PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “method comparison”

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 577 records · Page 32Linked to original sources
PubMed1992

A comparison of methods for sampling the deer tick, Ixodes dammini, in a Lyme disease endemic area.

The purpose of this study was to compare the trapping and examining of mice, drag sampling, and CO2-baited traps for their ability to detect the presence and abundance of immature deer ticks, Ixodes dammini, in a Lyme disease endemic area in southern New York State. Eight study sites were sampled 14 times between 28 May and 31 August by setting 49 live-traps, four CO2-baited traps, and drag sampling 500 m2. A total of 1540 nymphs and 3079 larvae was collected during the study. Drag sampling collected the most nymphs (705), while more larvae were recovered from CO2-baited traps (1105). Comparisons among the methods showed a significant difference in the numbers of both larval and nymphal ticks collected (P less than 0.01). There was a positive correlation between the numbers of nymphs collected by drag sampling and CO2-baited tick traps (rs = 0.83, P less than 0.05), and between the numbers of larvae collected by drag sampling and mouse trapping (rs = 0.75, P less than 0.05). These results suggest that drag sampling would be the single most reliable method for quantitatively sampling immature I. dammini populations in a Lyme disease endemic area.

Analysis of Variance↗
PubMed1998

European multicentre evaluation of the Super Aution SA-4220 urinalysis analyser.

A multicentre evaluation of the urine test strip analyser Super Aution-4220 was carried out in six laboratories. The analytical performance of the instrument with regard to imprecision, linearity, detection limit, drift, carry-over and method comparison was studied. Using the Aution stick 8 test strip the pH, glucose, protein, ketones, bilirubin, blood, urobilinogen and leukocyte esterase were analysed. Specific gravity measurements were performed by refractive index method. Within-run and between-run imprecision determined at three levels of analyte were good. No carry-over was observed. Obtained results were linear through all the described analytical range. No significant drift was detected. Method comparison with some quantitative methods was performed and showed a good correlation with most of the analytes. The study of interferences showed minor interferences by common therapeutic drugs with the measurement of some analytes. During the assessment period of about 6 months no breakdown occurred in any laboratory. The Super Aution urine analyser appeared to be a highly automated analyser of urinary test strips. The operation was simple and the maintenance required only a few minutes a day.

Artifacts↗
PubMed2004

Comparison of three methods of collecting nasal specimens for respiratory virus analysis.

BACKGROUND: Nasopharyngeal aspiration (NPA) is used widely in the collection of nasal specimens for respiratory virus diagnosis. The method has limitations in relation to technical expertise, patient anxiety, and apparatus dependence. Nasal washing (NW) offers an alternative approach. OBJECTIVE: To identify the merits of two different NW methods in comparison with NPA. DESIGN: Two hundred children with acute respiratory infection (ARI) were randomised to receive one of three collection devices: (i) standard NPA, (ii) NW using a 30ml ear-syringe bulb (NWb), or (iii) NW using a 5ml syringe (NWs) with a shortened (9cm) 8FG tube. Assessment focused on ease of procedure, acceptability to parent and child, and adequacy of epithelial cell yield for immunofluorescence testing. A short questionnaire was delivered. SETTING: Paediatric Ward of Kilifi District Hospital, (KDH) Kilifi, Kenya. SUBJECTS: Any child admitted with ARI between 5th November 2001 and 24th January 2002. RESULTS: Children recruited into NPA, NWb and NWs procedures numbered 62, 76 and 62, respectively (median age of 8 months). A higher proportion of children receiving NWb did not cry (43%) compared to those receiving NPA (13%) (OR 5.18; 95% CI 2.17-12.4). Whereas 66% of mothers were comfortable with NPA procedure, the proportion for NWs was 40% (OR 0.341; 0.163-0.714). Acceptability to the operator was marginally lower for NWs than NPA (79% vs 92%, OR 0.324, 0.107-0.974). For other observations there were no differences between the procedures; these were length of procedure (98% <5mins), the acceptable time interval for repeating a procedure (64% <1 week), comparison with blood collection (77% preferred the nasal specimen) and slides with 20 or more epithelial cells (overall 82%). CONCLUSION: Nasal washing methods provide simple and effective alternatives to NPA, with the NWb being the more acceptable, and have merits for use in resource poor and home settings.

Child, Preschool↗
PubMedDate not supplied

Enumeration of total yeasts and molds in foods by the SimPlate Yeast and Mold-Color Indicator method and conventional culture methods: collaborative study.

The relative effectiveness of the SimPlate Yeast and Mold-Color Indicator method (Y&M-CI) was compared to the U.S. Food and Drug Administration's (FDA) Bacteriological Analytical Manual (BAM) method and the proposed International Organization for Standardization (ISO) method, ISO/CD 21527, for enumerating yeasts and molds in foods. Test portions were prepared and incubated according to the conditions stated in both the BAM and ISO methods. Six food types were analyzed: frozen corn dogs, nut meats, frozen fruits, cake mix, cereal, and fresh cheese. Nut meats, frozen fruits, and fresh cheese were naturally contaminated. All other foods were artificially contaminated with either a yeast or mold. Seventeen laboratories throughout North America and Europe participated in the study. Three method comparisons were conducted. In general, there was <0.3 mean log count difference in recovery between the SimPlate method and the 2 corresponding reference methods. Moreover, mean log counts between the 2 reference methods were also very similar. The repeatability (Sr) and reproducibility (SR) standard deviations were comparable between the 3 method comparisons. These results indicate that the BAM method and the SimPlate method are equivalent for enumerating yeast and mold populations in foods. Similarly, the SimPlate method is comparable to the proposed ISO method when test portions are prepared and incubated as defined in the proposed ISO method.

Colony Count, Microbial↗
PubMed1980

[Statistical problems in the comparison of methods of clinical chemical analysis. Report on the workshop conference of the German Society for Clinical Chemistry held on June 28 and 29, 1979 in Hannover (Author's transl)].

Despite published recommendations and experimental protocols for the evaluation of clinical chemical analytical methods, the statistical evaluation of results still leaves many questions unanswered. The purpose of the workshop conference was to produce, and submit to discussion, recommendations for suitable statistical procedures, in particular for the comparison of different analytical methods.

Chemistry, Clinical↗
PubMed2004

Comparison of three methods to estimate the center of mass during balance assessment.

Evaluation of postural control is generally based on the interpretation of the center of pressure (COP) and the center of mass (COM) time series. The purpose of this study is to compare three methods to estimate the COM which are based on different biomechanical considerations. These methods are: (1) the kinematic method; (2) the zero-point-to-zero-point double integration technique (GLP) and (3) the COP low-pass filter method (LPF). The COP and COM time series have been determined using an experimental setup with a force plate and a 3D kinematic system on six healthy young adult subjects during four different 30 s standing tasks: (a) quiet standing; (b) one leg standing; (c) voluntary oscillation about the ankles and (d) voluntary oscillation about the ankles and hips. To test the difference between the COM trajectories, the root mean square (RMS) differences between each method (three comparisons) were calculated. The RMS differences between kinematic-LPF and GLP-LPF are significantly larger than kinematic-GLP. Our results show that the GLP method is comparable to the kinematic method. Both agree with the unified theory of balance during upright stance. The GLP method is attractive in the clinical perspective because it requires only a force plate to determine the COP-COM variable, which has been demonstrated to have a high reliability.

Adult↗
PubMed1980

A direct competitive binding radioimmunoassay for carcinoembryonic antigen.

We have incorporated commercially available CEA standard and antiserum into the triple isotope double antibody radioimmunoassay and we have evaluated this assay for the routine determination of CEA. The competitive protein binding (CPB) assay for CEA can be performed directly on serum or plasma without perchloric acid extraction. The assay sensitivity was 0.98 ng/ml, and the day-to-day precision as defined by the coefficient of variation was 12.5% and 13.3% for mean values of 7.6 and 23.9 ng CEA/ml, respectively. The normal range (X +/- 2 S.D.) for CEA determined with the direct CPB method was 3.2--6.2 ng CEA/ml for non-smokers. The upper limit of normal for smokers was 10.0 ng/ml. A method comparison study (Roche perchloric acid extraction vs. direct CPB) showed excellent agreement between the methods for plasma samples containing less than 20.0 ng CEA/ml. The least square analysis parameters were: N = 116, slope = 1.01, y-intercept = 3.5 ng/ml, Sy/x -2.05 ng/ml, and the correlation coefficient was 0.79. Recovery and dilution studies showed no demonstrable non-specific interference due to serum proteins in the direct CPB assay. The clinical significance of the direct CPB assay for CEA was assessed by correlating serial CEA values with the clinical status of patients with breast and colorectal cancer. Increasing CEA values correlated with progressive or recurrent neoplastic disease, and decreasing CEA values correlated with response of the patient to therapy. No false positive direct CPB values for CEA were observed in the clinical study or in the method comparison study. Our laboratory and clinical evaluation demonstrate that the direct CPB method is an accurate and reliable method for the quantitation of CEA. In addition, the method permits high volume analysis and eliminates the hazards to safety that are associated with perchloric acid.

Binding, Competitive↗
PubMed1982

A comparison of methods for the estimation of microbial nitrogen in duodenal digesta of sheep.

1. Six sheep, each fitted with a rumen cannula and re-entrant cannulas in the proximal duodenum and distal ileum, were given two diets (600 g dry matter (DM)/d) consisting of either grass silage (32.1 g nitrogen/kg DM) or dried grass (18.3 g N/kg DM). A net loss of N occurred between mouth and duodenum with the silage diet, indicating extensive ruminal degradation of dietary N, compared with a net gain on the dried-grass diet. Consequently, despite higher N intakes when silage was given, N flow at the duodenum was similar for both diets. 2. The proportion of microbial N in duodenal digesta N was estimated using diaminopimelic acid (DAPA), [35S]methionine (35S), 15N-enriched non-ammonia-N (15NAN) and amino acid profiles (AAP) as microbial markers. Isotopic labelling of rumen micro-organisms was achieved by intraruminal infusions of Na2 35SO4 and (15NH4)2SO4. 3. A comparison of all methods was made based on the marker concentrations in microbial fractions isolated by differential centrifuagation of strained rumen contents. With both diets, DAPA gave the highest estimates and AAP the lowest. Estimates based on 35S and 15NAN were intermediate and did not differ significantly (P greater than 0.05). 4. For the 15NAN, 35S and AAP methods, the effect of site of sampling of the microbial fraction, i.e. from rumen contents or duodenal digesta, was examined and in all instances mean estimates based on duodenally-derived microbes were higher. However, the differences were significant for only 15NAN with both diets (P less than 0.001), for 35S with the dried grass (P less than 0.05), and for AAP with the silage (P less than 0.05). Estimates based on duodenally-derived microbes were higher (P less than 0.05) using 15 NAN than those obtained using 35S with both diets. 5. Depending on the method used for estimating microbial N, estimates of the efficiency of microbial N synthesis in the rumen (g microbial N flow at duodenum/kg organic matter apparently digested in the rumen) ranged between 16 and 38 for the silage diet and 10 and 46 for the dried grass diet. Similarly, estimates of feed N degradability in the rumen ranged between 0.62 and 0.97 for the silage and 0.00 and 0.93 for the dried grass.

Amino Acids↗
PubMed1986

Optimal detection of the progression of coronary artery disease: comparison of methods suitable for risk factor intervention trials.

To assess the best method of quantitating progression of coronary disease, we studied four measurements in 114 coronary segments from 35 medically treated patients from whom angiograms were obtained 5 years apart. Only stenoses of less than 70% that were visualized in nearly identical projections on both angiograms were evaluated. Vessel edges were measured by use of catheter calibration and an automated computer algorithm yielding two "absolute dimensions" (mean and minimum diameters) and two measurements (percent stenosis and atheroma area) that required a "normal reference" diameter. The coefficient of variation for repeated segment measurements was less for mean and minimum diameter than for percent stenosis and area of atheroma. The best measure of progression of coronary disease as determined by t test comparison of different methods was the change in mean diameter over time (6.7 +/- 14.1% decrease), whether calculated on a per coronary segment or per patient basis (p less than .001). Based on this measurement and its standard deviation of progression of coronary disease in this patient subset with relatively benign disease, it is estimated that 470 patients per group would be required for an interventional study to demonstrate a 33% reduction in disease progression (207 patients for 50% reduction) at a 95% confidence level and 90% power.

Cardiac Catheterization↗
PubMed1983

[Comparison of clinical methods for the demonstration of radiation-induced lung changes. Experimental study on animals].

The purpose of this study was to compare the value of different imaging methods (radiography, computer tomography and scintigraphy) for demonstrating pulmonary fibrosis or radiation pneumonitis. The right lungs of 50 rabbits were irradiated with 3200 to 6200 rd. The lung changes were observed by the above methods over a period of 13 weeks. Histological examination served as the basis for evaluating the imaging methods. The comparison demonstrated the superiority of computer tomography when density measurements were included in the diagnostic criteria. The accuracy was about 95%. Scintigraphy was inferior to computer tomography as a quantitative method, using differences in the counts per unit area. Radiology as a subjective method achieved an accuracy of about 84%, approximately the same as scintigraphy.

Animals↗
PubMed2001

Radiation therapy for superficial esophageal cancer: a comparison of radiotherapy methods.

PURPOSE: A comparison of treatment outcomes in response to various methods of radiotherapy for superficial esophageal cancer (SEC) was carried out for a large series of patients. METHODS AND MATERIALS: During the period from March 1987 to November 1998, 147 patients with superficial esophageal cancer received definitive radiation therapy at nine radiotherapy institutions in Japan. Fifty-five patients were treated with external radiation therapy alone, 69 with high-dose-rate intracavitary radiation therapy with or without external radiation therapy, and 23 with low-dose-rate intracavitary radiation therapy and external radiation therapy. RESULTS: The 5-year survival rates for mucosal and submucosal cancer patients were 62% and 42%, respectively. The 5-year cause-specific survival rates for mucosal and submucosal cancer patients were 81% and 64%, respectively (p = 0.013). There was no statistically significant difference in the survival rates for either mucosal or submucosal cancer patients between treatment groups. Metastasis was observed only in submucosal cancer patients. Esophageal ulcers developed only in patients who received intracavitary radiation therapy, and were especially common in patients treated with a fraction size of 5 Gy or more. CONCLUSIONS: The use of intracavitary radiation therapy does not influence the survival or local control rate of SEC. Optimal radiotherapy methods for SEC should be determined by a randomized clinical trial.

Adult↗
PubMed1992

Supercritical fluid extraction of polychlorinated biphenyls and pesticides from soil. Comparison with other extraction methods.

A comparison is made of supercritical fluid extraction (SFE) with two other techniques widely used for the extraction of polychlorinated biphenyls (PCBs) and organochlorine pesticides in soil. Extraction conditions for the SFE of PCBs and pesticides were first determined. An experimental approach was set up to determine the influence of different extraction parameters such as pressure, extraction time, static and dynamic extraction, restrictor type and collection solvent for off-line SFE. The use of carbon dioxide at 50 degrees C and 20 MPa, 10 min static followed by 20 min dynamic extraction with collection in iso-octane were been found to be the optimum conditions. Two types of soil, with a low and high content of organic carbon, respectively, spiked with 16 PCBs and organochlorine pesticides with a wide range of volatility and polarity at a level of 5 ng/g dry matter, were used as test materials. Conventional solvent extraction gives a good extraction yield for soil with a low content of organic carbon, but for peat soil the recoveries decrease dramatically to 30% for DDE, DDT and PCB 138 and 153. The recoveries with Soxhlet extraction are good, but an extra clean-up step before analysis is necessary. SFE gives good extraction yields for PCBs and organochlorine pesticides, varying between 85 and 105% with a reproducibility of 5% for each component for both types of soil. SFE is a fast, clean and reproducible method for the extraction of PCBs and organochlorine pesticides from these two soil matrices.

Carbon↗
PubMed2004

Using nuclear morphometry to discriminate the tumorigenic potential of cells: a comparison of statistical methods.

Despite interest in the use of nuclear morphometry for cancer diagnosis and prognosis as well as to monitor changes in cancer risk, no generally accepted statistical method has emerged for the analysis of these data. To evaluate different statistical approaches, Feulgen-stained nuclei from a human lung epithelial cell line, BEAS-2B, and a human lung adenocarcinoma (non-small cell) cancer cell line, NCI-H522, were subjected to morphometric analysis using a CAS-200 imaging system. The morphometric characteristics of these two cell lines differed significantly. Therefore, we proceeded to address the question of which statistical approach was most effective in classifying individual cells into the cell lines from which they were derived. The statistical techniques evaluated ranged from simple, traditional, parametric approaches to newer machine learning techniques. The multivariate techniques were compared based on a systematic cross-validation approach using 10 fixed partitions of the data to compute the misclassification rate for each method. For comparisons across cell lines at the level of each morphometric feature, we found little to distinguish nonparametric from parametric approaches. Among the linear models applied, logistic regression had the highest percentage of correct classifications; among the nonlinear and nonparametric methods applied, the Classification and Regression Trees model provided the highest percentage of correct classifications. Classification and Regression Trees has appealing characteristics: there are no assumptions about the distribution of the variables to be used, there is no need to specify which interactions to test, and there is no difficulty in handling complex, high-dimensional data sets containing mixed data types.

Adenocarcinoma↗
PubMed2000

Assessment of visually lossless irreversible image compression: comparison of three methods by using an image-comparison workstation.

PURPOSE: To determine the degree of irreversible image compression detectable in conservative viewing conditions. MATERIALS AND METHODS: An image-comparison workstation, which alternately displayed two registered and magnified versions of an image, was used to study observer detection of image degradation introduced by irreversible compression. Five observers evaluated 20 16-bit posteroanterior digital chest radiographs compressed with Joint Photographic Experts Group (JPEG) or wavelet-based trellis-coded quantization (WTCQ) algorithms at compression ratios of 8:1-128:1 and x2 magnification by using (a) traditional two-alternative forced choice; (b) original-revealed two-alternative forced choice, in which the noncompressed image is identified to the observer; and (c) a resolution-metric method of matching test images to degraded reference images. RESULTS: The visually lossless threshold was between 8:1 and 16:1 for four observers. JPEG compression resulted in performance as good as that with WTCQ compression at these ratios. The original-revealed forced-choice method was faster and as sensitive as the two-alternative forced-choice method. The resolution-metric results were robust and provided information on performance above visually lossless levels. CONCLUSION: The image-comparison workstation is a versatile tool for comparative assessment of image quality. At x2 magnification, images compressed with either JPEG or WTCQ algorithms were indistinguishable from unaltered original images for most observers at compression ratios between 8:1 and 16:1, indicating that 10:1 compression is acceptable for primary image interpretation.

Algorithms↗
PubMed2004

Performance characteristics of five automated serum cortisol immunoassays.

BACKGROUND: Serum cortisol measurements are used to help diagnose conditions of cortisol deficiency and excess. Automated, nonisotopic immunoassays are used in most clinical laboratories. METHODS: Linearity, imprecision, and method comparison studies for serum cortisol assays were performed with the Access, Advia Centaur, AxSYM, Elecsys 2010, and IMMULITE 2000 analyzers. RESULTS: All methods demonstrated acceptable linearity with the AxSYM method showing the least deviation from target values. The Elecsys 2010 method was the most precise for all three levels of quality control material. Method comparison studies demonstrated good concordance among methods except for two patient samples that gave results on the Elecsys 2010 that were significantly higher than the other methods. Differences in assay calibration were observed. CONCLUSIONS: Overall, all methods performed well. Additional calibration standardization efforts are required to truly harmonize the results from each assay. The Elecsys 2010 method is less specific than other automated methods based on two discordant patient results.

Autoanalysis↗
PubMedDate not supplied

Serum creatinine determination by high performance liquid chromatography and five automated chemistry analyzers.

A sensitive and specific procedure is described for the determination of serum creatinine by reverse phase high performance liquid chromatography. The method involves sample pretreatment with a cation exchange resin followed by the isocratic separation of creatinine and an external standard which are detected by their absorbances at 254 nm. The analytical recovery of creatinine from serum was 99.8 +/- 4.9 percent using this method. The between-day coefficients of variation for creatinine concentrations of 0.83 and 8.63 mg per dl were 3.07 percent and 3.2 percent, respectively. Results obtained with this reference method were compared to results obtained with five automated chemistry analyzers. The results showed that while the comparison methods correlated well with the reference method (r greater than 0.98 in all cases), those comparison methods based on the Jaffe reaction showed negative biases. In some cases, these biases were highly statistically significant. The difference between paired results obtained with some of the automated Jaffe-based assays exceeded 0.20 mg per dl in a substantial number of specimens with creatinine concentration in the range of 0.5 to 2.3 mg per dl. The measurement of acetoacetate concentrations of specimens submitted to our laboratory for serum creatine assays showed that interference by this substance with certain Jaffe-based assays could result in clinically significant false elevations in serum creatinine concentrations.

Acetoacetates↗