SEARCH · PubMed Health

Results for “Observer Variation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 73 records · Page 4Linked to original sources

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

Garden's classification of femoral neck fractures. An assessment of inter-observer variation.

Radiographs of 100 randomly chosen femoral neck fractures were assessed by eight observers using Garden's classification. The radiographs were classified identically by all eight in only 22 cases. Another 45 cases were classified by some observers as undisplaced fractures (Stages 1 and 2) and by others as displaced fractures (Stages 3 and 4). Between the different observers the number of displaced fractures varied from 63 to 89. These results show that observers had a relatively poor ability to delineate the various stages of Garden's classification.

Femoral Neck Fractures↗

PubMed1986

Observer variation in interactive computerized morphometry.

The validity of a test system in morphometric histopathology depends on the variation sources involved. Biological variation is one of the variation sources, but is also the object to be studied with morphometry. We studied the variation sources in interactive computerized morphometry in two test systems involving two different commercially available image analyzers. The measurements were made on nuclei in a microscopic field of 5 transitional cell tumors (papilloma and WHO grade I-III carcinomas) of the urinary bladder. It turned out that different observers selected a variable number of nuclei for measurements, the coefficient of variation (CV) in the number of nuclei being 11-11.5%. Mean CV in nuclear perimeter measurements was 4.4-4.8%, and in nuclear area measurements 8.2-8.6%. The variation in measurements by 1 observer was smaller, the CV values being 2.8% for the number of nuclei, 1.2% for nuclear perimeter, and 2.4% for nuclear area. The results showed that interobserver variation can be considerable in these systems. It is suggested that special sampling rules should be tested with the idea of finding the relevant approach with the smallest interobserver variation.

Carcinoma, Transitional Cell↗

PubMed1986

Observer variation in quantitative assessment of rheumatoid arthritis. Part I. Scoring erosions and joint space narrowing.

Six observers, including two bone and joint radiologists, two general radiologists, and two senior radiology residents, compared scores to quantitate radiographic findings in the hands and wrists of patients with rheumatoid arthritis. In the scoring system used, erosions and joint-space narrowing are graded separately. This scoring system differs from other methods in that equivocal findings are not scored, while ankylosis, subluxation, and dislocation are scored, and data from postoperative joints are included. Total radiographic scores were highly significantly correlated for all observers (R = .908-.958, P less than .001), as were subtotal scores for erosions (R = .723-.931, P less than .001) and joint-space narrowing (R = 0.843-0.966, P less than .001). Analysis of proximal interphalangeal, metacarpophalangeal, and wrist-joint scores showed highly significant correlations for all observers in each location. Highly significant correlations were found among three separate readings of two bone and joint radiologists (R = .950-.961, P less than .001). This scoring system provides highly consistent and reproducible results, even in the hands of less experienced observers.

Analysis of Variance↗

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↗

PubMed1987

Observer variation in quantitative assessment of rheumatoid arthritis Part II. A simplified scoring system.

A new and more comprehensive simplified scoring system to provide quantitative assessment of radiographic findings in rheumatoid arthritis was studied by six observers with different levels of expertise. Since the observers, film set, and joints scored were the same as in a prior study of a more detailed scoring method, a precise comparison of the results was made. Interobserver variation with the simplified scoring system was small; there were highly significant correlations of the total radiographic scores for all observers (R = .898-.978, P less than .001). There were highly significant correlations between scores obtained with the simplified scoring system and those obtained with the more detailed method (R = .920-.955, P less than .001). When the same joints were evaluated by the two methods, a significantly greater number of possible observations could be scored with the simplified scoring system than with the more detailed method (X2 = 131.07, P less than .001). The simplified scoring system required 2.3 times less time to use in the hands of experienced observers.

Arthritis, Rheumatoid↗

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↗

PubMed1987

Chromosome 18 aneuploidy: anatomical variations observed in cases of full and mosaic trisomy 18 and a case of deletion of the short arm of chromosome 18.

Cases of full and mosaic trisomy 18 and a body of an infant with the 18p-syndrome were dissected in detail to compare the anatomical variations associated with these 3 chromosome imbalances involving autosome 18. The types and numbers of morphologic variations present in both the full and mosaic trisomy 18 bodies were similar to the types and numbers of variations seen in all other cases of full trisomy 18 that have been studied by gross dissection. Apart from an atrial septal defect, the body of the infant with the 18p- imbalance showed only 2 striking defects: 1) deficiencies of the levator palpebrae superioris muscle of the upper eyelid, and 2) absence of the ligament of the head of the femur. The first variation provides a morphologic basis to explain the ptosis which is observed frequently in affected individuals. Absence of the ligament of the head of the femur may be a factor contributing to congenital dislocation of the hip, which is reported occasionally in affected individuals. In addition to providing more detailed information about the phenotype of individual aneuploidy syndromes, studies of cases of different imbalances of single autosomes may provide additional insights about the genotype/phenotype relationships of specific chromosome segments.

Brachial Plexus↗

PubMed1988

Observer variation in assessment of liver biopsies of alcoholic patients.

The aim was to construct a questionnaire analyzing pathological features possibly present in alcoholic liver disease, to assess its interobserver variation and to determine the influence of technical data on this variation. A total of 764 inpatients drinking 90 g (median) of pure alcohol per day for 25 years was observed; 402 patients were excluded because of associated nonalcoholic disease, refusal or contraindication to biopsy, leaving 362 patients included. Two pathologists independently analyzed each biopsy and completed a questionnaire including 41 items. Coefficient of concordance between observers was evaluated with the kappa statistic (k). The prevalence of 14 lesions was low, equal to or under 10%, leading to a nonsignificant concordance. For the 27 remaining features, two had an almost perfect degree of concordance (k greater than 0.81): presence of hepatocellular carcinoma and cirrhosis. Three had a substantial coefficient of concordance (k greater than 0.61): fibrous septa, size of cirrhotic nodules, and liver cell regeneration. Nine had a moderate (k greater than 0.41), 11 a fair (k greater than 0.21), and two a slight (k less than 0.21) coefficient of concordance. In terms of final diagnosis of alcoholic liver disease the concordance was substantial for cirrhosis with acute alcoholic hepatitis (k = 0.77), cirrhosis without alcoholic hepatitis (k = 0.75), acute alcoholic hepatitis without cirrhosis (k = 0.65) and normal liver (k = 0.64). Concordance was moderate for steatosis (k = 0.47) and slight for fibrosis alone (k = 0.16).(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholism↗

PubMed1985

Observer variation in bone lesion detection in thoraco-abdominal visceral CT images.

This study measured missed bone diagnosis on CT performed for lymph nodes or visceral spread of cancers and lymphomas. A bone-expert reading was compared to that of visceral-cancer oriented observers. From 100 examinations, 65% of bone abnormalities were not described by current reporting of cancer cases. Changes in windowing and contrast of the image produced large variations in CT readings. A slow search with different windowing decreases the false-negative ratio. A fast reading with invariable viewing parameters increases false interpretations, even for experienced radiologists.

Bone Neoplasms↗

PubMed1988

Observer variation in histologic classification of malignant and borderline ovarian tumors.

Eight hundred sixty-nine primary malignant or borderline ovarian tumors reported to the Norwegian Cancer Registry were reviewed. The histologic slides were randomly distributed to six observers and classified according to the World Health Organization classification of ovarian tumors. By rotation of slides, each tumor was successively reviewed by three observers. Each observer was given approximately 40 duplicates of slides he or she had typed before, mixed in with the slides for the third review. A contracted version of the classification with 27 entries was used in the analysis. Mean intraobserver reproducibility was 62% (kappa, 0.53), varying from 50% to 75% (kappa, 0.34 to 0.70) for the individual observers. The mean rate of agreement between two observers was 56% (kappa, 0.46), varying from 46% to 65% for the individual pairs of observers. The rate of full agreement among three observers was 41%. The most common disagreements were between different specific types of carcinoma, between undifferentiated and differentiated carcinoma, between borderline and malignant tumors, between unclassified and classified carcinoma, and between mixed and pure types of carcinoma. Very low reproducibility was obtained for mixed and unclassified carcinoma.

Carcinoma↗

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↗

PubMed1985

Observer variation in clinical examination of the nasal airway.

There has been no standardization of clinical assessment of the nasal airway between different clinical trials. In order to evaluate the reproducibility of tests in use in current clinical practice, a pre-trial inter-observer assessment of the nasal airway tests was made and an intra- and inter-observer assessment was made in 25 patients. Differing degrees of correlation were demonstrated, using the Kappa statistic. Suggestions are made to enable improved standardization of clinical examination of the nasal airways for clinical trials.

Clinical Trials as Topic↗