SEARCH · PubMed Health

Results for “Reproducibility”

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 1,441 records · Page 80Linked to original sources

PubMed2003

[Reproducibility of the shuttle walk test in children with cystic fibrosis].

INTRODUCTION: Exercise testing is useful in the respiratory evaluation of patients with cystic fibrosis. The shuttle walk test (SWT) is a progressive, externally paced, exercise test requiring the subject to walk/run back and forth between two fixed points. The aim is to assess the reproductibility of the SWT in paediatric patients with cystic fibrosis. METHODS: This prospective study recruited 31 children with stable disease. The patients performed two SWT one day (SWT 1 and 2) and two others (SWT 3 and 4) within 15 days. Only SWT 2 and 4 were assessed for reproducibility. RESULTS: 61% were boys, median age (range): 12.9 (7-18.9) years, median Shwachman score (range): 80 (65-100), median values for FEV1 and FVC (range): 92 (55-154) and 92 (64-140)% predicted, respectively. Median distance for SWT 2-4 (range): 910 (580-1020) and 925 (540-1020) metres. Reproducibility for SWT distance and physical activity measured by an accelerometer is very good (intra-class correlation coefficient=0.90 and 0.92, respectively). SWT distance correlated with physical activity (p=3.10(-4)) and weight (p=0.03). SWT distance was independent of the following parameters: height, weight-for-age Z-score, FEV1, FVC, Shwachman score, colonisation with Pseudomonas aeruginosa. CONCLUSIONS: The SWT is reproducible in paediatric patients with cystic fibrosis and provides assessment of respiratory performance that complements spirometric measures of lung function.

Adolescent↗

PubMed2003

[Reproducibility of centric relation of the patient with severe dental attrition for oral rehabilitation].

OBJECTIVE: Standards for determining mandibular position, especially the centric relation (CR), are in controversy because of anatomical, neurophysiological factors and research methods or instrument. The purpose of this study was to reevaluate the reproducibility of centric relation of the patients with severe dental attrition for oral rehabilitation. METHODS: Reproducibility of the centric relation of 6 patients with severe occlusal attrition was investigated by using D5A Denar fully adjustable articulator and the Pantronic recording system. RESULTS: 1. In supine position, anterior-posterior(AP) displacement of centric relation (CR) was 0.14 mm and superior-inferior(SI) displacements of CR were between 0.11 mm-0.12 mm. 2. In upright position, anterior-posterior displacement of CR was 0.35 mm and superior-inferior changes of CR were between 0.13 mm-0.20 mm. CONCLUSION: The CR is the most stable and reproducible position of mandibule in normal stomatological system and is useful as a reference position in occlusal treatment and functional rehabilitation.

Aged↗

PubMed2004

Reproducibility of spinal back-contour measurements taken with raster stereography in adolescent idiopathic scoliosis.

200 children with a mean age of 12.7 years were measured with the Quantec Spinal Image System (QSIS), which uses computerized raster stereography technology. The aim of the study was to assess the intraobserver reproducibility of QSIS metrics in scoliosis patients and to quantify the effect of postural sway on the measurements. Children were randomly assigned to 1 of 2 groups: Group 1 contained 198 subjects, having 3 digitized measurements of 1 scan; Group 2 contained 200 subjects, undergoing 3 separate QSIS scans with 1 measurenent of each scan. Random-effects variance components models were fit to each outcome variable of interest (subject, scan or measurement) separately for the single scan dataset and the 3 scan dataset. They revealed that data from Group 2 contained greater reliability than data from Group 1 (reliability > or = 80%). The reliability of these parameters was perfect if one performed 3 scans and 3 measurements per scan. Results demonstrate that the QSIS with 3 scans and 1 measurement yields reproducible data from mild idiopathic scoliosis patients and that postural sway has minimal effect on data reproducibility.

Child↗

PubMed1992

Intraobserver and interobserver reproducibility of the Nidek EAS-1000 Anterior Eye Segment Analysis System.

The NIDEK EAS-1000 is a camera and computer system designed to facilitate measurement and analysis of the anterior segment of the eye. To evaluate the interobserver reproducibility of the system, three examiners assessed the anterior chamber depth and peripheral angle measurement in 20 disease-free eyes. Intraobserver reproducibility was determined by each investigator's photographing and analyzing the same eye on three different occasions. Interobserver correlation for the anterior chamber depth (using the first three readings of the same eye made by each examiner) was 0.97, with an 95% CI of 0.94 to 0.98. Interobserver correlation for angle measurement (again using the first three readings of the same eye made by each examiner) was 0.89, with a 95% confidence interval (CI) of 0.81 to 0.95. Intraobserver correlations for anterior chamber depth were 0.98 for each of the three examiners (mean, 0.98), wiht a 95% CI of 0.91 to 0.99. Intraobserver correlations for anterior chamber depth were 0.98 for each of the three examiners (mean, 0.98), with a 95% CI of 0.91 to 0.99. The intraobserver CI for angle measurement was 0.97 (range, 0.95 to 0.99). The intraobserver and interobserver reproducibility of the NIDEK EAS-1000 system was excellent.

Adult↗

PubMed2004

The diagnostic accuracy and reproducibility of school dental screening using an index of treatment need.

OBJECTIVE: To test the use of an index in school screening programmes by assessing its accuracy in determining treatment need, and its reproducibility. BASIC RESEARCH DESIGN: Diagnostic accuracy was measured against a gold standard, inter-examiner and intra-examiner variation was measured by comparing the results of two examiners for the same subjects. Setting A large inner city primary school in Birmingham. PARTICIPANTS: 570 primary school children. OUTCOME MEASURES: Diagnostic accuracy was measured by sensitivity and specificity values. Reproducibility was measured by using kappa scores. RESULTS: The mean sensitivity for positive screening result was 81% and mean specificity for negative screening result was 97%. The kappa score for inter-examiner variation was 0.7 with agreement on decision to refer in 91% of cases. Intra-examiner variation was 11% for both examiners. CONCLUSION: The use of the index was shown to be both accurate and reproducible and is advocated for use in school dental screening programmes.

Child↗

PubMedDate not supplied

[The accuracy and reproducibility of the measurement of bone mineral content by single-photon absorptiometry (125I). The effect of source strength].

This study was aimed at verifying whether accuracy and reproducibility of mineral content measurements of bone phantoms by single-photon absorptiometry change as a function of source strength, and whether these changes depend on the phantom's width. To these purposes, the Norland 2780 bone mineralometer was used. With this unit, the mineral contents of two cylindrical phantoms of different diameter and of known mineral content were measured every week, 5 times on the whole, up to exhaustion of the source. Both accuracy and reproducibility decreased as source strength decreased. The lowest reproducibility was observed for the measurement of the smaller phantom with low source strength. It was therefore concluded that when source strength reaches the threshold value of 2000 cps, the measurement is so much affected as to jeopardize the reliability of short-term longitudinal studies of bone mineral content in patients.

Absorptiometry, Photon↗

PubMed2005

Does data rounding-off influence reproducibility index estimates?

The intraclass correlation coefficient (ICC) is the reproducibility index commonly used to assess the reproducibility level of continuous data. Such data are collected with finite precision (i.e., a finite number of decimal digits corresponding to the level of data rounding-off error). We therefore investigated the consequences of having finite precision for data on ICC estimates, thus comparing ICC estimates in presence of rounding-off to those associated with data with infinite precision. As long as the rounding-off level is less than 0.3sigmaX (where sigmaX is the standard deviation of the outcome measured), there is no practical consequence on the ICC estimate. Therefore, in most practical situations the consequences of rounding-off data on the estimation of reproducibility levels can be ignored.

Data Collection↗

PubMedDate not supplied

Interobserver reproducibility of immunohistochemical HER-2/neu assessment in human breast cancer: an update from INQAT round III.

The clinical interest in HER-2/neu is related to trastuzumab, a drug used to treat patients with invasive breast carcinoma overexpressing the HER-2/neu protein. It is very important to correctly identify those patients who may benefit from trastuzumab by accurate assessment of the HER-2/neu status. Of the various methods available, the Dako Herceptest for immunohistochemical assay is considered the most reliable to reach this goal. The aim of this study was to investigate within a group of Italian laboratories the reproducibility of the results of HER-2/neu assessment by means of the Dako scoring system on slides stained with the Herceptest kit. This study was also conceived as the continuation of one of our previous studies, which was similar in its aims but different in the classification criteria adopted. Our results show that, whereas the intra-observer reproducibility was generally satisfactory, the interobserver reproducibility was not. Moreover, our findings confirm that the two extreme classes (0 and 3+) are more easy to identify than the other two and that the Herceptest does not allow to discriminate optimally between scoring classes 2+ and 3+. These findings are relevant in clinical practice where the treatment choice is based on categories defined by this assay, suggesting the need of adopting educational programs and/or new reference materials to improve the assay performance.

Biomarkers, Tumor↗

PubMedDate not supplied

Reproducibility of a semi-quantitative food frequency questionnaire in Chaoshan area, China.

OBJECTIVE: To examine reproducibility of assessed intake of foods and nutrients according to a semi-quantitative food frequency questionnaire (SQFFQ) in adult doctors and nurses residing in Chaoshan area of China. SUBJECTS: The SQFFQ was administered first in October to December of 2004 to 120 adult doctors and nurses living in Chaoshan area of China and was then re-administered to 102 three months later between January and March of 2005 (SQFFQ 1 and SQFFQ 2). METHODS: Reproducibility was evaluated in terms of consumption of 10 food groups and energy and 34 macro- and micro-nutrients based on the SQFFQ from the 102 doctors and nurses. RESULTS: For intake of foods, Pearsom's correlation coefficients (CCs) with log-transformation and energy adjustment (minimum - median - maximum) range from 0.43 (eggs) - 0.84 - 0.90 (teas). Spearman's rank CCs with energy adjustment ranged from 0.77 (cereals) - 0.84 - 0.94 (milks). Kappa statistics with energy adjustment ranged from 0.53 (vegetables) - 0.63 - 0.82 (teas). For consumption of nutrients, Pearson's correlation coefficients (CCs) with log-transformation and energy adjustment (minimum - median - maximum) range from 0.83 (docosahexaenoic acid and oryzanin) - 0.88 - 0.90 (linolenic acid, vitamin A, folic acid, vitamin E, calcium, sodium, selenium and magnesium). Spearman's rank CCs with energy adjustment ranged from 0.81 (oryzanin and vitamin C) - 0.86 - 0.90 (sodium). Kappa statistics with energy adjustment ranged from 0.49 (protein) - 0.60 - 0.77 (sodium). CONCLUSION: Substantially high reproducibility was observed; it is possible to use the tailored, relatively simple, but comprehensive, self-administered SQFFQ to facilitate assessment of the association between lifestyle and health/disease in large-scale epidemiological studies.

Adult↗

PubMedDate not supplied

Determining a one-tailed upper limit for future sample relative reproducibility standard deviations.

A formula was developed to determine a one-tailed 100p% upper limit for future sample percent relative reproducibility standard deviations (RSD(R),%= 100s(R)/y), where S(R) is the sample reproducibility standard deviation, which is the square root of a linear combination of the sample repeatability variance (s(r)2) plus the sample laboratory-to-laboratory variance (s(L)2), i.e., S(R) = s(L)2, and y is the sample mean. The future RSD(R),% is expected to arise from a population of potential RSD(R),% values whose true mean is zeta(R),% = 100sigmaR, where sigmaR and mu are the population reproducibility standard deviation and mean, respectively.

Calibration↗

PubMedDate not supplied

The development of clinical prediction guides requires reproducible decision-making outputs: a field study.

BACKGROUND: The decisions taken by occupational physicians (OPs) generally show low reproducibility and reflect some uncertainties linked to the decision making process. AIM: The aim of the study was to evaluate the variability of different OP decisions in order to assess their reproducibility, which is regarded as a quality factor of the professional practice. METHODS: 4 OPs examined the records of 100 selected hospital workers with impaired health conditions in order to take decisions about job fitness, advice to workers, referral to clinical physician, need for further investigations, report of occupational disease and recommendation for the general practitioner. The variability of inter-individual decision was measured by percent agreement and Cohen's kappa test. RESULTS: After accounting for variability expected by chance, the agreement among decisions on job fitness ranged from fair to substantial, but high variability was observed for most other assessments. CONCLUSION: The observed inter-individual variability for some decisions taken by different OPs represents a crucial aspect to be dealt with, as the reproducibility of medical decisions is indispensable for the clinical prediction guides to be built and adopted for improving the practice.

Biomechanical Phenomena↗

PubMed2006

Reproducibility of wavefront measurements using the LADARWave aberrometer.

PURPOSE: To test reproducibility of lower and higher order aberration measurements using the Alcon LADAR-Wave system. METHODS: Measurements were obtained using the LADARWave aberrometer from 100 eyes (50 patients) who presented for refractive surgery. Each patient underwent 2 separate examinations a minimum of 1 day apart. Zernike polynomial values for these 2 separate measurements were recorded based on a calculated pupil size of 6.5 mm; reproducibility was assessed by analyzing the mean difference between the 2 measurements. RESULTS: The mean difference for defocus was 0.17 +/- 0.12 microm, which represented 2.6% +/- 1.9% of the mean defocus value (6.33 microm). The mean difference for astigmatism was 0.11 +/- 0.12 microm, which represented 23% +/- 26% of the mean astigmatism value (0.45 microm). The mean difference for coma was 0.06 +/- 0.06 microm, which represented 37% +/- 37% of the mean coma value (0.16 microm). The mean difference for spherical aberration was 0.04 +/- 0.04 microm, which represented 18% +/- 18% of the mean spherical aberration value (0.22 microm). CONCLUSIONS: Measurements for defocus were reproducible whereas measurements of astigmatism and higher order aberrations were more variable. The absolute root-mean-square differences between measurements were small, despite the many possible sources of error and variability. Surgical outcomes suggest that the LADARWave aberrometer is measuring at an appropriate clinical resolution.

Diagnostic Techniques, Ophthalmological↗

PubMed1991

[Reproducibility of measurements to assess the quality of dental restorations].

Criteria for assessment of the quality of dental restorations should be highly reproducible. To prove reproducibility of a set of modified Ryge-criteria we assessed the quality of 468 fillings (157 amalgam, 155 cast restorations, 156 composites). Assessment was done double-blind by two investigators. The amount of agreement between the investigators ranged from 56.1% to 88.4% depending on the criteria used. The more positive the results of the assessment and the more objectifiable the criteria, the higher was the amount of agreement. For an objective assessment the reproducibility of the method seems to be unsatisfactory.

Composite Resins↗

PubMed1991

Reproducibility of the rapid pull-through technique for categorizing lower esophageal sphincter pressure.

Duplicate measurements of basal lower esophageal sphincter (LES) pressure using a triple-lumen catheter and the rapid pull-through technique (RPT) were performed in 250 consecutive patients to determine their reproducibility for categorizing LES pressures as normal, hypertensive, or hypotensive. For all subjects, mean LES pressure did not differ for the two measurements (25.3 +/- 1.0 vs. 26.2 +/- 1.0 mm Hg, p greater than 0.5), but the correlation coefficient was only modest (r = 0.73). Reproducibility of categorization was 92% (230 of 250 subjects), and was best for subjects with normal (170/179, 95%) or hypotensive (24/26, 92%) values (for hypertensives: 36/45, 80%). Interstudy variability was least for the hypotensive group (1.8 +/- 0.2 mm Hg) and greatest for the hypertensive group (16.4 +/- 1.9 mm Hg). Likewise, the range of individual values from the triple-lumen catheter was least for the hypotensive subjects (4.7 +/- 0.7 mm Hg) and greatest for those with hypertensive LES pressure (32.5 +/- 2.6 mm Hg). These data show that, despite its interstudy variability, the RPT reproducibly categorizes basal LES pressure in greater than 90% of cases. The technique appears least reliable in determining hypertensive LES pressure, where diaphragmatic contraction may most significantly contribute to measurement variability.

Analysis of Variance↗

PubMed1991

[Reproducibility of Doppler measurements in renal circulation].

Duplex ultrasonography is now used to detect renal artery (RA) stenosis, but measurement reproducibility was not assessed systematically in renal circulation. Our aim was to definite intra and inter-observer variabilities of initial acceleration time (AT), peak systolic velocity (SV), and end-diastolic velocity (DV) in RA. We examined 12 hypertensive patients with angiographically normal RA and 2 normotensives. During these 14 explorations, all measurement were made by the operator A twice, and 13/14 times by the operator B twice. A duplex ultrasound CGR Radius CF* device was used with a 3.75 MHz probe. Once the RA spotted by color imaging, AT, SV, DV were measured by pulsed doppler aligning on arterial axis without angle correction with translumbar approach at different levels (distal trunk, hilus, sinus). SV intra-observer variabilities were for operator A on mean 30% at distal trunk, 3% at hilus, 4% at sinus; for B, there were respectively 16, 0, 2%. About DV, there were for A 3, 0, 1% and for B 2, 7, 0%. Reproducibility was worse about AT. SV inter-observer variabilities were 14, 2, 3%, for DV 13, 3, 2%, for AT 2, 6, 5%. Therefore indexes based on SV, DV, and AT with a less reproducibility may be used for screening or follow-up, but their diagnostic value is still to assess.

Adult↗

PubMed1991

[Ambulatory blood pressure, reproducibility, variability and change, placebo effect].

Blood pressure assessment by ambulatory recordings is a recent clinical method. What is the reproducibility and variability of the results and what is the circadian variation of blood pressure? How useful is the technique for evaluating therapeutic efficacy? Several groups have reported that the reproducibility is good within a group of patients but that this is not observed in case by case and measurement by measurement analysis; however, when the periods of observation are sufficiently long (several hours) the recordings are comparable. In clinical practice for an individual patient, it would seem better to compare the average daily pressure load, at rest and during activity, which is more reproducible than the hourly average of blood pressure. The circadian variation of blood pressure and short-term (within the hour) or long-term (24 hours) variability have been analysed in depth and although the ambulatory blood pressure shows the same circadian variation as invasive arterial measurement, it does not show instantaneous variability. The placebo effect is not marked when a large group of patients is studied. On the other hand, case by case analysis shows the persistance of this phenomenon in small numbers of cases and, in practice, these results make the maintenance of a placebo period in therapeutic trials a necessity. In conclusion, ambulatory blood pressure recording in daily medical practice enables the study of therapeutic variations in blood pressure over a 24 hour period. However, it does not yet enable satisfactory analysis of the variability of blood pressure.

Ambulatory Care↗

PubMed1991

The reproducibility and heritability of individual differences in osmoregulatory function in normal human subjects.

The rise in plasma vasopressin produced by infusion of hypertonic saline varies widely among healthy adults. To determine if these interindividual differences are reproducible, we used linear regression to analyze the relationship of plasma vasopressin to plasma osmolality during repeat hypertonic saline infusion in seven normal subjects. The results confirmed that the slope or sensitivity of the relationship differed widely between subjects (0.12 to 1.66 pg/ml/mOsm/kg) and revealed that these differences were highly reproducible. (r = 0.94 on repeat testing). The individual values for osmotic threshold were less variable (280 to 288 mOsm/kg) as well as less clearly reproducible (r = 0.61). To determine whether these differences are genetically influenced, we compared the vasopressin osmolality relationships within seven monozygotic and six dizygotic twin pairs. We found that the threshold and sensitivity values correlated significantly within monozygotes (r = 0.95 and 0.95) but not within dizygotes (r = 0.34 and 0.21). When the osmoregulation of thirst was similarly evaluated, the individual relationships were as variable as for plasma vasopressin, but only the threshold values in monozygotes correlated significantly (r = 0.92). In 80 healthy adults, the frequency distributions of the osmotic threshold and sensitivity of the vasopressin responses were essentially normal. We conclude that the sensitivity for vasopressin secretion as well as the osmotic thresholds for thirst and vasopressin demonstrate significant polygenetic variance among healthy adults.

Adult↗

PubMed1990

[Improvement of the reproducibility of the Elisa test for detecting anti-Trypanosoma congolese antibodies in cattle].

Simplicity and the potential automatization make the ELISA test a universal tool for the detection of antibodies, and, more recently, of antigens. But the reproducibility of results is not very good, due to many varying factors. We tried to improve the reproducibility of the ELISA test for the detection of anti-Trypanosoma congolense antibodies in cattle. For that, buffers are always used at room temperature to avoid temperature gradients in the plates. All volumes are increased to 200 microliters per well. Non-activated rabbit serum is used to block nonspecific sites and to reduce background signal. Better results were obtained with a homologous antigen (T. congolense) than with a heterologous one (T. evansi). Titration of the antigen concentration to be used must be checked for each new batch. A distribution is proposed which would permit a testing of each serum four times per plate and thus to calculate the mean and standard deviation for each serum. Finally, we propose that the reading should no longer be a function of time after contact between enzyme and substrat, but a function of the progress of the reaction measured in a target serum. Results show a very good reproducibility and in addition we propose a computerized monitoring system.

Animals↗