Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Observer Variation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1977

Atrophy of optic nerve fibres in compression of the chiasm. Observer variation in assessment of atrophy.

Different observers' assessment of atrophy according to a semi-quantitative method was analysed. Five observers scored the degree of atrophy on magnified black-and-white fundus photographs from normal controls and from patients with chiasmal lesions of different severity. Four of the five examiners achieved a reasonably uniform assessment of atrophy. The results of the test prompted some modification in the grading system.

Adenoma, Chromophobe↗
PubMed1992

Observer variation in functional examination of the temporomandibular joint.

Agreement between observers classifying TMJ sounds from data given in records of nonpatient adolescents was almost perfect in this interobserver study. Intraobserver and interobserver agreement in classifying all specific TMJ sounds at palpation and auscultation was acceptable to moderate (kappa value = 0.49 to 0.74). The agreement was considerably more reliable when classifying only one specific TMJ sound. Measurements of linear jaw opening showed small interobserver differences (coefficient of variation = 2.4 to 3.8). The significant difference found in calculating the angular mandibular opening may be the result of difficulties in maintaining maximum passive opening.

Adolescent↗
PubMed1990

Inter-observer variation in interpretation of chest X-rays.

139 chest x-rays of children with solid tumours or leukaemia were examined independently by three observers (a radiologist and two physicians) and a consensus report determined. There was total agreement between observers on 40 x-rays (29%). The radiologist agreed with the consensus report on a significantly greater number of x-rays (91%) than both physicians (62% and 46%). There was a high incidence of over-reporting of abnormalities by both physicians. This study reinforces the need for regular dialogue between radiologists and clinicians for optimum interpretation of chest x-rays.

Bronchography↗
PubMedDate not supplied

[Inter- and intra-observer variation in silicosis radiology].

The radiologic criteria are important for the diagnosis of silicosis and must be objective. Initial radiologic changes are nonspecific and sometimes misinterpreted. We asked six Pulmonologists with distinct training in pulmonary disease to interpret 112 chest films according to a simple established protocol. No further information was given. One year later, all the observers analysed the same films over again. Then, we compared the results among the observers and between the two analysis made by the same individual. In 34 cases (30%) there was unanimity in asserting or denying the presence of micronodules and in 74 cases (66%) there was an agreement among the three more experienced observers. The intraobserver variability ranged from 8% to 40% and it was more important in the least trained observers. We concluded that when interpreting early radiologic changes in silicosis inter and intraobserver variability was elevated, more objectivity was achieved by the observers with more experience in epidemiologic studies and that we must be careful in interpreting results of epidemiologic studies concerning this matter.

Adult↗
PubMed1990

Use of screening phase data to evaluate observer variation of sputum cytodiagnosis as an outcome measure in a chemoprevention trial.

Sputum samples obtained during the screening phase of a chemoprevention trial in heavy smokers were evaluated independently by trained cytotechnologists and classified for degree of cellular atypia according to the method of Saccommano et al. (G. Saccommano et al., Cancer (Phila.), 33: 256-270, 1974). The level of agreement within and between Observers A and B was calculated as the percentage of agreement and, in addition, a statistic was used (kappa) to correct for chance-expected agreement. Between observer agreement on 300 specimens from 130 subjects was 68% (204 of 300) (kappa = 0.58). Of the 96 disagreements, only 17 were of more than one category in the six-category classification. Within observer agreement for both Observers A and B was evaluated on a subset of 60 specimens from 49 subjects examined on two separate occasions by each observer. The percentage of within observer agreement was 80% for Observer A (kappa = 0.73) and 62% for Observer B (kappa = 0.49) (P less than 0.04). Altogether, 71% (25 of 35) of within observer discordant readings were confined to only one category. These data, obtained from the screening phase of the study, will allow us to refine the outcome measure for the trial without introducing bias that could result from knowledge of the actual study results. The failure of conventional cancer treatments to impact significantly on overall cancer mortality has led to an emphasis on prevention. If premalignant changes can be reliably detected at a time when the malignant process is reversible, then it may be feasible to intervene to prevent the occurrence of some cancers. The appropriate selection of subjects for such intervention trials and the subsequent demonstration of the efficacy of chemoprevention strategies are therefore crucial.

Etretinate↗
PubMed1992

Potential influence of observer variation in thromboprophylactic trials.

In order to investigate the influence of the interpretation of a postoperative venography, used as the scientific tool in a thromboprophylactic trial, twelve different evaluations of the same venography have been compared. Two hundred and nineteen patients, undergoing total hip replacement, fulfilled a randomized trial evaluating two different prophylactic regimens. Bilateral venography was performed 7-11 days after surgery, and the result of venography was defined as with or without deep venous thrombosis (DVT), irrespective of the location of a thrombus. The venograms were evaluated five times by different interpreters, and the criteria for the presence of DVT were recorded whether or not thrombi in minor veins were present. The incidences of DVT in the two prophylactic groups varied from 2.7 to 20.3% and from 13.5 to 34.2%, respectively, according to the diagnostic criteria. However, the risk reduction between the two groups was almost constant, no matter which type of evaluation was applied (7.9-15.1%), and was statistically significant at the 5% level in all but 4 of the 12 evaluations. It is concluded that despite uniformity in patient selection, the incidence of DVT is not uniform, even though it is stated that venography is used as the end point. The obvious interobserver variation did not change the conclusion when two regimens are compared in a specific randomized study.

Clinical Trials as Topic↗
PubMed1989

Inter-observer variation in symphysis-fundus measurements. A plea for individualised antenatal care.

Two groups of midwives were compared with regard to ability to detect small-for-gestational-age (SGA) babies using symphysis-fundus (S-F) measurements. The patients were all low-risk obstetric patients. In group A 2 midwives provided antenatal care to 97 patients; 14 delivered SGA babies, of which 12 were identified by S-F measurements (sensitivity 85.7%). In group B 15 midwives provided antenatal care to 126 patients, 12 delivered SGA babies, and 5 of these were identified (sensitivity 41.2%). It is considered that this difference was due to inter-observer variability. A plea is made for individualised antenatal care.

Adult↗
PubMed1990

Assessment of observer variation in measuring the Radiographic Vertebral Index in patients with multiple myeloma.

The Radiographic Vertebral Index (RVI) was assessed as a possible outcome measure for bone disease in myeloma by evaluating within and between reader reproducibility. Four readers (2 radiologists and 2 clinical hematologists) independently scored, on two separate occasions, the RVI on 40 radiographs from patients with myeloma. Each vertebra from third thoracic (T3) to fifth lumbar (L5) received a score of "1" if normal, "2" if biconcave and "4" if crushed or fractured. RVI global scores, therefore, could vary from a minimum of 15, for no damage, to a potential maximum of 60 in which all vertebrae are collapsed. Agreement was determined for each vertebra using crude percentage agreement and the kappa statistic (which corrects for chance-expected agreement) for categorical data, and for global score using analysis of variance and calculating intra-class correlation. With increasing mean abnormality score on individual vertebrae there was a corresponding increase in kappa and reduction in crude percentage agreement. Within readers, the mean percentage agreement across all vertebrae varied from 85.6 to 90.3% and the observed differences just reach statistical significance (p = 0.048). Mean kappa values ranged from 0.48 to 0.63 and were similar across readers. Differences in intra-reader agreement were not related to subspecialty. When between reader percentage agreement and kappa scores were assessed for radiologists and non-radiologist clinicians, no difference could be detected. Agreement with respect to intra-reader mean global RVI scores was excellent as illustrated by the intra-class correlation coefficient which varied from 0.89 to 0.94. The mean intra-class correlation for radiologists was 0.92, compared with 0.91 for non-radiologists.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1990

Observer variation in the scintigraphic diagnosis of solitary cold thyroid lesions.

In order to evaluate the reproducibility of the diagnosis of solitary cold thyroid lesions, two specialists in nuclear medicine and two specialists in endocrinology independently twice read 240 thyroid 99mTc pertechnetate scintigrams. No significant difference or interaction between the results obtained from the right and the left lobe was found. A solitary cold lesion was diagnosed in 100 of the 480 lobes; however, in only 30 did all four observers agree upon the diagnosis. Interobserver variation was determined by pairwise comparison of observers. The observed agreement was between 0.91 and 0.94. After adjusting for expected chance agreement, kappa values between 0.57 and 0.70 were found. Intraobserver variation was smaller than interobserver variation, revealing agreement rates of 0.93-0.96 and kappa values between 0.71 and 0.77. Agreement was related to large lesions, lesions located centrally in the lobe, and ovoid-shaped lesions. Clinicians should be aware to what extent they can rely on the information they use in their decisions. The considerable inconsistency in the evaluation of cold lesions on thyroid scintigrams should be taken into consideration, and calls in question the value of using thyroid scintigrams for deciding whether a patient should be referred for operation or biopsy.

Adolescent↗
PubMed1991

Observer variation in assessing neurophysical signs among patients with head injuries.

As an early phase in the development of a valid and reliable measure of the neurophysical sequelae after head injury, we carried out assessments of interrater agreement on representative items. The purpose of this study was to determine the degree of agreement among expert raters who independently measured neurophysical signs on patients undergoing physical rehabilitation after brain injury. Agreement was described using the index of crude agreement, expected agreement and Kappa. Therapists showed a high degree of agreement on those items forming part of a routine neurological assessment: prehension, coordination, voluntary movements and tendon reflexes. Crude agreement ranged from 77.8-100%. There was considerable discordance in assessing muscle tonus, equilibrium and protective reactions, spinal reflexes, tremor and dysmetria (crude agreement ranged from 49.7-97.9%). Although, the number of subjects was small, the information generated from this study will be useful in refining our instrument for the assessment of neurophysical signs.

Adult↗
PubMed1988

Population amalgamation and genetic variation: observations on artificially agglomerated tribal populations of Central and South America.

The interpretation of data on genetic variation with regard to the relative roles of different evolutionary factors that produce and maintain genetic variation depends critically on our assumptions concerning effective population size and the level of migration between neighboring populations. In humans, recent population growth and movements of specific ethnic groups across wide geographic areas mean that any theory based on assumptions of constant population size and absence of substructure is generally untenable. We examine the effects of population subdivision on the pattern of protein genetic variation in a total sample drawn from an artificial agglomerate of 12 tribal populations of Central and South America, analyzing the pooled sample as though it were a single population. Several striking findings emerge. (1) Mean heterozygosity is not sensitive to agglomeration, but the number of different alleles (allele count) is inflated, relative to neutral mutation/drift/equilibrium expectation. (2) The inflation is most serious for rare alleles, especially those which originally occurred as tribally restricted "private" polymorphisms. (3) The degree of inflation is an increasing function of both the number of populations encompassed by the sample and of the genetic divergence among them. (4) Treating an agglomerated population as though it were a panmictic unit of long standing can lead to serious biases in estimates of mutation rates, selection pressures, and effective population sizes. Current DNA studies indicate the presence of numerous genetic variants in human populations. The findings and conclusions of this paper are all fully applicable to the study of genetic variation at the DNA level as well.

Alleles↗
PubMed1989

Inter and intra-observer variation in ultrasonographic detection of gallstones: the Multicenter Italian study on epidemiology of cholelithiasis (M.I.COL.).

Inter and intra-observer agreement in classifying the presence of gallstones by ultrasonographic images according to established criteria was studied. A film recording of 50 routine ultrasonographic examinations of the gallbladder was read by each of the 46 observers who participated in the Multicenter Italian Study on Epidemiology of Cholelithiasis (M.I.COL.). The overall Kappa score for inter-observer agreement was 0.649, while intra-observer agreement was "good" or "excellent" (Kappa scores greater than 0.60) in 75% of the observers. No statistical difference for inter-observer agreement between "novices" and "expert" echographers was found in the overall Kappa statistic or in category-specific Kappa scores (gallstone, no gallstone, doubtful and inconclusive examinations) The present study suggests that the development of explicit criteria by a group of trained echographers does not eliminate inter- and intra-observer disagreement in categorizing subjects for gallbladder stones.

Cholelithiasis↗
PubMed1978

Observer variation in examination of knee joints.

The knees of 20 patients with rheumatoid arthritis were each examined on two occasions on the same morning by three observers. Assessments were made of joint warmth, synovial thickening, effusion, instability, quadriceps power, bony enlargement, range of movement, and knee circumference, and were graded on a scale of 0-4. Analysis of the results shows close intraobserver agreement for all measurements but considerable interobserver variation for all subjective measurements.

Arthritis, Rheumatoid↗
PubMed1977

Observer variation in the clinical diagnosis of mandibular pain dysfunction syndrome.

In preparation for a survey to investigate the prevalence of mandibular pain dysfunction syndrome (MDS) in a non-hospital group of individuals, the measure of agreement obtained by two observers when recording signs and symptoms of MDS in the same subjects was investigated. The criteria used for this purpose are defined. Two groups of subjects, 50 MDS patients and 50 individuals not complaining of the condition, were examined independently. Considerably more agreement between the two observers was reached with regard to patients than contrast subjects. Both observers showed more agreement in assessment during the opening movement of the mandible. It was suggested, therefore, that in order to reduce the observer error inevitably present during a survey, the signs and symptoms which manifest themselves during the opening movement of the mandible should be used to diagnose MDS rather than a more elaborate time-consuming technique.

Adolescent↗