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 1,585 records · Page 88Linked to original sources

PubMed1987

Reproducibility of responsiveness to a standardized bronchial allergen provocation-Rt compared to FEV1 as measurement of response to provocation.

Standardized bronchial allergen provocation was performed twice in nineteen extrinsic, well defined, stable asthmatic patients, with an interval of median 15 days (range 14-19) to study the reproducibility of the bronchial response. Smoking and medications were withheld prior to the provocation after a rigid scheme. Ten-fold increasing concentrations of allergen solution 0.9 ml were inhaled by tidal volume breathing for 5 min with intervals of 10 min. The bronchial response to inhaled allergen was determined by forced expiratory volume in the first sec (FEV1) and by total resistance to breathing (Rt) determined by an opening interrupter method. The provocation was continued until an allergen concentration causing at least 20%, decrease of the postsaline FEV1 or a 40% increase in Rt was reached. A PC20-FEV1 and a PC40-Rt was calculated by interpolation on the log-dose-response curve. The reproducibility of PC20-FEV1 allergen was high with a 95% confidence interval (CI) for a single determination being the observed value +/- 0.83, ten-fold concentration difference, the intraclass correlation (IC) was 0.99 and the coefficient of variation 8.46%. Concerning PC40-Rt a 95% CI for a single determination was calculated being the observed value +/- 0.58, ten-fold concentration difference, IC was 0.99 and the coefficient of variation was 5.79%. No significant correlation was found between differences in pre-challenge FEV1 and Rt values and the corresponding PC20-FEV1 and PC40-Rt values. Least square regression between PC20-FEV1 and PC40-Rt was performed for the first and the second provocation (P less than 0.05). We conclude that bronchial allergen challenge performed in stable asthmatics is highly reproducible and as such a valuable test in the diagnosis of allergic asthma when connected with anamnesis, skin-prick test and the level of specific immunoglobulin E in peripheral blood.

Adolescent↗

PubMed1985

Diagnosis and immunotherapy of mould allergy. II. Reproducibility and relationship between skin sensitivity estimated by end-point titration and histamine equivalent reaction using skin prick test and intradermal test.

To determine reproducibility and the optimal way of expressing skin sensitivity, simultaneous skin prick tests (SPT) and intradermal tests (ICT) were performed on 25 mould-allergic patients. The patients had a well-documented history of allergy to Cladosporium and Alternaria and were tested with partially purified standardized extracts of these two mould species. Skin prick tests were carried out on the volar side of the forearm and intradermal tests on the backs of the patients. The skin tests were performed as titration using quadruplicate determinations of 10-fold allergen dilutions. The area of the skin reactions measured by planimetry were plotted in a log-log system as a function of the allergen concentration. The reproducibility (SD/mean area X 100%) of the ICTs was significantly higher than that of the SPTs (17% versus 29%). A very low reproducibility was found with wheal areas less than 5 mm2. The dose response curve of the SPT wheal area was steeper than that obtained with ICT, both concerning ICT wheal and flare. Increasing the allergen concentration with a factor 10 resulted in a doubling of the wheal area in SPT, in contrast to a factor 1.7 using ICT. The coefficient of correlation using linear regression on the dose response curve was always higher than 0.9 with SPT and ICT wheal, but significantly lower with ICT flare. Skin sensitivity was estimated as end-point and histamine equivalent reaction. No significant correlation between SPT and ICT end-point titration was found contrary to the histamine equivalent reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1986

Reproducibility of standardized bronchial allergen provocation test.

Standardized bronchial allergen provocation was performed twice (with an interval of median 14 days (range 14-44)) in 19 extrinsic, well-defined asthmatic patients to study the reproducibility of the bronchial response. Smoking and medications were strictly withheld prior to the provocation. Ten-fold increasing concentrations of allergen solution 0.9 ml were inhaled by tidal volume breathing for 5 min at 10-min intervals. The actual dose given was expressed by the concentration of the solution used. Forced expiratory volume in the first second (FEV1) was used to determine responses, and the provocation continued until an allergen concentration (allergen PC20) was reached which caused at least 20% decrease of the post-saline FEV1. All provocations were followed by a bronchial reaction within clinically acceptable limits. The reproducibility was high, evaluated by the Spearman rank correlation coefficient Rho = 0.90 (P less than 0.01). It is concluded that bronchial provocation with allergens performed as outlined in this study represents a reproducible test which can be applied in routine allergy diagnostics, and in further investigations concerning specific bronchial reactivity.

Allergens↗

PubMed1986

Reproducibility of exercise-induced asthma in children.

The reproducibility of exercise-induced asthma (EIA) was studied in children with perennial asthma, using treadmill exercise challenge tests repeated at mean intervals of 1 week (Group I, n = 20), 1 month (Group II, n = 20) and 1 year (group III, n = 18). The protocol was standardized with respect to intensity and duration of exercise, time of last medication prior to exercise, air humidity, use of corticosteroids, asthma attacks, and 6) pollen season. The mean percentage fall in peak expiratory flow (PEF) following exercise remained significantly unchanged in the three groups. The reproducibility of EIA was improved compared with previous studies. Although the random variation of EIA tended to be greater in Group III, the individual severity of EIA was remarkably stable whatever the interval between tests. Improvements in baseline airway function between tests were not followed by a simultaneous decrease in EIA. In conclusion, the severity of EIA is reproducible in children with perennial asthma, when the exercise protocol is standardized for factors known to influence bronchial reactivity.

Adolescent↗

PubMed1991

Cavernosometry: methodology and reproducibility with and without pharmacological agents in the evaluation of venous impotence.

Venous impotence can be evaluated by cavernosometry, although this is a controversial issue. We have evaluated various techniques for cavernosometry: with and without intracavernous papaverine, with different dosages and modalities, with different modes of induction flow and at various intracavernous pressures. A standardised technique was tested and retested in 32 impotent men. If pharmacocavernosometry is accepted as the most reliable test and a maintenance flow less than 20 ml/min indicates optimal venous occlusion, plain cavernosometry gave 6% false positive and 16% false negative results. Pharmacocavernosometry was found to be highly reproducible with regard to maintenance flow for patients thought to have optimal venous occlusion and for those with supposed leakage. The induction flow was of no diagnostic value. After injection of papaverine the maintenance flow became a reproducible parameter for quantifying venous outflow and could be measured with an intracavernous pressure equivalent to systolic blood pressure to minimise cavernous arterial inflow and increase reproducibility.

Adult↗

PubMed1993

Reproducibility of parameters for assessment of diabetic neuropathy. The French Group for Research and Study of Diabetic Neuropathy.

This study evaluated the reproducibility of nerve function assessment in a group of 132 diabetic patients with moderate peripheral polyneuropathy. Patients were investigated at the beginning and the end of the run-in period (a 1-month placebo period) of a multicentre trial of an aldose-reductase inhibitor (Ponalrestat). Reproducibility was evaluated by performing four types of tests: quantitative visual scales of symptoms, quantitative sensory assessment (vibration perception thresholds in medial malleolus and great toe, foot thermal perception threshold to hot and cold), electrophysiological investigations on the dominant side (conduction velocities and potential amplitudes of sensory and median motor nerve, sural and peroneal nerves, amplitudes of F waves of median motor and peroneal nerves) and cardiac autonomic tests (Valsalva, deep-breathing, lying-to-standing). Reproducibility was poor for symptoms, thermal sensitivity, and potential amplitudes. It was satisfactory (total coefficient of variation < 50%) for all the other parameters and even very good (total variation coefficient < 26%, intra-subject variation factors corresponding to < 56% of total variance) for velocities of sensory and median motor and peroneal nerves, the amplitudes of F waves and the three autonomic tests. For most of the parameters total variance was mainly related to inter-subject variability. However, inter-subject variability for the three cardiac autonomic tests was very low and at least one cardiac autonomic test was altered in all the patients. Inter-centre variability was low for all the parameters, except for action potential amplitudes and for F wave velocity of the median motor nerve. This study suggests those parameters that are appropriate for the assessment of diabetic neuropathy and for therapeutic trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehyde Reductase↗

PubMed1981

Reproducibility of treadmill exercise in patients with intermittent claudication.

The reproducibility of pain limited exercise time (ET) and heart rate (HR) have been evaluated in repeated treadmill exercise tests in 24 patients with arterial occlusive disease of the lower limbs and intermittent claudication. The protocol includes a walking speed of 1 m/s and load increments of 10 watt/min and the two tests were separated by 1--14 days. The total ET was systematically increased by about 30 sec (P less than 0.05) at the second exercise test. The reproducibility of ET at the onset of leg pains was 34%, whereas the corresponding value at maximal leg pain was 16%. HR at the termination of the test did not differ systematically between the two tests and the reproducibility of HR was 6.1% and 5.5% at the onset of pain and maximal pain, respectively. It is concluded that a slight improvement in walking capacity at a second exercise test must be taken into account when evaluating different types of therapy in patients with intermittent claudication and, furthermore, that ET, walking distance or work load, should preferably be evaluated at or near maximal leg pain.

Adult↗

PubMed1985

Reproducibility of coronary haemodynamics and cardiac metabolism during pacing-induced angina pectoris.

The reproducibility of coronary sinus blood flow (CSBF) (thermodilution technique) and myocardial metabolism (exchange of oxygen, lactate, free fatty acids, glucose, citrate, glutamate and alanine) during two identical pacing periods separated by 45 min were studied in eight patients with chronic coronary artery disease. The mean of the individual difference (delta-values) between values during the first (T1) and second (T2) test, at corresponding times (rest, pacing and after 3-5 min of recovery), were calculated and expressed as a percentage of the resting level of each parameter in order to assess their reproducibility. All patients experienced angina pectoris during both pacing sessions, and pacetime to onset of symptoms did not differ between the tests. Group values for haemodynamics and exchange of metabolites were acceptably reproducible throughout the period under study. Mean delta-values of CSBF ranged from 10% to 16% and myocardial oxygen uptake from 14% to 22% in relation to the resting levels. In contrast, mean delta-values of metabolites ranged from 5% to 136% in relation to the respective A-V differences during the study. The greatest variation occurred during pacing and of all the metabolites lactate exchange varied most. A spontaneous variation in the degree of ischaemia during repeat stress tests might be the major reason for the metabolite variability. Changes in CSBF, however, tended to correlate inversely to the delta-aortocoronary sinus differences of substrates during pacing. Precision of chemical analysis and blood sampling technique were of minor importance for the variability. Since lactate exchange varied most, the study suggests that additional measurements should be made of more metabolites when assessing the efficacy of therapy by means of myocardial metabolism.

Adult↗

PubMedDate not supplied

Reproducibility of impedance cardiography hemodynamic measures in clinically stable heart failure patients.

BACKGROUND AND AIMS. One of the greatest challenges confronting physicians who are managing the care of patients with heart failure is to acquire objective data that signals treatment effectiveness and/or disease progression. The aim of this study was twofold: 1) to determine the extent to which (real time) impedance cardiography measurements obtained with a specific medical device (the BioZ) were reproducible in outpatients with clinically stable heart failure; and 2) to establish "normal" ranges of one week hemodynamic variability in this population of patients. Information of this nature would help clinical cardiologists and primary care practitioners to evaluate the implications of their patient's visit-to-visit hemodynamic variability. METHODS. A one group, prospective, time series design was used. The sample consisted of 62 patients who had clinically stable heart failure and who were being treated in an outpatient heart failure clinic at a university medical center. BioZ hemodynamic measures of cardiac output, contractility, and after load were obtained at five points in time: two, 10, and 60 minutes resting following a 40-50 foot walk on the first day and at two and 10 minutes resting following a 40-50 foot walk on the second day, one week later. RESULTS. Small but significant changes in cardiac output and cardiac index (mainly due to changes in heart rate) were seen during the 60-minute period on week one. Stroke index did not change during this period. In general, reproducibility between measurements taken on the same day and between days was quite good. Establishment of 95% confidence intervals helped define boundaries of variability in this population. Further clinical evaluation of the four patients whose values exceeded the 95% confidence intervals revealed unexpected, potentially relevant changes that could have accounted for their interday variability. Conclusion. The BioZ impedance cardiography measurements are responsive to hemodynamic activity-rest changes and are reproducible at a one week interval in clinically stable heart failure patients being treated in an outpatient clinic. Stroke index is a better measure of patient status than cardiac output or cardiac index. (c)2000 by CHF, Inc.

Journal Article↗

PubMed1987

Constant force probing with and without a stent in untreated periodontal disease: the clinical reproducibility problem and possible sources of error.

There is presently no satisfactory method of detecting periodontal disease activity at a specified site by means of clinical measurements. This study was designed to examine the possible sources of error with regard to probing measurement reliability. Intra-examiner reproducibility of probing measurements was studied at 766 sites in 10 patients with untreated periodontitis, using a 0.25 N hinged constant force probe (a) with a stent for guidance and landmark, and (b) without stent. The stent made little difference to overall reproducibility of probing depths, though it appeared to reduce variation in different areas. Repeated probing led to an increase in some measurements, perhaps by an effect on tissues. Reproducibility of probing depth was lower in deep pockets, and about 2% of all probing depth scores varied by 3 mm or more at the same site. 4 possible sources of measurement error were noted: visual and tactile observational error, positional error and tissue change. The results are discussed in relation to the clinical detection of periodontal disease activity.

Diagnostic Errors↗

PubMed1976

Reproducibility of response to a questionnaire on symptoms of masticatory dysfunction.

The aim of the present investigation was to check the reproducibility of answers to multiple-choice questions used in a questionnaire. The questionnaire was concerned with symptoms in patients with dysfunction of the masticatory system. Five main types of questions were tested by repetition within 1 week by 98 patients. Comparisons were also made between questionnaire data and clinical findings. The interval between the questionnaire and the clinical examination was 1 week. The best reproducibility was found for answers to a question about previous joint radiography, which was the simplest question with the fewest alternatives. The second best was found for a question about the duration of the symptoms referable to the masticatory system. The poorest reproducibility was noted for a question about masticatory muscle pain. The comparison between the questionnaire data and clinical findings showed the best agreement for joint sounds. The reported pain symptoms and palpatory tenderness seem to be different entities.

Humans↗

PubMed1985

Reproducibility of a clinical screening method for assessing gingival inflammation, pockets and plaque retentions.

The purpose of this study was to evaluate the reproducibility of the Periodontal Treatment Need System (PTNS), when plaque retentions were examined separately. A sample of 8000 persons was drawn to represent the Finnish population aged 30 yr and over. The first clinical examination (total sample) was made by a specially trained expanded-duty dental auxiliary (EDDA). During the second examination (2-6 months later), 20% of the total sample was reexamined by a dentist, and of those, every 6th patient was examined by the EDDA. Reproducibility of the PTNS was assessed as intra- and interexaminer agreement and was calculated using Cohen's kappa and weighted kappa. The intraexaminer weighted kappa values were 0.67 +/- 0.05 for the PTNS and 0.48 +/- 0.15 for plaque retentions. The interexaminer weighted kappa values between the PTNS registrations were 0.77 +/- 0.05 and 0.74 +/- 0.12 in plaque retentions when examinations were made within 1 day, and 0.53 +/- 0.05 and 0.37 +/- 0.07, respectively, when the interexaminer registrations were made with an interval of 2-6 months between them. The kappa values for intra- and interexaminer reliability reflect quite high reproducibility.

Adult↗

PubMed1989

Interaural cross-correlation coefficients in stereo-reproduced sound fields.

Interaural cross-correlation coefficients (ICCCs) were measured in stereo-reproduced fields where a KEMAR (Knowles electric manikin for acoustic research) was located. These ICCCs were then compared with those in an ideal, diffuse sound field. The ICCCs in a reverberant field are not reproduced accurately using a conventional two-channel stereo-reproduction technique. In four-channel stereo reproduction, however, the ICCCs can, for the most part, be reproduced accurately as in an ideal, diffuse sound field. Some experimental results are also shown for binaural discrimination of the ICCCs.

Acoustics↗

PubMed1997

Reproducibility and variability in neural spike trains.

To provide information about dynamic sensory stimuli, the pattern of action potentials in spiking neurons must be variable. To ensure reliability these variations must be related, reproducibly, to the stimulus. For H1, a motion-sensitive neuron in the fly's visual system, constant-velocity motion produces irregular spike firing patterns, and spike counts typically have a variance comparable to the mean, for cells in the mammalian cortex. But more natural, time-dependent input signals yield patterns of spikes that are much more reproducible, both in terms of timing and of counting precision. Variability and reproducibility are quantified with ideas from information theory, and measured spike sequences in H1 carry more than twice the amount of information they would if they followed the variance-mean relation seen with constant inputs. Thus, models that may accurately account for the neural response to static stimuli can significantly underestimate the reliability of signal transfer under more natural conditions.

Action Potentials↗

PubMed1988

Oxacillin, cephalothin, and vancomycin tube macrodilution MBC result reproducibility and equivalence to MIC results for methicillin-susceptible and reputedly tolerant Staphylococcus aureus isolates.

Measurement of antimicrobial killing endpoints of Staphylococcus aureus isolates in tube macrodilution MBC testing has been difficult because of multiple technical factors. A total of 41 fresh clinical isolates and 23 reputedly oxacillin-tolerant strains were examined by a modification of the Taylor MBC method. Oxacillin, cephalothin, and vancomycin MBCs were equal to MICs for most strains and were seldom more than fourfold greater than the corresponding MICs after a 48-h incubation. Oxacillin MBC result reproducibility for S. aureus ATCC 25923 and clinical isolates was better than that of cephalothin and vancomycin, and reproducibility improved after a 48-h incubation. Measurement of the percentage of the initial inoculum remaining after 24 and 48 h of incubation for the strains for which the MBCs were highest confirmed improved killing over a wide range of antimicrobial concentrations after a 48-h incubation. Since S. aureus MBC testing is expensive, is subject to error, and almost always gives results equal to the MIC, we suggest that MBC testing is an experimental reference laboratory test that should not be done by clinical microbiology laboratories. Antimicrobial selection should be based on reproducible and standardized MIC tests.

Anti-Bacterial Agents↗

PubMed1995

Analysis of factors affecting the accuracy, reproducibility, and interpretation of microbial community carbon source utilization patterns.

We determined factors that affect responses of bacterial isolates and model bacterial communities to the 95 carbon substrates in Biolog microtiter plates. For isolates and communities of three to six bacterial strains, substrate oxidation rates were typically nonlinear and were delayed by dilution of the inoculum. When inoculum density was controlled, patterns of positive and negative responses exhibited by microbial communities to each of the carbon sources were reproducible. Rates and extents of substrate oxidation by the communities were also reproducible but were not simply the sum of those exhibited by community members when tested separately. Replicates of the same model community clustered when analyzed by principal-components analysis (PCA), and model communities with different compositions were clearly separated on the first PCA axis, which accounted for >60% of the dataset variation. PCA discrimination among different model communities depended on the extent to which specific substrates were oxidized. However, the substrates interpreted by PCA to be most significant in distinguishing the communities changed with reading time, reflecting the nonlinearity of substrate oxidation rates. Although whole-community substrate utilization profiles were reproducible signatures for a given community, the extent of oxidation of specific substrates and the numbers or activities of microorganisms using those substrates in a given community were not correlated. Replicate soil samples varied significantly in the rate and extent of oxidation of seven tested substrates, suggesting microscale heterogeneity in composition of the soil microbial community.

Journal Article↗

PubMed1980

Reproducibility of serological titers.

Serologists are making increasing use of the term "reproducibility" when referring to the reliability or repeatability of serological tests. The practical use of the concept, however, has been limited by the absence of an appropriate numerical scale on which differing reproducibilities can be quantified and objectively compared. This limitation can be overcome by adopting the proposed quantitative measure of reproducibility. The recommended measure is a natural extension of the common practice of considering a serological test to be acceptably reporducible so long as replicate titers remain within a twofold range. The measure can be readily used in the field of serology, and examples are given of how this can be done.

Antibodies, Viral↗

PubMed1985

Accuracy and reproducibility of the AutoMicrobic System Gram-Negative General Susceptibility-Plus Card for testing selected challenge organisms.

A total of 180 selected strains of gram-negative bacilli were tested for susceptibility to nine antibiotics by the prototype General Susceptibility Card and reference broth microdilution MIC method, and 112 of 180 were tested by the modified Gram-Negative General Susceptibility-Plus Card (Vitek Systems, Inc., Hazelwood, Mo.). When category calls--susceptible, intermediate, and resistant for the prototype card and very susceptible, moderately susceptible, and resistant for the modified card--were identical or compatible (very susceptible by one method and moderately susceptible by the other), the methods were considered in qualitative or categorical agreement. The overall categorical agreement improved from 83% for the prototype card to 91.5% for the modified card, and the frequency of major and very major disagreements was reduced from 7.5 to 1%, respectively. Overall agreement between the modified card and reference method for both category calls and MICs (+/- 2 dilutions) was 90%. Of the results, 67% were identical, 22% were more susceptible with the modified card, and 11% were more resistant. Reproducibility of identical or compatible category calls and MICs obtained from three trials was 94.5%. The poorest accuracy and reproducibility were observed when testing Pseudomonas aeruginosa. The study suggests that the modified card can rapidly and efficiently perform susceptibility tests with an acceptable level of accuracy and reproducibility provided that the system is appropriately used for testing strains of the family Enterobacteriaceae with preset criteria for excluding organism-antibiotic combinations. The evaluation also indicates dramatic improvement in the technical performance of the modified card compared with its earlier prototype.

Anti-Bacterial Agents↗