Abdominal aortic aneurysm measurement: a critique of methods for comparison studies.
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Aorta, Abdominal↗
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Results for “method comparison”
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A method for comparison of biomedical publication quality across ISI discipline categories.
The purpose of this paper is to offer a method to help to objectively compare quality of publication in biomedical journals in different disciplines with varying ISI Impact Factors (IF). Three methods--the number of journals per ISI Journal Citation Report discipline category/10, the IF/10, and the log (IF+1)/10--were used to calculate an article score. The distribution of article scores were compared across three defined ISI discipline categories: two clinical categories, dentistry (ISI category--dentistry, oral surgery, and medicine, forty-five journals) and medicine (ISI category--medicine, internal and general, 110 journals), and one basic science category, physiology (ISI category--physiology, seventy-four journals). The use of article scores per discipline category enables a reasonable, relative comparison of the quality of biomedical publications of individuals across disciplines for the purpose of promotion or awarding of research grants.
Bibliometrics↗
[Objective determination of visual acuity. Improvement of an infrared nystagmography method and comparison with pattern visual evoked potentials].
BACKGROUND: The purpose of this study was to optimize a new nystagmographical method of objective assessment of visual acuity and compare it to an electrophysiological method. METHODS: In the nystagmographical method motionless brake marks were superimposed on a moving grating pattern, causing suppression of optokinetic nystagmus (OKN). The smallest brake mark that interrupted the OKN was taken as an objective measure for visual acuity (VA). In the electrophysiological method rapid sequences of high-contrast checkerboard patterns of different spatial frequency were presented in a pattern on-off mode in a foveal field. The VEP response function was extrapolated to 0 microV. The objective values of 94 healthy eyes with artificially reduced vision (VA 0.05-2.0) and 314 eyes with pathological reduction of VA due to different etiologies were compared. RESULTS. The selectivity of the nystagmographical method could be improved. With the exception of strabismic amblyopia, the results were closely correlated with the VA. The least VA could be estimated in steps of 0.06, 0.1, 0.2, 0.5 and 0.8. CONCLUSIONS: The new nystagmographical method yields useful information about the least VA if strabismic amblyopia is excluded.
Adolescent↗
Evaluation of the LIAISON thyroid chemiluminescence immunoassays.
The LIAISON thyroid hormone assays TSH, FT4, FT3, T4 and T3 were evaluated by determining the imprecision, the reference ranges, the functional sensitivity (TSH), the dilution characteristics (accuracy) (FT4, FT3), and the recovery after spiking (TSH, T4, T3). Furthermore, inter-method comparisons were performed with following methods: Elecsys (Roche Diagnostics; TSH), AxSYM (Abbott Diagnostics; TSH, FT4, FT3, T4), ACS:180 (Bayer Diagnostics; all analytes), Amerlex-M (Johnson & Johnson; T4) and LISO-Phase (Techno Genetics; FT4). The fully automated LIAISON random access analyser is based on microparticle immunoassays and chemiluminescence. The coefficients of variation (CV) of intra-assay imprecision were between 0.2-6.0%, except for the control sample with extremely low TSH concentrations and low T3 concentrations. Inter-assay imprecision was performed by measuring controls covering the measuring range over a period of 9 to 20 days, with CVs ranging from 2.3-16.0%. The suitability of the sample material was determined by analysing serum and samples treated with EDTA, citrate or heparin in parallel. The results showed good correlations of the thyroid hormone concentrations between serum and plasma samples except for LIAISON FT3, for which lower results were observed with EDTA-plasma. The regression analysis of correlation studies gave slopes from 0.849 to 0.957 for TSH, from 1.023 to 1.375 for FT4, from 0.670 to 0.911 for FT3, from 0.917 to 1.166 for T4 and 1.00 for T3 depending on the concentration range and the method of comparison. The LIAISON FT4 assay showed a trend towards higher values in the high concentration range when compared with the ACS:180. The ranges of thyroid hormone concentrations determined in serum taken from apparently healthy subjects were found to be in accordance with published data. The clinical sample study confirmed that the LIAISON thyroid hormone assays are sensitive methods for the differentiation of euthyroid subjects and patients with hyper- and hypothyroidism. In conclusion, the automated thyroid hormone immunoassays on the random-access LIAISON immunoassay analyser proved to be very satisfactory, both from the analytical and the clinical point of view.
Humans↗
Switching from HPLC/UV to MEIA for whole blood sirolimus quantitation: comparison of methods.
Sirolimus is a immunosuppressive agent for renal transplant recipients. Monitoring of whole blood sirolimus concentration is necessary in order to improve clinical outcomes. An increasing number of clinical laboratories (4-14% during 2005) are using microparticle enzyme immunoassay (MEIA) for sirolimus quantitation but previous reports indicated a high variability, with a mean difference of 17% for MEIA method vs. high-performance liquid chromatography/ultraviolet (HPLC/UV). This study was aimed at comparing the reliability of MEIA with the HPLC/UV method. Blood samples from transplant patients were processed using both HPLC/UV and MEIA assays. Comparison and Bland-Altman plots, as well as regression analysis and paired t-test were used to compare results of the assays. Concentrations were stratified into three groups and used to investigate whether any observed difference between methods could be influenced by sirolimus concentration. Regression analysis yielded a coefficient of correlation R of 0.9756, the line of best fit being y=0.9832x+0.1976. The statistical analysis showed no difference between the two sets of experimental data. The average percentage difference between the two methods was found to be -0.2+/-19.2%. On the basis of our present results, the tested MEIA assay is able to quantify sirolimus concentration with a clinically acceptable imprecision, similar to that of HPLC/UV method.
Blood Chemical Analysis↗
[Medicine and archaeology: comparison of methods].
Medicine and archaeology are human sciences: their diagnostic claim consists of establishing the link between the singular case and the general model. Comparing and contrasting the two processes is not limited to a game of "similarities-differences". It makes possible a finer analysis of different methods of data collection, either with or without the help of instruments, and a comparison of different ways of handling and classifying symptoms observed and documentary evidence gathered. It shows that archaeology, in contrast to medicine (with physiology and health), has as a discipline, no real precisely defined reference. It is suggested that it is in the interest of medicine and archaeology to compare their own working methods...and their imperfections.
Archaeology↗
[Stapes surgery using Fowler's and Schuknecht's methods. (A comparison of results)].
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Adult↗
Preparation of suspensions of pancreatic islet cells: a comparison of methods.
A comparative study for preparation of cell suspensions from pancreatic islets has been performed using mechanical or enzymatic dissociation with proteolytic enzymes such as trypsin, dispase, and pronase. Treatment of isolated pancreatic islets from neonatal rats with these enzymes proved to be superior to a mechanical dissociation method. The enzymatic dissociation was performed by fractionated treatment of pancreatic islets with low concentration of enzymes in Hanks' solution for 2-3 min at room temperature. With the exception of trypsin the percentage of single cells was consistently higher with dispase and pronase treatment, being 83-92%. Cell viability (dye exclusion) was more than 90%. Mechanical disintegration of pancreatic islets resulted in a low yield of single cells, and cell viability was considerably reduced in comparison with the enzymatic methods. Labeling of islet cells with Na2 51CrO4 and measurement of the basal 51Cr-release demonstrated superior membrane preservation after pronase or dispase treatment. Islet cells isolated either by fractionated dispase or pronase treatment were found to be well preserved and very suitable for the detection of circulating cell surface antibodies and their cytotoxic effects to islet cells.
Animals↗
Permeation of hairless mouse skin I: Experimental methods and comparison with human epidermal permeation by alkanols.
The permeation of intact hairless mouse skin by alkanols was studied. The method is described, and data for the quasi-steady-state and nonstationary-state aspects of mass transfer are given. Partitioning data also are presented. The permeability coefficients increased exponentially up to a carbon chain length of about eight (octanol). There was a marked temperature dependency (Ea congruent to 19 kcal for the series), and the partitioning was biphasic, increasing exponentially for alkanols larger than butanol. These data are compared with literature data on human skin tissues, and great similarity in all facets of behavior is noted.
Alcohols↗
Automated microneutralization: method and comparison with western blot for type-specific detection of herpes simplex antibodies in two pregnant populations.
A novel method for the detection of microneutralization was compared to Western blot for detection of type-specific antibodies to herpes simplex virus in two pregnant patient populations in Vancouver. From an unselected group of women in labor in a tertiary care obstetric hospital (426) and another group of women specially referred for assessment of genital herpes in pregnancy (195) 20 and 88%, respectively, were seropositive for herpes simplex virus type 2 antibodies by Western blot. During the study period, 93 (48%) of the high-risk group were culture positive for HSV-2 and all but one case was verified serologically by Western blot. Therefore, the sensitivity for Western blot in this high seroprevalence group was 99%. The false-negative case had longstanding recurrent infection and on retest was found to be a laboratory error. For microneutralization, type-specificity was especially difficult to distinguish among patients with mixed viral type patterns. Comparing microneutralization to Western blot as the gold standard, sensitivity, specificity, positive and negative predictive values were 84, 78, 97 and 40% respectively, for the referred group and 73, 82, 51 and 92%, respectively, for the unselected group. Poor negative and positive predictive values for the referred group and unselected populations, respectively, demonstrate that microneutralizations are not clinically acceptable for type-specific antibody detection. By contrast, serology by Western blot is very sensitive and apparently highly specific.
Antibodies, Viral↗
Comparison between methods for serotyping of Candida albicans produces discrepancies in results.
Serotyping of 101 clinical isolates of Candida albicans was done with two sets of Hasenclever original anti-Candida typing sera (HSN 1 and 2) and Iatron Candida Check factor 6 typing serum (IF6). The results of these two methods were compared with slide agglutination reactions of yeast with monoclonal antibody H9. Agglutination reactions with this antibody have been previously shown to correlate with serotype. Results indicate the following correlations: between HSN 1 and HSN 2 serotyping, 93% (kappa = 0.85; 95% confidence interval [CI], 0.70 to 0.99); between IF6 and HSN 1, 60% (kappa = 0.39, 95% CI, 0.19 to 0.58); and between IF6 and HSN 2, 74% (kappa = 0.77; 95% CI, 0.64 to 0.90). Results with HSN 1 and 2 antisera correlated with H9 reactivity at 85 and 89% (kappa = 0.88; 95% CI, 0.75 to 1.00; and kappa = 0.85; CI, 0.70 to 0.99, respectively), while agreement between IF6 and H9 reactivities was less than or equal to 64% (kappa less than or equal to 0.43; 95% CI, 0.14 to 0.60). Autoagglutination of yeast during IF6 serotyping occurred with 21 of the 101 (20.8%) yeast strains. In every case, these yeast strains were serotyped by the HSN methods without autoagglutination and were uniformly type B. This study implies that it may not be possible to make valid comparisons between studies which compare serotype prevalence unless the same methods are used to serotype the yeast. The practicality and utility of serotyping in epidemiological studies are discussed, as are some of the problems associated with the available methods.
Agglutination Tests↗
Comparison of methods for calculation and depiction of incidence infection rates in long-term care facilities.
Assessment of changes in endemic infections in health care facilities are often based on comparison of infection rates over time. This study compared two methods for calculating and depicting infection data at a hospital-based nursing home care unit. Prospective incidence surveillance of nursing home acquired infections was conducted over a 12-month period, during which time denominator information on census and patient care days was also collected. Monthly infection rates were calculated based on (a) census (number infections per month/average monthly census), and (b) care duration (number infections per month/average monthly resident stay days). Results showed average monthly infection incidence of 27.4 episodes, (range 19-37), with average monthly census of 166.2 (range 160.0-180.0) and average monthly patient days of 5056 (range 4631-5583). The average census based monthly infection rate was 16.5 (range 11.9-22.4); average care duration based monthly infection rate was 5.4 (range 3.8-7.2) episodes per 1000 patient care days. Results indicate care duration based rates demonstrate less marked rate fluctuation than census based findings, and that duration based rates are more similar to values observed in acute care hospital nosocomial infection rates, thus are less likely to be misunderstood or misinterpreted by staff. Institutions should consider analyzing their methods for depicting infection data to provide consistency and clarity in data reporting.
Cross Infection↗
Comparison of methods for identifying early methotrexate-induced hepatotoxicity in patients with rheumatoid arthritis.
Hepatotoxicity may complicate therapy with methotrexate in patients with rheumatoid arthritis. Prevention of cirrhosis may depend upon early identification of liver damage, usually accomplished by serial biopsy. To determine the adequacy of noninvasive methods for identifying hepatotoxicity, 22 sets of data were obtained in patients undergoing therapy with methotrexate for rheumatoid arthritis. Comparisons were made between liver biopsy, hepatocellular enzymes and two noninvasive radioisotopic methods that have been shown to be abnormal in hepatocellular disease: the rate constant of excretion of the 14C-aminopyrine and the time from injection to peak hepatic activity of 99mTc-diisopropylimidodiacetic acid. The hepatocellular enzymes and the time-to-peak-activity of diisopropylimidodiacetic acid were not useful predictors of methotrexate-induced hepatotoxicity. The aminopyrine breath test was abnormal in approximately half the patients with hepatotoxicity but showed poor specificity. Noninvasive methods remain inferior to biopsy for the detection of mild to moderate methotrexate-induced hepatotoxicity in patients with rheumatoid arthritis.
Adult↗
Comparison of methods to estimate body fat in growth hormone deficient adults.
OBJECTIVE: All of the presently used methods for in-vivo determination of body composition have inherent methodological errors and depend on various assumptions. We have therefore compared several different methods used to measure body fat in adult GH deficiency during GH treatment. DESIGN: Comparison of body composition data from a two-phase trial with an initial placebo-controlled, double-blind 6-month period, followed by open treatment with GH until all patients had received GH for 12 months. PATIENTS: Twenty-five patients with known GH deficiency entered the study. Baseline examinations were complete in 23 patients, and 22 patients (16 males, 6 females) completed all examinations after treatment. MEASUREMENTS: Body fat calculated from total body potassium (TBK) by whole-body 40K counting, total body water (TBW) by tritium dilution, total body nitrogen (TBN) by neutron activation, and bioelectric impedance (BIA) measurements were compared to body fat determinations by dual-energy X-ray absorptiometry (DEXA) in two-compartment and multicompartment body composition models. RESULTS: At baseline, DEXA fat mass agreed well at group level with measurements based on TBW or TBK alone, in a four-compartment model based on TBK and TBW, and a multicompartment model based on bone mineral (by DEXA), TBN and TBW. Body fat by BIA agreed less well. After 12 months of GH treatment, body fat decreased by all methods used. This decrease was smaller by DEXA than by the other methods. The four-compartment model based on TBK and TBW, and TBW alone, showed the best agreement with changes in DEXA fat. CONCLUSION: All methods showed a decrease of body fat with GH treatment, but variation between methods was considerable.
Absorptiometry, Photon↗
Comparison of methods for the determination of antimicrobial resistance in Staphylococcus aureus from bovine mastitis.
The results of three standard methods (broth dilution, agar dilution, disk diffusion) and an experimental modification of the microdilution method for determination of resistance to ampicillin, cephalotin, cloxacillin, neomycin, novobiocin, penicillin and streptomycin were compared using 151 Staphylococcus aureus isolates obtained from cases of mastitis. The accuracy of the dilution methods was compared by determination of minimum inhibition concentrations (MIC, MIC50, MIC90 and modal MIC) and by assessment of the agreement within the tolerance of +/-1 dilution step in 2-fold dilution series. The results of the dilution methods were further compared with those of the reference disk diffusion method and the strains were classified as sensitive or resistant using the interpretation criteria for human strains. The comparisons indicated that MIC characteristics and the final classification as sensitive or resistant were method-dependent. Resistance to aminoglycoside antibiotics was observed more often when using broth dilution methods, especially when the broth was supplemented with lactose.
Ampicillin↗
Studies on a radioassay for intrinsic factor antibody: comparison of methods and false positive results due to elevated serum B12 levels.
Availability of a kit method (Corning Immo Phase IFAB) for intrinsic factor antibody (IFAB) has made it possible for a routine radioimmunoassay (RIA) laboratory to test for the antibody, thereby providing another aid in diagnosing pernicious anemia. Comparison of data from a charcoal method with the kit method was favorable, each method detecting 35 (74%) positives and 12 (26%) negatives of 47 pernicious anemia patients. Compared with a charcoal method study the kit method had fewer false positives due to elevated serum B12. False positive results occurred for only 24 hours after a 1-mg injection of B12, and results remained negative the following seven days. The authors' studies supported the manufacturer's statement that results are unreliable when the serum B12 level exceeds 3,500 pg/ml. Clinical experience with the Corning Immo Phase IFAB test and false positive results is summarized.
Anemia, Pernicious↗
Comparison of methods for measuring surface roughness of ceramic.
The aim of this investigation was to compare two methods of assessing the surface texture of finished dental ceramic; a laser reflectivity method (LSR) and a contact stylus tracing method. Identical ceramic blocks (Dicor MGC) were finished using a variety of techniques and devices, and the surface texture characterized by LSR and contact stylus tracing to enable comparisons to be made between the two methods. The results indicate that there is little correlation between the two measuring methods. Therefore, laser reflectivity should not be exclusively used to measure the surface texture of contoured and finished ceramic materials. The development of sophisticated surface characterization parameters suggest that the surface characteristics of dental restorations and other related surfaces should be described using more than one surface measurement parameter. Surface parameters should be chosen which can both quantify surface roughness and provide information on the shape of the surface under investigation.
Dental Polishing↗
High concordance of results of testing for human papillomavirus in cervicovaginal samples collected by two methods, with comparison of a novel self-sampling device to a conventional endocervical brush.
A user-friendly self-sampling method for collecting representative cervical cell material would lower the threshold for women to respond to the invitation for cervical screening. In the present article, we introduce such a device; we have evaluated its sensitivity and specificity to detect high-grade cervical intraepithelial neoplasia (CIN), via high-risk human papillomavirus (hrHPV) detection and liquid-based cytology (LBC), compared to endocervical brush samples obtained by gynecologists. Women who had a cervical smear reading of moderate dyskaryosis or worse or a repeat equivocal Pap smear result in the cervical screening program (n=64) and healthy volunteers (n=32) took a self-obtained sample at home prior to their visit to the gynecological outpatient department. At the outpatient department, an endocervical brush smear was taken, followed by colposcopy and biopsy whenever applicable. Both self-obtained samples and endocervical brush samples were immediately collected in Surepath preservation solution and used for LBC and hrHPV testing (by general primer-mediated GP5+/6+PCR). hrHPV test results showed a good concordance between the two sample types (87%; kappa=0.71), with sensitivities for prevalent high-grade CIN that did not differ significantly (92% and 95%; P=1.0). The hrHPV test on self-obtained samples proved to be at least as sensitive for high-grade CIN as cytology on endocervical brush samples (34/37 versus 31/37; P=0.5). LBC showed a poor concordance between self-obtained and endocervical brush samples (60%; kappa=0.27). In conclusion, self-obtained samples taken by this novel device are highly representative of the hrHPV status of the cervix. In combination with hrHPV testing, the use of this device may have implications for increasing the attendance rate for cervical screening programs.
Adolescent↗