Interobserver Variability (interobserver + variability)

Distribution by Scientific Domains

Selected Abstracts

Interobserver variability in determination of anaerobic threshold by cardiopulmonary exercise testing

ANAESTHESIA, Issue 1 2010
K. Patrick
No abstract is available for this article. [source]

Visual Quantitative Estimation: Semiquantitative Wall Motion Scoring and Determination of Ejection Fraction

M.D., Steven J. Lavine
Ejection fraction (EF) is the most commonly used parameter of left ventricular (LV) systolic function and can be assessed by echocardiography. Quantitative echocardiography is time consuming and is as accurate as visual estimation, which has significant variability. We hypothesized that each echocardiographer has developed a mental set of guidelines that relate to how much individual segment shortening constitutes normal function or hypokinesis of varying extents. We determined the accuracy of applying these guidelines to an accepted technique of EF determination using a retrospective analysis of consecutive two-dimensional echocardiographic studies performed on patients who had radioventriculography (RVG) within 48 hours. Using a 12 segment model, we scored each segment at the base and mid-ventricular level based on segmental excursion and thickening. The apex was scored similarly but with 1/3 of the value based on a cylinder-cone model. EF was determined from the sum of segment scores and was estimated visually. We termed this approach visual quantitative estimation (VQE). We correlated the EF derived from VQE and visual estimation with RVG EF. In the training set, VQE demonstrated a strong correlation with RVG(r = 0.969), which was significantly greater than visual estimation(r = 0.896, P < 0.01). The limits of agreement for VQE (+12% to ,7%) were similar to the limits of RVG agreement with contrast ventriculography (+10% to ,11%) with similar intraobserver and interobserver variabilities. Similar correlation was noted in the prediction set between VQE and RVG EF(r = 0.967, P < 0.001). We conclude that VQE provides highly correlated estimates of EF with RVG. (ECHOCARDIOGRAPHY, Volume 20, July 2003) [source]

Are adjunctive markers useful in routine cervical cancer screening?

Application of p16INK4a, HPV-PCR on ThinPrep samples with histological follow-up
Abstract The objectives of the study were to evaluate 1) the diagnostic sensitivity and specificity of p16INK4a as a marker for high-grade cervical lesions, 2) the results of a real-time polymerase chain reaction detecting high-risk human papillomavirus, and 3) the interobserver variability of the p16INK4a interpretation. A total of 232 ThinPrep samples were stained for p16INK4a, and HPV-DNA PCR was performed on 107 specimens with inclusion of both benign and abnormal cytology. Histological follow-up information was collected. The diagnostic sensitivity of ASC+ with CIN2+ in histology as endpoint was 96% for p16INK4a and 100% for HR-HPV DNA PCR, and the diagnostic specificity was 41% and 27%, respectively. If p16INK4a had been used for triage of the ASC samples, then 18 patients (42%) could have been spared unnecessary follow-up procedures compared to six patients (21%) with the HR-HPV DNA test. Diagn. Cytopathol. 2008;36:453,459. © 2008 Wiley-Liss, Inc. [source]

Interobserver and Intraobserver Variability of Flow-Mediated Vasodilatation of the Brachial Artery

Iana Simova M.D.
Flow-mediated endothelial-dependent vasodilatation (FMD) of the brachial artery is a method capable of detecting endothelial dysfunction. In order to implement this method in future clinical research studies, its reproducibility and precision have to be assessed. The aim of the study is to evaluate the inter- and intraobserver variability of FMD performed in our department. We investigate 40 patients. FMD is measured by two independent observers to test the interobserver variability, and repeated by the first observer to test the intraobserver variability. We compare the baseline and post-ischemic diameter of the brachial artery and the percent dilatation. The correlation coefficients for these comparisons are high (>0.92) with a significance of less than 0.001. The inter- and intraobserver variability is further tested comparing the mean values of the baseline and post ischemic diameter of the brachial artery and the percent dilatation. The absolute values of the mean paired differences and the standard deviations (SDs) of the differences are 0.02850 ± 0.05942, P = 0.004, 0.01175 ± 0.08177, P = 0.369 and 0.28375 ± 1.61561, P = 0.273, respectively for the interobserver variability and 0.00475 ± 0.04663, P = 0.523, 0.00050 ± 0.05267, P = 0.952 and 0.15725 ± 1.19922, P = 0.412, respectively for the intraobserver variability. It can be concluded that the inter- and intraobserver variability for FMD performed in our department is acceptable. FMD can be performed precisely and accurately, with a satisfactory reproducibility and can be safely and reliably implemented in future clinical research studies. [source]

Grading of dysplasia in Barrett's oesophagus: substantial interobserver variation between general and gastrointestinal pathologists

M Kerkhof
Aims:, To determine interobserver variation in grading of dysplasia in Barrett's oesophagus (BO) between non-expert general pathologists and expert gastrointestinal pathologists on the one hand and between expert pathologists on the other hand. Methods and results:, In this prospective multicentre study, non-expert and expert pathologists graded biopsy specimens of 920 patients with endoscopic BO, which were blindly reviewed by one member of a panel of expert pathologists (panel experts) and by a second panel expert in case of disagreement on dysplasia grade. Agreement between two of three pathologists was established as the final diagnosis. Analysis was performed by , statistics. Due to absence of intestinal metaplasia, 127/920 (14%) patients were excluded. The interobserver agreement for dysplasia [no dysplasia (ND) versus indefinite for dysplasia/low-grade dysplasia (IND/LGD) versus high-grade dysplasia (HGD)/adenocarcinoma (AC)] between non-experts and first panel experts and between initial experts and first panel experts was fair (, = 0.24 and ,,= 0.27, respectively), and substantial for differentiation of HGD/AC from ND/IND/LGD (, = 0.62 and ,,= 0.58, respectively). Conclusions:, There was considerable interobserver variability in the interpretation of ND or IND/LGD in BO between non-experts and experts, but also between expert pathologists. This suggests that less subjective markers are needed to determine the risk of developing AC in BO. [source]

Systematic review: endoscopic and imaging-based techniques in the assessment of portal haemodynamics and the risk of variceal bleeding

Summary Background, Invasive measurement of the hepatic venous pressure gradient (HVPG) is regarded as the gold standard for risk stratification and the evaluation of pharmaceutical agents in patients with portal hypertension. Aim, To review the techniques for endoscopic and imaging-based assessment of portal haemodynamics, with particular emphasis on trials where the results were compared with HVPG or direct portal pressure measurement. Methods, Systematic search of the MEDLINE electronic database with keywords: portal hypertension, variceal bleeding, variceal pressure, endoscopic ultrasound, Doppler ultrasonography, magnetic resonance angiography, CT angiography, hepatic venous pressure gradient. Results, Computed tomography angiography and endoscopic ultrasound (EUS) have been both employed for the diagnosis of complications of portal hypertension and for the evaluation of the efficacy of endoscopic therapy. Colour Doppler ultrasonography and magnetic resonance angiography has given discrepant results. Endoscopic variceal pressure measurements either alone or combined with simultaneous EUS, correlate well with HVPG and risk of variceal bleeding and have a low interobserver variability. Conclusions, Endoscopic and imaging-based measurements of portal haemodynamics provide an alternate means for the assessment of complications of portal hypertension. Further studies are required to validate their use in risk stratification and the evaluation of drug therapies in patients with portal hypertension. [source]

Semiautomatic segmentation and stenosis quantification of 3D contrast-enhanced MR angiograms of the internal carotid artery

Cornelis M. van Bemmel
Abstract A technique is presented for the segmentation and quantification of stenosed internal carotid arteries (ICAs) in 3D contrast-enhanced MR angiography (CE-MRA). Segmentation with sub-pixel accuracy of the ICA is achieved via level-set techniques in which the central axis serves as the initialization. The central axis is determined between two user-defined points, and minimal user interaction is required. For quantification, the cross-sectional area is measured in the stenosis and at a reference segment in planes perpendicular to the central axis. The technique was applied to 20 ICAs. The variation in measurements obtained by this method in comparison with manual observations was 8.7%, which is smaller than the interobserver variability among three experts (11.0%). Magn Reson Med 51:753,760, 2004. © 2004 Wiley-Liss, Inc. [source]

Technical note: Standardized and semiautomated Harris lines detection

S. Suter
Abstract Arrest in long bone growth and the subsequent resumption of growth may be visible as radiopaque transverse lines in radiographs (Harris lines, HL; Harris, HA. 1933. Bone growth in health and disease. London: Oxford University Press). The assessment of individual age at occurrence of such lines, as part of paleopathological skeletal studies, is time-consuming and shows large intra- and interobserver variability. Thus, a standardized, automated detection algorithm would help to increase the validity of such paleopathological research. We present an image analysis application facilitating automatic detection of HL. On the basis of established age calculation methods, the individual age-at-formation can be automatically assessed with the tool presented. Additional user input to confirm the automatic result is possible via an intuitive graphical user interface. Automated detection of HL from digital radiographs of a sample of late Medieval Swiss tibiae was compared to the consensus of manual assessment by two blinded expert observers. The intra- and interobserver variability was high. The quality of the observer result improved when standardized detection criteria were defined and applied. The newly developed algorithm detected two-thirds of the HL that were identified as consensus lines between the observers. It was, however, necessary to validate the last one-third by manual editing. The lack of a large test series must be noted. The application is freely available for further testing by any interested researcher. Am J Phys Anthropol, 2008. © 2008 Wiley-Liss, Inc. [source]

The Validity and Reliability of the Reflux Finding Score (RFS),

Peter C. Belafsky MD
Abstract Background The evaluation of medical and surgical outcomes relies on methods of accurately quantifying treatment results. Currently, there is no validated instrument whose purpose is to document the physical findings and severity of laryngopharyngeal reflux (LPR). Objective To evaluate the validity and reliability of the reflux finding score (RFS). Methods Forty patients with LPR confirmed by double-probe pH monitoring were evaluated pretreatment and 2, 4, and 6 months after treatment. The RFS was documented for each patient at each visit. For test,retest intraobserver reliability assessment, a blinded laryngologist determined the RFS on two separate occasions. To evaluate interobserver reliability, the RFS was determined by two different blinded laryngologists. Results The mean age of the cohort was 50 years (± 12 standard deviation [SD]). Seventy-three percent were women. The RFS at entry was 11.5 (± 5.2 SD). This score improved to 9.3 (± 4.7 SD) at 2 months, 7.3 (± 5.5 SD) at 4 months, and 6.1 (± 5.2 SD) at 6 months of treatment (P <.001 with trend). The mean RFS for laryngologist no. 1 was 10.8 (± 4.1 SD) at the initial screening and 10.8 (± 4.0 SD) at the repeat evaluation (r = 0.95, P <.001). The mean RFS for laryngologist no. 2 was 11.1 (± 3.8 SD) at the initial screening and 10.9 (± 3.7 SD) at the repeat evaluation (r = 0.95, P <.001). The correlation coefficient for interobserver variability was 0.90 (P <.001). Conclusions The RFS accurately documents treatment efficacy in patients with LPR. It demonstrates excellent inter- and intraobserver reproducibility. [source]

Lack of agreement between rheumatologists in defining digital ulceration in systemic sclerosis

Ariane L. Herrick
Objective To test the intra- and interobserver variability, among clinicians with an interest in systemic sclerosis (SSc), in defining digital ulcers. Methods Thirty-five images of finger lesions, incorporating a wide range of abnormalities at different sites, were duplicated, yielding a data set of 70 images. Physicians with an interest in SSc were invited to take part in the Web-based study, which involved looking through the images in a random sequence. The sequence differed for individual participants and prevented cross-checking with previous images. Participants were asked to grade each image as depicting "ulcer" or "no ulcer," and if "ulcer," then either "inactive" or "active." Images of a range of exemplar lesions were available for reference purposes while participants viewed the test images. Intrarater reliability was assessed using a weighted kappa coefficient with quadratic weights. Interrater reliability was estimated using a multirater weighted kappa coefficient. Results Fifty individuals (most of them rheumatologists) from 15 countries participated in the study. There was a high level of intrarater reliability, with a mean weighted kappa value of 0.81 (95% confidence interval [95% CI] 0.77, 0.84). Interrater reliability was poorer (weighted , = 0.46 [95% CI 0.35, 0.57]). Conclusion The poor interrater reliability suggests that if digital ulceration is to be used as an end point in multicenter clinical trials of SSc, then strict definitions must be developed. The present investigation also demonstrates the feasibility of Web-based studies, for which large numbers of participants can be recruited over a short time frame. [source]

Improving the reproducibility of diagnosing micrometastases and isolated tumor cells,

CANCER, Issue 2 2005
Gábor Cserni M.D., Ph.D.
Abstract BACKGROUND The latest edition of the tumor-lymph node-metastasis (TNM) classification of malignant tumors distinguishes between isolated tumor cells (pN0) and micrometastases (pN1mi). The reproducibility of these categories has not been assessed previously. METHODS Digital images from 50 cases with low-volume lymph node involvement from axillary sentinel lymph nodes were circulated twice for evaluation (Evaluation Rounds 1 and 2) among the members of the European Working Group for Breast Screening Pathology, and the members were asked to categorize lesions as micrometastasis, isolated tumor cells, or something else and to classify each case into a pathologic lymph node (pN) category of the pathologic TNM system. Methods for improving the low reproducibility of the categorizations were discussed between the two evaluation rounds. , Statistics were used for the assessment of interobserver variability. RESULTS The , value for the consistency of categorizing low-volume lymph node load into micrometastasis, isolated tumor cells, or neither of those changed from 0.39 to 0.49 between Evaluation Rounds 1 and 2, but it was slightly lower for the pN categories (0.35 and 0.44, respectively). Interpretation of the definitions of isolated tumor cells (especially with respect to their localization within the lymph node), lack of guidance on how to measure them if they were multiple, and lack of any definitions for multiple simultaneous foci of lymph node involvement were listed among the causes of discordant diagnoses. CONCLUSIONS The results of the current study indicated that the definitions available have minor contradictions and do not permit a reproducible distinction between micrometastases and isolated tumor cells. Refinement of these definitions, therefore, is required. One refinement that may improve reproducibility is suggested in this report. Cancer 2005. © 2004 American Cancer Society. [source]

Evaluation of the new Ocuton S tonometer

Giorgio Marchini
ABSTRACT. Purpose:, To evaluate the intra- and interobserver variability of the Ocuton S tonometer, its correlation with Goldmann tonometry, the reliability of self-tonometry and the safety of the instrument. Methods:, Thirty-five healthy subjects and 45 patients with primary open-angle glaucoma (POAG), aged from 38 to 80 years (mean age: 64.6 ± 12.2 years), underwent tonometry with the Ocuton S tonometer in one eye chosen at random. The intra- and interobserver variability between two operators (kappa coefficient), the Ocuton S/Goldmann correlation and the reliability of self-tonometry were evaluated by performing two tonometries on each patient in subgroups. Each tonometry was considered as the mean of three consecutive measurements. Central ultrasonic pachymetry, keratometry and corneal biomicroscopy were also evaluated. Results:, The intra- and interobserver variability ranged from 0.38 to 0.66. The difference between the means of intraocular pressure (IOP) with the Ocuton S (24.4 ± 4.7 mmHg) and the Goldmann tonometer (18.1 ± 4.7 mmHg) was statistically significant (p < 0.0001). Linear regression analysis revealed a good Ocuton S/Goldmann correspondence (r = 0.88, p = 0.0001). However, IOP values detected with the Ocuton were consistently overestimated, compared to those detected with the Goldmann tonometer. The correlation between corneal thickness and IOP was statistically significant both for the Goldmann (r = 0.510, p = 0.021) and for the Ocuton S tonometer (r = 0.520, p = 0.019). No correlation was found between keratometry and IOP. The mean measurement obtained by self-tonometry (21.9 ± 3.6 mmHg) showed no statistically significant difference when compared to the mean measurement obtained by an expert operator (21.3 ± 3.4 mmHg). Conclusion:, The Ocuton S tonometer is a safe instrument that can be used easily by the patient. However, in comparison to the Goldmann tonometer , it overestimates IOP and requires further technical and methodological refinements in order to ensure greater reliability. [source]


Julio CB Ferreira
SUMMARY 1Maximal lactate steady state (MLSS) corresponds to the highest blood lactate concentration (MLSSc) and workload (MLSSw) that can be maintained over time without continual blood lactate accumulation and is considered an important marker of endurance exercise capacity. The present study was undertaken to determine MLSSw and MLSSc in running mice. In addition, we provide an exercise training protocol for mice based on MLSSw. 2Maximal lactate steady state was determined by blood sampling during multiple sessions of constant-load exercise varying from 9 to 21 m/min in adult male C57BL/6J mice. The constant-load test lasted at least 21 min. The blood lactate concentration was analysed at rest and then at 7 min intervals during exercise. 3The MLSSw was found to be 15.1 ± 0.7 m/min and corresponded to 60 ± 2% of maximal speed achieved during the incremental exercise testing. Intra- and interobserver variability of MLSSc showed reproducible findings. Exercise training was performed at MLSSw over a period of 8 weeks for 1 h/day and 5 days/week. Exercise training led to resting bradycardia (21%) and increased running performance (28%). Of interest, the MLSSw of trained mice was significantly higher than that in sedentary littermates (19.0 ± 0.5 vs 14.2 ± 0.5 m/min; P = 0.05), whereas MLSSc remained unchanged (3.0 mmol/L). 4Altogether, we provide a valid and reliable protocol to improve endurance exercise capacity in mice performed at highest workload with predominant aerobic metabolism based on MLSS assessment. [source]