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Comparison of five automated serum and whole blood folate assays.

Serum and whole blood folate measurements are used to establish folate deficiency. Most methods used in clinical laboratories are automated, nonistopic methods that use folate-binding protein. Linearity, imprecision, and method comparison studies, including serum and whole blood hemolysates, were performed with the Access, Advia Centaur, ARCHITECT i2000, Elecsys 2010, and IMMULITE 2000 methods. The QuantaPhase II radioassay served as the comparison method. (Proprietary information is given in the text.) The Access and IMMULITE 2000 methods had higher systematic errors in linearity studies than the other 3 methods. The imprecision of all methods was acceptable (coefficient of variation, < 10%) even at low folate concentrations with the exception of the Elecsys 2010 (coefficient of variation, 16%). Method comparison studies using serum samples revealed calibration differences between the Access and Elecsys 2010 methods and the comparison method. Method comparison studies using whole blood samples showed poorer agreement between each of the automated methods and the comparison method than was seen with serum samples. The ARCHITECT i2000 folate assay demonstrated the best analytic performance. The poor agreement seen with whole blood hemolysates likely is due to calibration differences and differences in hemolysate preparation conditions.

Blood Chemical Analysis↗

Moderating variables in the relationship between social comparison and depression: an evolutionary perspective.

This study investigated the relationship between social comparison and depression utilizing an evolutionary framework. It investigated the moderating effects on social comparison of the importance of comparison dimensions to the person, and of the perceived importance of the dimensions to other people. An adaptation of a measure of self-esteem (Self Attributes Questionnaire; Pelham & Swann, 1989) was utilized. This consisted of 10-point Likert scale ratings on 10 individual social comparison dimensions (e.g. intelligence, social skills, sense of humour). Questions were added to explore beliefs regarding the importance of social comparison dimensions. Data were collected from a combined clinical sample and non-clinical sample of 174 people. The findings support the prediction that the relationship between social comparison on a particular dimension and depression is moderated by the perceived importance of that dimension in attracting the interest of others.

Adolescent↗

Accuracy of memory for brightness of colored lights measured with successive comparison method.

Successive and simultaneous brightness comparisons between test colors and a comparison white were performed to study how accurately the brightness of colored lights was maintained in memory. The test colors were monochromatic lights chosen from 410 to 670 nm and a white light. The stimulus duration was 1 sec, and test-comparison stimulus-onset asynchronies in successive comparisons were more than 11 sec depending on the experiments. The results show that the variability of successive brightness comparisons was 1.5-2.0 times greater than that of simultaneous brightness comparison. This degree of deterioration of brightness discrimination is reasonably consistent with those of hue and saturation discrimination previously reported. Brightness shifts in the darker direction were found for most colors.

Color Perception↗

A comparison of the cost-effectiveness of five strategies for the prevention of non-steroidal anti-inflammatory drug-induced gastrointestinal toxicity: a systematic review with economic modelling.

OBJECTIVES: To assess the relative effectiveness, patient acceptability, costs and cost-effectiveness of four strategies for the prevention of non-steroidal anti-inflammatory drugs (NSAIDs)-induced gastrointestinal (GI) toxicity: (1) Cox-1 NSAIDs plus histamine-2 receptor antagonist (H2RA), (2) Cox-1 NSAIDs plus proton pump inhibitors (PPIs), (3) Cox-1 NSAIDs plus misoprostol, and (4) Cox-2 NSAIDs (later expanded to 4a Cox-2 coxibNSAIDs and 4b Cox-2 preferential NSAIDs). DATA SOURCES: Electronic databases up to May 2002. REVIEW METHODS: Relevant studies were selected, assessed and analysed. Pooled relative risk ratios (RR) from the systematic review were combined with up-to-date UK resource use and unit costs data in an incremental economic analysis. A probabilistic decision-analytic model was designed and populated with data to carry out incremental economic analysis. Incremental cost-effectiveness ratios (ICERs) were generated for the outcome measure, endoscopic ulcer or serious GI event averted, against total cost, and non-parametric bootstrapping was used to simulate variance of these ICERs. RESULTS: Of 118 selected trials, including 125 relevant comparisons (which included 76,322 participants) only 138 deaths and 248 serious GI events were reported. Seven comparisons were judged to be at low risk of bias. Comparing the gastroprotective strategies against placebo, there was no evidence of effectiveness of H2RAs against any primary outcomes (few events reported), PPIs may reduce the risk of symptomatic ulcers [RR 0.09, 95% confidence interval (CI) 0.02 to 0.47], misoprostol reduces the risk of serious GI complications (RR 0.57, 95% CI 0.36 to 0.91) and symptomatic ulcers (RR 0.36, 95% CI 0.20 to 0.67), Cox-2 'preferentials' reduce the risk of symptomatic ulcers (RR 0.41, 95% CI 0.26 to 0.65) and Cox-2 'coxibs' reduce the risk of symptomatic ulcers (RR 0.49, 95% CI 0.38 to 0.62) and possibly serious GI events (RR 0.55, 95% CI 0.38 to 0.80). All strategies except Cox-2 'preferentials' reduce the risk of endoscopic ulcers. There were only 12 direct comparisons between gastroprotective strategies. All they suggest is that Cox-2 preferentials are better than misoprostol for preventing GI complications. Indirect comparisons suggested that PPIs may prevent symptomatic ulcers better than Cox-2 coxibs, but this is very weak evidence. For prevention of endoscopic ulcers PPIs and misoprostol appear more successful than H2RAs and misoprostol is better than Cox-2 preferentials. There were no UK head-to-head published economic analyses with regard to the main gastroprotective strategies. There were generally insufficient data with regards to cardiac or renal outcomes, serious GI outcomes or life-years gained to populate the mode. Mean (2.5th and 97.5th percentile) costs per endoscopic ulcer averted compared with Cox-1 NSAIDs alone were as follows: Cox-1 plus H2RAs, -186 pounds (-555 to 804); Cox-1 plus PPIs, 454 pounds (251 to 877); Cox-1 plus misoprostol, 54 pounds (-112 to 238); Cox-2 selective NSAIDs, 263 pounds (-570 to 1280), or Cox-2 specific NSAIDs, 301 pounds (189 to 418). With regard to the prevention of endoscopic ulcers, Cox-1 NSAID plus H2RA is a dominant option. Cost-effectiveness acceptability analysis showed a 95% probability that this combination was less costly and more effective. Cost-effectiveness acceptability frontiers showed that if the decision-maker is willing to pay up to 750 pounds to avoid an endoscopic ulcer, then Cox-1 plus H2RA is the optimal strategy. If the decision-maker is willing to pay over 750 pounds, the optimal strategy is NSAID plus misoprostol. Between 1900 pounds and 3750 pounds, Cox-2 selective inhibitors are optimal, and over 3750 pounds, Cox-2 specific inhibitors become optimal. NSAID plus PPI is never the optimal strategy. Sensitivity and subgroup analyses suggest that Cox-1 NSAID plus H2RA and Cox-1 NSAID plus misoprostol become more cost-effective in the older age group. Some conclusions were associated with high levels of uncertainty. CONCLUSIONS: Although there is a very large body of evidence comparing Cox-2 NSAIDs with Cox-1 NSAIDs, this is not matched by studies of the other types of gastroprotectors or by studies directly comparing active gastroprotective strategies. This lack of direct comparisons led to the use of indirect comparisons to help understand the relative efficacy of these strategies. Indirect evidence in itself is weak and was also hampered by lack of evidence in the underlying studies (where the gastroprotectors were compared with placebo). Economic modelling suggests that Cox-1 NSAID plus H2RA or Cox-1 NSAID plus PPI are the most cost-effective strategies for avoiding endoscopic ulcers in patients requiring long-term NSAID therapy. All strategies other than Cox-2 selective inhibitors reduce the rate of endoscopic ulcer compared with Cox-1 alone. The economic analysis suggests that there may be a case for prescribing H2RAs in all patients requiring NSAIDs. Misoprostol is more effective, but is associated with a greater cost and GI side-effects which may be unacceptable for patients. However, when assessing serious GI events, the economic analysis is sufficiently weakened by the data available as to render clear practice recommendations impossible. Further large, independent RCTs directly comparing various gastroprotective strategies are needed. These should report items such as major outcomes, primary data, adverse events, assessment of practice and patient preference.

Anti-Inflammatory Agents, Non-Steroidal↗

Similar mechanisms underlie curvature comparison by static and dynamic touch.

In four experiments, we tested whether haptic comparison of curvature ranging from -4/m to +4/m is qualitatively the same for static and for dynamic touch. In Experiments 1 and 3, we tested whether static and dynamic curvature discrimination are based on height differences, attitude (slope) differences, curvature differences, or a combination of these geometrical variables. It was found that both static and dynamic hepatic curvature discrimination are based on attitude differences. In Experiments 2 and 4, we tested whether this mechanism leads to errors in the comparison of stimuli with different lengths for static and dynamic touch, respectively. If the judgments are based on attitude differences, subjects will make systematic errors in these comparisons. In both experiments, we found that subjects compared the curvatures of strips of the same length vertically, whereas they made systematic errors if they were required to compare the curvatures of strips of different lengths. Longer stimuli were judged to be more curved than shorter stimuli with the same curvature. We conclude that similar mechanisms underlie static and dynamic haptic curvature comparison. Moreover, additional data comparison showed that static and dynamic curvature comparison is not only qualitatively, but also quantitatively similar.

Humans↗

[Analysis of paired comparison data based on experimental design: expression using structural equation modeling].

Paired comparison is a useful method for assessing ranks among several objects, and it enables us to obtain more reliable data than assessing objects one by one. But paired comparison principally provides information only about the ranks of the objects. On the other hand, experimental design provides a framework for elucidating causal associations. If we could analyze paired comparison data by the experimental design framework, it would be a very effective method. But experimental design, in its original form, is not readily applicable to paired comparison data. However, if we adopt the perspective of structural equation modeling (SEM), we can deal with paired comparison and experimental design in a unified way, because they are both submodels of SEM. The purpose of this study is to provide a new method to analyze causal connection of paired comparison data by using SEM. Here, two actual numerical examples are shown, one of which is obtained by within-subject design and the other is obtained by between-subject design.

Humans↗

Comparison of subjective sleep quality in patients with cancer and healthy subjects.

PURPOSE/OBJECTIVES: To compare the subjective sleep quality of a group of patients with cancer undergoing treatment and a normative sample of healthy comparison subjects. DESIGN: Secondary analysis of data from a single time point in a repeated measures descriptive-correlational study. SAMPLE/SETTING: Convenience sample of 15 patients with cancer receiving antineoplastic therapy and admitted to a tertiary university medical center for fever or neutropenia and 52 healthy comparison subjects without sleep disturbances. Although both groups were of similar age, a higher percentage of men comprised the comparison group. METHODS: Patients completed the Pittsburgh Sleep Quality Index (PSQI) on the first day of hospitalization to reflect their perceptions of sleep for the month prior to hospitalization. Healthy comparison subject scores on the PSQI were obtained from a published report outlining psychometric properties of the PSQI (Buysse, Reynolds, Monk, Berman, & Kupfer, 1989). MAIN RESEARCH VARIABLES: Sleep latency, sleep duration, sleep efficiency, sleep disturbances, medication use, daytime dysfunction, and global sleep quality. FINDINGS: Patients with cancer reported significantly poorer overall sleep quality accompanied by more daytime dysfunction. The incidence of specific sleep disturbances, such as snoring and dyspnea, was not different between the groups. CONCLUSIONS: This small sample of patients reported significantly poorer sleep quality than an historical comparison group. Specific sleep disturbances commonly seen in the general population were not problematic for the patients with cancer. Limited sample size and use of an historical comparison group need to be considered in interpreting and applying these findings. Additional research is needed to further characterize the nature of sleep problems in patients with cancer. IMPLICATIONS FOR NURSING PRACTICE: Nurses need to assess sleep in their patients, including its impact on quality of life and functional status.

Adult↗

[Neighborhood comparison of Cryptomeria fortunei plantation by using different variables].

Neighborhood comparison is defined as the proportion of the nearest greater neighbors to a given reference tree measured by a certain variable. By this way, the dominant differentiation degree of individual wood could be measured well. In this paper, the variables DBH, biomass, canopy breadth, and tree height were used to make the neighborhood comparison of Cryptomeria fortunei plantation in Chongzhou forest farm. The results showed that the neighborhood comparison measured by DBH and biomass had a slight fluctuation range and the highest reliability. Nevertheless, due to the effects of various tree types, the neighborhood comparison measured by canopy breath and tree height was not as reliable as that measured by the former two variables. The average value of the neighborhood comparison measured by DBH and biomass was visibly higher than that by canopy breath and tree height, indicating that the differentiation degree of individual's DBH and biomass was further greater than that of individual's canopy breath and tree height. It was possible that increasing individual's DBH to enhance its biomass, and thus, to achieve its predominance status among individuals' competition was the main strategy of individual's differentiation. Neighborhood comparison should also be taken as an instructive reference in modifying the spatial structure of stand.

Biomass↗

Method comparison of cardiac marker assays on PATHFAST, StratusCS, AxSYM, Immulite 2000, triage, elecsys and cardiac reader.

The purpose of this evaluation was to perform a method comparison of the assays for cardiac troponin I (cTnl), CK-MB, myoglobin, and NT-proBNP on the automated PATHFAST Immuno-Assay Analyzer with respective immunoassays on other commercially available immunoanalyzers. The PATHFAST assays are immunochemiluminescent assays (in single reagent cartridges) employing two mono- or polyclonal antibodies in a sandwich test format. The calibration materials for cTnI and CK-MB are standardized to the reference materials NIST SRM 2921 (troponin CIT complex) and IRMM-IFCC 455 (CK-MB mass). The PATHFAST assays for cTnI, CK-MB, myoglobin, and NT-proBNP on the PATHFAST Analyzer were compared using 118 (NT-proBNP: 90) plasma samples from patients with different cardiovascular diseases with those on the Dade Behring StratusCS Analyzer, on the Abbott AxSYM System, on the DPC IMMMULITE 2000 Analyzer, on the Biosite Triage Meter Plus System, on the Roche Elecsys Immuno Analyzer 2010 and Roche Cardiac Reader System, respectively. The correlation coefficients for the comparison of cTnI methods ranged from 0.953 to 0.982, those for the comparison of myoglobin methods ranged from 0.776 to 0.992, and those for the comparison of CK-MB methods ranged from 0.835 to 0.999, with the Triage System giving in all comparisons the lowest correlation. Also the comparison of PATHFAST NTproBNP against the Roche Elecsys assay yielded a very good correlation (r = 0.992). The slopes of the regression line among methods showed considerable variation indicating that standardization efforts by international groups are indispensable to achieve harmonization of results. In summary, this evaluation study confirms the overall good correlation of the results obtained with assays for cardiac markers developed on the PATHFAST analyzer with those on other immunoassay platforms and thus the analytical reliability of the developed methods.

Automation↗

Comparison groups in research on families with mentally retarded members: a methodological and conceptual review.

A review and critique of the use of comparison groups in mental retardation family research was provided. Issues addressed include matching on age versus competency of the mentally retarded family member, description of comparison groups in published research, demographic equivalence of groups, matching strategies, populations from which samples were drawn, appropriateness of tasks/instruments across groups, and the role of theory in comparison group selection. Unique concerns relating to sibling research and studies of mentally retarded parents were discussed. Caution was expressed concerning the translation of comparison research findings into intervention targets for families with mentally retarded members. Alternatives to comparison group designs were presented as well as recommendations for selecting and describing comparison samples.

Adolescent↗

Mentally retarded children's abilities in the process of comparison.

Mentally retarded children were asked to make various types of comparisons between sets and subsets of objects. Results showed that they succeeded when the comparison involved numerically unequal subsets of objects within the same set. When sets, or subsets, were numerically equal, the children clearly failed; instead of rejecting both alternatives in the comparison question, they selected one. With other comparisons, within and between sets and subsets of objects, the children guessed at an answer, and there was a tendency to answer in accordance with the most recently uttered part of the comparison question. These results indicate that although retarded children are thoroughly acquainted with certain aspects of language and its use in the process of comparison, other important aspects have yet to be learned.

Adolescent↗

Evaluation and comparison of blood pressure profiles of Pakistani cohort of children.

OBJECTIVE: To determine the blood pressure profile of children in Metroville, a lower middle class urban community of Karachi, Pakistan, and compare it to Pakistan National Health Survey of children. DESIGN: A research survey. PLACE AND DURATION OF STUDY: The study was conducted by National Institute of Cardiovascular Diseases, Karachi from 1996 2002. SUBJECTS AND METHODS: The blood pressure data was generated at the base line examination of MHS and was used to define the BP profile of urban Metroville children, age 2-17 years. Similar data of Pakistan National Health Survey (PNHS) undertaken by Pakistan Medical Research Council (PMRC), was used for comparison. RESULTS: A comparison of the blood pressure profile of the MHS with that of the PMRC showed that blood pressure was lower in the MHS. Additionally, comparison of the PMRC profile with USA data showed higher diastolic pressure in the PMRC. Comparison of Pakistani profiles with European data also showed higher blood pressure in Pakistani children. CONCLUSION: It is concluded that the MHS represents the BP profile of children in newly emerging lower middle class urban communities in Pakistan. PMRC data represents national average and can be used to define the blood pressure characteristics of urban communities similar to Metroville. The comparison with affluent countries highlighted the urgent need for community based preventive programs to combat hypertensive diseases in Pakistan.

Adolescent↗

Multiple method comparison: statistical model using percentage similarity.

BACKGROUND: Method comparison typically determines how well two methods agree. This is usually performed using the difference plot model, which measures absolute differences between two methods. This is often not applicable to data with wide ranges of absolute values. An alternative model is introduced that simplifies comparisons specifically for multiple methods compared to a gold standard. METHODS: The average between a new method and the gold standard is represented as a percentage of the gold standard. This is interpreted as a percentage similarity value and accommodates wide ranges of data. The representation of the percentage similarity values in a histogram format highlights the accuracy and precision of several compared methods to a gold standard. The calculation of a coefficient of variation further defines agreement between methods. RESULTS: Percentage similarity histograms of several new methods can be compared to a gold standard simultaneously, and the comparison easily visualized through use of a single 100% similarity reference line drawn common to all plots. CONCLUSION: This simple method of comparison would be particularly useful for multiple method comparison and is especially applicable for centers collating for external quality assessment or assurance programs to demonstrate differences in results between laboratories.

Biometry↗

A comparison of the acute toxicity of chemicals to fish, rats and mice.

The acute toxicity of chemicals to rainbow trout, as shown by intraperitoneal injections (IP LD50), oral dosing (oral LD50) and aqueous exposure (LC50) was compared with published values for IP LD50S and oral LD50S of mice and rats. The method of comparison was by simple linear regression analyses of log-transformed data, modified to recognize that X (fish toxicity) was neither fixed nor measured without error. Within-species comparisons demonstrated very strong linear correlations (r = 0.866-0.998) between IP and oral LD50S. Variability was least for the fish data since it was all generated in one laboratory. Comparisons between species of IP and oral LD50S gave correlation coefficients ranging from 0.59 to 0.95 with the majority over 0.80. Correlations were best (r = 0.83-0.94) between fish LD50S and rat and mice IP LD50S. Correlations were poorest between fish and mammalian oral LD50S (r = 0.59-0.66) because the sample sizes and the ranges of values were very small. In all cases, the slopes were close to, or equalled, 1.0. Comparisons of fish LC50S to fish or mammalian LD50S were not as successful. Correlation coefficients ranged from 0.19 to 0.83. Presumably the cause was the aqueous exposure. Interactions of the chemicals with water (e.g. dissociation) and with lipid membranes (partitioning) should cause considerable variations in uptake efficiency. However, adjustments of LC50S for dissociation constants and partition coefficients did not improve these correlations, probably because there were few chemicals for which all data were available. These comparisons demonstrate a potential for a wider use of surrogate species in toxicity testing and for adapting existing data from mammalian toxicology to aquatic hazard assessments.

Animals↗

Monitoring data quality through comparisons between data systems.

Since its creation in 1960, the National Center for Health Statistics (NCHS) has placed a high value on the quality of the information and statistics collected and published by its data systems. An important component of a comprehensive data quality monitoring system for a statistical agency such as NCHS is the comparison of statistics between data systems. Between-data-systems comparisons are used to monitor the consistency and comparability of statistics across data systems and between NCHS data systems and outside sources of data. This paper focuses on between-data-systems comparisons and describes a number of methodological analyses that can be used to evaluate data quality. The methodological analyses presented include the evaluation of time trends, the estimation of survey method effects, the evaluation of response error, the measurement of definitional and concept effects, and the detection of inconsistencies between data systems. The paper concludes with a discussion of the complexities of the between-data-systems comparisons and an assessment of the net benefits from such comparisons.

Data Collection↗

Blank comparison analysis of emergent symbolic mapping by young children.

Eight typically developing children first learned to select pictures in response to dictated words in a three-choice matching-to-sample format. Next, the matching-to sample baseline was transformed via a stimulus control shaping procedure: Matching trials displayed two pictures and a third stimulus (termed a "blank" comparison). The blank was to be selected if the dictated sample did not match either of the displayed pictures. The blank comparison baseline was then used to evaluate the children's response to matching displays that presented novel sample and comparison stimuli. The blank comparison method permitted the children to indicate whether the novel sample-comparison pair were related (by selecting the picture) or not related (by selecting the blank). The method was used to evaluate emergent symbolic mapping and learning of new word:picture matching relations by the children. This study illustrates new, potentially more informative methods for analyzing symbol mapping in young children. The methods were shown to have considerable promise for advancing theoretical analyses of emergent mapping in both behavior analytic and developmental language research.

Association Learning↗

A qualitative comparison of two contrast media for cerebral angiography. A clinical method.

A qualitative comparison of two contrast media for cerebral angiography with regard to contrast should, preferably, be based on a comparison made in two different hemispheres of one patient. Two problems then arise which made evaluation difficult. Vasodilation occurs after the first contrast injection as a result of which the second contrast medium to be compared flows into a dilated vascular tree. In addition, in the case of a comparison in two different hemispheres, variations of image geometry occur, resulting in differences of sharpness and contrast. The method of solving these problems is discussed and is illustrated by a comparison of two contrast media which might be expected to produce differences in contrast because of their physical properties. The results of this clinical comparison show that the expected differences can be partly demonstrated.

Adolescent↗

[Shower-bath and its influence on the behaviour of the aerobic resident flora of the human skin. Half-side comparisons between a single shower bath with and without bath supplements (author's transl)].

A method for the in vivo investigation of shower-bath supplements and their influences on the human skin flora is presented. The shower-bath supplement is added in a constant dosis directly to the shower-jet to obtain constant conditions of shower-bathing on the human skin. Different concentrations of the shower-bath supplement in neighboured areas of the skin can be avoided and this allows to make comparative investigations of the effect of shower-bath supplements to the normal human skin flora. The reproducibility of the results and the accuracy of the method were investigated in half-side comparisons of the aerobic resident flora of the flexor sides of the forearms in three groups of volunteers, 60 persons in total. A marketable product in two slightly differing modificatons was used as shower-bath supplement. Half-side comparisons between each of the two supplements against water alone and between the shower-bath supplements directly were performed. The detergent washing method was used for sampling the skin flora. Statistically significant changes of the aerobic resident flora in the half-side comparison between the two supplements were obvious only 24 h after a single bath. It could be proved that the results can be reproduced at different times and with different groups of vlunteers. Further more, that a half-side comparison between th two shower-bath supplements detects more sensible differences in the effect on the human skin flora of the two marketable products than the comparison of each supplement with water alone.

Adult↗