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PubMed2001

Prospective comparison of nonenhanced helical computerized tomography and Doppler ultrasonography for the diagnosis of renal colic.

PURPOSE: We evaluate the accuracy of nonenhanced helical computerized tomography (CT) and Doppler ultrasonography for the diagnosis of renal colic. MATERIALS AND METHODS: Our study includes 109 patients, with 218 kidneys, who presented with unilateral flank pain. All patients underwent nonenhanced helical CT, Doppler ultrasonography and excretory urography (IVP). CT was evaluated for the presence of ureteral stones and manifestation of ureteral obstruction. For Doppler ultrasonography the renal resistive index was measured for the left and right kidneys in each patient, and change in resistive index between ipsilateral and contralateral kidneys was calculated and considered positive for ureteral obstruction with values 0.04 or greater. As a reference standard, absence of obstruction was considered if IVP was negative and the cause of flank pain was confirmed not to be urological. Obstruction was diagnosed not only by positive IVP, but also by patient followup until passage or retrieval of ureteral stones. Results of CT and change in resistive index were compared with those of the reference standard. RESULTS: Unilateral ureteral obstruction was confirmed in 52 patients, while no obstruction was found in 57. Of the 57 patients without ureterolithiasis the change in resistive index results was negative in all patients with a specificity of 100%, while CT was negative in 55 with a specificity of 96%. Of the 52 patients with ureteral obstruction CT was positive in 50, and change in resistive index was positive in 47 with a sensitivity of 96% and 90%, respectively, with a difference of no significant value. CONCLUSIONS: Nonenhanced helical CT and change in resistive index are sensitive and specific tests that can contribute significantly to the diagnosis of acute unilateral renal obstruction. They can replace IVP, particularly in situations in which it is undesirable.

Adult↗
PubMed2005

Bacteriophage-based assays for the rapid detection of rifampicin resistance in Mycobacterium tuberculosis: a meta-analysis.

OBJECTIVE: To summarize, using meta-analysis, the accuracy of bacteriophage-based assays for the detection of rifampicin resistance in Mycobacterium tuberculosis. METHODS: By searching multiple databases and sources we identified a total of 21 studies eligible for meta-analysis. Of these, 14 studies used phage amplification assays (including eight studies on the commercial FASTPlaque-TB kits), and seven used luciferase reporter phage (LRP) assays. Sensitivity, specificity, and agreement between phage assay and reference standard (e.g. agar proportion method or BACTEC 460) results were the main outcomes of interest. RESULTS: When performed on culture isolates (N=19 studies), phage assays appear to have relatively high sensitivity and specificity. Eleven of 19 (58%) studies reported sensitivity and specificity estimates > or =95%, and 13 of 19 (68%) studies reported > or =95% agreement with reference standard results. Specificity estimates were slightly lower and more variable than sensitivity; 5 of 19 (26%) studies reported specificity <90%. Only two studies performed phage assays directly on sputum specimens; although one study reported sensitivity and specificity of 100 and 99%, respectively, another reported sensitivity of 86% and specificity of 73%. CONCLUSIONS: Current evidence is largely restricted to the use of phage assays for the detection of rifampicin resistance in culture isolates. When used on culture isolates, these assays appear to have high sensitivity, but variable and slightly lower specificity. In contrast, evidence is lacking on the accuracy of these assays when they are directly applied to sputum specimens. If phage-based assays can be directly used on clinical specimens and if they are shown to have high accuracy, they have the potential to improve the diagnosis of MDR-TB. However, before phage assays can be successfully used in routine practice, several concerns have to be addressed, including unexplained false positives in some studies, potential for contamination and indeterminate results.

Antibiotics, Antitubercular↗
PubMed2000

Ruggedness study of HPLC peptide mapping for the identity of a drug compound: a chemometrics approach.

A statistically more reliable approach than the traditional visual inspection of peptide maps to identify a drug compound is to generate a set of reference standards from a designed experiment that incorporates many possible factors that affect variation of peptide mapping. In fact, the experiment can be done for a ruggedness study as part of a high-performance liquid chromatography (HPLC) method validation. Once the ruggedness is proved with the study, those articles in the experiment may form a set of reference standards, and future articles can be compared to the set later to prove identity. A quantitative analysis of the ruggedness study can be done using a chemometrics approach, principal component analysis (PCA). The analysis is used to reduce the many channels of peptide maps to a few manageable dimensions. The scores projected onto the reduced dimensions are used to test factor effects of the ruggedness study. As a by-product, the analysis provides visual inspection of the set of articles in the experiment for any outliers and anomalies.

Antibodies, Monoclonal↗
PubMed2006

Clinical evaluation of a 16S ribosomal RNA polymerase chain reaction test for the diagnosis of lymph node tuberculosis.

UNLABELLED: Reports on the sensitivity of polymerase chain reaction (PCR) for the diagnosis of lymph node tuberculosis (TB) show divergent results. We evaluated the accuracy of the Roche Amplicor Mycobacterium tuberculosis PCR test with lymph node aspirate and biopsy samples. METHODS: The study was conducted at a public reference hospital in Lima, Peru. From the period of January 2003 to January 2004, we included patients who had lymphadenopathy and in whom the attending physician suspected TB. Aspirate and biopsy samples were submitted for culturing in Lowenstein-Jensen medium, for histopathologic testing, and for PCR. The sensitivity and specificity of PCR were calculated against a reference standard based on histopathologic findings and culture. RESULTS: Our study included 154 patients. Median age was 29 years (interquartile range, 21-40 years); 97 patients (62.9%) were men. Twenty-nine patients (18.8%) had acid fast bacilli-positive histopathologic findings, and 44 (28.6%) had a positive culture result. Using the combination of histopathologic findings and culture as reference standard, 55 patients (35.7%) had a diagnosis of tuberculous lymphadenitis. The sensitivity of the PCR test was 58.2%, and the specificity was 93.9%. For biopsy tissue only, the sensitivity of PCR was 52.7%, and the specificity was 97.0%. For aspirate samples only, the sensitivity of PCR was 47.3%, and the specificity was 96.0%. CONCLUSION: The Amplicor PCR test revealed low sensitivity and high specificity for the diagnosis of lymph node TB. The sensitivity was higher in cases in which the bacillary load was high--in acid fast bacilli-positive samples and among HIV-infected patients. Considering the results of microbiological and PCR tests together, there was still a patient group in whom no final diagnosis could be established.

Adult↗
PubMed2004

Grading airway stenosis down to the segmental level using virtual bronchoscopy.

OBJECTIVE: To assess the sensitivity of noninvasive virtual bronchoscopy based on multirow detector CT scanning in detecting and grading central and segmental airway stenosis using flexible bronchoscopic findings as the reference standard. MATERIALS AND METHODS: In a blinded controlled trial, multirow detector CT virtual bronchoscopy and flexible bronchoscopy were used to search for and grade airway stenosis in 20 patients. CT scan data were obtained with a multirow detector CT scanner using 4 x 1 mm collimation. Flexible bronchoscopy findings were graded by a pulmonologist and served as the reference standard for 176 central airway regions (ie, trachea, main bronchi, and lobar bronchi) and 302 segmental airway regions. The extent of airway narrowing was categorized as grade 0 (no narrowing), grade 1 (< 50%), or grade 2 (> or =50%). RESULTS: Flexible bronchoscopy revealed 30 stenoses in the central airways and 10 in the segmental airways. Virtual bronchoscopy detected 32 stenoses in the central airways (sensitivity, 90.0%; specificity, 96.6%; accuracy, 95.5%) and 22 in the segmental airways (sensitivity, 90.0%; specificity, 95.6%; accuracy, 95.5%). The number of false-positive findings was higher in the segmental airways (13 false-positive findings) than in the central airways (5 false-positive findings), which caused a lower positive predictive value for the segmental airways (40.9%) than for the central airways (84.4%). Flexible and virtual bronchoscopic gradings correlated better for central airway stenosis (r = 0.87) than for segmental airway stenosis (r = 0.61). CONCLUSION: Although a high sensitivity was found for the detection of both central and segmental airway stenosis, the number of false-positive findings was higher for segmental airways. However, noninvasive multirow detector CT virtual bronchoscopy enables high-resolution endoluminal imaging of the airways down to the segmental bronchi.

Aged↗
PubMed2005

Definition of the post-thrombotic syndrome, differences between existing classifications.

BACKGROUND: Accepted diagnostic criteria exist for the diagnosis of deep vein thrombosis (DVT). However, no uniform definition for the diagnosis and treatment of the post-thrombotic syndrome (PTS) exists. We examined the various definitions of PTS that are used and their relationships with invasive venous pressure measurement. METHODS: Patients who had previously suffered a documented DVT underwent clinical evaluation of both lower limbs in which we used five clinical definitions to grade PTS. We included the definition of Widmer, the CEAP classification, the venous clinical severity score (also without compression therapy), and the definitions according to Prandoni and Brandjes in the evaluation. We compared all the clinical scoring systems with invasive ambulatory venous pressure measurement. RESULTS: In total 124 patients were enrolled in whom both legs were evaluated. Thirteen patients had previously suffered bilateral DVT and nine patients had had an ipsilateral recurrent DVT. In the limbs with DVT, 10 (7%) to 29 (21%) were defined as severe PTS, compared to 0-4 (4%) in the control legs. Mild-to-moderate PTS in the DVT legs ranged from 23 to 49%, compared to 13-34% in the control legs. Overall the presence of any PTS in the DVT legs varied from 30% (VCS without compression) to 66% (Brandjes). The scoring systems of Brandjes and VCS showed a tendency towards more legs to be defined as severe PTS. Absolute frequencies of PTS in DVT legs were highest for the classifications according to Widmer, Prandoni and Brandjes. Differences in proportions of any PTS calculated between DVT and control legs varied from 18 to 39%, while odds ratios varied between 2.2 and 5.2 for the different definitions. The CEAP classification and definition of Brandjes show a moderate relation to Widmer, kappa=0.53 and 0.52, respectively. The VCS shows in all comparisons a poor correlation (kappa 0.22-0.41). Prandoni has a moderate correlation with most definitions (kappa 0.40-0.44). CONCLUSION: All clinical definitions of PTS were highly associated with the reference standard of ambulatory venous pressure, with higher AVPs observed in the more severely affected groups. The ability of the scoring systems to discriminate between DVT and control legs as well as the observed prevalence of PTS differed substantially. In part this is due to the considerable overlap in AVP in the different clinical groups, reflecting the fact that our reference standard has substantial deficiencies. No clear advantage was found in any one system of classification over the rest.

Bandages↗
PubMed2000

Evaluation of LabRespond, a new automated validation system for clinical laboratory test results.

BACKGROUND: Manual validation of laboratory test results is time-consuming, creating a demand for expert systems to automate this process. We have started to set up the program "LabRespond", which covers five validation levels: administrative, technical, sample, patient, and clinical validation. We present the evaluation of a prototype of an automated patient validation system based on statistical methods, in contrast to the commercially available program "VALAB", a rule-based automated validation system. METHODS: In the present study, 163 willfully altered, erroneous test results out of 5421 were submitted for validation to LabRespond, VALAB, and to a group of clinical chemists (n = 9) who validated these test results manually. The test results rejected by three or more clinical chemists (n = 281) served as a secondary reference standard. RESULTS: The error recovery rates of clinical chemists ranged from 23.9% to 71.2%. The recovery rates of LabRespond and VALAB were 77.9% and 71.8%, respectively (difference not significant). The false-positive rates were 82.7% for LabRespond, 83.6% for VALAB, and 27.8-86.7% for clinical chemists. Using the consensus of three or more clinical chemists as the secondary reference standard, we found error recovery rates of 64.8% for LabRespond and 72.2% for VALAB (P = 0.06). Compared with VALAB, LabRespond detected more (P = 0.003) erroneous test results of the type that were changed from abnormal to normal. CONCLUSIONS: The statistical plausibility check used by LabRespond offers a promising automated validation method with a higher error recovery rate than the clinical chemists participating in this study, and a performance comparable to VALAB.

Clinical Laboratory Techniques↗
PubMed2001

[Detection of submicroscopic chromosome abnormalities by comparative genomic hybridization].

INTRODUCTION: The purpose was to detect chromosome abnormalities in dysmorphic and mentally retarded individuals with normal karyotypes by means of comparative genomic hybridisation (CGH). MATERIAL AND METHODS: One hundred and forty-four individuals with normal karyotype underwent CGH analysis with a new detection technique where fixed limits are replaced by dynamic standard reference intervals. This method provides improved resolution and thereby detects minor chromosome abnormalities. RESULTS: Fifteen minor abnormalities (10%) and one trisomy 9 mosaic were found. Eleven were interstitial deletions or duplications, which cannot be detected by screening with other cytogenetic techniques. Three were terminal deletions or duplications and one was a terminal unbalanced translocation. DISCUSSION: CGH analysis with dynamic standard reference intervals is a new objective and quantitative method, which is suitable for screening for small chromosome abnormalities that can not be detected by conventional chromosome analysis. The method is recommended for use in the investigation of dysmorphic and mentally retarded individuals, in whom abnormalities are not found by ordinary karyotyping.

Chromosome Aberrations↗
PubMed1988

Simultaneous determination of the prodrug zofenopril and its active drug in plasma by capillary gas chromatography-mass-selective detection.

After oral administration of zofenopril, the active sulfhydryl angiotensin-converting enzyme inhibitor is released. Zofenopril is currently under clinical investigation as an antihypertensive. Blood samples are reacted with N-ethylmaleimide, immediately after collection, processed into plasma and stored frozen for subsequent analysis. After addition of two internal reference standards, one each for the prodrug and the active compound, the plasma samples are purified by a combination of liquid-liquid and solid-phase extractions. The dried methylated extracts are reconstituted with tetramethylbenzene and chromatographed by automated splitless injection on a fused-silica capillary column, connected to a mass-selective detector. The analytes and the internal reference standards are chromatographically resolved and a common fragment ion is monitored for the analytes. A limit of quantitation of approximately 1 ng/ml of plasma is achieved.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

Comparative analysis of monoclonal antibody based enzyme immunoassay, modified genome electrophoresis & electron microscopy procedures for rotavirus diagnosis from faecal specimens.

BACKGROUND & OBJECTIVES: Reliable and rapid diagnosis of rotavirus infection is necessary for patient management. Several newly introduced commercial enzyme immunoassays (ELISAs) have been evaluated using direct electron microscopy (DEM) with or without direct ultracentrifugation as the standard reference method, and have shown varying results. METHODS: In the present study we compared the diagnostic efficacy of the three methods viz., monoclonal antibody (MAb) ELISA, modified polyacrylamide gel electrophoresis (PAGE) and DEM without ultracentrifugation in the detection of rotaviruses from 211 stool specimens. The data were analysed by two latent class model (2LC) in the absence of a gold standard reference method. RESULTS: Rotavirus was detected in 42 specimens by MAb-ELISA; in 40 specimens by PAGE and in 33 specimens by DEM. The estimates of sensitivities and specificities of the three methods were analysed by 2LC method. The analysis revealed no significant variation among the three methods. However, DEM was found with a comparatively lesser sensitivity over the other two methods. INTERPRETATION & CONCLUSIONS: Though DEM was found to be relatively less sensitive than the other two methods, the differences were not significant, and all the three methods were highly specific. Moreover, DEM has the additional advantage of detecting non-group A and other gastroenteritis viruses. The findings suggest the use of highly sensitive and specific MAb-ELISA and PAGE in parallel to detect group A, non-group A and atypical rotavirus infection in the population.

Antibodies, Monoclonal↗
PubMed2003

Validation of family history data in cancer family registries.

BACKGROUND: Although family history information on cancer is used to infer risk of the disease in population-based, case-control, cohort, or family-based studies, little information is available on the accuracy of a proband's report. In this study, we sought to determine the validity of the reporting of family history of cancer by probands in population-based and clinic-based family registries of breast, ovarian, and colorectal cancers. METHODS: To assess the accuracy of probands' reported family history of cancer in their relatives, we compared the family history from the personal interview of each proband to a reference standard that included pathology reports, self-reports, or death certificates on the relatives. Our study included 1111 families that accounted for 3222 relatives who were verified. To account for within-family correlations in the responses, we used a generalized estimating equation approach. RESULTS: The probability of agreement between the proband-reported cancer status in a relative with the reference standard varied by cancer site and by degree of relationship to the proband. This probability for first-degree relatives was 95.4% (95% confidence interval [CI]=92.6-98.3) for female breast cancer; 83.3% (95% CI=72.8-93.8) for ovarian cancer; 89.7% (95% CI=85.4-94.0) for colorectal cancer; and 79.3% (95% CI=70.0-88.6) for prostate cancer. CONCLUSIONS: We found high reliability of probands' reporting on most cancer sites when they reported on first-degree relatives and moderate reliability for their reporting on second- and third-degree relatives. Overreporting of cancer was rare (2.4%). Race or ethnicity and gender of the proband did not influence the accuracy of reporting. However, degree of relationship to the proband, type of cancer, age at diagnosis of the proband, and source of ascertainment of probands were statistically significant predictors of accuracy of reporting.

Adult↗
PubMed1995

The role of antineutrophil cytoplasmic antibody (c-ANCA) testing in the diagnosis of Wegener granulomatosis. A literature review and meta-analysis.

PURPOSE: To summarize the literature on the clinical utility of antineutrophil cytoplasmic antibody (c-ANCA) as a diagnostic marker for Wegener granulomatosis. DATA SOURCES: A structured literature search was done using MEDLINE; this search, combined with a manual search, yielded 747 articles for potential inclusion. These articles passed through a 4-stage review. Studies were included if they had a specified reference standard and a systematic method of patient selection and if a 2 x 2 contingency table could be constructed from their results. Fifteen articles met these criteria. DATA EXTRACTION: 3 physicians reviewed all selected articles. Detailed data abstraction was done, and the quality of the study methods was assessed. Items abstracted included the method of patient selection, the study design, the reference standard, the c-ANCA testing technique, disease activity, and the test results. Disagreements among reviewers were resolved by consensus. Contingency tables were used to calculate the operating characteristics for Wegener granulomatosis overall and for active and inactive Wegener granulomatosis. RESULTS: The sensitivities of c-ANCA testing for overall Wegener granulomatosis ranged from 34% to 92%, and the specificities ranged from 88% to 100%. The pooled sensitivity was 66% (95% CI, 57% to 74%), and the pooled specificity was 98% (CI, 96% to 99.5%). Four articles provided data on disease activity. For active disease, the pooled sensitivity was 91% (CI, 87% to 95%), and the pooled specificity was 99% (CI, 97% to 99.9%). For inactive disease, the pooled sensitivity and specificity were 63% and 99.5%, respectively. CONCLUSIONS: Although c-ANCA test results may serve clinicians as adjunct evidence for the diagnosis of Wegener granulomatosis, these results must be viewed in the context of the patient's clinical picture and disease activity and the prevalence of Wegener granulomatosis in the clinical setting in which the patient is seen.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed2005

Retrospective and prospective evaluation of the Amplicor HPV test for detection of 13 high-risk human papillomavirus genotypes on 862 clinical samples.

BACKGROUND: Persistent infection with a subgroup of at least 15 high-risk human papillomavirus (HPV) genotypes is considered as a necessary although insufficient etiological factor in the development of cervical carcinoma. As a consequence, HPV testing has recently become an important part of the cervical carcinoma screening and detection algorithms. AIM OF THE STUDY: To evaluate the analytical performance of a recently developed polymerase chain reaction (PCR)-based Amplicor HPV test (Roche Molecular Systems) in comparison with the Hybrid Capture 2 HPV DNA test (hc2) (Digene Corporation) for the detection of 13 high-risk HPV genotypes. Inhouse consensus PGMY09/PGMY11 and CPI/IIg PCRs targeting two different HPV genes coupled with HPV genotyping were used as an HPV internal reference standard. MATERIALS AND METHODS: In the retrospective evaluation, 550 cervical scrape specimens with previously established HPV status were included. Additionally, 312 cervical scrape specimens were tested prospectively for the presence of 13 high-risk HPV genotypes by both hc2 and Amplicor HPV test. RESULTS: In the retrospective evaluation, the Amplicor HPV test results agreed almost completely with the HPV internal reference standard results. In the prospective evaluation performed on 312 samples, the concordant Amplicor and hc2 results were obtained in 85.9% of samples tested. CONCLUSION: In our hands, the Amplicor HPV test demonstrated high analytical sensitivity and specificity. The higher analytical specificity of Amplicor in comparison to that of hc2 can be considered clinically useful. Prospective studies with clinical endpoints are urgently needed to assess the clinical utility of the higher analytical sensitivity of the Amplicor HPV test for primary HPV screening and triaging patients with ASC-US.

DNA Probes, HPV↗
PubMed2006

Comparing performance of Morbidity and Mortality Conference and National Surgical Quality Improvement Program for detection of complications after urologic surgery.

OBJECTIVES: The detection of postoperative complications is a necessary quality-of-care endeavor. Despite its historical role, the Morbidity and Mortality (M&M) Conference depends on voluntary reporting and may be an insufficient mechanism for comprehensive complication surveillance. In response to this concern, we compared the concordance between complications voluntarily reported at the M&M Conference and those identified prospectively by the National Surgical Quality Improvement Program (NSQIP). METHODS: For a single calendar year (2004), we compiled a comprehensive list of complications that were either identified and voluntarily entered into our department's electronic M&M Conference database and/or identified prospectively (from an explicit sample of cases) by a trained research associate-based NSQIP protocol. For analytic purposes, we treated NSQIP as the reference standard for the detection of complications. We then determined the sensitivity of the M&M Conference for the identification of complications at a patient and event level. Logistic regression modeling was used to evaluate for an association between complication category (ie, organ system affected) and detection by the M&M Conference. RESULTS: The NSQIP detected 347 complications in 176 patients. Using this reference standard, the patient-level and event-level sensitivity of the M&M Conference was 25% (44 of 176) and 14% (47 of 347), respectively. The sensitivity of the M&M Conference varied by NSQIP complication category (P = 0.08). Circulatory events were 11 times more likely to be reported at the M&M Conference than urinary complications (odds ratio 11.3, 95% confidence interval 2.4 to 53.7). CONCLUSIONS: Compared with the NSQIP, the M&M Conference has a low (but variable) sensitivity for the detection of postoperative complications. Therefore, despite its limitations, the NSQIP may provide a better foundation for urologic quality improvement endeavors.

Adolescent↗
PubMed2004

The validity of emergency department triage blood pressure measurements.

OBJECTIVE: Automated blood pressure (ABP) devices are ubiquitous at emergency department (ED) triage. Previous studies failed to evaluate ABP devices against accepted reference standards or demonstrate triage readings as accurate reflections of blood pressure (BP). This study evaluated ED triage measurements made using an ABP device and assessed agreement between triage BP and BP taken under recommended conditions. METHODS: A prospective study was conducted at an urban teaching hospital. Patients were enrolled by convenience sampling. Simultaneous automated and manual triage BPs were obtained using one BP cuff with a Y-tube connector. Research assistants were certified in obtaining manual BP as described by the British Hypertension Society (BHS). Patients were placed in a quiet setting, and manual BP was repeated by American Heart Association (AHA) standards. Data analysis was performed using methods described by Bland and Altman. The ABP device was assessed using Association for the Advancement of Medical Instrumentation (AAMI) and BHS criteria. RESULTS: One hundred seventy-one patients were enrolled. Systolic BP (sBP) range was 81 to 218 mm Hg; diastolic BP (dBP) range was 43 to 130 mm Hg. Automated vs. manual sBP difference was 3.8 +/- 11.2 mm Hg (95% confidence interval [CI] = 2.1 to 5.4); dBP difference was 6.6 +/- 9.0 mm Hg (95% CI = -7.9 to -5.2). Manual triage BP vs. AHA standard SBP difference was 11.6 +/- 12.8 mm Hg (95% CI = 9.1 to 14.1); dBP difference was 9.9 +/- 10.4 mm Hg (95% CI = 7.9 to 12.0). The ABP device failed to meet AAMI criteria and received a BHS rating of "D." Poor operator technique and extraneous patient and operator movement appeared to hamper accuracy. CONCLUSIONS: ABP triage measurements show significant discrepancies from a reference standard. Repeat measurements following AHA standards demonstrate significant decreases in the measured blood pressures.

Adult↗
PubMed2006

Automated detection of lung nodules in multidetector CT: influence of different reconstruction protocols on performance of a software prototype.

PURPOSE: To evaluate the accuracy of software for computer-aided detection (CAD) of lung nodules using different reconstruction slice thickness protocols in multidetector CT. MATERIALS AND METHODS: Raw image data sets for 15 patients who had undergone 16-row multidetector CT (MDCT) for known pulmonary nodules were reconstructed at a reconstruction thickness of 5.0, 2.0 and 1.0 mm with a reconstruction increment of 1.5, 1.0 and 0.5 mm, respectively. The "Nodule Enhanced Viewing" (NEV) tool of LungCare for computer-aided detection of lung nodules was applied to the reconstructed images. The reconstructed images were also blinded and then evaluated by 2 radiologists (A and B). Data from the evaluating radiologists and CAD was then compared to an independent reference standard established using the consensus of 2 independent experienced chest radiologists. The eligible nodules were grouped according to their size (diameter > 10, 5 - 10, < 5 mm) for assessment. Statistical analysis was performed using the receiver operating characteristic (ROC) curve analysis, t-test and two-rater Cohen's Kappa co-efficient. RESULTS: A total of 103 nodules were included in the reference standard by the consensus panel. The performance of CAD was marginally lower than that of readers at a 5.0-mm reconstruction thickness (AUC = 0.522, 0.517 and 0.497 for A, B and CAD, respectively). In the case of 2.0-mm reconstruction slices, the performance of CAD was better than that of the readers (AUC = 0.524, 0.524 and 0.614 for A, B and CAD, respectively). CAD was found to be significantly superior to radiologists in the case of 1.0-mm reconstruction slices (AUC = 0.537, 0.531 and 0.675 for A, B and CAD, respectively). The sensitivity at a reconstruction thickness of 1.0 mm was determined to be 66.99 %, 68.93 % and 80.58 % for A, B and CAD, respectively. The time required for detection was shortest for CAD at reconstruction slices of 1.0 mm (mean t = 4 min). The performance of radiologists was greatly enhanced when using CAD: sensitivity 91.26 % and 94.17 % for CAD+A and CAD+B, respectively (AUC = 0.889 and 0.917). CAD was most advantageous in the detection of nodules < 10 mm. CONCLUSION: At a 1.0-mm reconstruction thickness, CAD's ability to detect nodules < 10 mm is superior to that of radiologists and its relatively short evaluation time makes it a viable second reader.

Diagnosis, Computer-Assisted↗
PubMed1994

An enzyme-linked immunosorbent assay (ELISA) for quantitation of adducts of granulocyte-macrophage colony stimulating factor (GM-CSF) and human serum albumin (HSA) in stressed solution mixtures.

HPLC analyses of GM-CSF in solution mixtures containing both GM-CSF and HSA showed losses of GM-CSF which could not be accounted for using conventional electrophoretic and/or RP-HPLC techniques. Further investigation of these mixtures by immunoblotting and by immunoaffinity chromatography demonstrated the presence of high molecular weight (> 67,000 GM-CSF related species. No such species was detectable in solutions of GM-CSF alone. This experiment pointed to the formation of an adduct between GM-CSF and HSA in the solution mixtures. To probe further the hypothesis of a GM-CSF/HSA adduct, an immunologically based test was conceived which could react only with this type of hybrid molecule. A sandwich enzyme-linked immunosorbent assay (ELISA) was developed using two antibodies, anti-GM-CSF (capture antibody) and anti-HSA (detection antibody), as part of the quantitation of GM-CSF/HSA adducts. After confirming its existence by ELISA, a GM-CSF/HSA adduct was isolated from the solution mixture containing both GM-CSF and HSA. This isolate served as a primary reference standard in the ELISA assay. The immunoassay has a subnanogram sensitivity and is highly specific for GM-CSF/HSA adducts in the presence of either free GM-CSF or free HSA. As a verification, conjugates of GM-CSF/HSA were synthesized using a cross-linking reagent. These covalent conjugates reacted positively in the ELISA and are employed as a convenient alternative reference standard.

Chromatography, Affinity↗
PubMed2006

Evaluating the accuracy of a simple heuristic to identify serious causes of low back pain.

BACKGROUND: Among patients presenting with low back pain (LBP), GPs have to identify those with serious, treatable conditions. However, excluding these conditions in every patient with LPB is time consuming and of low yield. We have suggested that identifying those patients where these serious conditions need to be considered can be made more efficient through asking patient if they feel their LBP is new or unfamiliar in some way. OBJECTIVE: To evaluate the diagnostic validity of a simple heuristic based on the patient's view of the familiarity of LBP. METHODS: Cross-sectional diagnostic study with delayed-type reference standard, nested within a three-arm randomized trial of quality improvement for LBP. A total of 1378 patients presenting, with LBP, to one of 126 participating GPs were included. They were asked whether their LBP was familiar or not (index test). At 1 year, patients were interviewed with regard to relevant conditions that in hindsight might explain their LBP. Reviewers deciding on disease status (reference standard) were blinded to the results of the index test. RESULTS: Totally 1190 patients answered the index test question and were available for interview at 1 year. Only four of these had a serious cause of their LBP. Two of these were identified by the familiarity heuristic, resulting in low sensitivity. CONCLUSION: The number of diseased patients was too small to obtain a reliable estimate of sensitivity. Low prevalence of serious disease in primary care poses difficulties for diagnostic research. In hindsight we would question whether an RCT-setting emphasizing non-specific LBP is suitable for this kind of research. At present, the familiarity heuristic cannot be recommended for patients presenting with LBP.

Adult↗