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PubMed1997

Event-related potentials in a two-choice task involving within-form comparisons of pictures and words.

Behavioral as well as electrophysiological evidence suggests that words are processed differently than pictures in a variety of tasks. In this study fifteen adult subjects were tested on a speeded "same-different" judgment task between printed names and drawings of common objects. In one condition, subjects decided on the identity between their internal image of the object that was named by S1 (word) and a subsequently presented drawing of an object (Word-Picture condition). In a second condition, comparisons were made on the basis of the name of the depicted object (Picture-Word trials). Event-related potentials (ERPs) were recorded from 12 scalp locations in response to the second item in each pair. No-match waveforms were characterized by larger N350 and P500 deflections compared to Match ERPs. The two responses could be distinguished on the basis of their lateral and anterior-posterior scalp distribution. Within-form comparisons involving pictures produced increased positivity between 150 and 600 ms poststimulus onset at posterior recording sites, whereas the opposite effect was noted at anterior sites during the early portion of the ERP. Decisions on word stimuli were associated with prolonged reaction time and longer N350 peak latency compared to decisions on pictures. These results demonstrate the existence of independent sources of ERP variability, each possibly reflecting a different aspect of cognitive comparisons. Latency and reaction time data provided valuable information regarding differences in the course of the comparison process when linguistic, as opposed to pictorial, stimuli/representations were involved.

Adolescent↗

PubMed1994

Mild pediatric traumatic brain injury: adjusting significance levels for multiple comparisons.

The outcome following mild traumatic brain injury (TBI) is controversial. We addressed this topic in a study of neurobehavioural and 'real-world' functioning among 53 children with mild TBI and their matched controls, using statistical methods recently developed for multiple comparisons. Because the study involved calculation of 414 p-values, four methods of adjustment for multiple comparisons, including the Bonferroni method, were used to avoid 'false-positive' statistical significance. The additional three methods allowed greater insight into the data than provided by the standard Bonferroni adjustment. Results showed that at initial testing, three areas of 'real-world' functioning (eating, domestic and home/community living skills) had weak but statistically significant associations with mild injury. No other specific areas of neuro-behavioural or 'real-world' functioning had plausible associations with the injury either initially, at 1 year, or when changes over the year were considered. However, the adjustment for multiple comparisons provided additional results. There were statistical significant associations of the injury with the entire domain of neurobehavioural variables both initially and at 1 year. These results suggest that the injury affects a spectrum of neurobehavioural skills weakly, rather than a single area substantially. The gain from using multiple comparison methods is discussed.

Activities of Daily Living↗

PubMed2003

Comparison of grass and legume silages for milk production. 2. In vivo and in sacco evaluations of rumen function.

Two experiments were conducted to investigate the basis for higher voluntary intakes and increased alpha-linolenic acid content in milk from cows offered clover silages. Six cows with rumen and duodenal cannulae were used in a four-period changeover-design experiment. Cows received 8 kg/d of dairy concentrate and had ad libitum access to one of six silage treatments: grass, red clover, white clover, alfalfa, and 50/50 (dry matter basis) mixtures of grass with red clover or white clover. The rumen fermentability of grass, red clover, white clover, and grass/red clover silages was also evaluated in a nylon bag study. Legume silages led to increased dry matter intake and milk production in comparison with grass silage. There was no significant effect of legume silages on rumen pH and volatile fatty acid concentrations, but a significant increase in rumen ammonia concentration with the legume silages, reflecting their higher protein content. The inclusion of white clover or alfalfa silage, but not red clover silage, in diets led to an increase in molar proportions of isobutyric, iso-valeric, and n-valeric acids in comparison with diets based on grass silage. Rumen fill was significantly lower, and rumen passage rates were significantly higher for cows offered alfalfa or white clover silages. However, the markedly different particle size distribution of rumen contents with these feeds suggests very different mechanisms for the high intake characteristics: high rates of particle breakdown and passage with alfalfa, and high rates of fermentation and passage with white clover. Microbial energetic efficiency (grams microbial N per kilogram organic matter apparently digested in the rumen) was highest for cows offered alfalfa silage, intermediate for clover silage, and lowest for cows offered grass silage. These differences reflect the higher rumen outflow rates for legume silages in comparison with grass silage. However, the effect of these differences on N-use efficiency (feed to milk) was probably quite small in comparison with effects of N intake. Although the biohydrogenation of alpha-linolenic acid was still high for red clover silage (86.1% compared with 94.3% for grass silage), there was a 240% increase in the proportion of alpha-linolenic acid passing through the rumen. This explains the increased recovery of alpha-linolenic acid from feed into milk with diets based on red clover silage.

Animal Feed↗

PubMed2002

The locus and nature of semantic congruity in symbolic comparison: evidence from the Stroop effect.

Pictures of animals with names of animals printed within the pictures were presented for comparative judgments of size based on either the pictures or the names. The picture-word compounds were compared faster with picture than with word as the relevant dimension. The comparisons of pictures were free of interference from the irrelevant names, but the comparisons of names suffered considerable Stroop interference from the irrelevant pictures. Large effects of semantic congruity characterized the comparisons of both pictures and words. Stroop congruity and semantic congruity did not interact even for comparison of words in which both were present, leading instead to additive effects. The results support theories that (1) place semantic congruity in the decision stage and (2) minimize the role of semantic processing as the basis of the semantic congruity effect.

Adult↗

PubMed2004

Comparison of four different methods for Salmonella detection in fecal samples of porcine origin.

Performances of four detection methods were evaluated for recovery of Salmonella spp. in naturally contaminated fecal specimens of porcine origin. The NMKL 71 method consisted of enrichment in Rappaport-Vassiliadis broth and plating on xylose-lysine-desoxycholate medium, whereas the SP-VG-M002 method relied on a Diasalm enrichment followed by streaking on xylose-lysine-tergitol 4 agar (XLT-4). The VIDAS SLM method was composed of double enrichment in Muller-Kauffmann tetrathionate broth and in M broths before processing in a VIDAS device. If the results were positive, the VIDAS ICS immunoenrichment was performed and the result transferred onto three different selective media. The VIDAS ICS protocol is an immunoconcentration step followed by plating on XLT-4. Seventy-eight samples were tested with all four methods simultaneously, leading to 34 positive samples with at least one method. For this assay, VIDAS SLM revealed 31 positive samples (91.2%), whereas the average positive percentage of the three other methods was 37.3% (P < 0.001). Two-paired comparisons with the VIDAS SLM method were also performed. McNemar values were systematically highly significant (P < 0.001). The proportion of agreement was significantly inferior (P < 0.05) for the comparison of VIDAS ICS and VIDAS SLM (68.7%) compared with the two other paired comparisons (average percentage, 81.5%). The conclusion reached by this trial is that VIDAS SLM significantly improves the recovery of Salmonella in naturally contaminated fecal specimens. For the paired-comparisons, NMKL 71 and SP-VG-M002 were comparable in terms of efficiency, whereas the VIDAS ICS protocol, as established by the manufacturer for food samples only, seemed less efficient than the other two.

Animals↗

PubMed2005

Measuring the significance of participant evaluation of acceptability of cases in the College of American Pathologists Interlaboratory Comparison Program in cervicovaginal cytology.

CONTEXT: The quality of gynecologic cytology slides within educational and proficiency testing programs may deteriorate during use. Participant evaluation of the acceptability of these slides subsequent to possible deterioration is not known. OBJECTIVE: To assess participants' evaluation of the acceptability of slides circulating within an educational gynecologic cytology glass slide program. DESIGN: The College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology is a peer comparison and educational program that evaluates the ability of the participants to correctly classify gynecologic cytology preparations. The program uses both expert review and field validation to select slides for the graded portion of the program. Participants were asked to assess the acceptability of slides within the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology, and their responses were assessed with respect to type of slide preparation, validation status, and reference diagnosis. In addition, we compared the cytodiagnostic discordancy rates of slides that were deemed acceptable by participants with those that were deemed unacceptable. SETTING: Participant assessments were derived from pathologists and cytotechnologists from cytology laboratories of all types. RESULTS: A total of 17,210 slide interpretations were reviewed, and 2.91% of the cases were labeled unacceptable by participants. For all slides, the percentage of cases called unacceptable varied from 1.65% for cases with a reference interpretation of herpes to 45% for cases with a reference interpretation of unsatisfactory. The percentage of slides deemed unacceptable was higher for validated slides than for educational slides (3.27% vs 2.55%, P = .006). The discordancy rate (to reference diagnosis series) for cases deemed unacceptable was significantly higher than the discordancy rate for cases deemed acceptable for both validated (10.39% vs 1.76%) and educational slides (21.72% vs 3.53%, P < .001). CONCLUSION: Greater than 97% of all slides in the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology were judged acceptable by participants. Despite expert review and field validation, a small percentage of slides (almost 3%) in this program were deemed unacceptable by participants. These results support the use of participant evaluation of cases to continually improve the quality of cases in this program.

Clinical Competence↗

PubMed2005

North American pretransfusion testing practices, 2001-2004: results from the College of American Pathologists Interlaboratory Comparison Program survey data, 2001-2004.

CONTEXT: Pretransfusion testing of whole blood and red blood cell recipients is regulated by the federal government under the authority of the Clinical Laboratory Improvement Amendments of 1988. Regulated tests include determination of ABO group, Rh D type, antibody detection, antibody identification, and crossmatching. A wide variety of methods and reagents are available for these regulated tests. During 2001-2004, the College of American Pathologists (CAP) Interlaboratory Comparison Program (Proficiency Testing) J-Survey collected data from more than 4000 laboratories regarding their pretransfusion testing practices. Those data are presented in this report. OBJECTIVE: To assess current testing practices for ABO grouping, Rh D typing, antibody detection, and crossmatching in North America. DESIGN: Data collected for the CAP Interlaboratory Comparison Program (Proficiency Testing) J-Survey were analyzed for trends in laboratory testing practice during 2001- 2004. The data were grouped for analysis by peer group (testing method used) for ABO grouping, Rh D typing, antibody detection, and crossmatching and then analyzed. SETTING, PATIENTS, OR OTHER PARTICIPANTS: Subscribers to the CAP Interlaboratory Comparison Program Transfusion Medicine J-Series. RESULTS: The most common testing schemes used in North America during 2001-2004 are as follows: ABO grouping (most laboratories perform tube testing: 97.6% in 2000 and 91.1% in 2004); Rh D typing (most laboratories perform tube testing: 97.7% in 2001 and 91.1% in 2004); antibody detection (most laboratories perform tube testing: 69.7% in 2001 and 55% in 2004, most frequently with the low ionic strength solution anti-human globulin [AHG] method, 48.3% in 2001 and 39.9% in 2004; as of 2004 slightly more laboratories use the gel AHG method [42%] than the low ionic strength solution AHG tube method); crossmatching for alloimmunized patients (most laboratories perform tube testing using a low ionic strength solution AHG method; 55.8% in 2001 and 47.6% in 2004); and crossmatching for nonalloimmunized patients (tube testing using an immediate spin method; 42% in 2001 and 40.4% in 2004). CONCLUSIONS: Most North American laboratories currently favor tube methods when performing ABO grouping, Rh typing, antibody screening, and crossmatching. However, there has been a significant increase in the use of gel-based methods in recent years, especially for antibody detection and crossmatching. Data collection and data analysis of CAP Interlaboratory Comparison Program Survey results allow for assessment of laboratory proficiency and provide insights into current North American practice trends in pretransfusion compatibility testing.

Blood Banks↗

PubMed1994

A comparison of the benefits of roller pump versus constrained vortex pump in adult open-heart operations utilizing outcomes research.

The purpose of this study was to compare roller pump and centrifugal pump technologies in routine adult open-heart operations to demonstrate the usefulness of applying a proven method of uniform risk stratification (outcomes research). Objective and readily available preoperative patient data was collected retrospectively on 102 non-randomized and consecutive adult open-heart operations. Group 1 consisted of 51 adult open-heart operations utilizing a roller pump for arterial blood perfusion. Group 2 consisted of 51 adult open-heart procedures utilizing a constrained vortex pump for arterial blood perfusion. A comparison between the frequency of occurrence of 53 different preoperative risk factors in the roller pump group and the centrifugal pump group found no statistically significant differences (p < 0.05). Outcome data for the roller pump and centrifugal pump groups included such data comparisons as intensive care unit length of stay (LOS), post operative LOS, total LOS, total patient charge, reimbursement, morbidity, and mortality, which revealed no statistically significant differences (p < 0.05). Further comparison studies of roller pumps versus centrifugal pumps for arterial blood perfusion should incorporate this kind of comprehensive data comparison and analysis to reasonably assure that both pump groups are very similar before outcomes research is performed.

Cardiopulmonary Bypass↗

PubMed1999

Necessary sample size for method comparison studies based on regression analysis.

BACKGROUND: In method comparison studies, it is of importance to assure that the presence of a difference of medical importance is detected. For a given difference, the necessary number of samples depends on the range of values and the analytical standard deviations of the methods involved. For typical examples, the present study evaluates the statistical power of least-squares and Deming regression analyses applied to the method comparison data. METHODS: Theoretical calculations and simulations were used to consider the statistical power for detection of slope deviations from unity and intercept deviations from zero. For situations with proportional analytical standard deviations, weighted forms of regression analysis were evaluated. RESULTS: In general, sample sizes of 40-100 samples conventionally used in method comparison studies often must be reconsidered. A main factor is the range of values, which should be as wide as possible for the given analyte. For a range ratio (maximum value divided by minimum value) of 2, 544 samples are required to detect one standardized slope deviation; the number of required samples decreases to 64 at a range ratio of 10 (proportional analytical error). For electrolytes having very narrow ranges of values, very large sample sizes usually are necessary. In case of proportional analytical error, application of a weighted approach is important to assure an efficient analysis; e.g., for a range ratio of 10, the weighted approach reduces the requirement of samples by >50%. CONCLUSIONS: Estimation of the necessary sample size for a method comparison study assures a valid result; either no difference is found or the existence of a relevant difference is confirmed.

Clinical Laboratory Techniques↗

PubMed1999

The "random-coil" state of proteins: comparison of database statistics and molecular simulations.

This study presents a comparison of two models of the random-coil state, one based on statistical distributions from the structural database and the other based on molecular dynamics simulations. The database model relies on the assumption that the random- or statistical-coil state of a particular residue can be described by its conformational distribution in a sufficiently diverse subset of protein structures. The molecular dynamics model is based on distributions from molecular simulations carried out on "dipeptide" models (single residues with N-terminal acetyl and C-terminal N'-methyl amide blocking groups). A comparison of the two models for the residues Ala, Asn, Asp, Gly, and Val indicates that the database distributions are greatly influenced by long-range interactions and dominated by specific recognizable elements of protein structure. In contrast, the limited structural scope of the dipeptide models presents the extreme case of a peptide under the influence of only short-range interactions. The models were evaluated by a comparison of scalar coupling constants calculated from the conformational distributions and compared with experimentally values determined for unstructured peptides. Although the models gave different distributions, there was similar agreement with experiment. This comparison emphasizes the differences and limitations in each model and highlights the difficulty in presenting an accurate picture of the random-coil state. Proteins 1999;36:407- 418.

Computer Simulation↗

PubMed2000

General deming regression for estimating systematic bias and its confidence interval in method-comparison studies.

BACKGROUND: Various forms of least-squares regression analyses are used to estimate average systematic error (bias) and its confidence interval in method-comparison studies. When assumptions that underlie a particular regression method are inappropriate for the data, errors in estimated statistics result. In this report, I present an improved method for regression analysis that is free from the usual simplifying assumptions and is generally applicable to linearly related method-comparison data. METHODS: Theoretical equations based on the Deming approach, further developed by physicists and extended herein, were applied to method-comparison data analysis. Monte Carlo simulations were used to demonstrate the validity of the new procedure and to compare its performance to ordinary linear regression (OLR) and simple Deming regression (SDR) procedures. RESULTS: Simulation studies included three types of data commonly encountered in method-comparison studies: (a) constant within-method SDs for both methods, (b) constant within-method CVs for both methods, and (c) neither SDs nor CVs constant for both methods. For all cases examined, OLR produced unreliable confidence intervals of the estimated bias. However, OLR point estimates of systematic bias were reliable when the correlation coefficient was >0.975. SDR produced reliable estimates of systematic bias for all cases studied, but the confidence intervals of systematic bias were unreliable when SDs of methods varied as a function of analyte concentration. CONCLUSION: Only iteratively reweighted general Deming regression produced statistically unbiased estimates of systematic bias and reliable confidence intervals of bias for all cases.

Albumins↗

PubMed2000

[Effects of dimensional and social comparisons on ability assessment and satisfaction with performance].

The study deals with the question whether internal dimensional comparisons (comparisons of one's own achievement in a task with one's own achievement in another task) contribute to the development of task-specific self-evaluations. In an experimental study, N = 135 student subjects who had worked on two different types of tasks received manipulated achievement feedback with reference to dimensional and social comparisons. Results indicated the relevance of dimensional comparison information. Subjects scored their own ability and contentment with their result in the first type of task more positively (negatively) when they had received a better (worse) result than in the second task.

Achievement↗

PubMed2000

Protein structure comparison using the markov transition model of evolution.

A number of automatic protein structure comparison methods have been proposed; however, their similarity score functions are often decided by the researchers' intuition and trial-and-error, and not by theoretical background. We propose a novel theory to evaluate protein structure similarity, which is based on the Markov transition model of evolution. Our similarity score between structures i and j is defined as log P(j --> i)/P(i), where P(j --> i) is the probability that structure j changes to structure i during the evolutionary process, and P(i) is the probability that structure i appears by chance. This is a reasonable definition of structure similarity, especially for finding evolutionarily related (homologous) similarity. The probability P(j --> i) is estimated by the Markov transition model, which is similar to the Dayhoff's substitution model between amino acids. To estimate the parameters of the model, homologous protein structure pairs are collected using sequence similarity, and the numbers of structure transitions within the pairs are counted. Next these numbers are transformed to a transition probability matrix of the Markov transition. Transition probabilities for longer time are obtained by multiplying the probability matrix by itself several times. In this study, we generated three types of structure similarity scores: an environment score, a residue-residue distance score, and a secondary structure elements (SSE) score. Using these scores, we developed the structure comparison program, Matras (MArkovian TRAnsition of protein Structure). It employs a hierarchical alignment algorithm, in which a rough alignment is first obtained by SSEs, and then is improved with more detailed functions. We attempted an all-versus-all comparison of the SCOP database, and evaluated its ability to recognize a superfamily relationship, which was manually assigned to be homologous in the SCOP database. A comparison with the FSSP database shows that our program can recognize more homologous similarity than FSSP. We also discuss the reliability of our method, by studying the disagreement between structural classifications by Matras and SCOP.

Databases, Factual↗

PubMed2000

Structure mapping in the comparison process.

Carrying out similarity and analogy comparisons can be modeled as the alignment and mapping of structured representations. In this article we focus on three aspects of comparison that are central in structure-mapping theory. All three are controversial. First, comparison involves structured representations. Second, the comparison process is driven by a preference for connected relational structure. Third, the mapping between domains is rooted in semantic similarity between the relations that characterize the domains. For each of these points, we review supporting evidence and discuss some challenges raised by other researchers. We end with a discussion of the role of structure mapping in other cognitive processes.

Adult↗

PubMed2001

A comparison between different formats of educational feedback to junior doctors: a prospective pilot intervention study.

OBJECTIVES: Audit feedback is conventionally given in the format of an average performance of the department relative to established guidelines. The impersonality of this feedback format may compromise audit outcome. The aim of the study was to compare personal, peer-comparison feedback, an effective method of changing physician practice, to the 'conventional' departmental one. METHODS: Eleven SHOs working at a central London A&E department were audited in terms of the adequacy of their documentation process. The study comprised patients presenting with closed head injury, acute asthma and chest pain of possible cardiac origin. Personal peer-comparison feedback and average departmental feedback was given for the first two groups, respectively. No feedback was given for the chest pain group, acting as a temporal control. The outcome measure was documentation of the minimum variables, as specified by departmental guidelines. RESULTS: The peer-comparison feedback group showed a significant improvement (p-value<0.0001) in two out of three target variables audited, in contrast to the departmental feedback group and the control group which did not show a significant improvement in any of the variables. CONCLUSIONS: Personal, confidential peer-comparison feedback was more effective than departmental feedback, in an audit of process of junior doctors. This pilot study should form the basis of a larger study (more SHOs, wider range of conditions) to establish unequivocally the best format for educational feedback.

Education, Medical, Continuing↗

PubMed2002

When you and I are "we," you are not threatening: the role of self-expansion in social comparison.

Many theories of self-evaluation emphasize the power of social comparison. Simply put, an individual is thought to gain esteem whenever she or he outperforms others and to lose esteem when he or she is outperformed. The current research explored interdependent self-construal as a moderator of these effects. Two studies used a priming task to manipulate the level of self-construal and investigate effects of social comparison in dyadic (Study 1) and group situations (Study 2). Both studies demonstrated that when the target for comparison is construed as part of the self, his or her successes become cause for celebration rather than costs to esteem. Additionally, gender differences in chronic relational and collective self-construals moderated the patterns of social comparison in a form similar to that of priming relational and collective self-construals.

Cooperative Behavior↗

PubMed2003

Quantitative comparisons of cancer induction in humans by internally deposited radionuclides and external radiation.

PURPOSE: To compare quantitative estimates of lifetime cancer risk in humans for exposures to internally deposited radionuclides and external radiation. To assess the possibility that risks from radionuclide exposures may be underestimated. MATERIALS AND METHODS: Risk estimates following internal exposures can be made for a small number of alpha-particle-emitting nuclides. (1) Lung cancer in underground miners exposed by inhalation to radon-222 gas and its short-lived progeny. Studies of residential (222)Rn exposure are generally consistent with predictions from the miner studies. (2) Liver cancer and leukaemia in patients given intravascular injections of Thorotrast, a thorium-232 oxide preparation that concentrates in liver, spleen and bone marrow. (3) Bone cancer in patients given injections of radium-224, and in workers exposed occupationally to (226)Ra and (228)Ra, mainly by ingestion. (4) Lung cancer in Mayak workers exposed to plutonium-239, mainly by inhalation. Liver and bone cancers were also seen, but the dosimetry is not yet sufficiently good enough to provide quantitative estimates of risks. Comparisons can be made between risk estimates for radiation-induced cancer derived for radionuclide exposure and those derived for the A-bomb survivors, exposed mainly to low-LET (linear energy transfer) external radiation. Data from animal studies, using dogs and rodents, allow comparisons of cancer induction by a range of alpha- and beta-/gamma-emitting radionuclides. They provide information on relative biological effectiveness (RBE), dose-response relationships, dose-rate effects and the location of target cells for different malignancies. RESULTS: For lung and liver cancer, the estimated values of risk per Sv for internal exposure, assuming an RBE for alpha-particles of 20, are reasonably consistent with estimates for external exposure to low-LET radiation. This also applies to bone cancer when risk is calculated on the basis of average bone dose, but consideration of dose to target cells on bone surfaces suggests a low RBE for alpha-particles. Similarly, for leukaemia, the comparison of risks from alpha-irradiation ((232)Th and progeny) and external radiation suggest a low alpha RBE; this conclusion is supported by animal data. Risk estimates for internal exposure are dependent on the assumptions made in calculating dose. Account is taken of the distribution of radionuclides within tissues and the distribution of target cells for cancer induction. For the lungs and liver, the available human and animal data provide support for current assumptions. However, for bone cancer and leukaemia, it may be that changes are required. Bone cancer risk may be best assessed by calculating dose to a 50 micro m layer of marrow adjacent to endosteal (inner) bone surfaces rather than to a single 10 micro m cell layer as currently assumed. Target cells for leukaemia may be concentrated towards the centre of marrow cavities so that the risk of leukaemia from bone-seeking radionuclides, particularly alpha emitters, may be overestimated by the current assumption of uniform distribution of target cells throughout red bone marrow. CONCLUSIONS: The lifetime risk estimates considered here for exposure to internally deposited radionuclides and to external radiation are subject to uncertainties, arising from the dosimetric assumptions made, from the quality of cancer incidence and mortality data and from aspects of risk modelling; including variations in baseline rates between populations for some cancer types. Bearing in mind such uncertainties, comparisons of risk estimates for internal emitters and external radiation show good agreement for lung and liver cancers. For leukaemia, the available data suggest that the assumption of an alpha-particle RBE of 20 can result in overestimates of risk. For bone cancer, it also appears that current assumptions will overestimate risks from alpha-particle-emitting nuclides, particularly at low doses.

Animals↗

PubMed2003

Method comparison studies for prostate specific antigen and unconjugated estriol immunoassays.

OBJECTIVE: Method comparison studies were performed in order to move a semi-automated prostate specific antigen (PSA) immunoassay and a manual unconjugated estriol (uE3) immunoassay to an automated chemistry immunoassay analyzer. The results of the two method comparison studies are compared. DESIGN: Serum samples collected on patients with physician orders for PSA or uE3 were assayed by both methods. PSA samples were assayed on a Hybritech Tandem Photon ERA and on two Beckman Coulter Access instruments. UE3 samples were assayed by RIA and on two Beckman Coulter Access instruments. Linear regression analysis was performed on both sets of data and within-run precision and dilution studies were performed on the PSA Access method. SETTING: Clinical chemistry laboratory, West Virginia University Hospitals Inc, Morgantown WV. RESULTS: PSA linear regression analysis for the two methods (ERA and Access 1) were y = 1.0008x + 0.0393, r = 0.9976, SE = 0.1319, n = 37 and (ERA and Access 2), y = 1.0019x + 0.0486, r = 0.9964, SE = 0.1632, n = 37. Within-run precision studies for both Access instruments produced acceptable coefficient variations and dilution study results were in PSA reportable range. uE3 linear regression analysis for the two methods (RIA and Access 1) were y = 1.4105x - 0.3741, r = 0.8696, SE = 0.8330, n = 33 and (RIA and Access 2) were y = 1.315x - 0.2292, r = 0.8643, SE = 0.7964, n = 33. CONCLUSION: The results of the method comparison studies for PSA were acceptable and the automated PSA immunoassay method was adopted. The results of the uE3 comparison studies did not show good correlation; the automated method was not adopted.

Automation↗