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PubMed1980

A study in the measurement of corneal endothelial cell density using the specular microscope.

Six subjects who never wore contact lenses underwent six determinations of corneal cell density using each of two measurement modes: Mode A: the eye was applanted once and pairs of photographs were taken; Mode B: the eye was applanated and a single photograph was taken. For each measurement mode data were collected on two separate sessions (Test, Retest). Chi-square analysis revealed a significantly larger proportion of uncountable photographs from the first measurement session, and analysis of variance revealed that Mode A was less reliable than Mode B upon retesting. It was concluded that Mode B was the preferred measurement mode, and that many more than six determinations be made on the initial session in order to obtain six readable photographs. Finally, estimates of inter and intra-session variation, intra-pair variation, and inter and intra-observer variation are given.

Cell Count↗
PubMed1989

Doppler ultrasonography of the fetoplacental circulation--normal reference values.

Normal reference values for the resistance index, A/B ratio and pulsatility index of the umbilical artery obtained by Doppler ultrasonography are presented. The resistance index and A/B ratio values are very similar to those previously published, indicating no need to formulate normal values for different populations. The pulsatility index differed from other published values, probably reflecting different calculation methods built into the spectrum analysers rather than differences in waveforms. The resistance index had the lowest coefficient of variation and showed least inter-observer variation. For routine use the resistance index is preferable to other indices.

Adult↗
PubMed1994

Inter-observer variability in ultrasonic evaluation of abdominal aortic aneurysms.

This study was undertaken to assess the consistency in 16 independent observations of the diameters of abdominal aortic aneurysms by diagnostic ultrasound. Confidence intervals were developed for the anterior-posterior dimension and the transverse dimension. Clinical treatment decisions should be made with appreciation that measurements of diameter increases greater than 0.21 cm in the anterior-posterior dimension and 0.31 cm in the transverse dimension are significant and are not a result of inter-observer variation.

Aortic Aneurysm, Abdominal↗
PubMed1994

Prescribing endodontic retreatment: towards a theory of dentist behaviour.

The large variations observed in dentists' management of periapical lesions in endodontically treated teeth suggest that disease concepts used in clinical practice should be investigated. In the present study it was hypothesized that dentists regard various periapical conditions as different stages on a health continuum. Variations could then be regarded as the result of the individuals selection of differing cut-off points for prescribing retreatment. The hypothesized decision-making model was tested using dental students in Amsterdam (Holland), Gothenburg (Sweden) and Pavia (Italy). The students were shown six simulated cases among which the quality of root filling seal and presence of post and crown were systematically varied. For each case, management of five periapical conditions was assessed. Five options were offered: no therapy, wait-and-see, nonsurgical retreatment, surgical retreatment, and extraction. For each examiner and case a 'retreatment preference score (RPS)' was established. The investigation showed large interindividual variations in RPS. A statistically significant higher mean RPS was seen among students in Pavia compared with students in Amsterdam and Gothenburg. Among all observers and cases it was found that if retreatment was proposed for a certain size of lesion, retreatment was subsequently selected for all larger lesions. The experiment gave evidence in support of the proposed hypothesis. The data also suggest that the choice of retreatment criterion is affected by values, costs of retreatment and technical quality of the original treatment.

Adult↗
PubMed1979

Variations of technique in the face-lift operation.

Observed variations in face-life technique prompted an analysis of these techniques to determine whether experience correlated with certain aspects of the surgery. A questionnaire was returned by 565 of 1,750 plastic surgeons, quantifying varying techniques in over 121,000 face lifts. The respondents were placed into three groups according to the number of rhytidectomies performed, and correlations were determined.

Face↗
PubMed1990

Regional cerebral blood flow velocity patterns in newborn infants.

Using range-gated pulsed Doppler sonography, cerebral blood flow velocity (CBFV) waveforms from the anterior cerebral artery (ACA), middle cerebral artery (MCA) and circle of Willis artery (CW) were examined in a total of 34 newborn infants. We compared the pulsatility index (PI) from the three cerebral arteries sampled in 10 term and 10 preterm (29 +/- 2 weeks) newborn infants without a history of perinatal asphyxia or intracranial pathology. The Pl in the ACA ranged from 0.60 to 1.03. There were no significant differences in Pl between the three vessels by paired comparisons. The Pl of the MCA differed from that of the ACA by 0.00 +/- 0.05. The variation coefficient (CV) was 7%. For CW with ACA, the difference was 0.00 +/- 0.04 and CV was 6%. Both intra- and interexaminer variation in Pl measurements were studied in another 14 infants. The variation coefficients were 5-8% for all three cerebral arteries. We showed that CBFV waveform patterns were similar in regional cerebral arteries, with Pl being a consistent CBFV index. In normal cerebral circulation, the intervessel Pl differences were within observer variations. Deviation from this may suggest abnormal regional cerebral haemodynamics.

Blood Flow Velocity↗
PubMed1994

Genetic variation of foot-and-mouth disease virus during persistent infection in cattle.

Genetic variation of foot-and-mouth disease virus O1 Campos has been analyzed in consecutive isolates recovered over a one- or two-year period from four cattle with experimental persistent infection. Comparisons of RNase T1 two-dimensional maps and nucleotide sequences of the VP1-coding region revealed a continual, although irregular, increase in the fixation of mutations as the infection progressed. Most changes were not conserved in consecutive isolates. These results, together with the substantial rates of genomic variation observed between some pairs of strains recovered at close time periods, suggested the coexistence of heterogeneous populations in which variants evolve independently from each other, and predominate at irregular time intervals. Furthermore, non-related patterns of variation were observed in the four animals. Similarly, genetic diversity of representative strains from major serotype O outbreaks in endemic disease regions of southeastern Brazil and central eastern Argentina which occurred between 1958 and 1983, suggested that outbreak strains are also likely to represent fluctuations of heterogeneous populations which evolve independently from each other. The possible role of persistent infections in the introduction of variant populations in the field is discussed.

Amino Acid Sequence↗
PubMedDate not supplied

[Systemic-psychodynamic model for family evaluation].

In this paper a family evaluation instrument called systemic-psychodynamic family evaluation model is described. Also, the second stage of the validation study of this instrument is presented (which deals with the inter-observers variation). Twenty families were studied. They were assessed always by the same interviewers designated as experts. They are all family therapy specialists and their assessment was used as the evaluation reference standard or "gold standard". The observers were psychiatrists without previous training in family therapy. For the purpose of the interview, both experts and observers were blind to the medical diagnosis of the patients. During the first stage of the validation study the observers did not have a reference guide which resulted in a low concordance rating. For the second stage, a 177 item guide was used and a considerable increase in the concordance rating was observed. Validation studies like the one used here are of considerable value to increase the reliability and further utilisation of evaluation instruments of this type.

Evaluation Studies as Topic↗
PubMed1990

Is the penile brachial index a reproducible and useful measurement?

The intra- and inter-observer variation in the measurement of the penile brachial index (PBI) was prospectively assessed in 30 patients. An appreciable error was discovered that cast doubt on the reliability of the measurements. Up to 20% of patients deemed normal by one observer would be deemed abnormal by a second. The PBI appears to be an inaccurate and poorly reproducible test of penile blood flow which can lead to a false diagnosis and subsequent management of impotent patients. There would appear no justification for the continued use of the penile brachial index in the assessment of erectile dysfunction.

Adult↗
PubMedDate not supplied

Diagnostic problems of early leprosy in field studies.

A Series of exercises were undertaken in order to develop methodology for consistency and reliability of clinical diagnosis of leprosy under field conditions in longitudinal studies. It was observed in initial studies that the field investigators could miss about 35% of cases of leprosy, mostly those with early manifestations. After training and experience, the proportion of missed cases came down to about 20%. In about 14% of females with patches suggestive of leprosy the patches were present in the covered areas of the body and so are likely to be missed during examination in field situations. One hundred forty two individuals with suspicious and definite leprosy lesions detected by paramedical workers were examined by a senior medical officer experienced in leprosy on two different occasions at an interval of three months for leprosy diagnosis. The concordance rates for diagnosis and classification of leprosy were about 80% and 70% respectively; and corresponding values for kappa were 0.59 and 0.62 similar to earlier experiences in inter-observer variation studies.

Adolescent↗
PubMed1995

Efforts to improve interobserver agreement in histopathological grading.

The present study aimed to assess the interobserver variation in histopathological grading of 88 slides by four experienced pathologists who, before the start of the study, reached consensus about the method of grading through a joint session behind a discussion microscope. The results were compared with two previous studies, the first assessing the observer variation under normal conditions, the second doing the same after theoretical agreement about which morphological characteristics were relevant for grading. In the present study the pathologists first made a provisional diagnosis on low power view, followed by a final diagnosis on high power view, scoring various morphological characteristics as in the second study. The unweighted and weighted group kappa values for the final diagnosis were 0.41 and 0.71 respectively in the present study (after the consensus meeting), compared to 0.33 and 0.70 respectively in the second study (after only theoretical consensus), and 0.28 and 0.55 in the first study (without consensus). We conclude that a consensus meeting appears to be useful to improve the interobserver agreement.

Female↗
PubMed1981

Pattern of group I fibre projections from ankle flexor and extensor muscles in man.

Variations in the H-reflex of soleus, tibialis anterior, quadriceps and short head of biceps femoris muscles were studied in normal man, preceded by a conditioning stimulus applied to either gastrocnemius medialis, the inferior branch of soleus or the common peroneal nerve. The observed variations were evoked by low threshold afferents, had a very short latency suggesting oligosynaptic linkage and disappeared during a selective ischaemic blockade of group I fibres; they were therefore regarded as due to group I fibre stimulation. Biphasic variations were observed in almost all cases: evidence is presented that the early low threshold effects, facilitatory for synergistic and inhibitory for antagonistic motoneurone pools, are due to stimulation of Ia fibres, while the subsequent opposite effects which had a slightly higher threshold are Ib in origin. Even though the pattern of projections of group I fibres from ankle flexors and extensors is qualitatively the same in normal man as in the spinal cat, large quantitative differences are observed; in normal man the effects of group I fibres from ankle flexors and extensors upon close synergistic and direct antagonistic motoneurone pools are weak, and often negligible, whereas they are extremely potent upon quadriceps motoneurones.

Adult↗
PubMed1995

Thickness of patellofemoral articular cartilage as measured on MR imaging: sequence comparison of accuracy, reproducibility, and interobserver variation.

OBJECTIVE: Since the thickness of cartilage is an important indicator of the status, progression and response to therapy of articular disorders, assessment of it is desirable. This study was undertaken to assess the accuracy, precision, and reliability of magnetic resonance (MR) measurements of articular cartilage. METHODS: Fifteen cadaveric patellas were imaged in the axial plane at 1.5 T. Gradient echo and fat-suppressed FSE, T2-weighted, proton density, and T1-weighted sequences were performed. We measured each 5-mm section separately at three standardized positions, giving a total of 900 measurements. These findings were correlated with independently performed measurements of the corresponding anatomic sections. A hundred random measurements were also evaluated for reproducibility and interobserver variation. RESULTS: Although all sequences were highly accurate (range r = 0.78-0.82), the T1-weighted images were the most accurate, with a mean difference of 0.25 mm and a correlation coefficient of 0.85. All sequences were also highly reproducible (mean difference between -0.09 and 0.05 mm) with little inter-observer variation (mean difference -0.04 and 0.11 mm). In an attempt to improve the accuracy of the MR measurements further, we retrospectively evaluated all measurements with discrepancies greater than 1 mm from the specimen. All these differences were attributable to focal defects causing exaggeration of the thickness on MR imaging. CONCLUSION: MR imaging is accurate, precise, and reliable as a basis for measuring articular cartilage and may potentially be usable to monitor progression of articular disorders. Care must be taken not to overestimate the thickness of areas with surface defects.

Adult↗
PubMed1990

Assessment of congestive heart failure in chest radiographs. Observer performance with two common film-screen systems.

The effect of observer variations and film-screen quality on the diagnosis of congestive heart failure based on chest radiographs was studied in 27 patients. For each patient, two films were exposed, one with the Kodak Lanex Medium system and one with the Agfa MR 400 system. The films were presented to three observers who assessed the presence of congestive heart failure on a three-graded scale. The results showed no significant difference between the two systems but large systematic differences between the observers. There were also differences between the two ratings by the same observer that could not be explained by the film-screen factor. It is concluded that the choice between these two systems is of little importance in view of the interobserver and intraobserver variability that can exist within the same department.

Heart Failure↗
PubMed1992

Postprandial gallbladder emptying is related to intestinal motility at the time of meal ingestion.

The characteristics of meal-induced gallbladder emptying in healthy individuals are subject to wide variation. We hypothesized that some of the observed variation might relate to ingestion of the meal during different phases of the migrating motor complex (MMC). Recording of gastrointestinal pressure was combined with scintigraphic recording of bile kinetics during infusion of 99mTc-HIDA. The material consisted of 12 healthy men. Group 1 (n = 6) had a fat-rich meal in phase I, and group 2 (n = 6) had the meal in a phase II. With the end of the meal ingestion as zero, the following results emerged. The subjects in group 1 had a median (range) lag period before beginning of gallbladder emptying of 13.5 (9.0-22.5) min. In group 2 gallbladder emptying began during the meal ingestion in four subjects, and the median lag period was 0 min (minimum, -9.0; maximum, 13.5 (p = 0.02)). The median percentage change of gallbladder counts during the observation period of 54 min in group 1 was 11.5% (from 19% filling to 25% emptying). The corresponding figures in group 2 were 41% (from 2% to 91% emptying (p less than 0.05)). This difference was due to the difference in duration of lag periods, as the emptying rates measured from the end of the lag periods were equal. In conclusion, the onset of postprandial gallbladder emptying relates to the phase activity of the MMC at the time of ingestion.

Adult↗
PubMed1995

Rotator cuff disorders: interobserver and intraobserver variation in diagnosis with MR imaging.

PURPOSE: To determine interobserver and intraobserver variation in the interpretation of magnetic resonance (MR) images in rotator cuff disorders. MATERIALS AND METHODS: MR images of the shoulder in 97 patients were retrospectively reviewed twice, with a 3-week interval. Surgical findings indicated a full-thickness tear in 29 patients, grade 1 impingement in 19 (tendinitis), and grade 2 impingement (partial tear) in 26. The control population comprised 23 asymptomatic volunteers or patients. RESULTS: All observers were accurate in the diagnosis of a full-thickness tear (89%-98%), with good intraobserver (kappa = 0.67-0.84) and interobserver agreement (kappa = 0.74-0.92). In diagnoses of tendinitis, partial tear, and normal cuff, there were wide ranges of sensitivity (13%-74%) and specificity (72%-93%), as well as poor interobserver (kappa = 0.12-0.60) and intraobserver agreement (kappa = 0.35-0.78). CONCLUSION: Full-thickness tears of the rotator cuff can be accurately identified at MR imaging with little observer variation. Consistent differentiation of normal rotator cuff, tendinitis, and partial thickness tears is more difficult.

Female↗
PubMed1990

Differences between observers in blood pressure measurement with an automatic oscillometric recorder.

Blood pressure measurements made with a Dinamap oscillometric blood pressure recorder by two observers on a total of 2596 male and female subjects aged between 25 and 59 living in nine British towns were examined for evidence of observer differences. After adjusting for age, body mass index and town, significant differences between the two observers were found for systolic pressure, 3.07 mmHg (P = 0.001) for male subjects and 2.08 mmHg (P = 0.036) for female subjects. Observer differences for mean arterial pressure and diastolic pressure were less than 1 mmHg and were not significant. The magnitude of observer differences also varied between towns and, when tested statistically, was significant in male subjects for systolic (P = 0.011), mean arterial (P = 0.009) and diastolic pressure (P = 0.002); for female subjects it was significant only for diastolic pressure (P = 0.023). We conclude that although the highly automated Dinamap has kept observer variation within acceptably low limits in field study conditions, the problem has not been altogether eliminated.

Adult↗