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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↗

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↗

PubMed1988

Observer variation in the assessment of dysplasia in ulcerative colitis.

Six histopathologists allocated 100 sections from patients with long-standing ulcerative colitis into four diagnostic categories, regular hyperplasia, reactive atypia, low-grade and high-grade dysplasia. Their allocations were analysed using kappa statistics, including Fleiss's multiple kappa for groups of observers, and agreement on specific diagnoses was explored by constructing a conditional probability matrix. The nature of their disagreements was investigated using coefficients for systematic and haphazard errors. Over the four diagnostic categories there was a wide range of pairwise agreement from a low of 49% up to 72% and kappa values were only 'fair' or 'moderate'. As expected, agreement over the two categories 'dysplasia' vs 'no dysplasia' was better, ranging from 68% to 84%, and for 'atypia present' (reactive atypia, low- and high-grade dysplasia) vs "no atypia' two pairings achieved over 90% and 11 pairings over 80% agreement. In view of its clinical importance, conditional agreement on high-grade dysplasia, pairwise agreement on this diagnosis ranged from 100% down to as low as 33%. However, most of these disagreements fell into the low-grade dysplasia category so that closer follow-up and further biopsies would still have been indicated. It is a truism that the basis for safe management is careful co-operation between clinicians and pathologists who have all the relevant facts and who know and trust one another's judgement. Thus, several aspects of the ideal diagnostic process cannot be evaluated in inter-observer studies and the element of artificiality should be borne in mind when applying the findings to diagnostic practice. Nevertheless, the low level of agreement on the diagnosis of high-grade dysplasia achieved by certain pairings of specialist pathologists is a disturbing outcome of this study. Inaccuracies should be minimized by a concensus approach and we therefore recommend referral of putative cases of dysplasia to interested pathologists for further opinions. We would also advocate that pathologists faced with appearances which are indefinite between reactive atypia and dysplasia, would do better to describe them in terms of "atypia, significance uncertain', so that closer surveillance is undertaken, rather than force them into more precise diagnostic categories which may be incorrect.

Colitis, Ulcerative↗

PubMed1979

Chemical basis of the electrophoretic variation observed at the alcohol dehydrogenase locus of Drosophila melanogaster.

The amino acid substitution responsible for the different electrophoretic mobility of the ADHs alleloenzyme and the ADHf alleloenzyme of the alcohol dehydrogenase from a Nigerian population of Drosophila melanogaster has been established as lysine (ADHs) for threonine (ADHf). This result is discussed with reference to the charge state model of electrophoretic variation, in conjunction with other know substitutions at this locus. It is concluded that electrophoretic methods should be capable of distinguishing many alleloenzymes which have identical isoelectric points without recourse to explanations involving conformational variability.

Alcohol Oxidoreductases↗

PubMed1983

Radiographic evaluation of endodontic therapy and the influence of observer variation.

In radiographic evaluation of the results of endodontic therapy the development or persistence of periapical radiolucencies often serve as criteria for therapeutic failure. In the present study the influence of inter- and intraexaminer variation on these results was investigated. Three endodontists and three radiologists interpreted periapical conditions and quality of root filling seal in radiographs of 119 endodontically treated roots. Consensus on the presence of periapical lesion was reached in 27% of cases classified as pathologic. In 6% reports of increased width of the periodontal membrane space accorded. The examiners agreed completely on normal periapical conditions in 37% of the cases. On assessing the quality of root filling seal the opinions of observers differed even more. Complete agreement on cases with adequate and defective seal was reached in 25% and 12%, respectively. For the individual examiner the widened periodontal membrane space was the diagnosis most difficult to reproduce. The present study indicates that the large variation noted among clinical and radiographic studies on the results of endodontic therapy could partly be explained by difficulties in defining and maintaining criteria for radiological evidence of periapical disease.

Clinical Competence↗