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PubMed1988

Measurement of choroidal melanomas: a comparison of methods.

The prognosis for death from metastatic choroidal melanoma following enucleation has been shown to be strongly correlated with a number of risk factors of which the most important are age of onset, aggressive cell types and tumour volume. The advantages of enucleation for the treatment of choroidal melanomas are put into question by the singular lack of a parallel increase in life expectancy following this treatment, and evidence that it may promote the development of metastatic disease. Alternative forms of treatment have been introduced including observation of small and asymptomatic tumours. We are using a computer-aided system for serial measurement and statistical analysis of area and volume of choroidal melanomas. A comparison of results using our method and the conventional method of estimating volume by the product of basal area and height for 51 measurements on 15 eyes over a 6-month period showed an overestimation of volume by conventional methods which could be corrected by applying a "shape constant" determined by linear regression. Calculation of tumour growth rates is also shape-dependent, and a slowing in growth rate or even a reduction in melanoma size is possible.

Choroid Neoplasms↗
PubMed2001

Comparison of self-report, video observation and direct measurement methods for upper extremity musculoskeletal disorder physical risk factors.

The prevention of work-related musculoskeletal disorders has become a national priority in many countries. Increasingly, attempts are made to quantify those exposures that increase risk in order to set exposure limit values. This study used commonly employed field measurement methods and tools in order to perform an inter-method comparison between three primary methods of risk factor exposure assessment: self-report questionnaires, observational video analysis and direct measurement. Extreme posture duration, repetition, hand force (estimated from electromyography) and movement velocity were assessed for 18 subjects while performing each of three jobs processing tree seedlings. Results indicated that self-reports were the least precise assessment method, which consistently overestimated exposures for each of the measured risk factors. However, adjustment of the reports as psychophysical scales may increase agreement on a group level. Wrist flexion/extension duration and repetition were best measured by electrogoniometer. Electrogoniometric measures of wrist deviation duration and frequency were less precise than video analysis. Forearm rotation duration and repetition, grip force and velocity appeared to be best quantified by direct measurement as measured by electrogoniometer and electromyography (EMG) (as root-mean-square amplitude). The results highlight the fact that it is as important to consider and report estimated measurement error in order to reduce potential exposure misclassification in epidemiologic studies.

Arm↗
PubMed1998

Nitrate and nitrite content in daily hospital diets during the winter season--comparison of analytical and calculation methods.

A comparison of two methods: analytical and calculation on an estimation of dietary intakes of nitrate and nitrite from six different types of general hospital diets was studied. Studies were performed in the winter season of 1996-1997. It was found that the mean daily intake of nitrates was 85 mg per person in the analytical method, and 65 mg per person in the calculated method. The estimation of average dietary intakes of nitrite was adequate: 1.67 mg per person (the analytical method) and 1.18 mg per person (the calculated method). The main source of nitrates were vegetables, whereas the main source of nitrites was meat and meat-containing products. We suggest that the different methodologies, analytical and calculation methods, for measuring dietary intakes of nitrate and nitrite from diets make it possible to make direct comparisons of intakes.

Animals↗
PubMed1997

[Value of impedance rheography as a screening method in comparison with Doppler index in peripheral arterial occlusive disease].

BACKGROUND: Determination of the ankle-arm-index (AAI) by Doppler ultrasound is the method of choice as a screening test for peripheral arterial occlusive disease (PAOD). The easily performed Impedance Rheography (IR) may serve as an alternative screening method. This study investigates the correlations between parameters obtained by IR curve to the AAI. METHODS: 56 patients (62.8 +/- 13 years, m = 37, f = 19) were included in the study. IR was performed on both shanks using ring electrodes below the knee and above the ankle (bipolar leads, frequency 90 kHz, test voltage 2.5 Vpp). The AAI was obtained by a 8 Mz ultrasound probe. RESULTS: AAI < or = 0.85 showed significant correlations (p < 0.0001) to parameters of the IR curve: Crest Time (GZ, r = 0.67), Rise of the Pulse Wave (PA, r = 0.82), Relative Pulse Volume (RP, r = 0.82) and the Rheographic Quotient (RQ, r = 0.86). AAI > 0.85 showed no or only weak correlations to RI parameters. Underlying the following limits for rheographic parameters (GZ = 159 ms, PA = 3.3, RP = 0.43 vp/s and RQ = 0.4 vp), sensitivity and specify was determined: GZ: 68% and 100%, PA: 84% and 88%, RP: 68% and 92%, RQ: 77% and 88%. CONCLUSIONS: Impedance rheography correlates significantly with the AAI. Therefore this method seems to be well suited as a screening test for PAOD.

Adult↗
PubMed1989

A method for comparison of animal and human alveolar dose and toxic effect of inhaled ozone.

Present models for predicting the pulmonary toxicity of O3 in humans from the toxic effects observed in animals rely on dosimetric measurements of O3 mass balance and species comparisons of mechanisms that protect tissue against O3. The goal of the study described was to identify a method to directly compare O3 dose and effect in animals and humans using bronchoalveolar lavage fluid markers. The feasibility of estimating O3 dose to alveoli of animals and humans was demonstrated through assay of reaction products of 18O-labeled O3 in lung surfactant and macrophage pellets of rabbits. The feasibility of using lung lavage fluid protein measurements to quantify the O3 toxic response in humans was demonstrated by the finding of significantly increased lung lavage protein in 10 subjects exposed to 0.4 ppm O3 for 2 h with intermittent periods of heavy exercise. The validity of using the lavage protein marker to quantify the response in animals has already been established. The positive results obtained in both the 18O3 and the lavage protein studies reported here suggest that it should be possible to obtain a direct comparison of both alveolar dose and toxic effect of O3 to alveoli of animals or humans.

Administration, Inhalation↗
PubMed1977

Recording urethral pressure profile: comparison of methods and clinical implications.

Urodynamic evaluation of urethral sphincter efficiency can be carried out by constant carbon dioxide perfusion, constant water perfusion, or the use of membrane catheters. A comparison of these three techniques was made in in vitro and in vivo experiments. Results, and advantages and disadvantages of each method are discussed. From all factors considered in this study--responsiveness to pressure changes sensitivity to pressures at various levels along the urethra, and reproducibility and accuracy of the profile--the membrane catheter system was by far superior to either of the flow systems.

Animals↗
PubMed2003

Reaction monitoring of enzyme-catalyzed ester cleavage by time-resolved fluorescence and electrospray mass spectrometry: method development and comparison.

Two complementary methods for reaction monitoring of the esterase-catalyzed cleavage of bis(2-pyridylmethyl)(2-acetoxyphenyl)amine are developed and compared. While enzyme-amplified lanthanide luminescence (EALL) allows for the time-resolved fluorescence determination of the intrinsically non-fluorescent product, both substrate and product of the enzymatic reaction may be determined simultaneously by electrospray mass spectrometry (ESI-MS). Excitation wavelength for the Tb(III) complex of the reaction product is 297 nm and emission was detected at 545 nm, which is the characteristic emission wavelength of the terbium(III) ion. In contrast to other EALL techniques, the presented method allows for the direct monitoring of an enzymatic conversion without any further sample preparation (e.g., rebuffering). For the mass spectrometric measurements the mass traces were set to m/z=306, 328, 348, and 370 for the protonated ester, the resulting phenol and their sodium adducts, respectively.

Catalysis↗
PubMed2002

Acute toxicity of chlorophenols to earthworms using a simple paper contact method and comparison with toxicities to fresh water organisms.

An acute toxicity test of chlorophenols on earthworms (Eisenia fetida) was performed using a simple paper contact method proposed by OECD testing guideline no. 207, that were applied as an earthworm toxicity test. The median lethal concentration, EC50, had significant correlation with logP(ow) (1-octanol/water partition coefficient) of the chemicals. The toxicity of chlorophenols on E. fetida was compared with toxicities for other species: an algae (Selenostrum capricornutum), a crustacean (Daphnia magna), and a fish (Oryzias latipes). It was found that the toxicity of chlorophenols was almost same for E. fetida and for fresh water organisms. These results suggest the possibility of drawing correlations between the effects of pollutants on living things in different environments, fresh water and soil.

Animals↗
PubMed2000

Comparison of methods for teaching clinical skills in assessing and managing drug-seeking patients.

AIMS: New medical graduates lack clinical skills in assessing and managing patients seeking drugs of dependence. This study compares the effectiveness of three different clinical skills training methods, with similar content, which were developed to teach these skills to senior medical students. METHODS: A preliminary survey indicated that common problems seen by primary care practitioners included both new and previously known patients seeking either benzodiazepines or opiates. The common content of the teaching was determined from this survey. A didactic small group tutorial (DT), a video-based tutorial (VBT) using professional actors, and a computer-aided instruction package using digitized video (CAI) were developed with this common content, and trialled with undergraduate medical students over 2 years in a parallel-group design. Outcome was assessed by student feedback, performance on a case-based written examination and by a structured evaluation of interviews with simulated patients requesting drugs. Comparison was also made between methods on the basis of knowledge tests. RESULTS: No difference was seen in written examination and simulated patient outcomes between the three groups. However, the VBT was thought by the students to be preferable to other methods. The estimated development costs of CAI were higher, but total costs over a 6-year period were lower than for the DT and VBT. The results suggest that clinical skills can be taught equally effectively through several different methods. Collaboration between institutions in the development of widely applicable CAI tools should be an efficient and economical mode of teaching with a wide range of applications.

Clinical Competence↗
PubMedDate not supplied

Comparison of methods to assess coronary heart disease prevalence in South Asians.

BACKGROUND: Migrants from the Indian subcontinent (South Asian migrants) in the United Kingdom have high mortality from coronary heart disease (CHD) in comparison to the indigenous population. Few studies have assessed the prevalence of CHD in South Asians, and the applicability of conventional survey methods in this population is not known. In this pilot random population survey of South Asian men and women living in West London, the prevalence of CHD as judged by the Rose questionnaire, past cardiac history, cardiologist and resting electrocardiogram were compared. METHODS: Subjects aged 30-64 years from randomly selected households were invited for a cardiological assessment. A lay person administered the Rose questionnaire and recorded the past cardiac history. A cardiologist also made an independent assessment and a 12-lead electrocardiogram was recorded and analysed according to the Minnesota code. RESULTS: Three hundred and seventy-six individuals (192 men and 184 women) were assessed. The prevalence of angina in men and women, respectively, was 3.1% and 4.9% by the Rose questionnaire; 2.6% and 2.2% by past cardiac history; and 4.2% and 0.5% according to the cardiologist. The prevalence of myocardial infarction in men and women, respectively, was 5.2% and 2.2% by the Rose questionnaire, 3.6% and zero by past cardiac history and 3.6% and 0.5% by the cardiologist. Q/QS codes were present in 1.6% men and 0.5% women and ischaemic codes in 13% men and 14% women. Ischaemic changes were not associated with any cardiac history in 72% of men and 92% of women. For a diagnosis of CHD in men, there was poor agreement between the Rose questionnaire and either the past cardiac history or the cardiologist's assessment, but moderate agreement between the past cardiac history and the cardiologist. Agreement was poor between all three methods for a positive diagnosis of CHD in women. CONCLUSION: Current accepted epidemiological methods for assessing CHD prevalence may be inaccurate in South Asians, especially women. Electrocardiogram abnormalities suggestive of ischaemia are common in South Asians and are usually not associated with evidence of CHD. Thus, their value as indicators of CHD is questionable.

Adult↗
PubMed1992

Estimating total analytical error and its sources. Techniques to improve method evaluation.

The process of method evaluation starts with identifying goals either to demonstrate the clinical validity of an assay or to identify assay error sources that require improvement. Taguchi's idea of continual quality improvement vs the notion of meeting or failing specification has been applied to clinical chemistry. In this article, I propose a model of assay performance that includes the terms random interferences and protocol-specific biases (a series of systematic errors). I explain these terms, as well as the consequences of failing to consider them. To validate an assay clinically, I recommend direct estimation of total analytical error from a method comparison. To identify assay error sources that require improvement, I recommend a multifactor protocol (in addition to a method comparison). Individual error sources are related to total analytical error with the use of an error propagation technique. Much of the proposed data analysis techniques are straightforward but not routinely practiced. I demonstrate principles with the use of a cholesterol assay.

Chemistry, Clinical↗
PubMed1994

A comparison of methods for calibrating parallel-plate chambers/.

All dosimetry protocols for calibrating the output of electron beams recommend the use of parallel-plate ionization chambers, but the method of determining their value of Ngas is a matter of concern. The AAPM Protocol (TG 21) recommends a direct comparison with a calibrated cylindrical chamber in phantom at dmax with the highest available electron energy beam. This must be done by the user. Since all calibration laboratories traditionally use 60Co for megavoltage chamber calibrations, two alternate procedures based on exposures in-air, or in-phantom, have been proposed. All methods use correction factors in the data reduction. To verify the consistency of the three methods, we have measured Ngas using each of these techniques for six of the most commonly used and commercially-available parallel-plate ionization chambers. The paired cylindrical and parallel-plate ionization chambers, and phantom materials/buildup caps were matched to the wall composition of the plane chambers, as recommended in TG 39. A 22 MeV electron beam was used for the electron irradiations. The ionization chambers were then taken to an Accredited Dosimetry Calibration Laboratory (ADCL), where 60Co calibrations were performed. The results demonstrate that, by using the appropriate correction factors for the chambers described in this work, all three methods yield values for Ngas that are within 1% of each other.

Biophysical Phenomena↗
PubMed2003

A systematic comparison of methods to measure HIV-1 specific CD8 T cells.

Several methods are now available to evaluate the frequencies of virus-specific CD8 T cells but require a systematic comparison to help at choosing the best strategy for evaluation. First, we compared the ELISpot-IFNgamma assay, intracellular IFNgamma staining and HLA class I tetramer-binding assay to quantify the HIV-specific CD8 T cells. Second, we determined the frequency of recognition of HIV antigens and evaluated whether the mode of antigen presentation might influence the results: We compared HIV antigen presentation in the same ELISpot-IFNgamma assays by using recombinant vaccinia viruses (rVVs) encoding for HIV-LAI Gag, Pol, Env, Nef, Tat and Vif proteins, or a panel of 49 synthetic 8-11 amino acid length peptides tested either individually or pooled. Third, we compared the antigens recognized by memory CTL analysis using chromium release assay (CRA) on CTL lines and by effector CD8 cell analysis using ELISpot assay. Our results show that: (1) Flow cytometry and ELISpot assay measuring IFNgamma production give the same frequency of HIV-specific CD8 T cells; (2) tetramer-binding assay detects more HIV-specific CD8 T cells than other methods; (3) pools of optimal peptides and sum frequencies of individual optimal peptides give similar results in ELISpot assay; (4) ELISpot assays using peptides are more sensitive than those using rVV; and (5) CRA and ELISpot assay when using rVV provide a comparable profile of HIV antigen recognition by memory CTLs (CRA) and effector CTLs (ELISpot) in two thirds cases. These results have important implications for the choice of immunological methods to evaluate CD8 T cells responses to vaccines.

AIDS Vaccines↗
PubMed2003

[Significance of the visual evaluation method using the two-visit method (two-sample preference test suggested by Ferris)].

To increase the accuracy of the visual evaluation method, we studied the significance of the two-sample preference test using the two-visit method, as proposed by Ferris. Advantages of this method include not only its ability to estimate whether the image quality of the sample is statistically the same but also its ability to distinguish the difference between samples more clearly than when using the conventional two-sample preference test or paired-comparison method. However, a disadvantage is that this method involves two observations of the same sample. When using chest images, even if a difference between the samples is not recognizable by the conventional method, a significant difference can be elicited with this method. The data obtained by this method can be evaluated with the paired-comparison method, so some samples may be ranked as well. Therefore, we verified that the two-sample preference test, which Ferris formulated, is useful in visual evaluations.

Humans↗
PubMed2004

Detection of nonesterified (free) fatty acids in bovine serum: comparative evaluation of two methods.

A method comparison study for the determination and quantitation of nonesterified fatty acids (NEFAs) in serum, using the commercial "NEFA C" enzymatic test kit, was performed using the spectrophotometric method recommended by the manufacturer and a modified procedure optimized for the use of a microplate reader, a 96-well microtiter plate, and small sample volumes (10 microl). Linearity, sensitivity, and precision using the test kit were determined for each method of detection. The assay was linear from 0 to 1.97 mEq/liter for both procedures, and the limits of detection were determined to be 0.22 (+/- 0.074) and 0.05 (+/- 0.002) mEq/liter for the spectrophotometer and microplate reader, respectively. Pairs of measurements for bovine serum samples were compared and evaluated by a mean difference plot method and not regression analysis, a method that has been shown to be inappropriate for method comparison studies. The difference plot was used to evaluate the systematic bias between the 2 methods. Random error is reported on the basis of SD differences, and "limits of agreement" are used to describe the maximum differences likely to occur between the 2 methods. Results suggest that the microplate reader method can be used reliably in place of the recommended spectrophotometric method. The microplate reader method is preferred because of its high throughput capabilities, simultaneous analysis of all the standards and samples, use of small sample and reagent volumes, and reduction in labor requirements and costs.

Animals↗
PubMed2001

Comparison of methods of bag and mask ventilation for neonatal resuscitation.

BACKGROUND: There are a variety of manual bagging devices used for neonatal resuscitation. To our knowledge, there has been no comparison of the ability of different operators to utilize such devices for the delivery of predetermined inspiratory and end-expiratory pressures. In addition, the use of prolonged inflation may be of benefit for infants who require bag and mask ventilation, and there has been no evaluation of the ability of a variety of operators to reliably deliver such breaths using currently available equipment. METHODS: We utilized a neonatal manikin (Laerdal Armonk, NY) with a functional larynx and lungs, and a clear cushioned mask (Owens-BriGam, Morganton, NC). We studied a latex-free disposable anesthesia type bag (Model 5126 Vital Signs, Totawa, NJ), a Jackson-Rees (JR) type anesthesia bag (Model E191 Anesthesia Associates, San Marcos, CA) fitted with a Norman elbow and a flow-control tail-piece (Dupaco, Oceanside, CA), and the Neopuff (Fisher and Paykel, Auckland, New Zealand), an FDA approved mechanical device that is flow-controlled and pressure-limited, specifically designed to facilitate neonatal resuscitation. The ventilating pressures were continuously recorded throughout the process. We evaluated neonatal nurses, neonatal nurse practitioners, neonatal staff and fellows, pediatric residents and neonatal respiratory therapists. RESULTS: The peak inspiratory pressure (PIP) was significantly different between operators using either anesthesia bag, P<0.001. Similar results were found for positive end-expiratory pressure (PEEP) with a significant difference among the operator groups, P<0.001. All the differences in post hoc analysis were between the therapists and the other groups, P<0.05. Therapists produced significantly higher pressures than the other groups for both PIP and PEEP (P<0.001). The PIP was similar for all groups using the Neopuff device. The PIP and PEEP delivered by the Neopuff differed from the other two devices independent of the operators (P<0.05). On post hoc analysis, there was a significant difference between the disposable anesthesia bag and Neopuff for both PIP and PEEP for the therapists, whereas among the non-therapists, there was a difference in PIP with the JR device producing a greater PIP (26.6+/-3.8 cmH(2)O) compared with the Neopuff and disposable anesthesia bag (24.8+/-1.1 cmH(2)O, 24.8+/-4.3 cmH(2)O). The level of PEEP was significantly different among all three devices for the non-therapists (1.3+/-1.6 cmH(2)O, Disposable; 2.9+/-1.2 cmH(2)O, JR; 4.7+/-0.5 cmH(2)O, Neopuff; P<0.05). Only the therapists were able to consistently deliver PEEP with the anesthesia bags, whereas all operators could generate the target PEEP with the Neopuff (P<0.05). We compared the pressure delivered during the first second to the pressure delivered during the fifth second during prolonged 5-s inflations. The absolute differences between the first and fifth second for the Neopuff versus the anesthesia bags were significantly different with a median of 7.1 cmH(2)O for the anesthesia bags compared with 0.2 cmH(2)O for the Neopuff, P<0.001, reflecting the difficulty in obtaining and maintaining the target inflation pressures. CONCLUSIONS: Our experience suggests that the Neopuff, a purpose-built neonatal resuscitator ventilator, facilitates the delivery of the desired airway pressures while maximizing the operators ability to obtain and maintain a patent airway, and facilitates the delivery of prolonged inflations. Further research is required to determine the clinical benefit of end-expiratory pressure and prolonged inflations in neonatal resuscitation.

Analysis of Variance↗
PubMed1993

Comparison of methods of evaluating hearing benefit of middle ear surgery.

The objective of this paper is to compare two methods of predicting the level of subjective patient benefit following reconstructive middle ear surgery. This should have always been an important consideration in advising patients regarding surgery, but assumes even more relevance in these days of clinical audit and cost benefit analysis. The two methods studied were the '15/30 dB rule of thumb' (Smyth and Patterson, 1985) and the 'Glasgow plot' (Browning et al., 1991). The predictions of benefit for each of the two methods were compared to the assessment of actual benefits by the patient post-operatively. The results of this comparison in 153 patients were analysed, the rule of thumb was found to be somewhat more sensitive in predicting patient benefit.

Audiometry↗