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Results for “Observer Variation”

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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↗

PubMed1995

Observer variation in assessment of quality of life in patients with oesophageal cancer.

Quality of life (QOL) assessment may improve the evaluation of treatment for oesophageal cancer but patient compliance using self completion questionnaires is often poor. The use of a proxy to estimate QOL might improve data collection from patients who are either unable or unwilling to complete the questionnaire. This study examined whether a doctor or patients' carers could accurately assess QOL using the QLQ-C30 questionnaire developed by the European Organisation for Research and Treatment of Cancer Study Group on Quality of Life. One doctor, 52 patients and 39 carers completed the instrument independently. Proxy and patient ratings were analysed for agreement using weighted kappa scores. Agreement was poor or moderate in most QOL scales and items (kappa < or = 60). This study demonstrates that a carer or doctor is not sufficiently accurate to postulate the patient's responses to the questionnaire. Quality of life data, therefore, should come from the patients themselves.

Adult↗

PubMedDate not supplied

Observer variation in the assessment of adequacy and neoplasia in cervical cytology.

OBJECTIVE: To measure variation in reporting within and between cytotechnologists in a routine cytology laboratory and to assess if attending training courses and discussing many cases alter agreement levels. STUDY DESIGN: The study involved nine cytotechnologists each screening 100 cervical smears and recording the results. The same 100 smears were given a different identity number and the process repeated about six months later. Between the two occasions, two participants attended a training course, and two others discussed many other cases with the aim of reaching agreement on diagnostic criteria. RESULTS: The number of smears judged by the participants on either occasion as adequate varied between 87 and 100, and as adequate and negative, between 36 and 65. Percentage intraobserver agreement on the first round diagnosis of a negative smear varied between 88.5 and 100, and of an abnormal smear, between 58.5 and 91.2. CONCLUSION: Attending the same training course and in-depth discussion of other cervical smears appear to have had the effect of increasing some aspects of interobserver agreement between the two pairs of individuals involved.

Female↗

PubMed1995

Observer variation and reproducibility of endoscopic ultrasonography.

To investigate interobserver variation and reproducibility of endosonographic findings, both experienced and inexperienced endosonographers evaluated depth of tumor invasion (T stage) and presence of lymph node metastasis (N stage) in 50 patients with nonobstructing esophageal carcinoma. Results were compared with the findings by surgical pathology of the resected specimens. The kappa statistic (kappa) was used to assess interobserver and intraobserver agreement and consistency of accurate interpretation (reproducibility) for the two groups. Agreement between the experienced endosonographers was excellent (kappa = > .75) for T1 and T4 lesions, good (kappa = .61) for T3 lesions, but only poor (kappa = > .46) for T2 lesions. The overall agreement between the experienced endosonographers was equally good for both T and N stages. Agreement between the inexperienced endosonographers was poor for all T stages but was good for lymph node metastasis (kappa = .52). For experienced endosonographers, endosonographic reproducibility of histologically confirmed T4 lesions was excellent, followed closely by T3 and T2 lesions; T1 tumors were frequently interpreted differently by the same endosonographer. Reproducibility of N stage determinations was excellent for N0 lymph nodes and good for N1 nodes. Thus, for experienced endosonographers, interobserver agreement was excellent for all T stages except T2, whereas reproducibility of determination of depth of tumor invasion was good to excellent for T2, T3, and T4 lesions but poor for T1 lesions. As yet poorly defined operator and machine-dependent factors that cause misinterpretation of T1 and T2 tumors will require additional study.

Endoscopy↗

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↗

PubMed1993

The reliability of autopsy diagnostics: inter-observer variation between pathologists, a preliminary report.

The aim of the study was to analyse the agreement between pathologists regarding macroscopic autopsy diagnostics. Four pathologists examined 35 autopsies and determined the principal disease and its complications, the immediate cause of death, other major diseases and their complications, and minor diseases. The participants were paired and their diagnoses were analysed by using kappa statistics for interobserver variation. The agreement on the principal disease was almost perfect between the participants (kappa values between 0.83 and 0.97), whereas that on the immediate cause of death was moderate/substantial (kappa values between 0.43-0.75). The list of all other major diseases and their complications was almost complete for each observer, but that of the minor diseases showed a more considerable variation. In spite of the high level of agreement it is recommended that the autopsy findings be discussed among pathologists if the clinical picture cannot be explained satisfactorily, and that the cause of death be determined by the clinicians after the demonstration of the autopsy.

Autopsy↗

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↗

PubMed1983

Inter-observer variation in refraction and visual acuity measurement using a standardized protocol.

Reproducible measures of refraction and visual acuity are necessary in clinical and population studies of eye diseases. Inter-observer differences in measurements of these parameters were evaluated using the Early Treatment of Diabetic Retinopathy Study (ETDRS) protocol. No clinically significant interobserver variation was found for refraction or visual acuity measurements between three observers. This study confirms that when standardized measurement procedures are used, observer differences as a source of variability in the data can be minimized.

Evaluation Studies as Topic↗

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↗

PubMed1980

Intra- and inter-observer variation in functional examination of the masticatory system.

Occlusal variables and clinical signs of functional disturbances of the masticatory system were studied with respect to intra- and inter-observer differences in 11-year-old children and adults. Inter-observer differences were present in all registrations made. They were relatively small when measuring the movement capacity of the mandible but large when measuring the distance between RP-IP. The clinical dysfunction index was recorded with an agreement of 82% (Scott's pi = 0.69) in children, 73% (Scott's pi = 0.58) in adults. Repeated registrations performed 5 weeks apart in the child group showed high agreement while repeated registrations with an interval on one year in the adult group revealed considerable variations for mandibular mobility and for the clinical dysfunction index. The study showed that intra-observer constancy is larger than that between different observers. Thus repeated registrations in longitudinal studies should be done by the same observer. In order to control unavoidable observer errors, and to minimize the influence of the large, normal fluctuation of clinical signs that are known to occur, longitudinal studies should include control groups.

Adolescent↗

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↗

PubMed1983

Reproducibility and observer variation at computed tomography and ultrasound of the normal pancreas.

In order to evaluate the reproducibility of computed tomography (CT) and ultrasound (US), 13 patients with a normal pancreas were examined twice with the two techniques by the same observers. The results of the measurements of the pancreas were reproducible using both CT and US. In estimating the intraobserver variation at CT in 20 patients, the location and spread of the measurements of the diameters of the pancreatic head were reproducible, but the diameters of the pancreatic body and tail were significantly larger at the second observation. Further, the differences in the measurements of the size and dispersion of the pancreatic diameters at CT between two observers were significant, apart from the diameter of the pancreatic tail, where no significant difference was noted. The differences between two observers were greater than for the same. Using US, the results may indicate that the measurements were even less reproducible than using CT, both for the same observer and between two observers. However, all the measured diameters within the 95 per cent confidence intervals, were within the normal range. Consequently, even if most measurements differed significantly, these differences may probably not lead to any false conclusions concerning the limits of the normal size of the pancreas.

Diagnostic Errors↗

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↗

PubMed1981

Observer variation in the angiocardiographic diagnosis of mitral valve prolapse.

The purpose of this study was to assess the reliability of the angiocardiographic diagnosis of mitral valve prolapse by measuring agreement between observers using defined diagnostic criteria. Sixty high-quality left ventriculograms, selected to include many that showed possible mitral valve prolapse, were reviewed by three angiocardiographers. Disagreement between observers as to positivity occurred in 26 percent and 30 percent of the cases on two reviews, and disagreement as to specific scallop involvement occurred in 68 percent and 78 percent of the cases. A specific observer agreed with himself in interpretation of positive 78 to 82 percent of the time and in the interpretation of specific scallop involvement 55 to 90 percent of the time. These results indicate that in the absence of generally agreed upon quantitative angiocardiographic criteria for the diagnosis of mitral valve prolapse, there is considerable variability among observers in the interpretation of mitral valve prolapse by angiocardiographic studies.

Angiocardiography↗