[Observer variation in physical examination of the chest].
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Adult↗
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Decision making in radiographic imaging.
In 1987, the U.S. Department of Health and Human Services issued guidelines for prescription of dental radiographic examinations, and although these recommendations have been reprinted in several widely circulated publications, it seems that the adoption of these guidelines is far from common, even among U.S. dental schools. The recommended criteria are founded on the existing knowledge of prevalence and progression of the most common dental diseases and on the fact that occult diseases within the jaws are uncommon. There are, however, other factors that may influence the decision on the time and extent of a radiographic examination, which may lead to deviations from the suggested guidelines. These factors include: education, peer influence, patient's preference, legal considerations, the dentist's field of interest or specialty, the training of the staff, and practice routine. The diagnostic interpretation of radiographs is far from a completely objective process, even if it is a question as simple as the presence and/or extent of a carious lesion. Numerous studies have shown a large variation among observers, both with regard to the occurrence and extent of carious lesions, in bite-wing radiographs. Caries diagnosis is only one example of many situations where significant observer variation is found. The more complex the diagnostic task, the more variation can be expected. The effect of observer variation on treatment decisions regarding carious lesions is used as an example of the problems encountered daily in the dental practice.
American Dental Association↗
Normal fetal growth evaluated by longitudinal ultrasound examinations.
Fetal weight estimation was evaluated using the equations of Warsof, Shepard and Hadlock in 192 patients, less than 3 days before delivery. Warsof's and Hadlock's equations resulted in significantly better weight estimates compared to Shepard's equation. No systematic error was found below 2500 g by use of Warsof's equation, whereas Shepard's and Hadlocks's equations resulted in significant over-estimation in the low weight group. In a study of 5 fetuses, of 27-38 weeks gestational age, the intra-observer variation was calculated to 4.6%, whereas the coefficient of variation among observer means was 2.9%. The mixed intra- and inter-observer coefficient of variation was 6.5%. Thirty-five low-risk, uncomplicated pregnancies with reliable last menstrual dates were investigated longitudinally with ultrasound measurements of fetal weight. Population growth curves of fetal weight, fetal femur length, abdominal circumference and biparietal diameter were constructed by weighted polynomial regression. After 27 weeks of gestational age the weight growth curve showed only insignificant non-linearity. Compared to a Danish growth curve based on birth weights, significant higher mean weight was found, especially before 31 weeks of gestational age. The 10th and 90th percentiles for the individual percentage deviation change was +/- 4.4% per 28 days.
Body Weight↗
Trachoma: evaluation of a new grading scheme in the United Republic of Tanzania.
A new simplified grading system for trachoma, which is based on the presence or absence of five selected key signs, has been assessed. The level of inter-observer variation and of variation for individual observers (intra-observer variation) showed that the system had good reproducibility following a training period that included interactive clinical teaching. The grading scheme was quickly learned by experienced ophthalmologists and auxiliary health personnel (ophthalmic nurses). The scheme should therefore be suitable for widespread application in field surveys of trachoma.
Allied Health Personnel↗
Measurements of tooth length in panoramic radiographs. 2: Observer performance.
Observer performance in tooth-length measurements in panoramic radiography has been examined. Sixty-four teeth, evenly distributed between maxillary first molars, second premolars and mandibular first and second premolars, were fixed in plastic moulds. Each cast was radiographed with an Orthopantomograph, twice with steel balls indicating the cusps and apices of the teeth and once without them. One observer measured the radiographic tooth length twice in both radiographs with indicators in order to estimate the true radiographic tooth length and the repositioning error, and twice in the radiographs without indicators. Seven other observers measured the tooth length on the radiographs without indicators, twice applying their own criteria and twice using defined criteria. The accuracy of the tooth-length measurements was calculated by comparing the true radiographic tooth length with the measurements of the seven observers. The intra-observer variation was defined as the difference between two measurements on the same radiograph. The accuracy and the precision of the tooth-length measurements were highly influenced by the observer performance. The mean radiographic tooth length of the seven observers was closer to the true radiographic tooth length when the observers applied the defined criteria. The inter- and intra-observer variation was higher for the measurements of the maxillary teeth (0.3-1.9 mm) compared with the mandibular teeth (0.3-0.9 mm) for most observers. The highest intra-observer variation was found for the palatal root of the maxillary first molar. The intra-observer variation of four observers decreased somewhat when the defined criteria were used; for the other three observers, however, the variation increased.(ABSTRACT TRUNCATED AT 250 WORDS)
Humans↗
Stress, catecholamines, and sleep.
Difficulties in defining stress stem from its subjective nature. Measurements of stress based on its effects on physical and mental morbidity tend to be speculative because of the multifactorial causation of stress-related diseases, and the characteristically long time-lag between stress states and morbidity. In this study catecholamine output was measured in a group of adults Oxfordshire villagers and the observed variations were related to their lifestyles and health perceptions. A marked circadian variation was observed with adrenaline showing the most marked associations with lifestyle. In men it was possible to account for a relatively high proportion of the variation in adrenaline excretion by relating values to certain factors associated with stress. In women there appears to be a similar association between adrenaline output and the social class of the husband. Data were also obtained on sleep characteristics, which were assessed with regard to lifestyle. Very broadly, sleep duration is related to the level of waking activity, while sleep latency and quality are correlated with people's self-perception of health.
Adolescent↗
Variation between observers in the estimation of airway resistance and thoracic gas volume.
Variations in the estimation of airway resistance (Raw) and thoracic gas volume (Vtg) made by different observers using body plethysmography have been investigated. Five observers determined Raw and Vtg in normal subjects using prerecorded signals so that intrasubject variations were eliminated. The slopes of the oscillography tracings required to make the determinations were assessed using a cursor and a scale fitted to the oscilloscope. Significant and consistent differences in Raw determined by different observers were found,with a mean range of 37%. Great care should therefore be taken when comparing results obtained by different observers. The variation between observers measuring Vtg was significant and consistent but of much smaller magnitude than was the case for Raw, having a mean range of 12%.
Airway Resistance↗
A simplified working formulation of non-Hodgkin's lymphomas based on quantifiable histologic criteria.
Quantifiable criteria for a Simplified Working Formulation of non-Hodgkin's lymphomas are proposed. Biopsy specimens from 582 patients followed from 8.5 to 18.0 years were classified according to the Working Formulation. In addition, on hematoxylin and eosin-stained histologic sections, differential counts among six lymphoma cell types were performed. In each lymphoma 100 cells were counted from representative areas. The intralymphoma variation observed by this method was insignificant for the reproducibility of classification. Five histologic types were defined: (1) follicular small cell (less than or equal to 25% large cells), (2) follicular large cell (greater than 25% large cells), (3) diffuse small (less than or equal to 10% large cells), (4) diffuse large cell (greater than 10% large cells), and (5) lymphoblastic (greater than 20% lymphoblasts). These criteria had clinical significance with regard to prognosis, leukemic conversion, and meningeal involvement. The intraobserver and interobserver reproducibility of the Simplified Working Formulation was, respectively, 91% and 88%.
Cell Count↗
Pyruvate carboxylase and phosphoenopyruvate carboxykinase in cultured human fibroblasts.
The activities of pyruvate carboxylase and phosphoenolpyruvate carboxykinase were measured in cultural human fibroblasts. Considerable variation was observed in strains derived from different individuals. The activities of both enzymes throughout the culture cycle were measured in two strains. In these strains the specific activities of the enzymes increased during log phase and remained constant during the stationary phase. However, one cell strain exhibited a high activity of pyruvate carboxylase which remained unchanged throughout the culture cycle, suggesting that this enzyme may be regulated differently in different strains of cultured human cells. Familial studies suggest that the observed variations in pyruvate carboxylase activity may be due to a genetic polymorphism.
Avidin↗
Transcriptional patterns of growth factors and proto-oncogenes in human glioblastomas and normal glial cells.
To document over-expression of proto-oncogenes in tumors, it is necessary to determine the level of expression in the progenitor normal tissue. These studies compare the levels of nuclear transcription of a series of growth-factor related genes and proto-oncogenes in human glioblastoma cell lines with those in three normal glial cell populations. The unusual finding was that levels in the three normal glial cell populations varied considerably for several genes and thus overexpression of a specific gene in a tumor cell when compared to just one normal glial cell population would not necessarily represent overexpression. In this study, we compared the level of 17 genes in 7 tumors to the highest level of each gene found in any of three normal glial cell populations. Over-expression of PDGF-B in 4/7 glioblastoma cell lines, EGFR in 1/7, neu in 1/7 IGF-2 in 1/7 and ros in 2/7 was observed. The variation observed in the normal glial cell populations emphasizes the possibility that the normal glial cell populations represent different glial cell lineages and/or stages of differentiation and that the tumors could have arisen from different normal glial cells. Matching lineages of normal and tumor cells, probably by monoclonal antibody reactions, may be required to accurately define over-expression.
ErbB Receptors↗
Assessment of outcome in patients with low-back pain.
The Low-Back Outcome Score has been devised as a new and accurate rating system for patients with low-back pain. Thirteen factors, such as pain, employment, sporting ability, rest required, and activities of daily living, were included; subjective opinion was excluded. Pain and active pursuits were weighted. Presentation of the score as a questionnaire, excluding examination findings, eliminated both interobserver variation and observer variation with time. The score was applied retrospectively in a follow-up study of conservatively treated patients and was found to be more comprehensive and more discriminating than the Oswestry Disability Score, the Waddell Disability Rating, or the Waddell Physical Impairment Rating. The Low-Back Outcome Score is recommended for further evaluation in future prospective studies in low-back pain.
Back Pain↗
Inability of caliper measurement to enhance observer agreement in the interpretation of coronary cineangiograms.
Important clinical decisions are made on the basis of the interpretation of the degree of stenosis in the coronary cineangiogram. Thus, minimization of observer variation (both intra and inter) is crucial. The purpose of this investigation was to determine if measurement of stenotic lesions by caliper (CM) as compared with the usual eyeball method (EM) would reduce observer variation. Five observers, using the AHA scoring system, estimated maximal luminal narrowing in 14 segments on 10 films providing 2 reports on each film by EM and 2 by CM, thus making observations on 2800 segments. This allowed analysis of intraobserver variation for each reporter for method EM and CM, and for interobserver variation by each method. Since chance agreement is an important component in an observational study, a correction for this was made using the Kappa statistic. The results revealed that the mean Kappa by EM was 0.71 compared to 0.63 by CM (1 being perfect agreement and 0 no agreement). Agreement was much greater in proximal rather than distal segments. Interobserver agreement was consistently higher by EM K = 0.62 than CM K = 0.53 (p = 0.0007). A delineation of the types of disagreement and their clinical significance are important considerations in the evaluation of observer variation. It is concluded that the use of a caliper does not enhance either intra or interobserver agreement.
Cineangiography↗
Regional observer performance variation in the evaluation of gated cardiac blood pool studies.
Receiver operating characteristic (ROC) analysis demonstrated that regional variations of sensitivity exist in the detection of wall motion abnormality in cardiac blood pool imaging studies. The observer response is significantly better in the apex than either the septum or posterolateral wall segments. The observer errors tend to be false-negative in the posterolateral wall segment and false-positive in the other two segments. Image presentation can make a significant difference to the overall sensitivity, and the monochrome cine-sequence performed best in this study.
Gated Blood-Pool Imaging↗
An assessment of disability rating scales used in multiple sclerosis.
Twenty patients with clinically definite, stable multiple sclerosis were examined independently by three of us at the same visit and given scores on the Ambulation Index, Expanded Disability Status Scale, and Kurtzke Functional System scales. Observer error accounted for 12% to 55% of the variation observed between individual Kurtzke Functional System scores, 17.1% of the variation observed between the patients' Expanded Disability Status Scale scores, and only 3.9% of the variation between Ambulation Index scores. The implications of these findings for the choice of scales in clinical trials are described.
Adult↗
[Observer agreement in the measurement of leg length].
The lower limb length measurement is an important element for the diagnosis of mechanical or structural lumbar pain. Also it has been used for referral pain associated with hip or knee osteoarthritis or the groin and suprapubic areas. The aims of the present study were: 1) to measure the intra and inter observers variation; 2) to measure the intra-method variation using two different techniques for lower limb length measurement, one called the "apparent measure" (9) and comparing both with the radiological measurement technique. Two medical doctors, training on the techniques for lower limb measurement, performed the measurements. The exclusion criteria were flexion deformity of the hip or an overweight greater than 20% over the mean weight expected according to age and sex. A correlation coefficient and its 95% confidence interval (CI) were estimated, one tail test (Ho: r = 0.75). Seventeen patients fulfilled the inclusion criteria, 15 females and two males. The mean age was 35.8 years +/- 13.0 (SD). The correlation coefficient for the inter-observers variation using the "apparent measure" was 0.99 (CI = 0.985) and for the difference between legs it was 0.88 (CI = 0.10). The inter-observers variation for lower limb length measurement using the technique of "real measure" showed a correlation coefficient of 0.77 (CI = 0.95) and for the difference in length between legs it was 0.99 (CI = 0.85). The intra-observer correlation coefficient was 0.95 (CI = 0.85). The correlation coefficient for the inter-observer using the X-ray pictures was 0.98 (CI = 0.92).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
[Coding of cause of death for mortality statistics--a comparison with results of coding by various statistical offices of West Germany and West Berlin].
1.136 death certificates representing all 1985 Bremen cardiovascular deaths and a 50%-sample of non-cardiovascular deaths in the age group 25-69 years were analyzed for reliability of nosologists' coding according to ICD-coding rules (9th revision). The 1.136 photocopied death certificates were used to assess intra-observer-variation in Bremen and to determine inter-observer-variation among 7 nosologists from 6 different State Statistical Offices and the Federal Statistical Office. Intra-observer-agreement in Bremen was found to be similar to the results presented in a comparable US-study: Bremen: 92.1%; Curb et al. 1983: 94.8%-96.1%; 3-digit-ICD-Code. Inter-observer-agreement was found to be much lower in Germany than in two US-studies: 3 coders agreeing on 3-digit-ICD-Code: Bremen: 67.7% (average, 3 coders out of 7); Curb et al.: 90.2% (3 coders); 3 coders agreeing on 4-digit-ICD-Code: Bremen: 61.5%; NCHS 1980: 90.3%. Agreement-rates were also much lower in Germany than in the USA (Curb et al.) when particular disease groups were analysed: Ischaemic heart disease (ICD 410-414): Bremen: 82.7% (average); USA: 97.2%; cerebrovascular disease (ICD 430-438): Bremen 65.6% (average); USA: 93.2%; neoplasms (ICD 140-239): Bremen: 94.0% (average); USA: 97.8%. We conclude that training, individual characteristics of nosologists, and other factors may cause important artifacts when comparing German mortality statistics on a regional level or during different time intervals.
Berlin↗
Precision of Larsen grading of radiographs in assessing progression of rheumatoid arthritis in individual patients.
A study was designed to evaluate observer variation in the assessment of radiographic deterioration of individual patients using the Larsen grading system. Radiographs of hands and feet of 52 patients were assessed by three observers. Each patient had paired films taken one year apart which were assessed together for change in score. To assess within-observer variation each set of films was read twice by all observers. The average progression was 11.6 (SD 9.0). Analysis of the source of variation showed the single observer replication SD to be 3.7 but that for different observers to be 5.5. This may be interpreted as indicating that to achieve 95% confidence of detecting a true change an increase in Larsen score of 8 is required if the same observer assesses or up to 11 if a different observer assesses.
Arthritis, Rheumatoid↗
The reduction of inter- and intra-observer variability for defining regions of interest in nuclear medicine.
The use of region-of-interest (ROI) techniques to quantify data obtained in radionuclide images is commonplace. However, the reproducibility of quantitation due to inter- and intra-observer variations using particular methods of deriving ROIs is often not appreciated. We examined such variations in the results obtained by four independent observers of varying experience using four methods of depicting a ROI about an organ. The set of image data consisted of renal scans with varying target-to-background ratios, and the ROI facilities included two edge-detection methods. The results indicated that, once observers were experienced with edge-detection methods, a lower inter- and intra-observer variation could be achieved, although the technique of 'shrinking' a ROI about a subjectively chosen display level was reasonably satisfactory. In terms or reproducibility, the least satisfactory method of depicting a ROI was the commonly used manually guided 'bug' around arbitrarily chosen display levels representing the boundary of an organ.
Humans↗