those of normal controls. The specific LAI response was dose-dependent and occurred only when a critical dose of 0.5 X 10(3) was employed. Following in vitro challenge with DF, radio-immunoassay using an antiserum to LTC4 detected immunoreactive material in supernatants of PBL from DF-allergic individuals. When highly enriched mononuclear cells from non-allergic individuals were armed with cytophilic allergen-specific IgE and challenged with the specific allergen, they lost the property of glass adherence and released a substance that was immunoreactive with LTC4. The results suggest that the chain of events leading to the LAI response in PBL from allergic individuals involves primary recognition of the allergen by specific IgE antibodies bound to receptors on mononuclear cells. The cells are thus triggered to synthesize cysteinyl-containing leukotrienes which mediate the LAI phenomenon. The results suggest that this assay may be used to study allergen-antibody interaction and the subsequent events leading to the clinical picture of atopic diseases.

Allergens↗
PubMed1988

Sensitivity, specificity, and predictive value of body surface cultures in a neonatal intensive care unit.

We analyzed 24,584 cultures obtained from 3371 infants during a three-year period to determine how frequently body surface culture isolates matched those obtained subsequently from body fluids. The sensitivity, specificity, and predictive values of surface cultures were calculated daily for the two weeks up to and including the day that a body fluid culture was obtained. Isolates from cultures of material from the ear canal, nasopharynx, axilla, umbilicus, groin, rectum, stomach, and endotracheal tube were rarely the same as those recovered from blood or fluids of the cerebrospinal, joint, pleural, pericardial, and peritoneal spaces. With a frequency of sepsis of 3.3% among patients in our neonatal intensive care unit, the optimum sensitivity, specificity, and positive predictive values of surface cultures were 56%, 82%, and 7.5%, respectively. These values did not improve substantially for any specific times of surface cultures prior to sepsis, for anatomic sites cultured, or for pathogens recovered. We conclude that surface cultures are of limited value in predicting the etiology of sepsis in neonates.

Algorithms↗
PubMed2004

Sensitivity, specificity, positive predictive value, and negative predictive value of the dipyridamole sestamibi stress test in predicting graft occlusion or > or = 50% new native coronary artery disease in men versus women and in patients aged > or = 65 years versus < 65 years who had prior coronary artery bypass grafting.

The sensitivity, specificity, positive predictive value, and negative predictive value of the dipyridamole sestamibi stress test (DSST) in predicting graft obstruction or > or = 50% new native coronary artery disease (CAD) in 88 men compared with 56 women with prior coronary artery bypass surgery were 96% and 94% (p = NS), 30% and 67% (p = NS), 91% and 96 % (p = NS), 50% and 57% (p = NS), respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of the DSST in predicting graft obstruction or > or = 50% new native CAD in 92 patients aged < 65 years were 95% and 95% (p = NS), 50% and 40% (p = NS), 96% and 87% (p = NS), and 43% and 67% (p = NS), respectively.

Adult↗
PubMed1995

Specific, sensitive, and rapid assay for human immunodeficiency virus type 1 pol mutations associated with resistance to zidovudine and didanosine.

The effectiveness of antiretroviral therapy may be limited by the development of human immunodeficiency virus type 1 (HIV-1) resistance. Monitoring for resistance will perhaps allow changes in therapy prior to deterioration in the patient's clinical or immunologic status. Our objective was to develop a rapid, specific, and sensitive genotypic assay for HIV-1 resistance to zidovudine (ZDV) and didanosine (ddI) which is simple to perform. In our assay the DNA of HIV-1 pol was amplified by PCR using two sets of nested oligonucleotide primers. Mutations of reverse transcriptase (RT) encoding amino acids (aa) 74 and 41, 70, and 215 which have been associated with HIV-1 resistance to ddI and ZDV, respectively, were detected with a ligase detection reaction (LDR) and indicated colorimetrically. The RT genotypes of 35 patient specimens (140 codons) blindly assessed for these mutations were in agreement by PCR-LDR and by dideoxynucleotide sequencing. To evaluate the limits of the assay, other specimens with mutations close to the ligation site were evaluated by PCR-LDR. The assay was sensitive and specific for all specimens except when mutations occurred within 2 bases on either side of the ligation site. In summary, this PCR-LDR assay specifically, sensitively, and rapidly detected pol mutations (RT aa 74, 41, 70, and 215) associated with HIV-1 resistance to ddI and ZDV.

Base Sequence↗
PubMed1997

Human papillomavirus testing as triage for atypical squamous cells of undetermined significance and low-grade squamous intraepithelial lesions: sensitivity, specificity, and cost-effectiveness.

OBJECTIVE: Our purpose was to evaluate the cost-effectiveness of the use of a Food and Drug Administration-approved human papillomavirus test in triaging patients with Papanicolaou smears showing atypical squamous cells of undetermined significance or a low-grade squamous intraepithelial lesion for colposcopy compared with an algorithm that used cytologic follow-up. STUDY DESIGN: Four hundred sixty-two women referred to our Colposcopy Clinic with a Papanicolaou smear report of atypical squamous cells of undetermined significance or a low-grade squamous intraepithelial lesion underwent repeat Papanicolaou smear, cervical colposcopy, directed cervical biopsy, and endocervical curettage. In addition, human papillomavirus testing by the Food and Drug Administration-approved HPV Profile (Digene Diagnostics, Silver Spring, Md.) test was done. A comparison of sensitivity, specificity, and cost-effectiveness of an algorithm determining the need for colposcopy on the basis of repeat cytologic testing versus an algorithm that incorporated repeat cytologic testing and human papillomavirus screening was done. The cost-effectiveness of both of these triage algorithms was also compared. RESULTS: As expected, high-risk human papillomavirus deoxyribonucleic acid was detected with greater frequency in relation to increasing severity of cervical intraepithelial neoplasia. In 268 women, the follow-up smear obtained in our clinic was reported as negative. High-risk human papillomavirus types were found in 23.5% of these women. In the human papillomavirus-negative women, 5.9% had grade 2 or 3 cervical intraepithelial neoplasia confirmed on cervical biopsy. In comparison, 20.6% of those with a positive result of the human papillomavirus test had grade 2 or 3 cervical intraepithelial neoplasia on biopsy (p < 0.001). Despite this difference, the sensitivity of a positive result of a high-risk human papillomavirus test in predicting the presence of grade 2 or 3 cervical intraepithelial neoplasia was only 52%. Among the women for whom a follow-up clinic Papanicolaou smear was reported as showing atypical squamous cells of undetermined significance or a low-grade squamous intraepithelial lesion, there was no difference in the frequency of biopsy-proved grade 2 or 3 cervical intraepithelial neoplasia between those women with a positive human papillomavirus test result and those with a negative test result. Colposcopy would have been recommended for 194 women because of a repeat clinic smear revealing atypical squamous cells of undetermined significance, a low-grade squamous intraepithelial lesion, or a high-grade squamous intraepithelial lesion, and in 21.6% of these grade 2 or 3 cervical intraepithelial neoplasia was shown on biopsy (sensitivity 63%, specificity 62%). Colposcopy would have been recommended for 180 women because high-risk human papillomavirus or a high-grade squamous intraepithelial lesion was detected at the clinic visit, and in 25% of this group grade 2 or 3 cervical intraepithelial neoplasia was shown on biopsy (sensitivity 67%, specificity 66%). Sensitivity and specificity were virtually identical for the two algorithms, but the cost of human papillomavirus testing was nearly double that of triage based on repeat cytologic testing alone ($692 vs $1246 per case). CONCLUSION: The Food and Drug Administration-approved HPV Profile test is not a cost-effective triage for patients referred with Papanicolaou smears reported as showing atypical squamous cells of undetermined significance or low-grade squamous lesions.

Algorithms↗
PubMed1986

Sensitivity, specificity and predictive value of two-dimensional echocardiography in detecting coronary artery aneurysms in patients with Kawasaki disease.

Seventy-seven patients with Kawasaki disease were prospectively evaluated from 1978 to 1983 to determine the sensitivity, specificity and predictive value for detecting coronary artery aneurysms with two-dimensional echocardiography. Seventy (91%) underwent selective coronary arteriography and are included in this report. The study was divided into two periods because of increased experience and the use of a systematic approach with two-dimensional echocardiography in the second period as compared with the first. Aneurysms were demonstrated in nine patients (13%). The coronary artery system was divided into six regions: proximal third of the main right coronary artery, distal right coronary artery, left main coronary artery, left anterior descending coronary artery, circumflex coronary artery and distal left coronary artery. The sensitivity and specificity were high when imaging the proximal regions, and improved from the first period to the second. Both sensitivity and specificity were lower for the more distal regions of the right and left coronary arteries. Overall, the sensitivity of two-dimensional echocardiography was 100% because there were no patients in our study who had isolated distal coronary artery aneurysms. Two-dimensional echocardiography is a sensitive and specific test for detecting aneurysms in the proximal portions of both the right and left coronary arteries, and is useful in selecting patients for invasive investigation with selective coronary arteriography.

Adolescent↗
PubMed1986

Antigen presentation by specifically sensitized macrophages in interferon-gamma induction.

Antigenic stimulation of specifically sensitized T lymphocytes to interferon-gamma (IFN-gamma) production requires the presence of macrophages. This study examines the ability of peritoneal macrophages from immunized mice to present the antigen to antigen-specific lymphocytes. Such cells presented purified protein derivative (PPD) of tuberculin at concentrations as low as 0.1 micrograms/ml to sensitized T lymphocytes. In contrast, peritoneal macrophages from unimmunized animals required 1,000-fold higher concentrations of antigen to stimulate the same lymphocytes. The presentation of low concentrations of antigen by macrophage from immunized animals was significantly blocked by anti-immunoglobulin antibody, indicating that the surface immunoglobulin receptors were critically involved in this phenomenon. These results suggest that surface immunoglobulins serve to focus antigens onto specific macrophages and that such cells are highly efficient at presenting linked antigenic determinants to T cells. The implication of these findings for the mechanism of IFN-gamma induction are discussed.

Animals↗
PubMed1992

Poor sensitivity, specificity, and reproducibility of detection of HIV-1 DNA in serum by polymerase chain reaction. The Transfusion Safety Study Group.

A series of recent studies have reported detection by the polymerase chain reaction (PCR) of cell-free human immunodeficiency virus type 1 (HIV-1) DNA (as opposed to virion RNA) in serum from both seropositive and seronegative persons. To evaluate the sensitivity, specificity, and reproducibility of PCR detection of cell-free HIV-1 DNA, we distributed coded panels containing 98 serum specimens obtained from well-characterized, infected individuals and control blood donors to the two laboratories with reported experience with this technique. Positive results were reported with HIV-1 gag primers (SK38/39) for 48 of 188 separate PCR determinations on DNA extracts from 44 serum samples from seropositive patients (25.5% sensitivity). HIV-1 gag signal was also reported for 28 of 151 PCR determinations on 34 samples from noninfected blood donors (18.5% false-positive rate). PCR for HIV-1 env DNA performed in one laboratory was negative on all specimens from seropositive and seronegative patients. Results for cell-free HIV-1 gag and human genomic (beta-globin or HLA DQ-alpha) DNA were inconsistent on replicate and serial specimens evaluated within each laboratory and between laboratories. These results indicate that current techniques for detecting cell-free HIV-1 DNA in serum lack adequate sensitivity, specificity, and reproducibility for widespread clinical applications.

Base Sequence↗
PubMed2000

The sensitivity, specificity, and reliability of radiographic periapical diagnosis of posterior teeth.

PURPOSE: The purpose of this study was to define the percent accuracy, sensitivity, specificity, and reliability of periapical radiographic diagnosis of periapical inflammatory disease. METHOD: A total of 140 cases were reviewed under ideal viewing conditions by 6 observers. For each case, observers determined whether periapical disease was evident and rated the confidence of their interpretation. RESULTS: The mean percent accuracy was 70.2%. The mean sensitivity and specificity were 0.65 and 0.78, respectively. The intraclass correlation coefficients for intraobserver and interobserver reliability were 0.66 and 0.54, respectively. CONCLUSION: Specificity of periapical radiographic diagnosis is higher than sensitivity. These results support the current guideline for selective use of periapical views based on patient symptoms and clinical signs. Finally, dentists have a good degree of reliability on repeated evaluations, but only fair agreement when compared with other dentists reading the same radiograph.

Adult↗
PubMed2002

Evaluating qualitative assays using sensitivity and specificity.

Sensitivity and specificity are two important indices of performance of qualitative assays. Evaluating these indices usually requires one to identify the true disease state of each subject involved in a study. This implies that a perfect test, a "gold standard," is needed to test each subject. However, a gold standard test cannot always be performed on all subjects, whether because of cost or adverse effect on a subject's welfare. In these situations, a common practice is to apply both a currently used assay and an investigational assay to the same specimen. If the testing results are discordant, a gold standard test is applied. This approach has been criticized by many and, in fact, the statistics based on this approach usually overestimate sensitivity and specificity. This paper proposes two alternative methods to estimate sensitivity and specificity. Simulation results show that these methods perform better than the commonly used existing ones. This paper proposes new acceptance criteria and designs to specific topics for the evaluation of blood related assays as well. To evaluate a qualitative assay related to blood specimens, one must also perform studies of storage conditions, interfering substances, and other related factors, in order to establish the equivalency of the assay under standard and various other conditions. To conduct these studies, true negative blood donor specimens are used as a sample from a nondiseased population; and blood donor specimens with spiked analyte are used to represent a sample from a diseased population. Currently, the target-spiking ranges and sample sizes are determined subjectively. This paper presents new acceptance criteria on acceptable conditions and objective standards for selecting the target-spiking range and sample size.

Algorithms↗
PubMed1997

Limitations of sensitivity, specificity, likelihood ratio, and bayes' theorem in assessing diagnostic probabilities: a clinical example.

We evaluated the extent to which the sensitivity, specificity, and likelihood ratio of the exercise test to diagnose coronary artery disease vary across subgroups of a certain patient population. Among 295 patients suspected of coronary artery disease, as independently determined by coronary angiography, we assessed variation in sensitivity and specificity according to patient history, physical examination, exercise test results, and disease severity in 207 patients with and 88 patients without coronary artery disease, respectively. The sensitivity varied substantially according to sex (women 30% and men 64%), systolic blood pressure at baseline (53% to 65%), expected workload (50% to 64%), systolic blood pressure at peak exercise (50% to 67%), relative workload (33% to 68%), and number of diseased vessels (39% to 77%). The specificity varied across subgroups of sex (men 89% and women 97%) and relative workload (85% to 98%). The likelihood ratio varied (3.8 to 17.0) across the same patient subgroups, as did the sensitivity. As each population tends to be heterogeneous with respect to patient characteristics, no single level of these parameters can be given that is adequate for all subgroups. Use of these parameters as a basis for calculating diagnostic probabilities in individual patients using Bayes' theorem has serious limitations.

Adult↗
PubMed1999

[The sensitivity, specificity and predictive value of PAIgG, reticulated platelets, thrombopoietin levels, and platelet size for the differential diagnosis of thrombocytopenia].

We evaluated measurements of PAIgG, reticulated platelets (RP), plasma thrombopoietin (TPO) levels, and platelet size to determine whether these parameters were useful for the differential diagnosis of idiopathic thrombocytopenic purpura (ITP), aplastic anemia (AA), and hypoplastic thrombocytopenia (HypoT). The percentage of RP (%RP) in patients with ITP was significantly higher (25.2 +/- 11.0%, P < 0.001) than in normal subjects (7.9 +/- 2.8), and the sensitivity, specificity, and predictive value of %RP in diagnosing ITP were 82%, 95%, 96%, respectively. On the other hand, TPO levels in patients with AA and HypoT were significantly higher (355.5 +/- 218.7 pg/ml, P < 0.001, and 376.4 +/- 347.2, P < 0.001, respectively) than in normal subjects (36.7 +/- 23.0). The sensitivity, specificity, and predictive value of TPO in diagnosing AA and HypoT were 88%, 89% and 86%, respectively. We also sought to determine whether the simultaneous measurement of %RP and TPO improved their value in the differential diagnosis of ITP, AA, and HypoT. However, simultaneous measurement did not yield significant improvements in sensitivty, specificity, or predictive value. These results indicated that measurements of %RP will suffice for the diagnosis of ITP, and that measurements of TPO are adequate for the diagnosis of AA and HypoT.

Aged↗