Realities of diagnosing Helicobacter pylori infection in clinical practice: a case for non-invasive indirect methodologies.
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BACKGROUND: The current, arbitrarily defined gold standard for the diagnosis of H. pylori infection requires histologic examination of two specially stained antral biopsy specimens. However, routine histology is potentially limited in general clinical practice by both sampling and observer error. The current study was designed to examine the diagnostic performance of invasive and non-invasive H. pylori detection methods that would likely be available in general clinical practice. METHODS: The diagnostic performance of rotating clinical pathology faculty using thiazine staining was compared with that of an expert gastrointestinal pathologist in 38 patients. In situ hybridization stains of adjacent biopsy cuts were also examined by the expert pathologist for further comparison. Receiver operator characteristic (ROC) analysis was performed to evaluate whether the diagnostic performance of the expert pathologist differed depending upon the histologic method employed. A similar analysis was made to evaluate the diagnostic performance of pathology trainees relative to the expert. In the absence of an established invasive gold standard, non-invasive testing methods (rapid serum antibodies, formal Elisa antibodies and carbon-14 urea breath testing) were evaluated in 74 patients by comparison with a gold standard defined using a combination of diagnostic tests. RESULTS: Using either rapid urease testing of biopsy specimens or urea breath testing as the gold standard for comparison, the diagnostic performance of the rotating clinical pathology faculty was inferior to that of the expert gastrointestinal pathologist especially with regard to specificity (e.g., 69 percent for the former versus 88 percent, with the latter relative to rapid urease testing). Although interpretation of in situ hybridization staining by the expert appeared to have an even higher specificity, ROC analysis failed to show a difference. The mean ROC areas for thiazine and in situ hybridization staining for trainee pathologists relative to the expert were 0.88 and 0.94, respectively. In untreated patients, urea breath testing had a sensitivity and specificity of 100 percent as compared with thiazine staining with a sensitivity of 83 percent and a specificity of 97 percent. Post-therapy, breath testing had a sensitivity of 100 percent but a specificity of only 86 percent as compared with invasive testing with a sensitivity and specificity of 100 percent. Rapid serum antibody testing and formal Elisa antibody testing agreed in 93 percent of cases (Kappa 0.78) with the rapid test being correct in three of the four disagreements. CONCLUSIONS: The current study illustrates a number of realities regarding H. pylori diagnosis. There is no diagnostic gold standard in general clinical practice. Accurate interpretation of specially stained slides is a learned activity with a tendency towards overdiagnosis early on. Urea breath testing is likely to be the diagnostic method of choice for untreated patients in general clinical practice although antibody testing is almost as accurate. Rapid antibody tests are at least as accurate as formal Elisa antibody tests. Urea breath testing is useful for confirming cure after therapy, but false-positive results may occur in some patients. (+info)
How does a change in the administration method affect the reliability of the COOP/WONCA Charts? World Organization of National Colleges, Academies and Academic Associations of General Practitioners/Family Physicians.
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BACKGROUND: An interviewer is often needed to administer the COOP/WONCA Charts to Chinese patients, and this may affect the reliability of results. OBJECTIVES: We aimed to find out the reliability of the COOP/WONCA Charts administered by an interviewer, and whether a change in the interviewer or administration method would affect the results. METHODS: We carried out a cross-sectional test-retest study on 487 Chinese adult patients attending a family medicine clinic in Hong Kong. The COOP/WONCA Charts were administered by the same interviewer, two different interviewers or self-completion and interviewer administration, on test and retest. The random, inter-observer and inter-method variances were compared with the inter-subject variance. The reliability coefficient of each COOP/WONCA Chart was calculated for each method of administration. RESULTS: Random errors could change the scores by 0.57-1.04, inter-observer variations could change the scores of four charts by 0.72-0.80, and a change in the method could change the physical fitness score by 1.79 and the daily activities score by 1.31, on a five-point scale. The reliability coefficients of the six COOP/WONCA Charts were 0.68-0.92 for one interviewer, 0.59-0.82 for two interviewers and 0.46-0.81 for two methods. CONCLUSION: The Chinese COOP/WONCA Charts were reliable in detecting real differences when administered by an interviewer. A change in the method of administration significantly decreased the reliability of the results. The use of more than one method of data collection in the same survey should be discouraged. (+info)
The influence of experience on the reproducibility of the ankle-brachial systolic pressure ratio in peripheral arterial occlusive disease.
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OBJECTIVES: to estimate the intra-observer variability of the measurement of the ankle-brachial systolic pressure index (ABPI) and to compare the reproducibility of the measurements by experienced vascular laboratory assistants and by less-experienced general practice personnel. DESIGN: repeated measurement of ABPI by general practitioners (GPs), GP-assistants and vascular laboratory assistants using a pocket Doppler device and a random-zero sphygmomanometer. METHODS AND MATERIALS: ABPI was measured in six patients with various degrees of PAOD by two experienced observers (vascular laboratory assistants) and by 24 less-experienced observers (18 practice assistants, six GPs). RESULTS: the total number of measurements was 354. The overall intra-observer variability estimate was 11.8% ABPI. The intra-observer variability was 7.3% in the experienced observers and 12.0% in the less-experienced observers. The difference of variability between experienced and less-experienced observers was significant. CONCLUSIONS: the ABPI is suitable in follow-up studies where repeated measurements are needed. Differences between measurements can be minimised by performing repeated measurements or by using more experienced observers. (+info)
The prognostic significance of tumor-associated antigen 22-1-1 expression in adenocarcinoma of the uterine cervix.
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We previously established (K. Sonoda et al., Int. J. Oncol., 6: 1099-1104, 1995) a novel monoclonal antibody, 22-1-1, generated from adenocarcinoma of the uterine cervix, and 22-1-1 antigen (Ag) was expressed in cancer cells derived mainly from the uterus and ovary. In this report, a relationship between 22-1-1 Ag expression and clinicopathological variables and the prognostic significance of 22-1-1 Ag were immunohistochemically investigated in adenocarcinoma of the cervix. Of 56 cases, the 22-1-1 Ag was negative in 7, 1+ in 14, 2+ in 26 and 3+ in 9 instances. The 22-1-1 Ag existed both in the cytoplasm and on the membrane of cancer cells. There was no correlation between 22-1-1 Ag expression and age, stage, grade, myometrial invasion, lymph-vascular space invasion, lymph node metastasis, and parametrial invasion. The estimated 5-year overall survival (OS) of patients with low 22-1-1 Ag expression (-/+) and high 22-1-1 Ag expression (++/ ) were 90.5 and 71.4%, respectively. Patients with high 22-1-1 Ag expression had significantly worse OS than those with low 22-1-1 Ag expression (log-rank test, P = 0.0193). In addition, lymph-node metastasis, age, and clinical stage were significantly related to OS in univariate analysis. Multivariate analysis for OS revealed a prognostic significance in 22-1-1 Ag expression, stage, age, and grade. These data suggest that 22-1-1 Ag expression may be related to prognosis in adenocarcinoma of the cervix. (+info)
Reliability and validity of noninvasive imaging of internal carotid artery pseudo-occlusion.
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BACKGROUND AND PURPOSE: Our study evaluated noninvasive tests for the diagnosis of atheromatous internal carotid artery (ICA) pseudo-occlusion. METHODS: Twenty patients (17 men, 3 women; mean age +/-SD, 64.3+/-11.6 years) with angiographically proven atheromatous ICA pseudo-occlusion (20 vessels) were prospectively examined with MR angiography (MRA; 2D and 3D time-of-flight techniques), color Doppler-assisted duplex imaging (CDDI) and power-flow imaging (PFI) with and without an intravenous ultrasonic contrast agent. As a control group, 13 patients (13 men; mean+/-SD age, 63.0+/-9.0 years) with angiographically proven ICA occlusion (13 vessels) were studied with the same techniques. For the determination of interobserver agreement (kappa statistics), the findings of each diagnostic technique were read by 2 blinded and independent observers who were not involved in patient recruitment and initial data acquisition. Specificity and sensitivity were calculated for all noninvasive techniques (observer consensus) in comparison to the standard of reference (intra-arterial angiography). RESULTS: Interobserver reliabilities were kappa=0.86 for intra-arterial angiography, kappa=0.90 for unenhanced CDDI, kappa=0. 93 for enhanced CDDI, kappa=0.93 for unenhanced PFI, kappa=1.0 for enhanced PFI, kappa=0.93 for 2D MRA, and kappa=0.77 for 3D MRA, respectively (P<0.0001). Specificities and sensitivities were 0.92 and 0.70 for unenhanced CDDI, 0.92 and 0.83 for enhanced CDDI, 0.92 and 0.95 for unenhanced PFI, 1.0 and 0.94 for enhanced PFI, 1.0 and 0.65 for 2D MRA, and 0.89 and 0.47 for 3D MRA, respectively. CONCLUSIONS: Advanced ultrasonographic techniques, especially PFI (with only 1 false-positive diagnosis of occlusion in the present series), can provide reliable and valid data to differentiate between ICA pseudo-occlusion and complete occlusion. In contrast, time-of-flight MRA at its present state is not capable of predicting minimal residual flow within a nearly occluded ICA. (+info)
Compliance with methodological standards when evaluating ophthalmic diagnostic tests.
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PURPOSE: To draw attention to the importance of methodological standards when carrying out evaluations of ophthalmic diagnostic tests by reviewing the extent of compliance with these standards in reports of evaluations published within the ophthalmic literature. METHODS: Twenty published evaluations of ophthalmic screening/diagnostic tests or technologies were independently assessed by two reviewers for compliance with the following methodological standards: specification of the spectrum composition for populations used in the evaluation, analysis of pertinent subgroups, avoidance of work-up (verification) bias, avoidance of review bias, presentation of precision of results for test accuracy, presentation of indeterminate test results, and presentation of test reproducibility. RESULTS: Compliance ranged from just 10% (95%CI, 1%-32%) for presentation of test reproducibility data and avoidance of review bias to 70% (95%CI, 46%-88%) for avoidance of work-up bias and presentation of indeterminate test results. Only 5 of the 20 evaluations complied with four or more of the methodological standards and none with more than five of the standards. CONCLUSIONS: The evaluations of ophthalmic diagnostic tests discussed in this article show limited compliance with accepted methodological standards but are no worse than previously described for evaluations published in general medical journals. Adherence to these standards by researchers can improve the study design and reporting of evaluations of new diagnostic techniques. Limited compliance, combined with a lack of awareness of the standards among users of research evidence, may lead to the inappropriate adoption of new diagnostic technologies, with a consequent waste of health care resources. (+info)
Digital image capture and automated analysis of posterior capsular opacification.
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PURPOSE: To develop and validate a digital imaging and analysis technique for assessing the extent of posterior capsular opacification after cataract surgery. METHODS: Retroillumination images of the posterior capsule were obtained by using a digital camera mounted on a slit lamp. The images were analyzed using an available image analysis software program. The image acquisition and analysis techniques were tested for face validity, reproducibility, and the ability to detect progression of capsular opacity over time. RESULTS: Digital retroillumination images were obtained without patient discomfort. Automated analysis of images correlated well with clinical grading both at slit lamp examination and when looking at the images themselves (Spearman's correlation coefficient >0.7). Analysis of images taken at different times showed high reproducibility (intraclass correlation >0.9), and the system was able to identify progression of capsular opacity over a 2-year period with a mean increase of 15.8% in progressors versus an increase of 0.6% in nonprogressors (P < 0.05). CONCLUSIONS: Digital retroillumination images of the posterior capsule can be obtained reliably, and automated analyses correlate well with clinical assessment. The system presented here uses commercially available instruments and software, and it is practical for use in longitudinal studies of posterior capsule opacification. It is reliable, easy to use, and can detect small changes in the percentage area covered by posterior capsule opacification over time. (+info)
Measuring geographic atrophy in advanced age-related macular degeneration.
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PURPOSE: To present a method developed for measuring areas of geographic atrophy (GA) in advanced age-related macular degeneration, METHODS: A microfilm reader projected the 30 degrees fundus photograph of the macula. Retinal landmarks, atrophic areas, and spared areas within the atrophy were traced, without access to drawings of other years. The total atrophic area was calculated, as was the atrophy within a four-disc-area circle entered on the estimated foveal center. The configuration of the atrophy was documented. RESULTS: Avoidable sources of discrepancy included variability in peripapillary atrophy seen on the photograph, and variability seen in the extent of the field. Reproducibility studies found a median absolute difference of 0.19 Macular Photocoagulation Study disc areas (DA) in total atrophy between repeat drawings, with 75% of repeat drawings having a difference of less than 0.33 DA. For central atrophy measures, there was a median difference of 0.08 DA, with 75% of pairs having a difference of less than 0.18 DA. Features making the definition of borders of GA difficult include the presence of drusen and pigmentary alteration, a fundus in which choroidal vessels are easily visible, and variation in the appearance of GA within a single area of atrophy. CONCLUSIONS: This method provides a reliable means of measuring the size of atrophic areas in GA and will be useful for measuring longitudinal change. It may be difficult to determine whether central spared areas are present, and correlation with visual acuity and macular perimetry may be helpful. (+info)